Cabling Wiring Guidelines Cranes

Document:

Cabling and wiring guidelines for cranes

Date: Date: Revision:

2007-03-23 1.1

Cabling bli ng and Wirin g Guidelines for Cranes

RELEASE PROJECTMANAGER Name Function

: Gerhard Fischer : Sales

RELEASE INTERNAL PRINCIPALS Name Function

: Hans Buurkes : Quality

Revision Date

:1.1 : 23. March 2007

The document content and the provide solutions are the intellectual property of Siemens the Netherlands NV. Copies to external parties can only be provided after a formal release of Siemens.

Siemens AG, A&D MC CR

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T AB LE OF CONTENTS

1

BACKGROUND ...................... .................................. .......................... ........................... ........................... ............................ ........................... ........................... .......................3 .........3

2

INTRODU INTRODUCTIO CTION N ........................... ......................................... ............................ ............................ ........................... ........................... ............................ ........................ ..............4 ....4 2.1 2.2 2.3 2.4

3

HIGH FREQUENCY DISTURBANCE .......................... ....................................... ........................... ............................ ............................ ...........................4 .............4 LONG MOTOR CABLES.......................... ........................................ ............................ ............................ ........................... ........................... ............................ ...............6 .6 COMMON MODE OSCILLATION .......................... ........................................ ............................ ........................... ........................... ............................ ..................7 ....7 BEARING CURRENTS.......................... ....................................... ........................... ............................. ............................ .......................... ........................... ..................7 ....7

SELECTION OF LOAD SIDE COMPONENTS COMPONENTS ........... .......... ........... ........... .......... ........... ........... ...8 3.1 M AXIMUM CABLE LENGTH WITHOUT OUTPUT CHOKES .......................... ........................................ ............................ .........................8 ...........8 3.2 M AXIMUM CABLE LENGTH WITH OUTPUT CHOKES ............................ .......................................... ........................... ........................... ................9 ..9 3.2.1 Iron-core Iron-core reactors reactors ........................... ........................................ ........................... ........................... .......................... ........................... ........................... ...............9 ..9 3.2.2 Ferrite-cor Ferrite-core e reactors reactors ........................... ........................................ ........................... ........................... ........................... ........................... ........................9 ...........9 3.2.3 Voltage limiting (dv/dt) filters.............................................................................................9 3.2.4 Sinusoida Sinusoidall filters filters .......................... ...................................... ......................... ........................... ........................... .......................... ........................... ..................10 ....10

4

SIZING SIZING OF CABLE CROSS CROSS SECTIONAL SECTIONAL AREA .......................... ...................................... ......................... ........................... .....................12 .......12 4.1 4.2

5

POWER POWER CABLE SELECTION SELECTION ......................... ...................................... ........................... ........................... .......................... ......................... .......................13 ...........13 5.1 5.2 5.3 5.4 5.4.1 5.4.2 5.4.3 5.4.4

6

CONDUCTORS ........................... ......................................... ............................ ............................ ........................... ........................... ............................ ......................12 ........12 PROTECTIVE CONDUCTOR............................ ........................................ .......................... ............................ ............................ ........................... ....................12 .......12

TYPES OF POWER CABLES .......................... ....................................... ........................... ............................ ............................ ........................... ....................13 .......13 INSULATION MATERIAL USED FOR POWER CABLES ........................... ........................................ ........................... ............................1 ..............13 3 SIEMENS RECOMMENDED POWER CABLES .......................... ........................................ ............................ ........................... .........................14 ............14 INSTALLATION GUIDELINES .......................... ....................................... ........................... ............................ ............................ ........................... ....................15 .......15 Wiring guidelines in accordance to EMC rules................................................................17 Wiring requirements as per IEC 60204-32......................................................................22 Wiring practices to be avoided........................................................................................26 Best practice screened power cable termination ........... ........... .......... ........... ........... ......28

INSTALLATION OF CONTROL CONTROL CABLES ..................... ................................... ........................... ........................... ............................ .....................30 .......30 6.1 INSTALLATION OF PROFIBUS CABLES .......................... ....................................... ........................... ............................ ............................ ................30 ..30 6.2 INSTALLATION OF ENCODER CABLES ............................ .......................................... ........................... ........................... ............................ ..................33 ....33 6.2.1 Installation of encoder cables at motor side....................................................................34 6.2.2 Installation of encoder cables at drive drive side .......... ............ ........... ........... ........... ............ ..36


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Background

Siemens supplies electrical components such as SIMATIC S7 programmable logic controllers, SIMOVERT MASTERDRIVES frequency converters and induction motors as components for installation on cranes in the harbour and other industries. Safe and reliable performance of the electrical components without disturbance or premature failure of electronic components depends on adequate installation and wiring practices. The following chapters detail cabling recommendations by Siemens.

This document summarizes recommendations from several sources as listed below. It has been compiled by Mabel Chin of Siemens Ptd. Ltd. Singapore and proof-read by Peter Dek and Pieter Olislagers of Siemens Nederlands N.V., The Hague, Netherlands. Particularly noteworthy are aspects covered in the international standard IEC 60204-32 providing requirements and recommendations relating to the electrical equipment of hoisting machines so as to promote; safety of persons and property, consistency of control response and ease of maintenance. IEC 60204-32

Safety of machinery - Electrical equipment of machines - Part 32: Requirements for hoisting machines

EN 954-1

Safety of machinery - Safety-related parts of control systems - Part 1: General principles for design

DIN VDE 0660 Part 12 – Protective conductor terminals EN 55011

Limits and methods of measurement measurement of radio disturbance characteristics of industrial, scientific and medical (ISM) radio-frequency equipment equipment

EN 61800-3

EMC product standard including special test methods for electric drive units

89/336/EWG

COUNCIL DIRECTIVE of 3 May 1989 on the approximation of the laws of the Member States relating to electromagnetic compatibility

73/23/EWG

Council Directive of 19 February 1973 on the harmonization harmonization of the laws of Member States relating to electrical equipment designed for use within certain voltage limits

Catalog DA65.10

Simovert Masterdrives Vector Control Catalogue 2003/2004

6SE7087-6QX60

Masterdrives Compendium Vector Control 1998

6SE7087-6CX87-8CE0 Installation Instructions for EMC Correct Installation of Drives Prysmian (Pirelli) catalog BU IS 2.1 × 2000

Flexible Electric Cables

Implementation Implementation of these recommendations is no substitute for a risk assessment of the crane, which needs to be made by the crane designer.


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Introduction

Variable speed drives have become an integral component of the electrical control system for cranes. The installation of variable speed drives on cranes with increasing crane ratead load and crane size has become a technical challenge. The following recommendations are intended to help the crane builder in carrying out the electrical installation and –cabling such that latest aspects of variable speed drives parasitic effects are covered.

2.1

High frequency distur bance

Variable Speed drives have advantages and disadvantages. One of the disadvantages is the high switching frequency of the semiconductor (IGBT) which can cause disturbances to other components. SIMOVERT MASTERDRIVES MASTERDRIVES frequency converters operate with a voltage-source DC link. In order to keep the power losses as low as possible, the inverter switches the DC link voltage to the motor winding in the form of voltage blocks. An reasonably sinusoidal current flows in the motor.

Figure 1: Block diagram showing output voltage V and motor current I of a frequency converter The described mode of operation in conjunction with high-performance semiconductor switching elements have made it possible to develop compact frequency converters which now play a vital role in drive technology. However, due to the fast switching, a pulse-type noise current flows to ground through parasitic capacitances CP at each switching edge. Parasitic capacitances exist between the motor cable and ground, and also within the motor. Siemens AG, A&D MC CR

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Figure 2a: Block diagram showing output voltage V and fault current Is The source of the earth current IS is the inverter, thus this earth current must also flow back to the inverter. Impedance ZN and ground impedance ZE act in the return flow path. Impedance ZN forms parasitic capacitances between the supply cable and ground, which is connected in parallel with the impedance (between phase and ground) of the supply transformer. The noise current itself and the voltage drops across ZN and ZE caused by the noise current can also affect other electrical units. Therefore, variable speed drives generate high-frequency noise currents. EMC stands for "Electromagnetic Compatibility" Compatibility" and, in accordance with the EMC Law §2(7), it defines "the capability of a unit to operate satisfactorily in an electromagnetic environment, without itself causing electromagnetic disturbances which would be unacceptable for other electrical units in this environment".


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Long motor cables

2.2

Effect of crane mechnical configurations on the length of the electrical cables: a) Machinery on trolley (MOT) + Shorter wire-ropes for hoist + No wire-ropes for trolley - Long electrical cables for hoist motors - Long electrical cables for trolley motors - Space constraints for hoist motors

b) Self-propelled trolley (SPT) + No wire-ropes for trolley - Long electrical cables for trolley motors

c)

Rope-towed trolley (RTT) + short cables to hoist and trolley motors - long wire-ropes for hoist and t rolley

d) Typical Gantry configuration - accumulated long motor cables

From all of the examples above, the gantry motion has t he longest motor cable. A typical STS crane with the inverters mounted in the machinery house on the girder, has accumulated gantry motor cable lengths reaching almost 1000 m.


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Common mode oscil lation

On large cranes with long motor f eeder cables (e.g. SPT and MOT configurations) in combination with pulsed line-side converters, a common-mode oscillation may occur that could lead to excessive phase-to-ground voltage stress on the motors.

Figure 2b: 2b: Principle circuit for co mmon-mode oscillation oscillation Engineering of the drive system is to carefully consider the entire power train comprising the medium voltage transformer, drive system with line-side converters and inverters on the common DC-bus , the motor with the insulation grade and the cabling between the different components.

2.4

Bearing Bearing cu rrents

Asymmetrical characteristics of the motor motor feeder cable in conjunction conjunction with the PWM switching switching pattern of the inverter leads to voltage building up between the rotor and the stator of the motor. I f this voltage exceeds a certain threshold value the grease film lubricating the bearing will collapse and bring about a metal-metal contact. This leads to premature bearing failures. As a consequence consequence all motor feeder cables cables are to be screened and of symmetric symmetric design.


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Selection Selection o f load side compo nents

The objective of the following chapters is to give a clear instruction on:1.

how to select select the correct load-side components

2.

how to select select suitable suitable cable and type.

3.

how to implement correct wiring practices. Dimensioning Dimensioning of cable cross sectional area Installation of power cables Installation of control cables • • •

The purpose of output chokes is to limit capacitive recharging currents into the capacitance of the motor feeder cable so as to protect the IGBTs in the drive. The selection of output chokes are dependant on the following parameters:parameters:1) Type of cables used used ( screened or unscreened unscreened ) 2) Number of motors motors supplied supplied from a converter converter Item 1 is reflected in Table 1. Item 2 is when a converter/inverter supplies supplies several motors (group drive), the capacitive charge/ discharge currents of the motor cables are added together. The total cable length is the sum of the cable lengths for the individual motors.

3.1

Maximum cable length witho ut outp ut chokes

The maximum cable lengths which can be connected to the standard Simovert Masterdrive unit without reactors are specified in table 1.

Table 1: Motor cable distance without output choke


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Maximum cable length with o utput chokes

3.2

In cases whereby there are longer power cables, they should be dimensioned dimensioned according to Table 2.

Table 2: Motor cable distance with output choke 1) 2) 3) 4) 5)

3.2.1 o

o

3.2.2

Cannot be used. In the case case of sizes M, N and Q, 2 inverters are connected in parallel and the number of reactors for the permissible cable lengths is therefore required for each inverter section. Applies to sizes E, E, F, G, J, K, L, N and and Q. Applies to size M. The effective capacitance capacitance per unit length of the PROTOFLEX EMC cable corresponds to that of an unshielded cable. With the PROTOFLEX EMC cable, the same motor cable lengths are therefore possible as with an unshielded cable.

Iron-core reactors Drives with with standard standard and non-standard induction induction motors with with a rated motor motor frequency (frequency at the start of field weakening) of up to 87 Hz and a maximum frequency of 200 Hz. Drives with with reluctance reluctance motors motors or permanent-magnet synchronous motors with with a maximum maximum frequency of 120 Hz.

Ferrite-core reactors Not relevant for cranes applications.

3.2.3

Voltage limiting (dv/dt) (dv/dt) filters

Voltage limiting filters (output dv/dt filters for SIMOVERTMASTERDRIVES SIMOVERTMASTERDRIVES Vector Control) should be used for motors where the voltage strength of the insulation system is not known or is inadequate. The dv/dt filters limit the voltage rate-of-rise to values of < 500 V/µs and the typical voltage spikes for the rated supply voltage to the following values: <1000 V at Vsupply ≤ 575 V, <1150 V at 660V ≤ Vsupply ≤ 690 V with a motor cable length of ≤ 150m. Siemens AG, A&D MC CR

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When reactors and filters are connected in series, the cable lengths can be dimensioned according to the Table 4.

Table 3: Motor cable distance with combination of reactors and dv/dt f ilter Note:The total cable length is the sum of the cable lengths connected to the individual motors. From a motor current of ≥ 120 A, single-motor drives can also be supplied with parallel cables (up to the maximum permissible permissible cable length) in t he case of standard units. The voltage limiting filters can be used up to a maximum frequency of 300 Hz.

The dv/dt filters can only be used with a motor connected.

Figure 3: Arrangement of output reactor and dv/dt filter 3.2.4

Sinusoidal filters

Sinusoidal filters ensure that the motor voltage and currents are almost sinusoidal. The harmonic distortion factor for a 50 Hz motor voltage with sinusoidal filter, for example, is approximately 5%. The stressing levels of motors which are supplied via sinusoidal filters are lower than the values specified in DIN VDE 0530. When engineering the drive, it should be ensured that the output voltage of Siemens AG, A&D MC CR

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converters and inverters with sinusoidal filters is approximately 85% of the associated supply voltage at 380 V to 480 V and approximately 90% at 500 V to 600 V. The sinusoidal filters for supply voltages of 380 V to 480 V are designed for a 6 kHz pulse frequency. The maximum output frequency is: 400 Hz for Compact units (sizes A to D), 200Hz for chassis units (sizes E to G). Note the current derating for chassis units as a result of the 6 kHz pulse frequency! • •

The sinusoidal filters for supply voltages of 500 V t o 600 V are designed for a pulse frequency of 3 kHz. The maximum output frequency is: 200 Hz for Compact units (sizes B to D), 100 Hz for chassis units (sizes E to G). • •

Sinusoidal filters are suitable for supplying Ex(d) motors. They limit the voltage stressing in the motor terminal boxes to below 1080 V up to a supply voltage of ≤ 500 V. For possible cable lengths, see Table 5.

Table 4: Motor cable distance with sinusoidal filter

Note The total cable length is the sum of the cable lengths to the individual individual motors. From a motor current of ≥ 120 A, single-motor drives can also be operated with parallel cables (up to the maximum permissible cable length) in the case of standard units.


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Sizing Sizing o f cable cros s sectio nal area area Conductors

4.1

Please refer to the recommended cross sectional area of the conductors for incoming and outgoing cables of every unit sizes of Simovert Masterdrives in the operation manual.

Protective conductor

4.2

The protective conductor is to be dimensioned considering the following functions: •

•

•

•

In the event of an earth fault, it must be ensured that no excessively high touch touch voltages voltages occur on the protective conductor as a result of voltage drops of the earth-fault current (<50 VAC or 120VDC, EN 50 178 Section 5.3.2.2, I EC 60 364, IEC 60 543). The earth fault current current flowing in the protective conductor conductor in the event of an earth fault fault must not overheat the protective conductor. In the event of a fault in accordance accordance with with EN 50 178, 178, Section 8.3.3.4, it is possible possible that continuous currents can flow through the protective conductor. The cross-section of the protective conductor is therefore to be dimensioned for this continuous current. Switchgear and motors motors are usually earthed separately separately using using a local earth electrode. electrode. With this constellation, the earth-fault current, in the event of an earth fault, flows through the parallel earth connections and is divided up. In spite of the cross-sections of the protective conductor as specified in the table, no non-permissible non-permissible touch voltages then occur with this kind of earthing.

Table 5: Recommended Cross section of external protective conductors •

•

The MASTERDRIVES MASTERDRIVES converters, inverters, rectifier units (>400 (>400 kW) and rectifier/ regenerative units limit the current to an effective value in accordance with the rated current, thanks to their rapid control. Given these these facts, we recommend recommend that the cross section section of the the protective conductor is is generally the same as the cross-section of the outer conductor for earthing the control cubicle and the motor.


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Power cable selection Types Types of power cables

Table 6: Overview power cable types

5.2

Insulation material used for p ower cables

In view of minimizing the capacitance between the motor phase conductors and ground (see section 2.1 capacitance CP) it is advicable to choose cables with an as low as possible specific capacitance (pF/m). The cable capacitance is directly proportional to the dielectrical constant of the insulation material of the cable. Material such as cross-linked polyethylene (XLPE) have a dielectric constant of about 2, rubber in contrast may have a dielectric constant of 5.


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Siemens recommended power cables

In general, we highly recommend Protoflex EMV 3 Plus due to the f act that:1. it can reduce the high frequency noise emission 2. it can can reduce reduce the the bearing bearing current effects effects 3. It has a minimal minimal effective capacitance capacitance per unit unit length which which is comparable comparable to that of a standard unscreened cable. (eg: 3X70+3X10 has capacitance of 290nF/km) 4. The geometric geometric arrangement of conductors and PE conductors is is chosen such as to ensure identical coupling capacitances capacitances between phase to phase and phase to PE as shown in the figure below.

L1 PE

PE

L2

L3 PE

Figure 4: Principle cross-sectional view of screened symmetric motor feeder cable

However, its important to check at the cable specifications with the suppliers! It is good to know that different cable suppliers used different material for their cable sheaths, different quality with geometrical propertie properties s and so on. Therefore, it is critical to compare the capacitance value/ unit length of all these cables and select t he one with the lowest value.


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Typical power cable electrical and mechanical characteristics: Electrical Characteristics:-

2

Table 7: Electrical specification PROTOFLEX EMV

Cable Design Specifications:-

Table 8: Mechanicall specification PROTOFLEX EMV

5.4

Installation Installation g uidelines

Typical wiring to the drive for the recommended power cable type


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Figure 5: Earthing and screening for connection for motor connection Using non-shielded motor cables, cables , the noise current flows in an undefined fashion back to the frequency converter, e.g. via the crane’s steel structure, cable ducts, cabinet frames. These current paths have a very low resistance for currents with a frequency of 50 or 60 Hz. However, the noise current induces a high-frequency component, which can result in problematical voltage drops. A shielded motor cable is necessary to enable the noise current to flow back to the frequency converter in a defined fashion. The shield must be connected to the housing of the frequency converter and to the motor housing through a large surface area. The shield now forms the easiest path for the noise current to take when returning to t he frequency converter.

Figure 6 Flow of the noise current with shielded motor cable A shielded motor motor cable with a shield connected at both sides causes the noise current to flow back to the frequency converter through the shield. The figure below illustrates the best wiring practices within as well as outside the panel enclosure following the 16 EMC rules in the next section which ensure minimu minimum m disturbances to other electrical components.


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Figure 7: Overview of best wiring practice adhering to EMC rules 5.4.1

Wiring gu idelines in accord ance to EMC EMC rules

Design of drives must be in conformance with EMC regulations. Rules 1 to 13 are generally applicable. Rules 14 to 16 are particularly important for limiting noise emission. emission. Rule 1 All of the metal cabinet cabinet parts must be connected connected through the largest possible possible surface areas (not paint paint on paint). Serrated washers should be used to ensure a good metal-metal contact. The cabinet door must be connected to the cabinet through grounding straps which must be kept as short as possible. Note: Grounding measures measures for machines are essentially a protective measure. However, in the case of drive systems, this also has an influence on the noise emission and noise immunity. A system can either be grounded in a star configuration or each component grounded separately. Preference should be given to the latter grounding system in the case of drive systems, i.e. all parts of the installation to be grounded are connected through their surface or in a mesh pattern. Siemens AG, A&D MC CR

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Rule 2 and 3 Signal cables and power cables must be routed separately (to eliminate coupled-in noise). Minimum clearance: 20 cm. If the minimum distance is not possible then partitions between power cables and signal cables as shown in the photo should be provided. The partitions must be grounded at several points along their length.

Group 1: very susceptible (eg: analogue signals) Group 2: Susceptible (eg: digital signals) Group 3: Noise source (eg: control cables) Group 4: Strong noise source (eg: output cables from drives) Note: Contactors, relays, solenoid valves, surge arrestors, electromechanical operating hours counters, etc. in the cabinet must be provided with surge suppressor devices, for example, RC elements, diodes, varistors. These surge suppressor devices must be connected directly at the coil. Rule 4 Non-shielded cables associated with the same circuit (outgoing and incoming conductor) must be twisted, or the surface between the outgoing and incoming conductors kept as small as possible in order to prevent unnecessary coupling effects. Rule 5 Eliminate Eliminate any unnecessary cable lengths to keep coupling capacitances and inductances low. Rule 6 Connect the reserve cables/conductors to ground at both ends t o achieve an additional shielding effect. Rule 7 In general, it is possible to reduce the noise being coupled-in by routing cables close to grounded cabinet panels. Therefore, wiring should be routed as close as possible to the cabinet housing and the mounting panels and not freely through the cabinet. The same applies for reserve cables/conductors. Rule 8 Encoders must be connected through a shielded cable. The shield must be connected to the encoder housing and at the SIMOVERT MASTERDRIVES through a large surface area. The shield must not be interrupted, e.g. using intermediate terminals. For chassis units (sizes ≥ E), the shields can be additionally connected using cable ties (cable connectors) at the shield connecting locations.


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Screen connection via serrated bars:

Figure 8a: Connecting signal cable shields via 2 serrated bars in the cabinet Screen connection via a single screen rail:

Figure 8b: Connecting signal cable shields via 2 screen rails in the cabinet Rule 9 The cable shields of digital signal cables must be connected to ground at both ends (transmitter and receiver) through the largest possible surface area. If the equipotential bonding is poor between the shield connections, an additional equipotential bonding conductor with at least 10 mm² must be connected in parallel to the shield, to reduce the shield current. Generally, the shields can be connected to ground (= cabinet housing) in several places. The shields can also be connected to ground at several locations, even outside the cabinet.


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Figure 9: Examples of shield connections

Foil-type shields are not to be favoured. Braided shields are at least 5 times more effective. Rule 10 The cable shields of analog signal cables can be connected to ground at both ends if the equipotential bonding is good. Good equipotential bonding is achieved if Rule 1 is observed. If low-frequency noise occurs on analog cables, for example: speed/measured value fluctuations as a result of equalizing currents (hum), the shields are only connected for analog signals at one end at the SIMOVERT MASTERDRIVES. The other end of the shield should be grounded through a capacitor (e.g. 10 nF/100 V type MKT). However, the shield is still connected at both ends to ground for high frequency as a result of the capacitor. Rule 11 If possible, the signal cables should only enter the cabinet at one side. Rule 12 If SIMOVERT MASTERDRIVES are operated from an external 24 V power supply, this power supply must not feed several consumers separately installed in various cabinets (hum can be coupled-in!). The optimum solution is for each SIMOVERT MASTERDRIVE to have its own power supply. Rule 13 Prevent noise from being coupled-in through the supply. SIMOVERT MASTERDRIVES and PLC / control electronics should be connected-up to different supply networks. If there is only one common network, the PLC / control electronics have to be de-coupled from the supply using an isolating transformer. Rule 14 In order to limit the noise emitted, all variable-speed motors have to be connected-up using shielded cables, with the shields being connected to the respective housings at both ends in a low-inductive manner (through the largest possible surface area). The motor feeder cables also have to be shielded inside the cabinet or at least shielded using grounded partitions. Suitable motor feeder cable e.g. Siemens PROTOFLEX-EMV-CY with Cu shield. Cables with steel shields are unsuitable.


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Cabling Wiring Guidelines Cranes

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