Table of Contents
Introduction .................................. ................................................... .................................. .......................... ......... 2 Sensors ensors .................................... ....................................................... ..................................... ............................ .......... 4 Limit Sw itches .................................... ...................................................... .................................... .................... 8 International International Limit Sw Sw itches ............................... ................................................ ................... .. 18 North American Limit Sw Sw itches ............................... ............................................. .............. 22 BER BERO Sensors................. ensors .................................. ................................... .................................... .................... 27 Inductive Proximity Proximity Sensors Sensors Theory Theory of Opera Operation .................. .................. 28 Inductive Proxi Proximit mit y Sensor Sensor Fa Family ................................. ......................................... ........ 40 Capa pacitive citive Proxi Proximit mit y Sensors Sensors Theory Theory of Operation Operation ................ 54 Capa pacitive citive Proximit roximit y Sensor Fa Family .................................. ....................................... ..... 57 Ultrasonic Ultrasonic Proximity Proximity Sensors ensors Theory Theory of Operation ................. ................. 59 Ultrasonic Ultrasonic Proximity Proximity Sensor Sensor Fa Family .............................. ....................................... ......... 68 Photoelectric Sensors Theory of Operation Operation ............................ ............................ 80 Photoelectric Fa Family of Sensors Sensors ................................... ............................................ ......... 93 Sensor Applications Applications .................................. .................................................... ............................. ........... 99 Review eview Answers Answ ers .................................... ...................................................... .............................. ............ 107 Final inal Exam xam ........................................ ............................................................ ................................... ............... 108
1
Introduction
Welcome to another course in the STEP 2000 series, Siemens Technical Education Program, designed to prepare our distributors t o sell Siemens Siemens Energy Energy & Autom ation products more effectively effect ively.. This course covers Sensors and related products. Upon completion of Sensors you should be able to: •
•
•
•
•
•
•
•
•
•
2
Describe advantages, disadvantages, and applications of limit switches, sw itches, photoelectric sensors, sensors, inductive sensors, sensors, capacit capacitive ive sensors, and ultrasonic sensors Describe design and operating principles of mechanical limit switche sw itches s Identify components of International International and and North America Am erican n mechanica mechanicall limit switches sw itches Describe design and operating principles of inductive, capacit capacitive, ive, ultrasonic, and photoelect ric sensors and describe differences and similarities Apply correction correction fa f actors w here appropria appropriate te t o proximit proximit y sensors Identify the various various scan scan tech t echniques niques of photoelectric phot oelectric sensors Identify ten categories of inductive sensors sensors and sensors sensors in each category Describe the effects of dielectric constant on capacitive capacitive proximit proximity y sensors Identify environmental environmental influences inf luences on ultra ult rasonic sonic sensors Identify types of ultrasonic ultrasonic sensors sensors tha t hatt require manua manual adjustment, can be used with SONPROG, and require the use of a signal eva evaluator luator
•
•
•
Describe the difference betw een light operate and dark dark operate operate modes of a photoelectric sensor Describe the use of fiber optics and laser technology used in Siemens photoelectric sensors sensors Select the t he type of sensor best best suited for a part particula icularr applicat applicat ion based on material, m aterial, sensing distance, dist ance, and and sensor load requirements
This knowledge w ill help you better underst understa and customer custom er applications. In addition, you will be better able to describe products to custom ers and and determine determ ine importa import ant differences betw een products. You should complete complet e Basics Basics of Electr Electr icit y and Basics Basics of Cont Cont rol Com ponent s before attempting Sensors. Sensors. An understanding of many of the concepts covered in Basics Basics of Electr Electr icit y and Basics Basics of Cont Cont rol Compo nent s is required for Sensors. Sensors. If you are an employee of a Siemens Energy & Automation authorized distributor, fill out the final exam tear-out card and mail in the card. We w ill ma m ail you a certifica certif icate te of completion complet ion if you score a passing grade. Good luck with your efforts. BERO, BERO, SIMAT SIM ATIC, IC, SONPROG, SONPROG, and SIGUARD SIGUARD are regis re gistt ered ere d trademarks of Siemens Energy & Automation, Inc. National Elect Electrical rical Code® Code® and NEC® NEC® are registered trademarks tradem arks of tthe he Na Nati tional onal Fire Protect Protect ion Association, Association, Quincy, Quincy, M A 02269. Portions of the National Electrical Code are reprinted with permission perm ission f rom NFPA NFPA 70-1999, Nat Nat ional Elect Electrical rical Code Code Copyright Cop yright,, 1998, National Fire Protect Protect ion Association, Quincy, Quincy, M A 02269. This reprinted m aterial is not the complete and official position of the National Fire Protection Association on the referenced subject subject w hich is represented represented by the t he standard standard in its entirety ent irety.. Underwriters Laboratories, Inc. is a registered trademark of Underw riters rit ers Laboratories, Laboratories, Inc., Northbrook, Nort hbrook, IL 60062. The abbrevia bbreviation “ UL” is understood to t o mea m ean n Underwriters Underw riters Laboratories, La boratories, Inc. National Elect Electrical rical Manufa M anufacturers cturers Association is located at 21 210 01 L. S Stt reet, reet , N.W., Washingt on, D.C. D.C. 20037 2003 7. The abbrevi abbreviation ation “ NE NEM M A” is understood understood t o mea m ean n National National Electrical Electrical Manufacturers Association. Other trademarks trademarks are are the property propert y of their respective owners. ow ners. 3
Sensors
One type t ype of feedback feedback frequently needed by industria indust riall-control control systems is the position of one or more components of the operation being controlled. Sensors are devices used to provide information on the presence or absence of an object.
Siemens Sensors
4
Siemens sensors include include limit switches, sw itches, photoelectric , inductive, induct ive, capacit capacitive, ive, and ultrasonic sensors. These product s are packaged in various configurations to meet virtually any requirement found in commercial and industrial applications. Each Each type of sensor w ill be discussed in detail. At At the end of the course an application guide is provided to help determine the right sensor for a given application.
Technologies
Limit switches use a mechanical actuator input, requiring the sensor to change change its output w hen an object object is physically physically touching the switch. sw itch. Sensors, Sensors, such such as photoelectric, inductive, induct ive, capacitive, and ultrasonic, change their output when an object is present, present, but not t ouching ouching the sensor. sensor. In addition t o the t he advantages advantages and and disadvant disadvantages ages of each of these sensor types, t ypes, different sensor technologies technologies are better suited for certa cert ain applications. applications. The following follow ing t able lists list s the t he sensor technologies technologies tha t hatt w ill be discussed in this course. S e ns o r
A d v a nt a g e s
Limit Sw Sw itch • High Current Current Capability • Low Cost Cost • Fami Fami liar "Low Tech" Sensi Sensing ng
D isad v a n t ag e s
A p p l ica t i ons
• Requires Physical Physical •Interlocking Contact with • Basic End-ofEnd-ofTarget Travel Travel Sensin g • Very Slow Slow Response • Contact Contact Bounce
Photoelectric • Senses all Kinds Kinds of • Lens Subject Subject to •Packaging Materials Contamination •Material • Long Life Life • Sensing Range Handling • Longest Sensing Sensing Affecte d by Color Color •Parts Detection Range and Reflect Reflect ivity • Very Fast Fast of Target Response Tim Tim e Induct Induct ive
• Resistant Resistant to Harsh Harsh • Distance Distance Environments Limitations • Very Predictable • Long Life Life • Easy Easy to Install
• Industrial and and Machines • Machine Tool Tool •Senses MetalOnly Targets
Capacitiv e
• Detects Through Through Some Containers Containers • Can Can Detect Non-Metallic Targets
• Very Sensitive Sensitive to Extreme Environmental Changes
• Level Sensing Sensing
Ultrasonic
• Senses all Materials
• Resolution • Repeatability Repeatability • Sensitive to Temperature Changes
•Anti-Collision •Doors • Web Brake Brake • Level Control Control
5
Cont act Arrangement
Contacts are available in several configurations. They may be normally norm ally open (NO), (NO), normally norm ally closed (NC), (NC), or a combination of normally open and normally closed contacts. Circuit symbols are used to indicate an open or closed path of current flow. Contacts are shown as normally open (NO) or normally norm ally closed (NC). (NC). The standa st andard rd met m ethod hod of showing show ing a contact contact is by indicating indicating the t he circuit condition it produces when the contact actuating device is in the deenergized or nonoperated state. For the purpose of explanation in this text a contact or device device shown in a state state opposite opposit e of its norma norm al state w ill be highlighted. highlighted. Highlighted Highlighted symbols sym bols used to indicate indicate t he opposite sta st ate of a contact contact or device are are not legitimate legit imate symbols. They are used here for illustrative illust rative purposes only. only.
M echa echanical nical limit switches, sw itches, which w hich will be covered covered in the next section, use a different set of symbols. Highlighted Highlighted symbols are used for illustrative purposes only.
6
Circuit Exampl e
In the following diagram a mechanical limit switch (LS1) has been placed placed in series with wit h a Run/S Run/Stop top conta cont act and the “ M ” contactor cont actor coil. The Run/Stop Run/Stop contact is in t he R Run un condition condit ion and t he m motor otor is running a process. This could be a conveyor conveyor or some other device. device. Note that that t he “ M ” contacts contacts and and the “ Run/ Stop” are shown show n highlighted, indicating indicating they are normally normally open contacts in the closed position. LS1 is a normally closed contact of the mechanical limit switch.
When an object makes contact with the mechanical limit switch the LS1 contacts will change state. In this example the normally closed contacts of LS1 open. The mechanical limit switch symbol is highlighted. The “ M ” contactor coil is deenergized, deenergized, returnin returning g the normally normally open conta contacts cts of the “ M ” contactor contactor to their normal position, stopping the motor m otor and the process.
7
Limit Switches
A typical limit switch sw itch consists of a switch swit ch body and and a an n operating operating head. The switch body includes electrical contacts to energize and deenergize deenergize a circuit. circuit . The operating head incorporates some s ome t ype of lever arm arm or plunger, referred t o as an an actuator. actuator. The standard limit switch is a mechanical device that uses physica physicall conta cont act to detect the presence presence of an object (t arget). When the t he target comes in contact with w ith the t he actuator actuator,, the actuator ctuator is rotated f rom its it s normal position to t he operating operating position. This mechanical operation activates contacts within the switch sw itch body. body.
8
Princip le of Operat Operat ion
A number of terms must be understood to understand how a mechanica mechanicall limit lim it switch sw itch operates. The free position is t he position of the actuator actuator w hen no external force is applied. Pretravel is the distance or angle traveled in moving the actuator from the free position to the operating position. The operating operating position is w here cont cont acts in the t he limit switch sw itch change from their normal state (NO or NC) to their operated state. Overtravel is the distance the actuator can travel safely beyond the operating operating point. point . Differential Differential tra t ravel vel is the t he distance traveled traveled betw een tthe he operating operating position and the release position. The release release position is w here the conta cont acts change change from their operated operated st ate to their t heir normal state. Release travel is the distance traveled from the release position to the free position.
9
M oment ary Operation Operation
One type of actuator operation operation is moment m omenta ary. ry. When t he tar t arget get comes in contact contact w ith the t he actuator actuator,, it rotates the actua actuator tor from the f ree position, through the pret ravel ravel area area,, to t he operating operating position. At this t his point the electrical cont cont acts in the t he switch sw itch body change state. A spring returns the actuator lever and electrical contacts to t heir free position w hen the actuator actuator is no longer in contac contactt w ith tthe he target. target.
Maintained Operation
In many applications it is desirable to have the actuator lever and electrical contacts remain in their operated state after the actuator is no longer in contact with the target. This is referred to as m ma aintained operation. operation. With Wit h ma m aintained operation operation the actuator ctuator lever lever and and contacts return t o their free f ree position w hen a force is applied applied to the actuator actuator in t he opposite direction. A forkstyle actuator is typically used for this application.
10
Snap-Acti Snap-Acti on Cont Cont act act s
There are two types of contacts, snap-action and slow-break. Snap-a Snap-act ction ion contacts cont acts open or close by a snap action regardless of the actuator speed. When force is applied to the actuator in the direction of travel, pressure builds up in the snap spring. When the actuator reaches the operating position of travel, a set of moveable moveable contacts accelera accelerates tes from its norma norm al position tow ards a set of fixed contacts. As force force is removed from t he actuator actuator itit returns ret urns to its f ree position. When the actuator reaches the release position the spring mechanism accelerates the moveable contact back to its original state. Since the opening or closing closing of the contac cont acts ts is not dependent on the speed of the actuator, snap-action contacts are particularly suited for low actuator speed applications. Snapaction contacts are the most commonly used type of contact.
11
Slow -Break -Break Cont Cont act act s
Switches with slow-break contacts have moveable contacts that are located in a slide and move directly with the actuator. This ensures the moveable contacts are forced directly by the actuat actuat or. or. Slow-break Slow-break cont acts can eit her be breakb reak-before-make before-make or make-before-break.
In slow-break switches with break-before-make contacts, the normally closed contact opens before the normally open contact closes. This allows allows the int erruption erruption of one function funct ion before continuation continuation of another function funct ion in a control sequence. In slow-break switches with make-before-break contacts, the normally open contact closes before the normally closed contact opens. This allow allow s the t he initiation of one function funct ion before the interru int erruption ption of another function.
Contact State Break-B Break-Befor efore-Make e-Make NO NC Free Posit io ion Open Clos ed ed Transition Open Open Operated ted Sta State Close losed d Open
12
Make-Before-B Make-Befor e-Break reak NO NC Open Clos ed ed Clos ed Clos ed Close losed d Ope Open
Contact Arrangements
There are are tw t w o basic basic contact configurations used in limit swit sw itches: ches: single-pole, double-throw (SPDT (SPDT)) and and double-pole, double-throw (DPDT) (DPDT).. This term t erminology inology ma m ay be confusing conf using if compared compared to t o simila sim ilarr terminology term inology for other sw itch or relay relay contacts, so it is best just to t o remember remem ber the following follow ing points. The single-pole, single-pole, double-throw double-throw contact arrangement rrangement consists of one normally norm ally open (NO) and one norm ally closed (NC) (NC) contact. cont act. The double-pole, double-throw (DPDT) contact arrangement consists of two normally open (NO) and two normally closed (NC) contacts. There are some differences in the symbology used in the North America Am erican n and International International style limit switches. sw itches. These are illustrated below.
Electri cal cal Ratin gs
Contacts are rated according to voltage volt age a and nd current. current . Rati Ratings ngs are generally described as inductive ratings. A typical inductive load is a relay relay or contactor cont actor coil. There are three com ponents ponent s to to inductive ratings: Make
The load a switch can handle when the m echanical echanical contacts cont acts close. cl ose. This is associat associat ed w ith inrush currents. currents. This is t ypically ypically t w o cycles cycles or less.
Break
The load a switch can handle when the m echanical echanical contacts contact s are opened. This is t he maximum continuous switch current.
Continuous
The load that a switch can handle without making or breaking a load.
13
The following ratings are typical of Siemens International and North American style limit switches.
Inducti ve AC Cont act act Ratin gs
Induct ive DC DC Cont act act Ratin gs
International a nd Nort North h American Style AC Volts Ma ke Bre a k Am p VA Am p VA 120 60 7200 6 720 240 30 7200 3 720
DC Volts 120 240
DC Volts 120 240
Load Loa d Connecti on
14
International Style Ma ke Bre a k Am p VA Am p VA 0. 55 69 0. 55 69 0. 27 69 0. 55 69
North American Style Ma ke Bre a k Amp VA Amp VA 0. 22 0. 22 0. 11 0. 11 -
Care must be made to ensure that multiple m ultiple loads on one one sw itch are are properly connected. connected. The correct w ay to t o w ire a switch sw itch is so that the t he loads loads are are connected to t he load load side of t he switch. sw itch. Loads Loa ds should never never be connected connected t o the line side of t he switch. sw itch.
Actuators
Several types of actuators are available for limit switches, some of w hich are are show n below. There are also also variati variations ons of actuat actuat or types. Actuators shown here are to provide you with a basic knowledge know ledge of various various types t ypes ava available. ilable. The type t ype of actuat actuat or selected depends on the application. pplication.
Roller Lever
The standard roller is used for most rotary lever applications. It is available in various lengths. When the length of the roller lever is unknow n, adjustable lengt h levers are are availa available. ble.
Fork
The fork style actuator must be physically reset after each operation and is ideally suited for transverse movement control.
15
Mounting Considerations
Limit switches should be mounted in locations which will prevent false operations by normal movements of machine components and machine operators. An important aspect of limit switch sw itch mounting m ounting is cam design. Improper ca cam design can can lead lead to t o premature switch sw itch fa f ailure. For lever arm arm actuators actuators it is alwa alw ays desirable to ha have ve the t he cam force perpendicular to the lever arm. For applications in which the cam is traveling at speeds less than 100 feet per minute a cam lever angle of 30 degrees is recommended.
Overrid Overrid ing and Non-Overridi Non-Overridi ng Cams
In overriding cam applications it is necessary to angle the trailing trailing edge of the cam in order to prevent prevent the lever lever arm arm from snapping back. back. Snapping Snapping bac b ack k of t he lever arm can cause shock loads on the switch which will reduce the life of the switch.
Non-Overriding cams are cams which will not overtravel the actuating mechanism.
16
Flexible Loop and Spring Rod
Flexible loop and spring rod actuators can be actuated from all directions, making making them suitable for applica applications tions in w hich the direction of approach is constantly changing.
Plungers
Plunger type actuators are a good choice where short, controlled machine machine move m ovement ments s are present present or w here space space or mounting does not permit a lever type actuator. The plunger can be activated in the direction of plunger stroke, or at a right angle to it s a axis. xis.
M ounti ng Conside Considerations rations
When using plain and side plunger actuators the cam should be operated in line with the push rod axis. Consideration should be given so as not to exceed the overtravel specifications. In addition, the t he limit switch sw itch should not be used as a mechanica mechanicall stop for f or the cam. When using roller top plunger the same considerations should be given as with lever arm actuators.
17
International Limit Sw Sw itches
International International mechanica mechanicall limit lim it switches sw itches are widely w idely used in m any countries, countr ies, including Nort Nor t h America. Amer ica. The Int International ernational Electrotechnical Comm ission (IEC) (IEC) and and t he National Electrical Electri cal M anufacturers anufacturers Associati Association on (NEM (NEM A) develop develop standa st andards rds for electrical equipment. Siemens international mechanical switches are built to IEC and NEMA standards. In addition, they are UL listed and CSA certified. International style switches consist of tw o ma m ajor components, the operating operating head and and switch sw itch body. body.
Internat Internat ional Lim Lim it Sw it ch Family Family
18
A large family of mechanical limit switches is available in the international international style to t o meet m eet virtua virt ually lly any any mechanica mechanicall limit switch sw itch application.
Operat Operat ing He Heads ads
Depending Depending on the t he switch, sw itch, Siemens Siemens interna int ernational tional style limit switches sw itches can be fitt ed w ith an any y of severa severall intercha int erchangea ngeable ble operating heads and actuators. actuators. Overt Overtra ravel vel plunger, roller plunger, plunger, roller or angular roller lever, plain or adjustable length roller lever, plain or spring rod, fork f ork lever, or coded sensing heads are available.
The actuator head can be rotated so that the switching direction of limit switches sw itches w ith roller crank, crank, adjustableadjustable-length length roller crank crank or rod actuators can operate from any side of the switch body. In addition, roller cranks can be repositioned to the left or right around the operating shaft.
19
Open-Type Limit Sw itches itches
Open-type limit switches are intended for use as auxiliary switches in cabinets, large enclosures, or locations where they are not exposed to dust and moisture. A miniature version is available vailable for limit lim ited ed space applicati applications ons such as autom autom atic door interlocking. Open-type switches use a plunger actuator.
Miniature Formed Housing Limit Sw itches itches
M iniature iniature formed housing limit switches sw itches are are used in applicati applications ons w here space is restrict rest ricted. ed. The glass-reinforced glass-reinforced fiber, flame-retardant molded plastic enclosure resists most shocks, impacts, cutting oils, and penetration from dust and water.
20
Replaceable Cont Cont act Block Blo ck Limit Sw itches itches
Siemens has developed two limit switch models with replaceable contact blocks, one with a formed plastic enclosure and one with a metal enclosure. The formed plastic version is in an enclosure enclosure similar to t he miniature limit switches sw itches discussed previously. previously. The m met etal al version is enclosed in die-cast aluminum . It is impervious to t o most m ost mechanica mechanicall shocks.
SIGUARD SIGUARD M echanical echani cal Interlock Interlock Sw it ches ches
Sensitivity ensitivit y to t o safety is an increasing increasing priority for the w orkplace. orkplace. M ost sensors cannot cannot be used in safet safety y circuits, including including proximit proximit y sensors sensors and and photoelectric sensors whic w hich h w ill be covered in later sections. Sensors used in safety circuits must meet stricter strict er design design and test sta st anda ndards rds specified by DIN and and IEC. IEC. The SIGUAR SIGUARD D line of International Internati onal style sty le sw itches it ches is designed for safety circuits. circuit s. SIGUAR SIGUARD D mecha m echanical nical interlock swit sw itches ches have triple trip le coded actuators actuators t hat act as a key key. These devices devices can can be used to control the t he position of doors, machine machine guards, guards, gates, and enclosure covers. They can also be used t o interrupt int errupt operation for user safety. They are ava available ilable in m iniature formed housing and meta met al housing models.
21
North Nor th American Limit Limit Switches Sw itches
North America Am erican n mecha m echanica nicall limit lim it switches sw itches are specifically specifically designed designed to meet m eet unique requirements requirements of the North Nort h American American market. These switches are comprised of three interchangeable components; contact block, switch body, and sensing head. North American limit switches meet UL (Underwriters Laborat Laboratory) ory) and CSA (Cana (Canadian dian Standards St andards Association). Associat ion).
Actuators
22
Like Like the t he International International limit switches, sw itches, Siemens Siemens North Nort h American American limit switches also accept a variety of operating heads and actuators.
NEM NE M A Type 6P Subm Subm ersibl e
The housing for North Nort h American Am erican NEM NEM A Type 6P submersible subm ersible limit switch sw itch is die-ca die-cast st m etal w ith an epoxy epoxy finish for harsh harsh industrial environments. In addition, the Siemens 6P submersible swit ch can can be used for watert ight applications. applications.
Class 54, Rotat ing in g Type yp e
Class lass 54 rotating limit switches sw itches are used used to limit lim it the tra t ravel vel of electrically elect rically operat operat ed doors, conveyors, conveyors, hoists, hoist s, and and similar sim ilar applicati applications. ons. The contacts cont acts are operated w hen tthe he external shaft is rotated sufficiently suff iciently.. Siemens Siemens rota rot ating sw itches employ a simple reduction worm and gear(s) to provide shaft-to-cam ratios of 18 to 1, 36 to 1, 72 to 1, or 108 to 1. In addition, long dwell cams are available which keeps contacts closed for longer periods of time. This may be necessary in hoist or similar applications. A fine adjustment cam is also available to increase the accura accuracy of t he number of shaft shaft turns required to cause the contacts to t o operate. operate.
23
M iniat ure, Prew ired, Sealed Switches
M iniature, iniature, prewired, sealed sealed sw itches allow allow for minia m iniaturiza turization tion of the electrica elect ricall connection. The switch sw itch is prewired and the t he termi ter minals nals and and connection connect ion are encapsulated encapsulated in i n epoxy. The sw itch it ch uses a single-pole, double-throw contact. cont act. The contact cont act can be w ired either eit her normally norm ally open (NO) or normally closed (NC). (NC). Depending on the t he load voltage, the cont act can make make up to t o 7.5 amps and break up to 5 amps.
3SE03 Hazardous Locat io ns, Typ e EX
Type EX limit switches are designed for extreme environmental service in locations where there exists a danger of an internal or external explosion of f lammable lamm able gasses, gasses, vapors, vapors, metal m etal alloy, alloy, or grain dust. EX switches are designated by the catalog number 3SE03-EX.
24
Enclosed nclo sed Bas Basic ic Sw it ches
North American limit switches are also available in an enclosed basic version. These sw itches are are designated by the t he catalog number num ber 3SE03-E 3SE03-EB. B. E Enclosed nclosed basic sw itches are preconfigured w ith it h a plunger actuator, actuator, booted plunger, roller lever, lever, booted boot ed roller lever, roller plunger, or a booted roller plunger.
25
Review 1 1)
A ___ _____ ____ ____ ____ ___ _ __ ____ ____ ____ ____ ____ __ is a type typ e of sensor that requires requires physica physicall contact w ith t he target. target.
2)
Which Which of of the follo follow w ing ing symbol symbols s iden identifies tifies a No Norma rmally lly Closed, Held Open limit switch? sw itch?
3.
_____ ___ ____ ___ ___ is the distance or angle angle traveled traveled in in moving the actuator from the free position to the operating position.
4.
The __ ____ ____ ____ ____ ____ __ __ ____ ____ ____ ____ ____ __ is where w here contacts in the limit switch change from their normal state to their operated operated state.
5.
In slo slow-br w-brea eak k switche swit ches sw with ith __ ____________ ___ ______ ______ ______ ___ - ___ _____ _____ ______ ____ _ cont con t acts, act s, t he norm nor m ally closed contact opens before the normally open contact closes.
6.
_____ ___ ____ ___ ___ defines the load load a switch sw itch can can handle handle when the mechanical contacts are opened. This is the maximum continuous switch current.
7.
For applica pplications tions in in which the cam cam is travel travelling ling at speeds less than 100 feet per minute a cam lever angle of ____ __ ____ ____ ____ ____ __ degrees is recom m ended. ended .
8.
An Interna Internationa tionall switch sw itch consists consists of an __ ____________ ______ ________ _____ ____ _ and sw itch it ch body. bo dy.
9.
____________ is is the trade trade name name for a t ype of International International switch sw itch suita suit able for safet safet y circuits.
10. The Siem Siemens ens ___ _____ ____ ____ ____ ___ _ submersible subm ersible sw itch it ch can can be used for watert ight applications. applications.
26
BERO Sensors
BERO is the trade name used by Siemens to identify its line of “ no-touch” no-touch” sensors. sensors. Siemens Siemens BERO BERO sensors sensors operate operate w ith no mechanical contact or wear. In the following application, for example, a BERO sensor is used to determine if cans are in the right position posit ion on a conveyor conveyor..
Types of BERO Sensors
There are four types typ es of BERO BERO sensors: induct ive, capacitive, capacitive, ultrasonic, and photoelectric. Inductive proximity sensors use an electromagnetic field to detect the presence of metal objects. Capa pacitive citive proximity sensors use an an electrosta electrost atic field to detect the presence of any object. Ultrasonic proximity sensors use sound w aves to detect the presence presence of objects. Photoelectric Photoelectric sensors react on changes in the received quantity of light. Some photoelectric sensors can even detect a specific color.
Se nsor
Obj e cts De te cte d
Te chnology
Induc ttiive Capacitive Ult ras onic
Met al al Any Any
Electromagnetic Field Elec t ros tat ic Field Sound Waves
Photoelec tric
Any
Light
27
Inductive Induct ive Proximit Proximityy Sensors Sensors Theory of Operation
In this section w e w ill look at at BER BERO inductive proximit proximit y sensors, sensors, a and nd how they detect the presence of an object object w ithout coming into physical physical contact w ith it . Inductive Inductive proximity proximit y sensors sensors are are availa available ble in a variety of sizes sizes and configurations confi gurations to t o meet m eet varying applications. Specific sensors will be covered in more detailed in the following section.
Electr om agnetic Coil and M etal et al Target Target
28
The sensor incorporates an electromagnetic coil which is used to detect the presence presence of a conductive conductive metal m etal object. The sensor will ignore the presence of an object if it is not metal.
ECKO
Siemens BERO inductive proximity sensors are operated using an Eddy Current Killed Oscillator (ECKO) principle. This type of sensor consists of four elements: coil, oscillator, trigger circuit, and an an output out put.. The oscillator oscillat or is an inductive induct ive capacit capacitive ive tuned circuit that creates a radio frequency. The electromagnetic field produced produced by the oscillator oscillator is emitted emit ted f rom t he coil away away from t he face of the sensor. sensor. The circuit has just enough feedback from the field f ield to keep the oscillator oscillator going.
When a met al tar t arget get enters ent ers the field, f ield, eddy currents currents circulate circulate w ithin it hin the t he target. t arget. This causes a load load on t he sensor, decreasing decreasing the amplitude of the electroma electrom agnetic field. f ield. As the tar t arget get approaches approaches the sensor the eddy edd y currents current s increase, increasing increasing the load on the oscillator and further decreasing the amplitude of the field. The trigger t rigger circuit circuit monitors m onitors the t he oscillator oscillator’s ’s amplit amplitude ude and at at a predetermined level level swit ches the output st ate of the sensor from its normal condition (on (on or off). As As the t he target moves m oves away from the sensor, the oscillator’s amplitude increases. At a predetermined level the trigger switches the output state of the sensor back to its normal condition (on or off).
29
Operatin Operatin g Volt age ages s
Siemens induct ive proximit y sensors include incl ude AC, AC, DC, a and nd AC/ AC/ DC (universa (universall voltage) volt age) models. The basic operating voltage volt age ranges are from 10 to 30 VDC, 15 to 34 VDC, 10 to 65 VDC, 20 t o 320 3 20 VDC, VDC, and and 20 t o 2 265 65 VAC. VAC.
Direct Current Devices
Direct Direct current current m odels are are typica t ypically lly three-wire devices (t (t w o-w o-w ire also available) requiring a separate power supply. The sensor is connected connected betw bet w een the positive and and negative negative sides of t he power supply. The load is connected between the sensor and one side of the power supply. supply. The specific polarity of the connection connection depends on the t he sensor model. In the follow ing example example t he load load is connected bet w een the negative side of the power supply and the sensor.
Out put Configurations
Three-wire, hree-wi re, DC proximit y sensor can either eit her be PNP (sourcing) (sourcing) or NPN (sinking). This refers to the type of transistor used in the output switching of the transistor. The following follow ing draw draw ing illustrates illustrates t he output stage of a PNP PNP sensor. The load is connected between the output (A) and the negative side of the pow power er supply (L-) (L-).. A PNP t ransistor switches sw itches the load load to t he positive side of of t he power supply (L+). (L+). When the t he transistor transistor switches sw itches on, a complete complet e pa path th of current current flow fl ow exists f rom L- through the load to t o L+. L+ . This is also referred referred to as current sourcing since in this configuration conventional current is (+ to -) sourced to the load. This terminology is often confusing to new users of of sensors since since electron current current f low (to + ) is from t he load load into t he sensor w hen the PNP transistor turns on.
30
The following drawing illustrates the output of an NPN sensor. The load load is connected bet w een the output out put (A) and and the t he positive side of the pow er supply (L+ (L+)). An NPN NPN tra t ransistor nsistor switches sw itches the load to t he negative side of the pow power er supply (L-). -). This is also referred referred to t o as current current sinking since the direction of conventional conventional current current is into the sensor w hen the transistor transistor turns on. Again, Again, the flow f low of electron current current is in the opposite direction.
Norm ally Open (NO) (NO) Normally Closed (NC)
Outputs are considered normally open (NO) or normally closed (NC) based on the condition of the transistor when a target is absent. If, for example, example, the t he PNP PNP output is off w hen the t arget arget is absent then it is a normally open device. If the PNP output is on w hen the ta t arget is absent it is a normally normally closed device. device.
Complementary
Transist ransistor or devices can also be complem comp lementary entary (four-w (four-wire). ire). A complementary complem entary output is defined as having having both norma norm ally open and normally closed contacts in the same sensor.
31
Series and Parallel Connections
In some applications it may be desirable to use more than one sensor to control a process. Sensors can be connected in series or in parallel. parallel. When sensors are connected connect ed in series ser ies all the t he sensors sensors must be on to t urn on the output. output . When sensors are are connected connected in pa para rallel llel either sensor will tturn urn the output out put on. There are are some limit ations tha t hatt must be considered considered w hen connecting sensors in series. In particular, the required supply voltage increases with the number of devices placed in series.
Shielding
32
Proximity sensors contain coils that are wound in ferrite cores. They can be shielded or unshielded. Unshielded sensors usually have ha ve a great great er sensing dist ance than shielded sensors.
Shielded Proxim Proxim it y Sensors Sensors
The ferrite core concentrates the t he radia radiated field in the direction of use. A shielded proximity sensor has a metal ring placed around around the core to restrict the lateral lateral radia radiation of the f ield. Shielded proximit proximit y sensors can can be flush f lush mounted in met al. A metal-free space is recommended above and around the sensor’s sensing surface. Refer to the sensor catalog for this specification. specification. If there t here is a met meta al surface surface opposite the t he proximity sensor it m ust be at least least t hree times the t he rated rated sensing distance of the t he sensor from the sensing surface. surface.
Unshielded Proximity Sensors
An unshielded proximity sensor does not have a metal ring around around the core to t o restrict lateral lateral radia radiation tion of the field. Unshielded sensors cannot be flush mounted in metal. There must be an area around the sensing surface that is metal free. An a area rea of at least three t hree times tim es the diameter diamet er of the t he sensing surface must be cleared around the sensing surface of the sensor. sensor. In addition, addition, the sensor must be mounted mount ed so that the t he metal surface of the mounting area is at least two times the sensing distance distance from the sensing face. If there t here is a metal surface surface opposite of the proximit y sensor it must be at least least three times tim es the rated rated sensing distance distance of the t he sensor sensor from t he sensing surface.
33
Mount ing M ultiple Sens Sensors ors
Care must be taken when using multiple mult iple sensors. sensors. When t w o or more sensors are mounted adjacent to or opposite one another, interference int erference or cross-talk cross-t alk can can occur producing false output outp uts. s. The following guidelines can generally be used to minimize interference. •
•
•
•
Opposite shielded sensors should be separated by at least four times tim es the t he rated rated sensing range range Opposite unshielded sensors should be separated by at least six times the rated sensing range Adjacent shielded sensors should be separated by at least two times the diameter of the sensor face Adjacent Adjacent unshielded sensors should be separat separat ed by at least least t hree times the t he diamet diameter er of the t he sensor sensor face face
These are general guidelines. BERO BERO proximit proxim ity y sensors ha have ve individual specifications which should be followed. For instance, some devices are rated as suitable for side-by-side mounting.
34
Standar St andard d Target Target
A standard target is defined as having a flat, smooth surface, made of mild m ild steel tha t hatt is 1 mm (0.04” ) thick. thick. Steel Steel is ava available ilable in various various grades. grades. M ild steel is composed of a higher higher content content of iron and carbon. carbon. The standa st andard rd target t arget used w ith it h shielded sensors sens ors has sides equal to the diameter of the sensing face. The standard target used with unshielded sensors has sides equal to the t he diamet diameter er of the sensing face face or three times t he rated rated operating range,w hichever is greater. greater. If the target is larger than the standard target, the sensing range does not change. However, if the target is smaller or irregular shaped the sensing distance (S n) decreases. The smaller the area area of t he target the closer it must m ust be to t o the sensing face face to be detected.
Target Size Correction Factor
A correction factor can be applied when targets are smaller than the standard target. To determine the sensing distance for a target that is smaller than the standard target (S new), multiply mult iply the rated sensing distance (S rated) times the t he correction correction factor (T). If, for example, a shielded sensor has a rated sensing distance of 1 mm m m and the t arget arget is half the t he size size of the st anda ndard rd target, the new sensing distance distance is 0.83 mm (1 mm x 0.83). 0.83). Snew = Srated x T Snew = 1 mm x 0.83 Snew = 0.83 mm Size of Target Compared to Standard Target 25% 50% 75% 100%
Correction Factor Shie Sh ield lded ed Unshi hield elded ed 0.56 0. 50 0.83 0. 73 0.92 0. 90 1.00 1. 00
35
Target Thickness Thickn ess
Thickness of the target is another factor that should be considered. The sensing dist ance is constant for f or the standa st andard rd t arget arget.. However, However, for nonferrous targets t argets such as brass, brass, aluminum, and copper a phenomenon known as “ skin effect” occurs. Sensing distance decreases as the target thickness increases. increases. If the t he target is other ot her than the standard standard targ t arget et a correction correction factor must be a applied pplied for the thic t hickness kness of the t he tar t arget. get.
Target Material
The target material also has an effect on the sensing distance. When the t he material is other than than mild st eel correction correction factors need to be applied.
Material Mild St eel, Carbon Aluminum Foil 300 Series Stainless Steel Bras s Aluminum Copper
36
Correction Factor Shiel Sh ield ded Unshie ield lded ed 1.00 1. 00 0.90 1. 00 0.70 0. 08 0.40 0. 50 0.35 0. 45 0.30 0. 40
Rated Operating Distances
The rated sensing sensi ng dist ance (S (Sn) is a theoretical value which does not take into account such things as manufacturing tolerances, operating temperature, and supply voltage. In some applications the sensor may recognize a target that is outside of the rated sensing distance. In other applications the target may not be recognized until it is closer than the rated sensing distance. distance. Severa Severall other ot her terms term s must m ust be considered considered w hen evaluating evaluating an application. The effective operating distance (S r) is measured at nominal supply volt age a att an am am bient t emperature emp erature of 23°C ± 0.5°. It t akes akes into int o account manufa m anufacturin cturing g tolera t olerances. nces. The effective effect ive operating operating distance is ± 10% of the rated rated operating operating distance. distance. This means the target will be sensed between 0 and 90% of the rated sensing distance. Depending on the device, however, the effective sensing distance can be as far out as 110% of the rated sensing distance. The useful switching distance (S u) is the switching sw itching distance measured under specified temperature and voltage conditions. The useful switching sw itching distance is ± 10% of t he effective operating distance. The guarant guaranteed eed operating distance dist ance (S (S a) is any switching distance for which an operation of the proximity switch within specific permissible operating conditions is guaranteed. The guara gua ranteed nteed operating operating dist ance is between betw een 0 and and 81% of t he rated operating distance.
37
Response Characteri Characteri sti c
Proximity sw itches respond to an an object only w hen it is in a defined area in front of the switch’s sensing face. The point at w hich the proximit proximit y switch sw itch recognizes recognizes an an incoming target is the t he operating point. The point at which an outgoing target causes the device to sw itch back back to its it s normal state state is called the release release point. The area area between betw een these t w o points is called called the t he hysteresis zone.
Respon se Cur Curve ve
The size and shape of the response curve depends on the specific proximity proximit y sw itch. The following follow ing curve represents represents one type of proximity proximity sw itch.
38
Review 2 1)
An __ _____ ___ _____ ___ __ sensor uses an an electrom electroma agnetic field and can only only detect det ect m etal objects.
2)
Which Which of of the follo follow w ing is no nott an an ele element ment of an an induc inductive tive proximity sensor. a. Target b. Electrical lectrical Coil c. Oscilla Oscillator tor d. Trigger Circuit Circuit e. Output Output
3)
An area surroun surrounding ding an unshi unshielde elded d inductiv inductive e prox proximit imity y sensor of at least ____________ times the area of the sensing face face must be met al free.
4)
Shield hielded ed iindu nductiv ctive e prox proximity imity senso sensors rs mounted mounted oppo opposite site each other should be mounted at least ____________ times the rated sensing area from each other.
5)
A stan standa dard rd t arget rget for an induc inductive tive pro proximity ximity senso sensorr is made of mild ____________ and is 1 mm thick.
6)
A correction correction factor factor of ____ _____ ____ ___ ____ should be be applied applied to a shielded shielded inductive inductive proximity sensor when w hen the targ t arget et is made of brass.
7)
The gua guara ranteed nteed opera operating dista distance nce of a an n inductiv inductive e proximit y sw itch it ch is bet w een 0 and ____ ______ ____ ____ ____ __ % of the rated operating distance.
39
Inductive Proximity Sensor Family
In this section we will look at the 3RG4 and 3RG04 families of inductive proximit proximity y sensors. 3R 3RG G4 refers to the t he first pa part rt of t he part pa rt number num ber that is used to identify identif y this line of sensors.
40
Categories
Inductive Induct ive proximit y sensors are ava available ilable in ten t en categories. Each Each category category w ill be briefly discussed discussed and follow follow ed by a selection selection guide.
Normal Requirements Cylindrical
Inductive proximit proximit y sensors designed for normal requirement requirements s are also also referred to as the standa st andard rd series. These sensors w ill meet the needs of normal or standard applications. Standard series sensors used for normal norm al requirements requirement s are ava available ilable in several sizes, including the shorty version which is used where mounting space is limited. The diameter sensing face ranges from 3 mm to 34 mm. m m. In addition, addition, standard standard series sensors sensors come with PNP or NPN outputs in 2, 3, or 4 wires. Standard series sensors can handle loads up to 200 mA.
41
Normal Requirements Cyli ndri cal cal Selection Guide
The following Inductive Proximity Selection Guide will help you find fi nd the t he right sensor for a given application. application. The housing dimension column refers to the diameter diamet er of the sensing face. The material column column identifies identif ies if the sensor body is m ade of stainless st eel (SST (SST), ), brass, or a molded plastic.
Housing Shielded Operating Dimension Material Sn (mm) Wires Unshielded Voltage (mm) 3, 4 5 6.5
8
12
18
20 30
34
42
SS T Bras s SS T SS T SS T SS T SS T Bras s SS T SS T SS T Bras s SS T SS T Bras s Bras s SS T SS T Bras s Bras s SS T SS T SS T Bras s Bras s SS T SS T Bras s Plas tic Bras s Bras s SS T SS T Bras s Bras s SS T SS T Bras s Plas tic
Shielded Shielded Shielded Shielded Uns hielded Shielded Shielded Shielded Shielded Shielded Uns hielded Shielded Shielded Shielded Shielded Uns hielded Uns hielded Uns hielded Uns hielded Shielded Shielded Shielded Shielded Shielded Uns hielded Uns hielded Uns hielded Uns hielded Un Uns hielded Shielded Shielded Shielded Shielded Shielded Uns h hiielded Uns hielded Uns hielded Uns h hiielded Un Uns hielded
0.6-0. 8 0.8 1.5 1.5 2.5 1 1 1.5 1.5 1.5 2.5 2 2 2 2 4 4 4 4 5 5 5 5 5 8 8 8 8 10 10 10 10 10 10 15 15 15 15 20
10-30 VDC 10-30 VDC 15-34 VDC 10-30 VDC 15-34 VDC 15-34 VDC 10-30 VDC 10-30 VDC 15-34 VDC 10-30 VDC 15-34 VDC 15-34 VDC 10-55 VDC 20-250 VAC 20-250 VAC 15-34 VDC 10-55 VDC 20-250 VAC 20-250 VAC 15-34 VDC 10-30 VDC 10-55 VDC 20-250 VAC 20-250 VAC 15-34 VDC 10-55 VDC 20-250 VAC 20-250 VAC 10-36 VDC 15-34 VDC 10-30 VDC 10-55 VDC 20-250 VAC 20-250 VAC 15-34 VDC 10-55 VDC 20-250 VAC 20-250 VAC 10-36 VDC
3 3 3 3 3 3 4 3 3 3, 4 3 3, 4 2 2 2 3, 4 2 2 2 3, 4 4 2 2 2 3,4 2 2 2 3 3, 4 4 2 2 2 3, 4 2 2 2 3
Normal Requirements Cubic Shape
Inductive proximit proximit y sensors designed for normal requirement requirements s are also available in a block or cubic shape.
Normal Requirements Cubic Shape Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm)
Optim ized ized for Solid State IInput nput s
Wires
5x5 8x8 18 Tubular (Flat Pack) 40x 26x12 26x40 x40x12 x12
Bras s Bras s Plastic
Shielded Shielded Shielded
0. 8 1. 5 4
10-30 VDC 10-30 VDC 10-30 VDC
3 3 3
Plastic Pla Plastic stic
40x 32x 12.5 Block with M14 40x40 (Limit Switch Style)
Plastic Plastic Plastic Plastic Plastic
Shielded Shie Shield lde ed Unshielded Shielded Shielded Uns hielded Shielded Uns hielded
2 2 4 2 2. 5 5 15 20
15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC
3, 4 3 3 4 3, 4 3, 4 4 4
40x40 x40x40 x40
Pla Plastic stic
40x40 x40x40 x40
Pla Plastic stic
40x60 (Flat Pack) 40x80 (Flat Pack)
Plastic Plastic Plas tic
Shie Shield lde ed Unshielded Shie Shield lde ed Unshielded Shielded Uns hielded Uns hielded
35 35 35 35 25 30 40
15-34 VDC 15-34 VDC 20-265 VAC 20-265 VAC 15-34 VDC 15-34 VDC 15-34 VDC
4 4 2 2 4 4 4
These tw o-w o-w ire devices devices are are optimiz optim ized ed for use with w ith solid sta st ate inputs such as PLCs and solid state timing relays. Optimized for solid state input sensors are available in tubular (shown) and block packs (not (not show n).
43
Opt im ized ized for Solid State IInput nput s Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Wires Unshielded Voltage (mm) 8 12 18 30 Block with M14 40x40 (Limit Switch Style)
Ext ra Duty
44
SS T Bras s Bras s Bras s Bras s Bras s Bras s Plas tic
Shielded Shielded Uns hielded Shielded Uns hielded Shielded Uns hielded Shielded
1 2 4 5 8 10 15 2.5
15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC 15-34 VDC
2 2 2 2 2 2 2 2
Plas tic Plas tic
Shielded Uns hielded
15 20
15-34 VDC 15-34 VDC
2 2
Some applicat applicat ions require a higher operat operat ing voltage, volt age, or or a faster faster switching sw itching frequency than is found w ith st anda ndard rd series sensors. sensors. This group of inductive proximity sensors provides a higher operat operat ing range and can ha handle ndle loads up to 300 m A. These are two-wire and three-wire devices available in either normally open (NO) or normally closed (NC) configurations. They are available in cylindrical or cubic shape.
Ext ra Duty Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 8 12
S ST Bras s
Shielded Shielded
1 2
Bras s Brass
Shielded Unshie shield lde ed
2 4
Bras s Bras s
U Un ns hielded Shielded
4 10
Bras s Bras s
Shielded Un Uns hielded
20
Bras s Plas ttiic
Uns hielded Un Unshielded
10
30
Bras s
Shielded
10
Bras s Bra Brass
Shielded Unshie shield lde ed
10 15
Bras s
Uns hielded
15
34
Plas ttiic
Un Unshielded
Block with M14
Pla Plasti stic
18
40x40 (Limit Switch Style)
40x60 (Flat Pack) 40x80 (Flat Pack)
Wires
10-65 VDC 20-265 VAC/ 20-320 VDC 10-65 VDC 20-265 VAC/ 20-320 VDC 10-65VDC 20-265 VAC/ 20-320 VDC 10-65 VDC 20-265 VAC/ 20-320 VDC 10-65VDC 20-265 VAC/ 20-320 VDC 20-265 VAC/ 20-320 VDC 10-65 VDC 20-265 VAC AC/ / 20-320 VDC 10-65VDC
3 2
20
20-265 VAC/ 20-320 VDC
2
Shielded
2.5
2
P lastic Plas tic Plas ttiic
Shielded U Un ns hielded Shielded
2.5 5 15
Plas tic Pla Plastic stic
Shielded Unshie shield lde ed
15 20
Plastic stic Pla Plastic stic
Unshie shield lde ed Unshie shield lde ed
20 30
Plas tic P la lastic
Uns hielded Shielded
30 30
Pla Plastic stic
Unshie shield lde ed
40
Pla Plastic stic
Unshie shield lde ed
40
P lastic
Uns hielded
40
20-265 VAC/ 20-320 VDC 10-65VDC 10-65 VDC 20-265 VAC/ 20-320 VDC 10-65 VDC 20-265 VAC AC/ / 20-320 VDC 10-65 VD VDC C 20-265 VAC AC/ / 20-320 VDC 10-65 VDC 20-265 VAC/ 20-320 VDC 20-265 VAC AC/ / 20-320 VDC 20-265 VAC AC/ / 20-320 VDC 10-65 VDC
3 2 3 2 3 2 3 2 2 3 2 3
3 3 2 3
2 3 2 2 2 3
45
Extreme Environmental Cond it ion s (IP68) (IP68)
IP protect protection ion is a Europea European n system of classification classification w hich indicates the degree of protection an enclosure provides against dust, dust , liquids, solid objects obj ects,, and personnel contact. contact . The IP system of classification is accepted internationally. Proximity switches sw itches classified classified IP68 IP68 provide protection protect ion aga against the penetration penetration of dust, complete complet e protection protect ion aga against inst electrica elect ricall shock, and protection against ingress of water on continuous submersion. subm ersion. These are threet hree- and and four f our-wir -wire e devices configured confi gured for NPN or PNP, norm ally closed clos ed (NC) or normally norm ally open ope n (NO) outputs.
Ext reme Environm Environm ental Cond it ion s (IP68) (IP68) Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 4. 5 6. 5 8 12
18
30
40x40 (Limit Switch Style)
46
S ST Brass Brass Plas tic Bras s Plas tic Bras s Plas tic Bras s Plas tic Bras s Plasti stic
Shielded Uns hielded Uns hielded Shielded Shielded U Un ns hielded Uns hielded Shielded Shielded U Un ns hielded Uns hielded Unshie shield lde ed
0.6 2.5 2.5 2 2 4 4 5 5 8 8 8
Plas tic Plas tic Bras s Plas tic Bras s Pla Plastic stic
U Un ns hielded Shielded Shielded Uns hielded Uns hielded Unshie shield lde ed
8 10 10 15 15 15
Plas tic Plas tic
Uns hielded Shielded
15 15
10-30 V DC 10-30 V DC 10-30 V DC 15-34 V DC 15-34 V DC 15-34 V DC 15-34 V DC 15-34 V DC 15-34 V DC 15-34 V DC 15-34 V DC 20-265 VAC 20-250 VDC 10-65 V DC 15-34 V DC 15-34 V DC 15-34 V DC 15-34 V DC 20-265 VAC VAC 20-250 VDC 10-65 V DC 15-34 V DC
Wires 3 3 3 3 3 3 3 3 3 3 3 2 3 3 3 3 3 2 3 4
Great Great er Rated Rated Operating Operat ing Sensing Range
These devices provide a greater operating distance in comparison comparison w ith standard standard proximity proximit y sw itches. Devices Devices are are t hree-w hree-w ire DC wit w ith h PNP or NPN NPN or AC and normally open (NO) or normally closed (NC) output configurations.
Greater Rated Operating Sensing Range Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 6. 5 8
Bras s S ST Bras s Bras s 12 Bras s Bras s Bras s 18 Plastic Bras s Bras s 30 Bras s Bras s Bras s 8x8 Bras s 40x40 Plas tic Plastic (Limit Plas Plastic tic Switch Plastic Style) 40x40 (Mini Plastic Base) 40x60 (Flat Plas tic Pack) 40x80 (Flat Plas tic Pack)
Wires
Uns hielded 3 Shielded 2 Uns hielded 3 Uns hielded 6 Shielded 4 Shielded 6 Uns hielded 10 Shielded 8 Uns hielded 12 Uns hielded 20 Shielded 15 Shielded 22 Uns hielded 40 Uns hielded 3 Shielded 20 Uns hielded 25 Unshie shield lded ed 40/2 40/25 5(adj) adj) Uns hielded 40 Shielded 20
10-30 VDC 15-34 VDC 10-30 VDC 10-30 VDC 15-34 VDC 10-30 VDC 10-30 VDC 15-34 VDC 10-30 VDC 10-30 VDC 15-34 VDC 10-30 VDC 10-30 VDC 10-30 VDC 15-34 VDC 10-65 VDC 1010-65 VD VDC C 10-65 VDC 10-30 VDC
3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
Uns hielded
50
10-65 VDC
3
Uns hielded
65
10-65 VDC
3
47
NAMUR
NAMUR is a standard issued by the Standards Committee of M ea easurement surement and Control Control of the chemical industry in Europe. Europe. Deutsche Industrie Normenausschuss (DIN) refers to a set of German standards now used in many countries. Like NAMUR, DIN 19234 is a set of standards for equipment used in hazardous locations.
Intr insically Safe Safe
NAMUR sensors are intrinsically safe only when used with an approved approved barrier power supply/outp supply/ output ut device and approved approved cabling. It is beyond the scope of t his course course to offer a complete explanation explanation on this thi s subject . You are encouraged to t o becom e familiar familiar w ith Articles Art icles 500 through t hrough 504 of the t he National National Electrica Electricall Code® w hich hich cover cover the use of electrical electrical equipment in locations locations w here fire or explosions explosions due to t o gas, gas, fla f lamm mm able liquids, combustible dust, dust , or ignitable fibers may be possible. possible.
Hazardous Environments
Although you should should never specify specify or suggest suggest the type of location, location, it is important im portant t o understand understand regulations regulations t ha hatt apply to hazardous locations. It is the user’s responsibility to contact local regulatory agencies to define the location as Division I or II and to t o comply w ith all applicab applicable le codes.
Divisions
Division I identifies a condition where hazardous materials are normally present present in the t he atmosphere. Divisi Division on II identifies identif ies conditions where an atmosphere may become hazardous as result of abnormal conditions. This may occur if, for example, a pipe cont aining a haza hazardous rdous chemical chem ical begins to t o leak.
Classes and Groups
Hazar Hazardous dous locations are further furt her defined def ined by class and group. Class I, Groups A through D are chemical gases or liquids. Class II, Group Groups s E, F, and G include f lamm able dust . Cla Class ss III is not n ot divided into groups. It includes all ignitable fibers and lints such as clothing fiber in textile text ile mills. p u o r G
A B C
D
48
Cla ss I Cla ss I I p u Groups A-D o Groups E-G r Gases and G Flammable Liquids Dust Ac et y lene E Metallic Dus t Hy drogen F Carbon Dus t Acetalde Acetaldehyde hyde G Grain Grain Dust Ethylene Methyl Ether Acetone Gasoline Methanol Propane
p u o r G
Cla ss I II Ignitable Fibers Ray on Jute
NAMUR Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 4. 5 8 12 18 30 40x40 (Limit Switch Style)
SST SST SST SST SST SST SST SST P las tic
Shielded Shielded Shielded Uns hielded Shielded Uns hielded Shielded Uns hielded Shielded
0.8 1.5 2 4 5 8 10 15 15
5-25 VDC 5-25 VDC 5-25 VDC 5-25 VDC 5-25 VDC 5-25 VDC 5-25 VDC 5-25 VDC 5-25 VDC
Wires 2 2 2 2 2 2 2 2 2
Pressure Proof roo f
These devices are used in extremely dynamic pressure stressing such as as the t he monitoring monit oring of pist on or valve valve limit positions, speed monitoring monit oring and and m mea easurement surement of hydraulic hydraulic m otors, and vacuum vacuum applicati applications. ons. The operating voltage volt age is 10 10 to to 30 VDC, with loads up to 200 mA. The operating distance of devices rated up to 7253 psi is 3 mm. These are three-wire devices w ith it h a PNP PNP or NPN, NPN, normally open (NO) or normally norm ally closed (NC) output.
Pressure Proof roo f Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 12
SST
Uns hielded
3
10-30 VDC
Wires 3
49
UBER UBERO Wit hout Reduct ion Fact act or/Weld or/Weld Field Imm une
Standard BERO proximity switches require a reduction factor for metals other than the standard target. UBERO products sense all metals without a reduction factor. They can also be used in applications near a strong magnetic fields.
UBER UBERO Wit hout Reducti on Fact act or/Weld or/Weld Field Imm une Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 8 12 18 30 40x40 (Limit Switch Style) 40x40 (Mini Base) 80x 80
50
Shielded Unshielded Brass or Shielded SST Uns hielded Brass or Shielded SST Uns hielded Brass or Shielded SST Uns hielded Plas tic Shielded Plastic Unshielded Plastic Unshielded S ST
Plas tic Plas tic Plas tic Plas tic
Shielded Uns hielded Uns hielded Uns hielded
Wires
1.5 4 2 8 5 12 10 20 15 25 40
10-30 VDC 10-30 VDC 10-30 V DC 10-30 VDC 10-30 V DC 10-30 VDC 10-30 V DC 10-30 VDC 10-30 VDC 10-30 VDC 10-30 VDC
3 3 3 3 3 3 3 3 4 3 4
15 25 35 75
10-30 VDC 10-30 VDC 10-30 VDC 10-30 VDC
3 3 3 4
AS-i
Actuator Sensor Interface Interf ace (AS (AS-i -i or AS-Interface) AS-Interface) is a system for networking binary devices such as sensors. Until recently, extensive extensive parallel parallel control w iring wa w as needed to t o connect sensors sensors to the controlling device. PLCs, for example, use I/O modules to receive inputs from binary devices such as sensors. Binary outputs output s are are used to t o turn on or off a process process as as the t he result of an input. Using conventional wiring it would take a cable harness of several parallel inputs to accomplish complex tasks.
AS-i replaces the complex cable harness with a simple 2-core cable. The cable is designed so tthat hat devices can only be connected correctly.
Inductive proximity sensors developed for use on AS-i have the AS-i chip and intelligence built into the device
51
AS-i Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 12 18 20 30 34 40x 40
Bras s Bras s Plas tic Bras s Plas tic Plas tic
Shielded Shielded Uns hielded Shielded Uns hielded Shielded
2 5 10 10 20 15
20-32 VDC 20-32 VDC 20-32 VDC 20-32 VDC 20-32 VDC 20-32 VDC
Analog Analog Outp ut
These devices are used w hen an analog analog value is required. In some applications applications it may be desireable desireable to know the dist ance a t arget arget is from f rom the sensor. sensor. The rated sensing sensi ng range of an inductive ana analog log sensor is 0 to t o 6 mm. m m. The output of t he sensor increases increases from 1 to 5 VDC or or 0 to t o 5 mA m A as the tar t arget get is m oved oved aw ay f rom the sensor.
Analog Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 12
52
Bras s
Uns hielded
0-6
10-30 V DC
Wires 4
Review 3 1)
Induc Inductive tive prox proximity imity sens sensor ors s are are divide divided d into into _______ _________ _____ ___ catego cat egorie ries. s.
2)
The maximum maximum sensi sensing ng ra range of an induc inductive tive pro proxi ximity mity sensor with a cylindrical style housing in the standard series (normal requirements) is ____________ mm.
3)
The maximum maximum operating operating volta voltage ge that that can can be used used on on an an inductive proximity sensor for increased electric requirements is ____________ VAC or ____________ VDC.
4)
___ ___ ____ ___ ____ ___ _ is a European uropean s system ystem of classification classification w hich indica indicates t he degree of prot ection an enclosure enclosure provides against dust, liquids, solid objects, and personnel contact.
5)
The maximum maximum sensi sensing ng ra range of an induc inductive tive pro proxi ximity mity sensor designated for greater rated distance is ____________ mm.
6)
___ ___ ____ ___ ____ ___ _ inductive proximit proximit y sensors sensors detect all meta met als without w ithout a reduction reduction factor.
53
Capacitive apaci tive Proximity roximit y Sensors Theory heor y of Operation perat ion
Capacitive proximity sensors are similar to inductive proximity sensors. sensors. The main difference betw een the t w o types t ypes is tha t hatt capacitive proximity sensors produce an electrostatic field instead of an electromagne elect romagnetic tic field. Capa Capacitive citive proximit y switches sw itches w ill sense metal met al as as w well ell as as nonmeta nonmet allic materials materials such as paper, glass, liquids, and cloth.
The sensing surface of a capacitive sensor is formed by two concentrically shaped metal electrodes of an unwound capacitor. When an object nears the sensing surface it enters the electrosta electrost atic f ield of the electrodes and cha changes nges the capacitance in an oscillator circuit. As a result, the oscillator begins oscillating. The trigger circuit reads the oscillator’s amplitude mplit ude and and w hen it reach reaches es a specific specific level level the t he output state of the sensor changes. changes. As the t arget m oves oves aw aw ay from f rom the t he sensor the oscillator’s oscillator’s amplitude decreases, decreases, switching sw itching the t he sensor output output ba back ck to its original original sta st ate.
54
Standard Stand ard Target Target and Dielect Dielect ric Constant
Standard Standard t arget argets s are specif sp ecified ied for each capacitive sensor s ensor.. The standard target is usually defined as metal and/or water. Capa pacitive citive sensors depend on the dielectric dielect ric constant of the target. The larger the dielectric number of a material the easier it is to t o detect. detect . The following follow ing graph graph shows show s the t he relationship relationship of the dielectric constant constant of a tar t arget get and the sensor’s ability ability t o detect the material based on the rated sensing distance (S r).
The following ta t able shows the t he dielectric dielectric constants of some m aterials. If, for example, a capacit capacitive ive sensor has a rated rated sensing distance distance of 10 mm m m and the t he tar t arget get is alcohol, alcohol, the effective sensing distance (S r) is approx approximately imately 85% of t he rated rated distance, distance, or 8.5 mm. mm . Ma te ria l A lc ohol A raldit e B ak elite Glas s M ic a Hard Rubber P aper-Bas ed Laminat e W ood Cable Cas ting Compound A ir, Vac uum Marble Oil-Impregnat ed Paper P aper P araffin P et roleum P lex iglas
Die l e ctric Constant
Ma te ri a l
Di e le ctri c Constant
25.8 3.6 3.6 5 6 4 4.5 2.7 2.5 1 8 4 2.3 2.2 2.2 3.2
Poly amide Poly ethy lene Poly proplene Poly s ty rene Poly viny l Chloride Porc elain Pres s board Silic a Glas s Si Silic a Sand Silic one Rubber Teflon Tu Turpentine Oil Trans former Oil Wat er Soft Rubber Celluloid
5 2. 3 2. 3 3 2. 9 4. 4 4 3. 7 4. 5 2. 8 2 2. 2 2. 2 80 2. 5 3
55
Detect De tect ion Throug Throug h Barriers Barriers
One application for capacitive proximity sensors is level detect det ection ion through t hrough a barrier. barrier. For For examp example, le, w water ater has a much higher dielectric than plastic. This gives the sensor the ability to “ see through” through” the plastic plastic and and detect the water.
Shielding
All Siemens capacit capacitive ive sensors are shielded. These sensors w ill detect conductive material such as copper, aluminum, or conductive fluids, and nonconductive material such as glass, plastic, cloth, clot h, and paper paper.. Shielded sensors can be flush f lush mounted mount ed w ithout adversely dversely affecting affecting t heir sensing sensing char chara acteristics. cterist ics. Ca Care must m ust be taken to ensure that t his type of sensor is used in a dry environment. Liquid on the sensing surface could cause the sensor to operate.
56
Capacitive Proximity Sensor Family
The 3RG16 product family identifies the Siemens capacitive proximity sensor. Units are available in DC or AC versions. Electronic controls such as SIMATIC® PLCs or relays can be controlled directly directly w ith the DC voltage version version.. In the t he case case of t he AC volt voltage age version version the t he load (contactor rel rela ay, solenoid valve) valve) is connected connected w ith the t he sensor sensor in series series directly directly to t o the AC voltage. Sensors Sensors are ava available ilable wit w ith h tw t w o-, three-, and and four-w four-w ire outputs.
Capacit ive Sensor Selection Guide
Housing Shielded Operating Dimension Material Sn (mm) Unshielded Voltage (mm) 18 30
40 40x40 (Limit Switch Style) 20x20 (Flat Pack)
Wires
Plas tic Met al Plas tic Met al Plas tic Plas tic Plas tic Plas tic Plas tic
Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded
5 10 10 10 10 20 20 20 20
10-65 VDC 20-250 VAC 20-250 VAC 10-65 VDC 10-65 VDC 20-250 VAC 10-65 VDC 20-250 VAC 10-65 VDC
3 3 2 4 4 2 4 2 4
Met al
Shielded
5
10-30 VDC
3
57
Review 4 1)
A main main diffe differen rence ce between an indu inductiv ctive e pro proxi ximity mity sensor and a capacitive proximity sensor is that a capacitive proximity sensor produces an ____________ field.
2)
Capa pacitive citive proximity proximity sensors w ill sense sense __ ____ ___ _____ ___ ___ material.
3)
The larger larger the ___ ____ ___ ___ ____ ___ __ constant constant of a material the easier ea sier it is for f or a capa capacitive citive proximity sense to detect. det ect.
4)
It is ea easier sier for a capa capacitiv citive e prox proximit imity y senso sensorr to detect detect ______ _________ _____ ___ _ than t han porce p orcelain. lain. a. teflon teflon b. marble marble c. petroleum petroleum d. pa paper per
5)
58
The maximum maximum rated rated sensing sensing distance distance of a capa capacitive citive proximity sensor is ____________ mm.
Ultrasonic Proximity roximit y Sensors Sensors Theory heor y of Operation perat ion
Ultrasonic proximity sensors use a transducer to send and receive high frequency sound signals. When a target enters the beam bea m t he sound is reflect reflected ed back back to the sw itch, causing causing it to energize or deenergize the output circuit.
Piezoelectric Disk
A piezoelectric ceramic disk is mounted in the sensor surface. It can transmit and receive high-frequency pulses. A highfrequency voltage is applied to the disk, causing it to vibrate at t he same f requency. requency. The vibrating disk d isk produces produce s high-frequency sound wa w aves. When transmitted transmitt ed pulses strike st rike a sound-reflecting sound-reflecting object, echoes are produced. The duration of the reflected pulse is evaluated at the transducer. When the target enters the preset operating operating range, range, the output of t he switch sw itch changes changes state. When t he tar t arget get leaves leaves the preset operating operating range, range, the t he output returns to its it s original original sta st ate.
59
The emitted pulse is actually a set of 30 pulses at an amplitude of 200 Kvolts. The echo can be in microvolts. m icrovolts.
Blind Zone
A blind zone exists directly in front of the sensor. Depending on the sensor the blind zone zone is from 6 to 80 cm. An object placed in the blind zone zone w ill produce an an unstable output.
Range Defini Defini t ion
The tim e interval between betw een the t ransmitt ransmitted ed signal signal and the echo is directly proportional proportional to t he distance distance betw een the object and sensor. sensor. The operating range range can be adjusted in term t erms s of its it s w idth and position w ithin t he sensing range. range. The upper limit can can be adjusted on all sensors. The lower limit can be adjusted only w ith certa cert ain versions. versions. Objects Objects beyond the upper limit do not produce a change at the output of the sensor. This is known as “ blanking blanking out out the t he ba back ckground” ground” . On some som e sensors, a blocking range range also exists. exist s. This is bet b etw w een the lower low er limit and the t he blind zone. zone. An An object in the blocking range prevents identification of a target in the operating range. There is a signal output assigned to both the operating range and the output range.
60
Radiation Pattern
The radiation pattern of an ultrasonic sensor consists of a main cone and several neighboring cones. The approximate approxim ate angle of t he m main ain cone is 5°. 5°.
Free Zones Zo nes
Free zones must be maintained around the sensor to allow for neighboring cones. The following examples show the free area required required for different diff erent situations.
Parallel Sensors
In the first f irst example, example, t w o sonar sonar sensors sensors with w ith t he same same sensing range range have been mounted m ounted parallel parallel to t o each other. The t arget argets s are vertical vertical to t o the t he sound cone. The dista dist ance betw een tthe he sensors is determined by the sensing range. For example, if the sensing range range of t he sensors sensors is 6 cm, cm , they must be located located at least least 15 cm apart.
t e g r a T
X t e g r a T
Sensing Range (CM) 6-30 20-130 40-300 60-600 80-1000
X (CM) >15 >60 >150 >250 >35 >350
61
M utual Interferenc Interference e
M utual utual interferenc int erference e occurs w hen sonar sonar devices are are mounted mount ed in close proximit proximit y to ea each ch other and and the t arget arget is in a position to to reflect echoes back back to a sensor in the proximity proximit y of the transmit transmitting ting sensor. sensor. In this case, case, the dist ance betw een sensors sensors (X) can be determined through experimentation.
Opposing Sensors
In the following example, example, tw t w o sonar sonar sensors sensors with w ith the t he same same sensing range have have been positioned posit ioned opposite opposi te of each each other. ot her. A minimum distance (X) is required between opposing sensors so that mutual interferance does not occur.
X
Sensing X Range (CM) (CM) 6-30 >120 20-130 > 400 40-300 >1200 60-600 >2500 80-1000 >40 >4000
62
Flat and Irregular Shaped Surface Surf aces s
Sonar sensors mounted next to a flat surface, such as a wall or smooth machine face, require less free area than sensors mounted next to an irregular shaped surface.
Sensing Range (CM) 6-130 20-130 40-300 60-600 80-1000
Angular Alignment
X (CM)
Y (CM)
>3 >15 >30 >40 >70
>6 > 30 > 60 > 80 >150
The angle angle of the t arget arget entering ent ering the sound cone must m ust also be considered. considered. The ma m aximum devia deviation tion f rom t he send direction t o a flat surface is ±3°.
If the t he angle were greater than t han 3° t he sonic pulses w ould be reflected away and the sensor would not receive an echo.
63
Liquids and Coarse-Grained Materials
Liquids, such as water w ater,, are also also lim ited it ed to t o an angular angular alignm alignment ent of 3°. Coarse-grained materials, such as sand, can have an angular angular deviation as much m uch as as 45°. 45°. This is because b ecause the sound s ound is reflect ed over a larger angle angle by coarse-gra coarse-grained ined m aterials.
Blanking Out Objects
An object ma m ay be located located in t he vicinity of the sound cone that causes improper operating of t he sensor. These objects object s can be blanked out by using an aperture made of a sound absorbing material mat erial such such as rock rock wool. w ool. This narrow narrow s the t he sound cone and prevents prevents pulses from f rom reaching reaching the interfering int erfering object.
64
Operating Operating M odes
Sonar Sonar sensors can can be setup set up to t o operate in several different modes: diffuse, reflex, and thru-beam.
Diffuse Mode
This is the standard mode of operation. Objects, traveling in any direction into t he operating operating range of the t he sound cone, w ill cause cause the sensor output t o sw switch itch states. This mode of operation operation is similar to a proximity sensor.
Reflex M ode
The reflex mode uses a reflector located in the preset operating range. range. The operating oper ating range is adjusted for t he reflect ref lector. or. The pulses are bounced off the reflector and the echo pulses are returned to the sensor. When a target blocks the echo pulses the output is activated. Typically used in applications where the target is not a good sound absorber.
Thru-Bea Thru-Beam m M ode
Thru-bea hru-beam m sensors consist consist of a transmitt transmitter er,, which w hich emits emit s ultrasonic pulses, and a receiver. If the beam between the transmitter and and the receiver receiver is interrupted interrupted the t he output of the receiver receiver switches sw itches state.
65
Environ m ental Influences
Sound travel time can be affected by physical properties of the air. This, in turn, can affect the preset operating distance of the sensor. Conditi on Temper emperatu ature re Pre Pressur ssure
Vacu Vacuu um Humid midity ity
Air Currents
Gas
Precipi Precipitatio tation n
Paint Mist Dus t
66
Effe ct Sonic Sonic wav wave e sp spee eed d ch chan ange ges s by 0.17 0.17%/° %/°K. Most Most sensors have have a compensation adjustment. With With normal atm atmo osph spheric va variati iatio on of of ±5%, sou sound velocity varies approximately ±0.6%. ±0.6%. Sound velocity velocity decreases 3.6% between sea level and 3 km above sea level. Adjust sensor for appropriate operating range. Sensor sors wi will not op operate in a vacuu cuum. Sou Sound ve velocit locity y incr incre eases ses as as hu humid midity ity incr incre eases. ses. Th This leads to the impression of a shorter distance to the target. The increase of velocity from dry to moisturesaturated air is up to 2%. Wind Speed <50 km/h - No Effect 50 - 100 km/h - Unpredictable Results >100 km/h - No Echo Received by Sensor Sens ors are designed for operation in normal atmospheric conditions. If sensors are operated operated in other types of atmospheres, such as carbon dioxide, measuring errors will occur. Rain or snow of norm normal al density density doe does s no nott impair impair the operation of a sensor. The transducer surface should be kept dry. Paint mist in the air will have no effect, however, paint mist should not be allowed to settle on transducer surface. Dust y environment s c a an n lower sens in ing range 25-33%.
Review 5 1)
Ultra Ultrason sonic ic prox proximity imity senso sensors rs use use h hig igh h freque frequenc ncy y ____________ signals to detect the presence of a target.
2)
The blind blind zone of an an ultras ultrasoni onic c prox proximity imity sensor sensor ca can be f rom _____ _______ _____ _____ __ - _____ _______ _____ _____ __ cm, cm , depe d ependi nding ng on the sensor. sensor.
3)
The a appr ppro oximate ximate an angl gle e of the main main soun sound d cone cone o off an ultrasonic proximity sensor is ____________ degrees.
4)
The free zone zone betw between een tw o p pa arallel rallel ultrasoni ultrasonic c sens sensors ors w ith a rated rated sensing range range of 20-130 20-130 cm must be greater than ____________ cm.
5)
The ma maximum ximum ang angle le of devi devia ation from the send send direction of an ultrasonic sensor to a flat surface is ____________ degrees.
6)
____ ___ ____ ___ ____ mode is the standa standard rd mode of opera operation for an ultrasonic sensor.
67
Ultrasonic Proximity roximit y Sensor Sensor Family Family
The ultrasonic ult rasonic proximit y sensor family consists consist s of a Thru-Bea hru-Beam m sensor senso r, compact com pact range (M 18, Com Compact pact Range 0, I, II, and and III), and modular (Modular Range II) sensors.
Thru-Beam
68
Thru-Bea hru-Beam m sensors consist of a tra t ransm nsmitt itter er and a receiver. The transmit transmitter ter sends a narrow narrow continuous tone. When a t arget is positioned betw een the tra t ransmitt nsmitter er and and the receiver receiver the tone t one is interrupted, which w hich causes causes the output of the receiver to change change state. st ate. The operating voltage is 20-30 VD VDC. C. The sw itching frequency is 200 Hz at 40 cm sensing distance.
Thru-Beam Receivers
There are two receivers available for the Thru-Beam sensors. Both use a PNP transistor tr ansistor.. One receiver provides a normally open (NO) contact and the other provides a normally closed (NC) (NC) contact. cont act.
The sensitivity and frequency setting of the Thru-Beam sensors is a function of the X1 connection on the receiver. Rec eceiv eiver er
Dis isttan anc ce (cm)
X1 Open X1 to LX1 to L+
5-150 5-80 5-40
Switching Frequency (Hz) 100 150 200
The minimum minim um size of a detectable object object is a function of the distance between betw een the tra t ransmitt nsmitter er and and the receiver. receiver. If the t he distance between betw een the t ransmitt ransmitter er and and the t he receiver receiver is less than 40 cm and and the mini m inimum mum ga gap p w idth between betw een two tw o objects objects is at at least 3 cm, objects of 2 cm or larger will be detected. If the distance between the sensors is less, even gaps of less than 1 mm can can be detected. At m aximum sensing distance, objects objects greater greater than 4 cm w ill be detected, provided provided the gap between betw een objects is greater greater tha t han n 1 cm. cm .
69
Com pact Range 0
Compact Range Range 0 sensors s ensors are ava available ilable wit w ith h an integrated int egrated or an separat separat e tra t ransducer. nsducer. They are are configured conf igured w ith it h a normally open (NO), normally closed (NC) or analog output. These sensors have a cubic shape (88 x 65 x 30 mm m m ). The sensors operate operat e on 18 35 VDC and can handle a load up to 100 mA.
Depending on the sensor, the sensing range is either 6 - 30 cm (separate (separate tra t ransducer) nsducer) or 20 - 100 100 cm (integrated transducer) t ransducer).. Switching frequencies vary from 5 Hz to 8 Hz. Compact Range 0 sensors ha have ve background background suppression. sup pression. This m eans the upper limit of t he sensing sensing range range is adjustable adjustable wit h a potentiomet er. er. Targets argets w ithin t he sensing range range but beyond beyond the t he switching sw itching range of the upper limit will not be detected.
70
Com pact Range I
Compact Range Range I sensors are availa available ble w ith it h a normally open (NO) or a normally closed (NC) contact. They are also available w ith t w o outputs, output s, one normally normally open (NO) (NO) and and one normally closed close d (NC (NC). ). These sensors sens ors have a c cylind ylindrical rical shape (M30 (M 30 x 150 mm). Several versions are available, including a separate transducer (shown) and a tilt ing head (not show n). The sensors operate on 20 - 30 VDC and can handle a load up to 200 mA.
Depending on the sensor the sensing range is either 6 - 30 cm, 20 - 130 cm, 40 - 300 cm, or 60 - 600 cm. Switching frequencies vary from 1 Hz to 8 Hz. Compact Range I sensors have ha ve background and foreground suppression. This m eans the upper and and lower limit s of the sensing range range are are adjustable adjustable with w ith separate potentiometer. Targets within the sensing range but beyond beyond the sw itching range range of the t he upper and lower limits limit s will w ill not be detected.
71
SONPROG
The ultrasonic sensors discussed so far (Thru-Beam, Compact Range 0, and Compact Range I) are either nonadjustable or can be adjusted manually with potentiometers. SONPROG is a computer comput er progra program, unique to Siemens, that is used to t o adjust adjust Compact Range II, Compact Range III, and Compact Range M 18 sensors. sensors. Se nsor Thru-Beam Comp mpa act Range Comp mpa act Range Compact Ra Range Comp mpa act Range Compa Compact ct Rang Range e
Adj ustme nt None 0 1 Po Poten tentio tiome mete terr I 2 Pote Poten ntio tiome mete terrs II SONPROG IIIII SON SONPR PRO OG M18 M18 SONPR SONPROG OG
W ith it h SONPR SONPROG sonar sensors can can be m atched individually to to the requirements of a particular application. An interface is connected between the sensor and an RS232 port of a computer. SONPROG can be used to set the following parameters: • • • • • • •
Beginning and end of switching range Sw itching hysteresis hysteresis Beginning and end of ana analog log charact characterist eristic ic End of blind bli nd zone zone End of sensing range range NO/NC contacts Potentiomet otent iometer er adjustm adjustments ents on sensors sensors on/off
These values can be print ed out and stored in a file. f ile. They are immed im mediately iately availa available ble w hen needed. When replacing a sensor, sensor, for example, the stored parameters can be easily applied to the new sensor.
72
Com pact Range II
Compact Range II sensors are similar in appearance to Compact Range I sensors. A major difference is t hat Compact Ra Range nge II sensors can be adjusted manually or with SONPROG. They are available vailable w ith it h a normally norm ally open (NO) or a normally closed (NC) (NC) contact. They are also available with two outputs, one normally open (NO) and and one norm ally closed (NC). (NC). These sensors sen sors have a cylindrical shape shape (M 30 x 150 mm m m ). Severa Severall versions are available, including a separate transducer. The sensors operate on 20 - 30 VDC and can handle a load up to 300 mA. Compact Range II sensors can be synchronized synchronized tto o prevent mut mutual ual interference when w hen using using multiple mult iple sensors sensors in close close proximity t o each other.
Depending on the sensor the sensing range is either 6 - 30 cm, 20 - 130 cm, 40 - 300 cm, or 60 - 600 cm. Switching frequencies vary from 1 Hz to 8 Hz. Compact Range II sensors have ha ve background and foreground suppression.
73
Com pact Range II Analo g Version Version
An analog version of the Compact Range II sensor is available. The analog measurement is converted by the sensor to digital pulses. A counter in LOGO! LOGO! or a PLC PLC counts t he pulses and makes the measurement conversion. If, for example, the switching sw itching output of the sensor were set such that 50 Hz w as equiva equivalent to t o 50 cm and the gate time tim e of LOG LOGO! was set for f or 1 second, LOG LOGO! O! w ould be able to t o accurately accurately convert an any y frequency to its correspondin corresponding g dist ance.
Com pact Range III
Like the t he Compact Ra Range nge II sensors, Compact Range Range III sensors can be adjust ed m manually anually or w ith it h SONPROG. SONPROG. They are available available with a normally open (NO) or a normally closed (NC) contact. They are also available with two analog outputs, 0 - 20 mA or 0 10 V VDC. DC. The sensors senso rs operate op erate on 20 - 30 30 V VDC DC and can handle a load up to 300 mA. Compact Range III sensors can be synchronized to prevent mutual interference when using multiple sensors in close proximity to each other. In addition, they offer an arithmetic mean feature. This is useful for liquid level sensing or other applications where reflection variations can occur. occur. The arithmeti arithm etic c mean m ean feature feature helps help s compensate com pensate for these variations.
74
Depending on the sensor, the sensing range is either 6 - 30 cm, 20 - 130 cm, 40 - 300 cm, 60 - 600 cm, or 80 - 1000 cm. Switching frequencies vary from 0.5 Hz to 5 Hz. Compact Range III sensors have background and foreground suppression.
Com pact Range M18
The small size (M18 x 101 mm) of the Compact Range M18 sensor makes makes it suited for applications applications w here space space is limited. lim ited. Compact Range Range M 18 sensors are ava available ilable wit w ith h a normally open (NO) or a normally closed (NC) contact. They are also available with an analog output (4 - 20 mA, 0 - 20 mA, or 0 - 10 VDC). VDC ). The sensors sen sors operate op erate on 20 - 30 VDC VDC and and can handle a load up to 100 mA.
Depending on the sensor the sensing range is either 5 - 30 cm or 15 - 100 cm and the switching frequency is either 4 or 5 Hz. Compact Range M18 M 18 sensors have have background suppression.
75
Com pact Range Range w it h for use wi t h AS-i AS-i
Siemens also manufactures ultrasonic sensors for use with AS-i. Four sensing ranges are available: 6 - 30 cm, 20 - 130 cm, 40 - 300 cm, cm , and and 60 - 600 cm. The swit sw itching ching frequency varies varies from 1 to 8 Hz.
Modular Range II and t he Signal Evalua Evaluato to r
The next group of ultrasonic ult rasonic sensors is M odular Range Range II. The Modular Range II consists of sensors and their corresponding signal evaluat evaluat or.The signal evaluato evaluatorr is required requir ed for M odular Range II sensors. Sensor Sensor values values are set using butt ons on the t he evaluator. evaluator. A tw t w o-line LCD LCD displays the set values. values.
76
The signal evaluator can operate a maximum of two Modular Range II sensors. It is supplied with a 20 - 30 VDC power supply. supply. It ha has s tw o sw switching itching outputs, one error error output output,, and and one analog output.
M odu lar Range Range II Sensors Sensors
M odule Range Range II sensors are ava available ilable in t hree versions: cubic sensors, cylindrical sensors, and spherical sensors. They have analog ana log and normally norm ally open (NO) or normally closed (NC) (NC) outputs. output s. As mentioned earlier, all settings and operations are done with a signal evaluator.
77
Depending on the sensor the sensing range is either 6 - 30 cm, 20 - 130 cm, 40 - 300 cm, 60 - 600 cm, or 80 - 1000 cm. Switching frequencies vary from 1 Hz to 20 Hz. Modular Range II sensors have background background and foreground suppression.
Accessories
78
An adjusting device with a mounting flange (shown) or bracket (not shown) show n) and and a 90° diverting divert ing reflect ref lector or are are availa available ble for M 30 spherical sensors. The adjusting device allow allow s the t he sensor to t o be positioned posit ioned in hard-to hard-to-mount -mount areas. areas.
Review 6 1)
Ultrasonic Ult rasonic ____ ______ ____ ____ ____ __-_ -___ ____ ____ ____ ____ ___ _ proximity proximit y sensors require a separat separat e tra t ransm nsmitt itter er and receiver. receiver.
2)
If X1 X1 is conn connec ected ted to L+ of a Thruhru-B Bea eam m ultraso ultrasoni nic c proximity sensor, the sensing range is ____________ to __________ ____________ __ cm .
3)
The maximum maximum sensing sensing range range of a Compact ompact Ra Range 0 ultrasonic ult rasonic sensor se nsor w ith it h a ____ ______ ____ ____ ____ __ t ransducer ransduce r is 6 - 30 cm.
4)
Compact Ra Range _ __ _____ ___ ____ ___ __ does not not offer foreground suppression. a. 0 b. I c. II d.III
5)
____ ___ _____ ___ ___ is a computer comput er progra program m used to adjust adjust Compact Range II, Compact Range III, and Compact Range M18 ultrasonic sensors.
6)
____ __ ____ ____ ____ ____ __ Ra Range nge IIII require a signal evaluator. evaluator.
7)
A signa signall eva evalua luator tor can can oper opera ate a maximum maximum of ____________ sensors. a. 1 b. 2 c. 3 d. 4
79
Photoelectri hotoelec tricc Sensors Theory of Operation
A photoelectric sensor is another another type t ype of position sensing device. Photoelectric sensors, similar to the ones shown below, use a modulated modulated light beam t ha hatt is either broken broken or reflected reflect ed by the target.
The control consists of an emitter (light source), a receiver to detect the em itted light, and and associa associated ted electronics that evaluate and amplify the detected signal causing the photoelectric’s output switch sw itch t o change change state. We are all all fa f amiliar w ith t he simple application application of a photoelectric photoelectric sensor placed placed in the entrance of a store to alert the presence of a customer. This, of course, is only one possible application.
80
M odulated Light Light
M odulated odulated light increases increases the sensing range range w hile reducing reducing the t he effect of ambient light. M odulated odulated light is pulsed at at a specific frequency bet w een 5 and 30 KHz. KHz. The photoelect phot oelectric ric sensor is able to distinguish the modula m odulated ted light from f rom ambient ambient light. light . Light sources sources used by these sensors range range in the light spectrum f rom visible green to invisible infrared. Light-emitting diode (LED) sources are typically used.
Clearance
It is possible that t wo photoelectric devices opera operating in close proximit y to t o each other can cause cause interference. int erference. The problem may be rectif ied w ith alignment or covers. covers. The follow ing clearances between sensors are given as a starting point. In some cases it may be necessary to increase the distance betw een sensors. sensors.
Sensor Mod Sensor Model el D4 mm / M5 M12 M18 K 31 K 30 K 40 K 80 L18 L50 (Diffus e) L50 L50 (Thr (Thruu-Be Beam am))
Distance Distanc e 50 mm 250 mm 250 mm 250 mm 500 mm 750 mm 500 mm 150 mm 30 mm 80 mm mm
81
Excess Gain
Many environments, particularly industrial applications, include dust, dirt, smoke, moisture, or other airborne contaminants. A sensor operating in an environment that contains these contaminants contam inants requires m ore light t o operate properly. There are six grades of contamination: 1. 2. 3. 4. 5. 6.
Clean lean Air (Ide Idea al condition condition,, clima climate te controlled controlled or sterile) sterile) Slight light Contamina Contamination tion (Ind (Indoor oor,, nonin nonindustria dustriall area areas, s, office office buildings) Low Lo w Con ontamin tamina ation (Wa (Ware reho hous use, e, ligh lightt indus industry try,, materia materiall handling operat operat ions) M ode odera rate te Con Contamin tamina ation (M illing illing ope opera ration tions, s, high high humidity humidit y, steam) High Contamina ontamination tion (Hea (Heavy vy pa particle la laden air, ir, e extreme xtreme wash down environments, grain elevators) Extreme/Sev xtreme/Sever ere eC Conta ontamina mination tion (C (Coa oall bins, bins, resid residue ue on on lens) lens)
Excess Excess gain gain represents represents t he a amount mount of light emitted emitt ed by the transmit transmitter ter in excess excess of the t he a amount mount required required to operate the receiver. receiver. In clean environments environment s an excess gain gain equal to t o or greater than 1 is usually sufficient to operate the sensor’s receiver. receiver. If, for exam exam ple, an environment contained enough airborne contamina contaminants nts to t o absorb absorb 50% of the t he light emitted emit ted by the tra t ransmitt nsmitter er,, a minimum excess excess gain gain of 2 would w ould be required required to operate the sensor’s receiver. Excess Excess gain is plott ed on a logarit logarithm hmic ic chart. The example shown below is an excess gain chart for an M12 thru-beam sensor. If the required sensing distance is 1 m there is an excess gain of 30. This means there is 30 times more light than required in clean cl ean air air hitting hitt ing the t he receiver. Excess Excess gain decreases decreases as sensing distance increases. Keep in mind that the sensing distance for thru-bea thru-beam sensors sensors is from the tra t ransmitt nsmitter er to the t he receiver and the sensing distance for reflective sensors is from the transmitter to the target.
82
Sw it ching Zones Zones
Photoelectric Photoelect ric sensors have a swit sw itching ching zone. zone. The sw itching it ching zone is based on the beam pattern and diameter of the light from the sensor’s sensor’s emitt em itter er.. The receiver receiver w ill operate operate w hen a target enters this area.
Symbols
Various symbols are used in the Sensor catalog (SFPC-08000) to help identif y the t ype of photoelectric phot oelectric sensor. sensor. Some Some symbols are used to indicate a sensor’s scan technique, such as diffuse, retroreflective, or thru beam. beam. Other Ot her symbols identify a specific specific feature of t he sensor, such such as fiber-opt fiber-optics, ics, slot, slot , or color sensor.
83
Scan Techni Techniqu qu es
A scan scan tec t echnique hnique is a method used by photoelectric phot oelectric sensors to detect an object object (target). In In part, the best technique to use depends on the target. Some targets are opaque and others are highly reflective. In In some cases it is necessary necessary to detect a change change in color. Scanning Scanning distance dist ance is also a factor in selecting select ing a scan scan tech t echnique. nique. Some Some techniques techniques w ork well w ell at greater distances while others work better when the target is closer to the sensor. sensor.
Thru-Beam
Separa Separatt e emitt em itter er and and receiver unit s are required for a thru-bea t hru-beam m sensor. sensor. The units unit s are aligned aligned in a way that t he greatest possible amount of pulsed light f rom the t he transmitt transmitt er rea reaches ches the receiver. receiver. An object (target) placed placed in the path of the t he light beam blocks blocks the light t o the t he receiver receiver, causing causing the receiver’s output to cha change state. When the t he tar t arget get no longer blocks blocks the t he light pa path th the receiver’s receiver’s output returns to its it s normal state. state. Thru-beam is suitable for detection of opaque or reflective objects. It cannot cannot be used to detect transparent transparent objects. In addition, vibra vib rati tion on can cause alignm alignment ent problems. problem s. The high excess gain of thru-beam sensors make them suitable for environments environments w ith airborne contaminants. The m aximum sensing range is 300 feet.
Thru-Beam Effective Beam
84
The effective effecti ve beam of a photoelect phot oelectric ric sensor is the region of the bea beam’s m’s diameter w here a target target is detected. detect ed. The effective beam on a thru-beam sensor is the diameter of the emitter and receiver receiver lens. The effective effect ive beam beam extends from f rom t he em emitt itter er lens to the receiver receiver lens. lens. The minimum m inimum size size of the target should equal equal the t he diamet diameter er of the t he lens.
Reflective or Retroreflective Scan
Reflective eflect ive and and retroreflect ive scan scan are tw o names for the t he same technique. The emitter and receiver are in one unit. Light from the emitter em itter is tra t ransmitt nsmitt ed in a straight straight line to t o a reflector reflector and returns t o the t he receiver. receiver. A normal norm al or a corner-cube corner-cube reflect or can be used. When a target target blocks the light path the t he output of the sensor changes state. When the target no longer blocks the light path the sensor returns returns to t o its it s normal sta st ate. The max m aximum imum sensing range is 35 feet.
Retroreflective Scan Effective Beam
The effective beam beam is tapered from the sensor’s lens to the edges of t he reflector. The minimum minim um size size of the t arget arget should equal equal the t he size size of the reflector.
Reflectors
Reflectors are ordered separately from sensors. Reflectors come com e in various sizes and can can be round or rect angular angular in shape or reflective t ape. The sensing distance is specified w ith a particular pa rticular reflect reflector or.. Reflect Reflective ive tape should not be used w ith polarized retroreflective sensors.
85
Retroreflective Scan and Shiny Shiny Object s
Retroreflective scan sensors may not be able to detect shiny objects. Shiny objects reflect light back to the sensor. The sensor is unable unable to differentiate betw een light light reflected ref lected from a shiny object object and light reflected reflect ed from a reflector. reflector.
Polarized Retroreflective Scan
A variation of retroreflective scan is polarized retroreflective scan. Polarizing filters are placed in front of the emitter and receiver lenses. The polarizing filter projects the emitter’s beam in one plane only. only. This light is said t o be polarized. polarized. A corner-cube corner-cube reflector must be used to rotate the light reflected back to the receiver. receiver. The polarizing polarizing filt f ilter er on the t he receiver allow allows s rotated rot ated light to pa pass ss throug t hrough h to t o the t he receiver receiver. In comparison comparison to t o retroreflective retroref lective scan, scan, polariz polarized ed retroreflective scan works w ell w hen trying to to detect shiny objects. objects.
86
Diffuse Scan
The emitter emit ter and receiver receiver are are in one unit. Light from the emitt em itter er strikes the target and the reflected light is diffused from the surface at all angles. If the receiver receives enough reflected light light the output w ill switch states. When no light light is reflected back ba ck to t he receiver receiver the output out put returns to its original original sta st ate. In diffuse scanning scanning the emitt er is placed placed perpendicular perpendicular to t o the t he target. The receiver will be at some angle in order to receive some of the scattered (diffuse) reflect reflection. ion. Only a small amount amount of light will reach the receiver, therefore, this technique has an effect effe ctive ive range of about 40”.
Diffuse Scan Correction Factors
The specified sensing range of diffuse sensors is achieved by using a matte white paper. The following correction values may be applied t o other ot her surfaces. These values are are guidelines guideli nes only and some trial and error may be necessary to get correct operation. Test Card (M at t e W hit e) W hit e Paper Gray PVC Print ed New spaper Light ly Colored Wood Cork W hit e Plast ic Black Plast ic Neoprene, Black Aut om obile Tires Alum inum , Unt reat ed Alum inum , Black Anodized Aluminum, Aluminum, M Ma atte (Bru (Brushe shed d Finis Finish) h) St ainless St eel, Polished
100% 80% 57% 60% 73% 65% 70% 22% 20% 15% 200% 150% 120% 230%
87
Diffuse Scan Scan w it h Background Suppression
Diffuse scan scan w ith ba backg ckground round suppression suppression is used to t o detect objects up to t o a certain certain distance. Objects Objects beyond the specified distance dist ance are are ignored. Background Background suppression is accomplished accomplis hed w ith a position position sensor detector (PS (PSD). D). Reflect Reflected ed light f rom the t he target hits the PSD at different angles, depending on the distance of the target. The greater greater the t he dista dist ance the t he narrower narrower the t he angle of the reflected ref lected light.
Diffuse Scan Effective Beam
The effective beam beam is equal equal to the size of the t arget w hen located located in the beam pattern.
88
Operating Operating M odes
There are tw o operating modes: mod es: dark operate (DO) and light operate (LO). Dark operate is an operating mode in which the load load is energiz energized when w hen light light f rom the t he emitter emitt er is absent absent from f rom the t he receiver.
Light operate is an opera operating m ode in w hich the load is energiz energized ed w hen light f rom the em itter reaches reaches the receiver receiver.
The following follow ing ta t able shows the relationship betw een operating operating mode and load status for thru, retroreflective, and diffuse scan.
Oper erat atin ing g Mo Mod de
Lig igh ht Pa Patth
Load Stat atu us Thru San and Diffuse Retroreflective Ligh ight Op Operate (L (LO) Not Bl Blocke cked Energized zed Deenergize ized Bloc k ed Deenergized Energiz ed Dark Op Operate (DO) Not Blo Blocke cked d Deenergize ized Ene Energize ized Bloc k ed Energiz ed Deenergiz ed
89
Fiber Opt ics
Fiber optics is not a scan technique, but another method for transmitting light. Fiber optic sensors use an emitter, receiver, and a flexible cable cable packe packed d w ith t iny fibers tha t hatt transmit transmit light. Depending on the sensor there may be a separate cable for the emitt emi tter er and and receiver, or it may m ay use a single cable. W hen a single cable is used, the emitter and receiver use various methods to distribute emitter emitt er and and tra t ransmitt nsmitter er fibers w ithin a cable. cable. Gla Glass ss fibers are are used w hen the emitter em itter source is infrared light. Pla Plastic stic fibers are are used when w hen the emitt em itter er source source is visible light. light.
Fiber optics can be used with thru-beam, retroreflective scan, or diffuse scan sensors. In thru beam light is emitted and received w ith individual individual cables. cables. In retroreflective and diffuse scan scan light is emitted and received with the same cable (bifurcated). Fiber optics is ideal for small sensing areas or small objects. Fiber optics have a shorter sensing range due to light losses in the fiber optic opt ic cables. cables.
90
Lasers
Lasers are sometimes used as sensor light sources. Siemens uses Class 2 lasers which have a maximum radiant power of 1 mW. Class Class 2 lasers require no protect p rotect ive measures m easures and and a laser protection officer is not required. However, a warning notice must be displayed when laser sensors are used. Laser sensors are available in thru-beam, diffuse scan, and diffuse diff use scan wit w ith h background background suppression versions. Lasers Lasers have have a high high intensity intensit y visible light, w hich hich ma m akes setup and adjustm adjustment ent easy. Laser technology allows for detection of extremely small objects object s at a distance. dist ance. The Siemens L18 sensor, for examp example, le, w ill detect an object of 0.03 mm at a distance of 80 cm. Examples Examples of laser sensor applications include exact positioning, speed detection, or checking thread thickness of 0.1 mm and over.
91
Review 7 1)
M odu odula lated ted ligh lightt of a Sie Siemens mens pho photoel toelec ectric tric sen senso sorr is pulsed at a frequency between ____________ and __________ KHz.
2)
Excess Excess __ ______ ___ _____ ___ _ is a measurement of the t he amount amount of light falling falling on the receiver in excess excess of t he minimum minim um light required to operate the sensor.
3)
___ ___ ___ ___ ____ ___ __ is a scan scan technique technique in w hich hich the emitter emitt er and receiver receiver are are in one unit. Light from the em itter is transmit transmitted ted in a straight straight line to t o a reflector and returned returned to the receiver.
4)
Polariz olarizing ing filters on on a retroreflective retroreflective scan scan senso sensorr orientate planes of light ____________ degrees to one another.
5)
The corr correc ection tion factor factor for diffuse diffuse sca scan n of cork cork with a photoelectric sensor is ____________ %.
6)
_____ ___ ___ ___ ____ operate operate is an an operating operating mode in w hich the load is energiz energized ed when w hen light from the emitter em itter of a photoelectric sensor is absent f rom t he receiver receiver.
7)
Fiber iber optics optics is is a scan scan techn techniq ique ue.. a. true true b. false false
8)
92
Siemens laser laser photoelectric photoelectric sensor sensors su use se Class lass __________ ____________ __ lasers lasers..
Photoelectric Family of Sensors
Siemens offers a w ide variety variety of photoelectric sensors, including thru-beam, retroreflective scan, and diffuse scan sensors. There are many photoelectric sensors to choose from. Choice depends on many factors such as scan mode, operating voltage, voltage, environment, environment, and output configurations. configurations. M ost of these sensors can be used with some or all scan techniques. In addition, specializ sp ecialized ed sensors such su ch as fiber opt ic, laser, laser, and color sensors are ava available. ilable. To help simplif sim plify y tthe he process of determining the right sensor selection guides are provided. These guides do not list all the features of a given sensor. For a more deta det ailed description refer t o the t he appropria appropriate te cat cat alog.
93
Thru-Beam Thru-Beam Sensors Sensors S e nsor D4/M5 M12 M18 M18M M18P K30 K35 K40 K50 K65 K80 L18 (Laser)
Ra nge
Vol ta ge
25 2 50 mm 4m 6m 12 m 12 m 12 m 5m 15 m 5m
10-30 VDC 10-30 VDC 10-36 VDC 10-30 VDC 10 10-30 VDC 10 10-36 VDC 10-30 VDC 10-36 VDC 10-30 VDC 15-264 VAC 50 m 10 10-30 VDC 50 m 10-36 VDC 20-320 VAC
50 m
10-30 VDC
Output Mode PNP PN P NPN NPN Relay DO LO X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X
X
X
X X
X X
X
X
ASS-ii M8 X
X X X X
X
Conne ction M12 M1 2 Cab able le Te Terrmi mina nals ls X X X X X X X X X X X X X X X X X
X
X
X
X
Housing Met al Met al Met al Met al Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Met al
Retro reflecti ve Sensors Sensors S e nsor M12 M18 M18M M18P K20 K30 K35 K40 K50 K65 K80 L50 (Laser) Light Array C40
94
Ra nge
Vol ta ge
1. 5 m 2m 2m 2m 2.5 m 4m 2. 5 m 6m 4m
10-30 VDC 10-36 VDC 10-30 VDC 10-30 VDC 10-30 VDC 10 10-36 VDC 10-30 VDC 10 10-36 VDC 10-30 VDC 15-264 VAC 8m 10-30 VDC 6m 10-36 VDC 20-320 VAC 12 m 10-30 VDC
Output Mode PNP PN P NPN NPN Relay DO LO X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X
X
X
1. 4 m
12-36 VDC
X
6m
10-36 VDC
X
X
X X
X X
X
X
X X
X
ASS-ii M8
X X X X X
X
Conne ction M12 M1 2 Cab able le Te Terrmi mina nals ls X X X X X X X X X X X X X X X X X
X
X
X
X X
X
Housing Met al Met al Met al Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Met al Plas tic
X
Plas tic
Diffuse Sensors S e nsor D4/M5 M12 M18 M18M M18P K20 K30 K35 K40 K50 K65 K80 C40
Ra nge
Vol ta ge
50 mm 30 c m 60 c m 30 c m 30 c m 30 c m 1. 2 m 50 c m 2m 90 c m
10-30 VDC 10-30 VDC 10-36 VDC 10-30 VDC 10-30 VDC 10-30 VDC 10-36 VDC 10 10-30 VDC 10-36 VDC 10-30 VDC 15-264 VAC 2m 10-30 VDC 2m 10-36 VDC 20-320 VAC 2.5 c m 10-30 VDC
Output Mode PNP PN P NPN NPN Relay DO LO X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X
X X
X
X
X
X X
X X
X
X
ASS-ii M8 X
X X X X X
X
Conne ction M12 M1 2 Cabl able e Te Terrmi minal nals s X X X X X X X X X X X X X X X X X X
X X
X
Housing Met al Met al Met al Met al Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic Plas tic
Diffuse Sensors with Background Background Suppression Suppression S e nsor
Ra nge
M18 M18P K20 K50
120 mm 100 mm 100 mm 25 c m
K65 K80 L50 (Laser) C40
Vol ta ge
10-36 VDC 10-30 VDC 10-30 VDC 10-30 VDC 15-264 VAC 50 c m 10 10-30 VDC 1m 10-36 VDC 20-320 VAC 150 mm 10-30 VDC 2.5 c m 10-30 VDC
Output Mode PNP PN P NPN NPN Relay DO LO X X X X X X X X X X X X X X X X X X X
X X
X X
X X
X
X
X
X
X
X
X
Conne ction AS-i S-i M8 M1 M12 2 Cabl able e Te Terrmi minal nals s X X X X X X X X X X X
X
X
X
X
X
X
X
X
Housing Met al Plas tic Plas tic Plas tic Plas tic Plas tic Met al Plas tic
95
Teach In
Some of the following sensors, such as the CL40, have a feature know n as Teach each In. This feature feat ure allows allow s tthe he user t o teac t each h the sensor what it should detect. detect . An object object to t o be detected is placed placed in front of the sensor so that that it knows know s w wha hatt t he a accepted ccepted reflected light is. The sensor is then t hen programm programm ed to t o respond only to t o this t his light . The CL40 uses a “ SET SET” butt button on tto o Teach each In. Other sensors have different methods to Teach In. Teach In can be used t o detect det ect a specific color, color, for example. Teach each In also w orks to detect tra t ranspa nsparent rent objects.
Fiber Optic Sensors
The basic operation is the same for optical fibers made of glass or plastics. plastics. Optical fibers are are fitt ed in front of t he transmitt transmitt er and and receiver and extend the “eye” of the sensor. Fiber optic cables are small and flexible and can be used for sensing in hard to access places.
96
Laser Diffuse Sensor w ith Analog Analog Output
The analog laser sensor is able to measure the exact distance of an object within its sensing range. This sensor uses a visible laser light with a highly accurate and linear output.
Col or BER BERO
The color BERO BERO uses 3 LEDs wit w ith h the t he colors red, green, and blue. Light is emitted em itted t o the targ t arget et and can can detect a specific specific color of reflect ref lected ed light . This sensor uses Teach each In to t o set t he color to be detected. The CL40 is also a fiber optic device.
Color Mark BERO
The color mark m ark BER BERO is also used t o detect det ect specific specif ic colors. This sensor works differently from the CL40. The color mark BERO uses green or red light for the emitter. The color is selected dependent on the t he contrast contrast of the t arget. arget. The target and background background color can be set separat separat ely.
97
Slot BERO
The tar t arget get is placed placed inside the t he slot of the sensor. sensor. Emitted light passes through the object. Different contrast, tears, or holes in the t arget arget w ill vary vary the quantity quantit y of light reaching reaching the receiver. receiver. This sensor uses Teach each In. It is available available w ith it h inf rared or visible red/green light
Selection Guide Sensor Type Fiber Optic
Laser Diffuse Analog Output Color BERO Color Mark BERO Slot BERO
Sens Sen sor
Ran ange ge
Volt Vo ltage age
K35 KL40 K30 K40 L50
75 mm 280 mm 120 mm 150 c m 45-85 mm
10 1 0-30 VDC 10 10-30 VDC 10-36 VDC 10-36 VDC 10 18-28 VDC
CL40
15 mm 10-30 VDC
X
X
C80
18 mm 10 10-30 VDC
X
X
X
X
G20
2 mm
10-30 VDC
Teach Output In P NP NP NPN X X X X X X X X X
X
X
Mode DO LO X X X X X X X X
X
X
X
X
X
X
Conne cti on M8 M12 Ca bl bl e X X X X X X X X X X
X X
Housing Plas tic Plas tic Plas tic Plas tic Plas tic
X
Plas tic
X
Met al
X
Met al
Review 8 1)
The maximum maximum sensing sensing range range of a K80, thru scan, scan, photoelectric sensor is ____________ m.
2)
_____ ___ ____ ___ ___ is an an example example of a photoelectric sensor sensor w ith it h Teach In. a. D4 b. K50 c. CL40 d. K30
98
3)
A ___ ____ ____ ___ ____ ___ _ is is a photoelectric photoelectric sensor that has has a slot slot w here the target is plac placed. ed.
4)
The maximum maximum sensing sensing range range of a Color M ark BE BERO C80 is ____________ mm.
Sensor Applications Applicat ions
There are any number of applications where sensors can be utilized, and as you have seen throughout this book there are a number of sensors to t o chose chose from. from . Choosing Choosing the right sensor can be confusing and takes careful thought and planning. Often, more tha t han n one sensor will do the job. As the t he applica application tion becomes more complex the more difficult it is to choose the right sensor for a given application. application. The follow ing application guide will w ill help you find the right sensor for the right application. application.
For further application assistance cont act your local sales office. Call (800) (800) 964-4414 964-4414 for nearest office.
99
Ultrasonic Sensors Application Level Measurement in Large Vess Vessels els (Tanks, (Tanks, Silos) Sensor 3RG61 13 Compact Range Range III
Application Level Measurement in Small Bottles Sensor 3RG61 12 Compact Range Range III
Sensor 3RG60 14 Compact Range Range I
Application Height Sensing Sensor 3RG60 13 Compact Range Range II
Application Quality Control
Application Breakage Sensing
Sensor 3RG61 12 Compact Range Range III
Sensor 3RG61 12 Compact Range Range I
Application Bottle Counting
Application Object Sensing
Sensor 3RG62 3RG62 43 43 Thru Beam
Sensor 3RG60 12 Compact Range Range II
Application Vehicle Sensing and Positioning
Application Stack Stack Height Sensing
Sensor 3RG60 14 Compact Range Range III
100
Application Anti-Collision
Sensor 3RG60 13 Compact Range Range II
For further fur ther application assistance contact cont act your local sales office. Call (800) 964-4414 964-4414 for nearest off ice.
Ultrasonic Sensors Application Contour Recognition Sensor 3RG61 13 Compact Range Range III
Application People Sensing Sensor 3RG60 12 Compact Range Range II
Application Diameter Sensing and and Strip Speed Control Sensor 3RG61 12 Compact Range Range III
Application Wire and Rope Rope Breakage Breakage Monit oring Sensor 3RG60 12 Compact Range Range I
Application Loop Control Sensor 3RG60 15 Compact Range Range II
For further application assistance cont act your local sales office. Call (800) (800) 964-4414 964-4414 for nearest office.
101
Photoelectric Sensors Application Verifying Objects Ob jects in Clear Bottles
Application Flow of Pallets Carrying Carrying Bottles
Sensor M 12 Thru Thru Beam
Sensor K40 Retroref Retroref lective
Application Counting Cans
Application Counting Bott Bottles les
Sensor K50 Polarized Retroreflective
Sensor SL18 SL18 Retroreflect ive
Application Counting Cartons
Application Car Wash
Sensor K65 Retroref Retroref lective
Sensor SL Thru Thru Beam
Application Reading Rea ding Reference Referen ce M arks for Trimm ing
Application Detect ing Persons Persons
Sensor C80 M ark Sensor Sensor
Application Controlling Parking Gate Sensor SL R Retroref etroreflective lective
102
Sensor K50 Retroref Retroref lective
Application End of Roll Roll Detect ion Sensor K31 Diffuse
For further fur ther application assistance contact cont act your local sales office. Call (800) 964-4414 964-4414 for nearest off ice.
Photoelectric Sensors Application Detect Det ecting ing Tab Tab Threads Threads Sensor KL40 Fiber Fiber Opt ic
Application Counting Countin g Packages Packages Sensor K80 Retroref Retroreflective lective
Application Detect ing Caps Caps on Bottles Sensor K20 K20 Diffuse wit h Background Suppression and K31 Thru Thru Beam Application Detecting Components Inside M etal Can Can Sensor K50 Background Suppression
Application Determining Orientation of IC Chip Chip
Application Detecting Items of Varying Heights
Sensor L50 Laser with Background Suppression
Sensor K80 Background Suppression
Application Detecting Orientation Orientation of IC Chip
Application Controlling Height of a Stack
Sensor Color Mark or Fiber Optic
Sensor SL Thru Thru Beam
Application Detecting Jams on a Conveyor
Application Counting Boxes Anywhere on a Conveyor
Sensor K50 Retroref Retroreflective lective
Sensor SL18 Right Angle Retroreflective
For further application assistance cont act your local sales office. Call (800) (800) 964-4414 964-4414 for nearest office.
103
Photoelectric Sensors Application Counting IC Chip Pins Sensor KL40 Fiber Optic
Application Batch Batch count ing and Diverting Cans Without Labels Labels Sensor K40 Polarized
Application Detect ing Presence Presence of Object to Start a Conveyor Sensor K35 Retroref Retroref lective
Application Verif ying Liquid Li quid in i n Vials Vials Sensor K35 Fiber Optic
Application Verif ying Cakes Cakes are Present in Transparent Transparent Package Sensor KL40 Fiber Optic
104
Application Detecting Reflective Objects Sensor K80 Polarized Retroreflective
Application Verifying Screws are Correctly Seated Sensor KL40 Fiber Optic
Application Verifying Lipstick Height Before Capping Capping Sensor M 5 or M 12 Thru Beam
Application Detecting Labels Labels wit h Transparent Background
Application M onitoring Objects Objects as they Exit Vibration Vibration Bowl
Sensor G20 Slot Sensor
Sensor K35 Fiber Optic
For further fur ther application assistance contact cont act your local sales office. Call (800) 964-4414 964-4414 for nearest off ice.
Proximity Switches Application Detecting the Presence of a Broken Drill Bit Sensor 12 mm Normal Requirements
Application Detect ing Presence Presence of Set Screw Screw s on Hub for Speed or Direction Control
Application Detecting Milk in Cartons Sensor Capacitive
Application Controlling Fill level of solids in a bin Sensor Capacitive
Sensor 30mm Shorty
Application Detect ing Full Full Open or Closed Valve Valve Post Postit ition ion
Application Detect ing Presence Presence of Can Can and Lid L id
Sensor 12mm or 18mm Extra Duty
Sensor 30mm Normal Normal Requirement s or UBERO, 18mm Normal Requirement Requirements s Gating Sensor
Application Detect ing Broken Broken Bit on M illing Machine Machine Sensor 18 mm
For further application assistance cont act your local sales office. Call (800) (800) 964-4414 964-4414 for nearest office.
105
Application Application Inquiry Providing a sensing device solution requires both knowledge of the application and answers to specific questions to obtain key additional facts. This page is intended to be photocopied and used as a self-help self -help guide in assessing assessing the t he scope of sensor sens or applications. applications. The information inform ation recorded recorded on this t his form may then be cross-che cross-checked cked with w ith t he product product specifications specifications found in our “ BERO BERO - Sensing Solutions” catalog t o obtain a pot potenti ential al solution solut ion to your applicat applicat ion. If your application involves machine guard safety interlocking, the use of standard standard position sensors could result in serious injury or death. Please Please contact cont act SE&A SE&A Sensor Mark M arketi eting ng for assist assistance ance at (630) 879-6000. 1.
2.
3.
Target arget M ate aterial rial ___ M et et al ___ Non-M et et al ___ Ferrous ___ Non-Ferrous ___ __ _ Transparent ransparent __ ___ _ Translucent ___ Opaque Target rget Desc Descript ript ion and and Dim Dim ensions ensions Target Finish (shiny/dull/matte, etc.) __________ Target arget Color Colo r ________ __________ __ Target arget Tex Textu ture re ___ _______ _______ ___ Target rget Orientation/Spa Orientation/Spacing cing Describe position of target when sensed relative relative to t o imm ediate ediate environment. Number Numb er of M ultiple ult iple Target argets s ____ ____ Number Num ber of Targets Nested Nest ed Together oget her ___ Spacing Spacing Betw Bet w een Target Targets s ____ ______ ___ _ Size of o f Targe Targett ___ _______ _______ ___
4.
Target arget M ovement /Speed/V /Speed/Velocit elocit y Describe Describe how the t arget arget approache pproaches s tthe he sensing area (Axial/Lateral). Target arget Speed ___ _______ _______ ___ Cycles per Second/Minut Second/M inute/et e/etc c __ ____ ____ __ Hours Hou rs machine machin e is run? ___ _____ _____ ___
5.
6.
106
Sensing Sensing Distance Distance From Target t o Sensor Senso r ___ ______ ______ ____ _ From Target Target t o Background Backgroun d ___ _____ _____ _____ __ Background ackground De Desc script ript ion Describe the background conditions.
7.
Physica hysical/Mount l/Mount ing Crit eria Is target accessible accessible from more t ha han n one side? Space Space a available vailable to install inst all sensor ____ _____ _ Sensor Orient Orien t ation Possibilit ossib ilit ies ____ _____ _ _________________________________
8.
Environment nvironment ___ Clean ___ Oily ___ Dust y ___ Hum id ___ Out door ___ Indoor __ ___ Submersion ___ Wash Wash down Temperature ________ Tem emper peratur ature e Variat Variation ion ___ ______ _____ __
9.
Load Requirement Load equirement s Descri Des cribe be t he Load ___ _____ _____ _____ _____ ______ ____ _ Induct Indu ctive: ive: Inrush Inru sh ___ _____ __ Sealed _____ _____
10. Cont rol Volt age Suppl Suppl y __________ VAC __________ __________ VDC 11. Outpu t Requirem Requirem ents ___ NPN ___ PNP ___ SCR ___ FET ___ Relay ___ Normally Open ___ Normally Closed ___ ___ Complim Compl iment entary ary ____ _____ _ LO/DO 12. Connection Preference ___ __ _ Connector/ Connector/M M atching Cordset Length of Sensor Prew Prewired ired Cable Cable (2 M eters et ers Standard) _____ _______ ___ _ ___ __ _ AS-i AS-i Interf Int erface ace
For further fur ther application assistance contact cont act your local sales office. Call (800) 964-4414 964-4414 for nearest off ice.
Review eview Answers Answ ers
Review 1
1) Limit switch; 2) d; 3) Pretravel; 4) operating position; 5) break-before-make; 6) Break; 7) 30; 8) operating head; 9) SIGUARD; 10) 6P
Review 2
1) inductive; 2) a; 3) 3; 4) 4; 5) steel; 6) 0.40; 7) 81%
Review 3
1) 10; 2) 20; 3) 265, 320; 4) IP; 5) 65; 6) UBERO
Review 4
1) electrostatic; 2) any; 3) dielectric; 4) b; 5) 20
Review 5
1) sound; 2) 6-80; 3) 5; 4) 60; 5) 3; 6) Diffuse
Review 6
1) Thru-Beam; 2) 5 to 40; 3) separate; 4) a; 5) SONPROG; 6) Modular; 7) b
Review 7
1) 5 and 30; 2) gain; 3) Ret Retroref roreflect lective; ive; 4) 90 degrees; 5) 65; 6) Dark; 7) b; 8) 2
Review 8
1) 50; 2) c; 3) G20; 4) 18
107
Final Exam
The final f inal exam exam is intended int ended to t o be a learning tool. t ool. The book m ay be used during duri ng the t he exam exam . A tear-out tear-out answer card is provided. After completing the final exam, mail in the answer card for grading. A grade of 70% or better is passing. Upon successful completion of the test a certificate will be issued. Questions
1.
The dista distanc nce e an an act actua uator tor arm tra travels els o on n a mecha mechani nica call limit switch sw itch from the release release position position to t he free posit pos ition ion is i s know n as ____ _______ ______ _____ __ . a. c.
2.
b. d.
Break Induct ive
Inter ternatio tional and IEC Inter ternatio tional an and No North rth Ame Amerrican North Ame merrican and BERO Inter ternatio tional an and BE BERO
Phot oelect ric Induct ive
b. d.
Ult rasonic Capacit ive
Whe When two or mo morre shielded inductiv tive proximity mity sensors are mounted opposite one another, they should be placed a distance of at least ____________ times the rated sensing range from each other. a. c.
108
M ake Cont inuous
____________ is a type of sen senso sorr tha thatt can can on only ly de detec tectt metal. a. c.
5.
Different ial Travel Release Travel
____________ are the two prod produc uctt line lines s for for Siemen iemens s mechanica mechanicall limit switches. sw itches. a. b. c. d.
4.
b. d.
____________ is a term term tha thatt desc descri ribe bes s th the e loa load da mechanica mechanicall limit switch sw itch can han handle dle when w hen the mechanical contacts close. a. c.
3.
Overt ravel Pret ravel
two four
b. d.
t hree six
6.
A corr correc ectio tion n facto factorr of __ ____________ is app pplilied ed to an an unshielded unshielded inductive inductive proximity sw itch w hen the target is 50% smaller than than the t he standard standard tar t arget. get. a. c.
7.
4 8
b. d.
6 10 10
Induct ive Phot oelect ric
b. d.
Ult rasonic Capacit ive
The app pprroxima ximate te ang angle le of the the main main cone cone of an an ultrasonic ult rasonic sensor is ____ ______ ____ ____ ____ __ degrees. a. c.
11.
NAM UR UBERO Increased Operatin ting Distan tance AS-i
____________ pro proximity ximity sens sensor ors s de dev velop elop an electrostatic field to detect the target. a. c.
10.
0.73 0.92
Whe When us using a capa pac citiv tive pro prox ximity mity sen sens sor with with a rated ted sensing distance of 10 mm t o detect polyamide, polyamide, the t he effective sensing distance is approximately ____________ mm. a. c.
9.
b. d.
____________ is a type type of of Sie Siemen mens s ind induc uctiv tive e pr proximity ximity switch that can detect all metal targets without a reduction factor. a. b. c. d.
8.
0.50 0.83
5 30
b. d.
10 10 45
A distan distance ce grea greater tha than n ____________ cm sho should uld be left between two ultrasonic sensors mounted opposite each other with a rated sensing range of 20 - 130 cm. a. c.
40 0 0 1200
b. d.
2 50 0 40 0
109
12.
Coa oarrsese-gra grained ined ma mater teria ials ls can can ha have as much much as as ____________ degrees angular deviation from the send direction of an ultrasonic sensor. a. c.
13.
3.6 25 - 33
Com pact Range 0 Com pact Range I Com pact Ra Range III M od odular Range II
X1 is open X1 is connect ed t o L+ X1 is connect ed t o LX1 is closed
Thru Beam Comp mpa act Ra Range 0 and Co Comp mpa act Ra Range I Compac mpact Ra Range I and Co Comp mpa act Ra Range II II Compa ompact Ra Rang nge e IIII and Compa ompact Ra Rang nge e IIIII
A 90° 90°div divertin erting g refl reflec ector tor is availa ilable ble for for use use with ____________ ultrasonic sensors. a. b. c. d.
110
b. d.
SONP ONPROG can can be be used used to adju adjust st __ ____________ ultrasonic sensors. a. b. c. d.
17.
0.17 5
The ma maxi ximum mum sen sensi sing ng dista distanc nce e of of a Thru hru Bea Beam m ultrasonic sensor is 80 cm when ____________ . a. b. c. d.
16.
5 90
A sign signa al eva evalu lua ator is is requ require ired d for for use use with __ ____________ ultrasonic sensors. a. b. c. d.
15.
b. d.
Sou ound nd vel veloc ocity ity decr decrea ease ses s __ ____________ % be betw tw ee een n sea level and and 3000 30 00 m abo above ve sea level. a. c.
14.
3 45
M 30 30 spherical Comp mpa act Ra Range M18 M18 sp spherical Compa ompact Ra Rang nge e 0 with Inte ntegr gra ated Trans ransdu duce cerr Thru Beam
18.
____________ scan scan is a pho photoele toelectri ctric c sca scan techn techniq ique ue in in w hich the planes planes of emitter emit ter light and reflected light are are orientated orient ated 90° to one another. a. b. c. d.
19.
____________ is a pho photoel toelec ectric tric senso sensorr tha thatt use three three LEDs with colors red, green, and blue and is can be used to detect a specific specific color of reflected ref lected light. a. c.
20.. 20
Polarized Retro trorefle flectiv tive Ret roref lect ive Diff use Thru
G20 CL40
b. d.
K30 C80
The ma maxi ximum mum sens sensin ing g rang nge e of the L1 L18 8 lase laserr photoelec phot oelectt ric sensor is _____ _______ ____ ____ ___ _. a. b. c. d.
12 m 50 m 100 m m 150 m m
111
Notes
112
