DATE: 18/07/2013
DOC.MIE11170 DOC.MIE1117 0
REV. 6.5.2
DISTANCE RELAY AUTOMATIC TESTING APPLICATION GUIDE
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SUMMARY
VISA
DATE 15/02/2010
Preliminary
Lodi
All
17/10/2012
Issued
Lodi
All
18/07/2013
Revised
Lodi
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REVISIONS N. PAG. 1 All 2 3
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SUMMARY
VISA
DATE 15/02/2010
Preliminary
Lodi
All
17/10/2012
Issued
Lodi
All
18/07/2013
Revised
Lodi
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..................................................... .................................... ........................ ..... 7 1 SAFETY AT WORK .................................... .................................................. ................ 11 2 TESTING A DISTANCE RELAY .................................. ..................................................... .................................... ............................... ............. 11 2.1 FOREWORD ................................... .................................................. ....... 12 2.2 DISTANCE RELAY CONNECTION. ........................................... ................................................... ................ 15 2.2 STARTING THE TEST PROGRAM ................................... 2.3 THE DISTANCE RELAY IS IN THE RELAY LIBRARY ...................... 16 2.4 THE DISTANCE RELAY IS NOT IN THE RELAY LIBRARY .............. 21 ................................................... ................ 22 2.4.1 The file is available ................................... ................. 23 2.4.2 The file is not available: Z - design ................. ...................................... ... 24 2.5 TEST OF THE RELAY CHARACTERISTIC ................................... ...................................................... ............................ .......... 24 2.5.1 Click and test .................................... .................................................... .............................. ............. 32 2.5.2 Repeat a test ................................... .........................37 37 2.5.3 Test a new relay characteristic .......................... ..................................................... ......................... ....... 42 2.6 VERIFY NOMINAL VALUES ................................... .......................................... 45 2.7 SEARCH THE R/X CHARACTERISTIC ........................................... ......................... 47 2.8 SOME MORE GENERAL FUNCTION SELECTIONS .........................
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Disclaimer
Every effort has been made to make this material complete, accurate, and up-to-date. In addition, changes are periodically added to the information herein; these changes will be incorporated into new editions of the publication. ISA S.R.L reserves the right to make improvements and/or changes in the product(s) and/or the program(s) described in this document without notice, and shall not be responsible for any damages, including but not limited to consequential damages, caused by reliance on the material presented, including but not limited to typographical errors.
Copies, reprints or other reproductions of the content or of parts of this publication shall only be permitted with our prior written consent. All trademarks trademarks are the the property property of their respecti respective ve holders. holders.
Copyright 2013© ISA S.R.L. Italy – All rights reserved.
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SHORT FOREWORD Dear ISA automatic relay test set user, I often wondered why the user’s manual is not very much used, even if it includes valuable information. As me too I am a user of such manuals, the answer I have given myself is that valuable information are concealed somewhere in the thick thing, and I do not have time to waste to find it. So, either the manual is actually of help, or I ignore it. This is why I decided to split the automatic relay test set manuals in three: specification, with all performance details; introductory guide, with the device description; application manual, with instructions about how to use it once its operation is understood. The idea is that you may read once the introductory guide or the specification, while you need to follow application examples more than once; so, why not to split the manual in three? Also, while the specification and the introductory guide change with the specific automatic test set: UTB, UTS, ART 3, BER 3, DRTS, DRTS 3, DRTS 6, DRTS 66, the application does not change, unless for few instances: for instance, transformer differential relays can be tested with six currents only with DRTS 6, unless you have an external three-currents option. This application guide is specially devoted to beginners, as it provides basic information about how to use the instrument instrum ent when testing the key relay types, so that you can get acquainted of the test set plus the TDMS software. Once key relay testing is understood, you should refer to the various program manuals for more details. Last but not least: with the test set, you got a set of documents, that includes this one: however, you cannot find the software manuals: where are they? Well, first of all they are in the HELP of each software: it is always at hand to explain about what you are doing; use it. Next, in the CD ROM that you got with the TDMS program, are also recorded all manuals, in all languages: so, it is a good idea that you copy them into your PC: PC : you can find it when you need it.
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Have a good work with ISA test sets! Luca Biotti Q&A Manager
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1 SAFETY AT WORK
The Product hereafter described is manufactured and tested according to the specifications, and when used for normal applications and within the normal electrical and mechanical limits will not cause hazard to health and safety, provided that the standard engineering rules are observed and that it is used by trained personnel only. The application guide is published by the Seller to be used together with the Product described in the corresponding document. The Seller reserves the right to modify the guide without warning, for any reason. This includes also but not only, the adoption of more advanced technological solutions and modified manufacturing procedures, and also the addition of other features, not available in the first release. The Seller declines any difficulties arising from unknown technical problems. The Seller declines also any responsibility in case of use beyond the Specifications, modification of the Product or of any intervention not authorized by the Seller in writing. The warranty includes the repair time and the materials necessary to restore the complete efficiency of the Product; so, it does not include other burdens, such as the transport and customs fee. Under no circumstances the warrantee includes any cost that the User may have suffered because of the Product unavailability and downtime. The Product is CE marked, and has been tested to operate according to EN 61010-1, with the following operating conditions: . Pollution degree 2: normally, non conductive pollution occurs; . Measurement category 2, for measurement inputs. Would the Product be used beyond these limits, its safety could be impaired.
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Mains supply characteristics is: from 85 to 265 V AC; 50-60 Hz. Power consumption: 100W at rest; up to 2000 W with the maximum output power. At the end of its life, the test set should be disposed in a waste dedicated to electric and electronic equipment. The Product deals with voltages and currents that may be lethal to the unadvertised user. Besides, in order to avoid any danger in case of fault inside the Product, the device under test should have the following characteristics: . Connection sockets must be not accessible; . Input circuits must have an isolation degree at least equal to the one of the Product.
!
. The symbol is related to dangerous output, and is located close to AC and DC voltage outputs. . The symbol
. The symbol protection fuse.
is located close to the ground socket.
is located close to the mains supply
The following table lists a number of situations that are potentially hazardous to the user and/or to the Product. Please consider this list, and refer to the introductory manual for further details. SITUATION
CAUSE OF RISK
CONTROL
TEST SET NOT GROUNDED
Capacitor dividers take the case at 110 V. The unit is not protected against common mode noise. See below for details. The test set ground and the neutral ground are connected to very distant points of the grid. There is a voltage differential
Ground connection
VOLTAGE (OR CURRENT) NEUTRAL CONNECTED TO
VN (IN) connected to ground
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GROUND
between the grounds; in case of fault, there is an heavy risk for the test set and for the operator. Besides, it is likely that transient spikes occur during the test; their value can exceed the rated isolation limits. The frequency and amplitude variations and the superimposed noise have caused the damage of the front-end circuit on DRTS test sets unless DRTS 66. The contact can be dangerous to the user or even the plant. The test set voltage outputs are protected only prior to the first test. Possible danger of over-heating components, specially with high ambient temperature
STAND-BY GENERATOR
OUTPUT CONTACTS A LIVE WIRE
LONG GENERATION OF ALL CURRENTS VERY OLD RELAY, WITH HEAVILY INDUCTIVE LOAD
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Spikes as the relay switches the measuring circuits
Supply waveform
Test before connecting
Check burden and duration Check burdens
Of these points, the first three are very hazardous, both for the user and the test set. THESE TYPES OF FAULT ARE NOT COVERED BY THE WARRANTY. Other information about the test set, coping with the Standard EN61010-1, paragraph 5.4.
The USB and ETHERNET ports are isolated with respect to the ground and all the internal circuitry at 1 kV AC, 50 Hz. Cleaning of the display can be done using a dry (or slightly wet) cloth. Do not use solvents, as they would penetrate the display, and cause a permanent damage.
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As soon as the mains supply plug is fit, the test set is powered-on and goes to a stand-by status. Removing the power supply cable is an emergency intervention: so, leave room around it so that it is possible to remove it. The test set is to be operated with the handle below it, and with the rear at least 0.1 m far from the wall . In fact, the cooling air flows from the rear, where it is sucked, to below the test set. If this flow is barred, the test set would increase its temperature, at the detriment of its expected life.
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TESTING A DISTANCE RELAY
2.1 F OREWORD
Distance relays behave as follows: . Measure the fault impedance, and . Trips with a different timing, according to the fault impedance value. On the R-X plane, zone 1 is a surface which includes all impedances that make the relay to trip with a delay equal to T1; the zone limit is a line that divides two zones. Testing a zone limit always involves two tests: one in zone A, the other one in zone A+1. As a consequence, there is always an approximation in finding a zone limit: it is the difference between the two impedances for which: . With fault Z(A), fault time is T(A), and . With fault Z(A+1), fault time is T(A+1). What the software does is to compute currents, voltages, angles corresponding to ZA and to Z(A+1); then, the test set applies the computed values to the relay and measures the corresponding timings. We don’t know where the limit actually is, and we don’t care, provided that the difference Z(A+1) – Z(A) is small enough, compared to the average (Z(A) + Z(A+1))/2, that is the test result. The following sketch shows the situation.
TIME T(A+1) T(A) IMPEDANCE Z(A)
Z(A+1) AVERAGE = TEST RESULT The above implies that key test parameters are zone timings: if they are wrong, test results will be meaningless. This is why,
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prior to start the automatic test, we suggest to verify that timings are correct. If timings are correct and zone limits are wrong, our test programs will automatically find the actual limits, with search algorithms that minimize the search time. 2.2 D ISTANCE RELAY CONNECTION
The connection of the distance relay to the test set involves the following minimum set of connections: . Three voltage outputs: they are V1, V2, V3 and VN. If you have six voltage inputs, connect among them the three zero references, and connect them to VN. . Three current outputs: they are I1, I2, I3 and IN. If you have six current inputs, connect among them the three zero references, and connect them to IN. . One trip contact. The connection follows the type of contact: if it is voltage free, connect one end of the contact to the C socket, and the other one to the C1 socket. If it is with voltage, connect C to the zero voltage reference, and C1 to the polarized contact. Other possible basic connections: . Power supply the relay by connecting the auxiliary voltage input to the test set V DC output. . Over-reach command. This command comes from the external Recloser logic, and it is typically connected to the auxiliary supply. So, connect the C socket of A1 to the supply positive, and the N.O. socket to the over-reach relay input.
The following figures shows the connection to DRTS6 and to DRTS 66.
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C
O
N
N
E
C
T
OI
N
T
O
D
R
T
S
6
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CONNECTION TO DRTS 66
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Before continuing, consider that: . There is no problem of the test set power when testing electronic or numeric relays; . In case of electro-mechanical relays, the problem of power can arise. Please refer to the test set introductory guide, where this problem is dealt. An idea to solve problems is that distance relays compute the impedance, i.e. the ratio of voltage vs. current. This means that if you halve both of them, you can perform the test at the expanse of a moderate accuracy reduction: this usually solves the power issue. In this situation, if the general starter is of the over-current type, you should temporarily halve the settings. 2.2 S TARTING THE TEST PROGRAM
The test of a distance relay is performed starting TDMS, and then pressing DISTANCE RELAYS: the following window is displayed.
PRESS HERE
The simplest testing situation is that you have a table with a number of impedance settings to be tested: in this situation, press Distance 21 and go to the “Verify nominal values” paragraph.
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If you wish to test the complete relay characteristic, the problem of inputting the relay setting is simplified if the relay is listed in the relay library: in this situation, the program accepts the relay settings as they are, and adapts them to the test program. The heavier alternative is to start the program and to design it by the editor provided. Other possibility: you have the nominal settings, and you want to have a look at the complete characteristics, without having to design it, also because you don’t know all relevant parameters. In this instance, go to the “search the R/X characteristic” paragraph. 2.3 T HE DISTANCE RELAY IS IN THE RELAY LIBRARY
For revision 6.5.2, the following relays are available in the library list. NOTE: we keep on adding the newest relays and manufacturers to our library; so, you could find some more relays. MANUFACTURER ABB AREVA
GENERAL ELECTRIC HITACHI ICE LANDIS & GYR MITSUBISHI NXT-PHASE PROTECTA SCLUMBERGER SEL SIEMENS SIFANG TOSHIBA VATECH XelPower
MODELS RAZFE, RAZOA, REL300, REL316, REL511, REL516, REL670, REZ-1, LZ92, LZ96 EPAC3000, LFZR, MICROMHO, OPTIMHO, P441-442-4442, P438, QUADRAMHO, P439, P443-445-446 ALPS, URD60, DLP21, TLS1B DMP-02XL PDZI-N DAM385, RN1 MDT-H L-PRO DV7036 RXAP33, ZDS8N, PXLP3000 SEL421, SEL321, SEL311 7SA511, 7SA513, 7SA522, 7SL24, 7SL27, 7SL32, 7SA611-612 CSL-101A GRZ-100, MXL1E OHMEGA KYD2X1
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If the relay to be tested is in the library, after pressing it, the manufacturer list is displayed.
For instance, the above is the selection of 7sa511 of SIEMENS. With the selection above, the following window is opened.
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PRESS THIS BUTTON AT THE END OF PROGRAMMING
The screen shows: . To the left, the distance relay setting parameters; . To the right, the corresponding characteristic diagram for the selected type of fault. The left part changes for each relay type, following the different settings of each distance relay (we have never found two equal settings, even from the same manufacturer!). At this point: - If you have the setting program of the relay, you can copy these settings into the window; - Same thing if you have these settings printed on some document; - Else, it is possible to read the settings from the relay itself. To do this, the relay needs to be supplied; now, may be you can feed it from the local auxiliary supply, or may be you can’t. In this last instance, you can use the DC voltage supply of the test set, as follows. . Go to TDMS and start DISTANCE 21: the following window is displayed.
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1 SET HERE THE AUXILIARY DC VOLTAGE SUPPLY
2 PRESS HERE TO GENERATE THE DC VOLTAGE
. Connect the auxiliary DC supply of your relay to the VDC sockets. . Press “Switch V DC on”: the relay is powered -on; you can read the settings. . Return to the relay settings page, and key in all parameters. . When you have finished, return to the DISTANCE 21 screen and exit. . Come back to the relay settings page, and press the Distance 21 button: the following message can be displayed, if the relay has different settings for LLL and LLn faults.
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If you answer No, two windows are opened: Z – Design and Distance 21; else, only Distance 21 is opened. We will deal with Z-Design later on; let us continue with Distance 21, that now opens up as follows.
THIS IS THE RELAY CHARACTERISTIC TO BE TESTED
The relay characteristic has been transferred to the Distance 21 program: now the actual testing can be performed. Prior to this, you can save the setting as a .MDB file, pressing File and then Save.
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After Save has been pressed, the common dialogue window is opened: you can save in the selected directory.
Pressing Save, the file is saved for future uses. 2.4 T HE DISTANCE RELAY IS NOT IN THE RELAY LIBRARY
If the relay to be tested is not in the library, press Distance 21 and select: FILE Open; the common file dialog window is opened.
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FILES THAT CAN BE OPENED
There are four types of files that can be used to load the characteristic curve: . MDB files, that are relay test results; . SET files, that are generated by Z – Design; . RIO files, that use a “standard” format, adopted by ABB and SIEMENS; . BPR files, that are generated by the former X.TEST 2000 programs.
2.4.1 The file is available In this instance you have to open the file: after this, the corresponding diagram is opened. If you open an .MDB file, you will have both the characteristic curve and test results; else, you only have the characteristic curve, as the one you have got from the library.
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2.4.2 The file is not available: Z - design This is a difficult situation, because it is necessary to edit the relay characteristic curve. To this purpose, it is available an editor, Z – design, that eases very much the task. First of all, go to File and select it:
Z-DESIGN SELECTION
The following window is opened:
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For the description of how to perform the editing, please refer to the Distance 21 manual. 2.5 T EST OF THE RELAY CHARACTERISTIC
Now you have the relay characteristic, and you want to test it. Prior to this, it is advisable to perform a short test that confirms that connections and settings are right: to this purpose, the “Click and test” selection is the right choice: performing few tests you avoid to waste time in case something is wrong. 2.5.1 Click and test . Select Network”: the following window is displayed.
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GO TO TEST WINDOW
Here, you can select many things. However, unless you have used Z – design to draw a new curve, these parameters are already set, and you can press “Generate prefault” to continue . Otherwise, you have to input parameters that you can find in the setting table. Few notes for some selections: for details, call Help or go to the Distance 21 manual. . Test mode: the easiest way to perform the test is to select I constant: the selected test current is used for all tests.
The Zs constant selection provides a much more accurate simulation of the fault; however, it asks for more test data, and causes the deformation of MHO curves: so, this is not for beginners.
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The CT side selection is obvious; however, don’t forget it: a lot of test time has been lost before understanding that the direction was wrong!
About Line parameters, and in particular the earth factor KE, what I can say is that distance relay manufacturers have applied all their fantasy to make things as difficult as possible. We have foreseen all possible ways of defining the earth coefficient, so that you can find whatever is your relay definition for this parameter: remember that it applies to single phase faults only. If you find errors when testing your relay, in 99% of instances the error comes from this parameter.
For more details, use Help or the Distance 21 manual.
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THIS IS THE FIRST ZONE....
AND THIS IS THE FIRST ZONE TIMING
THIS IS THE “NO TRIP”
TIMING
As explained in the introduction, key parameters are time delays: if they are too wrong, test result is impaired. ATTENTION: if you have four zone limits to test, you have to program five timings, the last one being greater than the biggest timing. About tolerances, it can be expressed either in absolute value or in percentage: the bigger one applies. Don’t select a tight tolerance, as it wound increase test time at no actual benefit: if you repeat tests with 0.5% tolerance on the same relay, you don’t get exactly the same result, because of different behaviour of the distance relay itself. As you see, it is even possible to program different timings for different faults: un-check the “Same time delay for all faults” box, select faults and program timings. Some more selections, that could confusing:
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- Use current zero crossing means that at test start the current is zero. This is a good choice for single phase and phase to phase faults, while with three phase faults it is not relevant. Check it. - Divide the characteristic by Inom: this is in case that settings are referred to the nominal current. - Apply V DC with a ramp. Most relays have a big capacitor on the auxiliary supply input: this serves to avoid loosing data in case of short duration supply drops. Sometimes, the capacitor is quite exaggerated, so the test set understands that there is a short circuit. In this instance, you can check this selection: generates a slow ramp on the supply, the capacitor is slowly charged and the test can continue. - Last, a comment about this: other selections are self-explaining (I hope; else, Help is there).
Z – t DIAGRAM…
AT THIS ANGLE What does it mean? Clever relay behaviour in the Z-t angle at which you want changing angle changes the get the following image.
boy, you got it: you can display the plane, once you have selected the the characteristic to be displayed: Z – t diagram. If you click on it, you
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NO TRIP FROM HERE ON NO TRIP IN THIS AREA... ZONE 3 TIMING..
ZONE 3 LIMIT
ZONE 2TIMING..
ZONE 2 LIMIT..
ZONE 1 TIMING..
ZONE 1 LIMIT..
AT THIS ANGLE
You have impedance on the X axis, and time on the Y axis. To the left of the Y axis, we are in the reversed direction, that in this instance is a no trip area: the displayed timing is the maximum time. To the right of the Y axis, you are in zone 1: you can read the timing, and the zone limit impedance, after which we have zone 2, and then zone 3; then there could be the general starter, and eventually the no trip zone. If you change the selected angle, zone limits change, but not zone timings. Once you have finished with settings, press the “G enerate prefault” button. As you do, the test set generates pre -fault values. From now on, don’t disconnect the relay unless after having pressed the “Reset” pushbutton. The “Test selection” window is opened.
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There are two folders: “General Functions” and “Advanced Functions”. Let us consider here only the basic functions: for the advanced ones, please refer to the software user’s manual.
After selecting “Click and test”, press “Confirm”:
The following window is displayed. If you move the mouse on the diagram, two cursors show up; to the left, the window shows the corresponding R,X coordinates, and Z, φ; it displays also the corresponding fault voltages and currents vectors. You can select the type of fault: the characteristic usually changes, and also currents and voltages. Move the cursors to a point inside zone 1, and click on it: the test is started, and when the relay trips you see to the left the test result: it is the last line after those you have opened.
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Let us have a better look at test result.
THIS IS THE FAULT IMPEDANCE...
AND THIS IS THE TRIP TIME: OK
As mentioned in the foreword, it is important to verify timings; so, move the cursor inside other zones, and click there, until all timings are verified.
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AND THIS IS THE TRIP TIME: OK
Verify that measured timings match with the programmed ones; then, delete these preliminary tests pressing the “Delete all tests” button. After this, you can continue with the automated characteristic test. Let us consider two instances: you have to repeat a test, or you have a new characteristic to test. 2.5.2 Repeat a test In this instance you have to open the former .MDB test result of the relay you want to test: the following window is displayed. In this instance, we have loaded the result of the verification of an ABB’s REL511 distance relay.
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The diagram shows the nominal curve (black line) and the tolerance limits (coloured band). Yellow dots are the former test results. To the left, are reported all tests performed and the corresponding results. If you want to repeat the same tests, go to “Test selection”, select “Sequence”.
SELECT SEQUENCE...
Press “Confirm”: the Test window is displayed.
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Move the mouse on N. 1, click it, keep it pressed, and move it down until all tests have been selected: as you release it, the window is now as follows.
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The dialogue window gives you a number of choices: as you want to repeat tests, select “Repeat selected tests”: the window becomes the following, and the test starts immediately.
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The test is executed by verifying one setting after the other, following the test sequence table to the left. When a result is obtained, the tested point is displayed in red. The test proceeds on all selected points, until the last one is finished. Note that the display shows only test results for faults selected in the “Fault” window; so, if you have selected more types of fault, you can access them by changing the fault selection. If you press now “Store all tests”, you can save test results in the location you want.
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2.5.3 Test a new relay characteristic In this instance you have opened a distance relay characteristic, and you want to test it: the following window is displayed. In this instance, we have loaded the 7SA511 characteristic.
The diagram shows the nominal curve (black line) and the tolerance limits (coloured band). Now, you have to press “Select Network”, and proceed as explained in the “Click and test” paragraph. Now, come back to “Test selection”, and select “Verify R/X characteristic: the following window is opened.
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What does it mean? It means that the test is performed as follows: . It verifies the zone limit settings at a given angle; . It measures zone timings, with faults that are the average of two zones; . Once an angle has been tested, the test proceeds with the next one, until all tests have been performed.
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Let us have a better look at test selections.
- Fault: you can choose which faults you want to test, single phase, two phase, three phase, all of them. Test time grows if you select all tests. Note that, once a test has been selected, you can come on this window again, and select another test: it will add to the former one. A good choice could be: . Select the complete test of one single-phase fault, and of one two-phase fault; . For other zones, program the test at 0°, 80° and 90°, checking “Test at this angle only”. - Start angle, stop angle and step angle are self-explanatory. Usually, default values are a good choice, unless you want a more accurate test of corners. - It is also possible to define a different impedance as a starting point of the search, by setting the Offset Z and Offset phZ values: this is useful for the Loss of field generator protection. The following pictures give the idea. Offset Z=
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- You can select the zone limits to be tested: last zone is the general starter. - 1-EXT selection refers to the test of first extended zone: if you check it, you can choose the auxiliary output to which the overreach command is connected. - Last, if you check “Perform border test”, the test will also verify that at tolerance limits the relay behaves correctly. This message box, if not disabled, reminds you that time settings are the most important parameters for the automatic testing.
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In case of doubt, please follow the “Click and test” sequence of the former paragraph. Now, once everything has been selected, you are on the Test window: all selected test points are displayed. Press the START button: tests are executed one after the other, until all tests have been performed.
To the left, the table lists test results.
The Error column tells the test result error: have a look at it, and, in case some result is beyond the tolerance limits, you can repeat
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it by clicking the mouse on the test you wish to repeat: the following window is opened.
PRESS HERE TO REPEAT THE TEST..
AND THEN HERE
As you press ”Repeat selected test”, the test is repeated, and the new result is displayed. When you are happy with your test results, press “Store all tests”: you can save test results in the location you want.
2.6 V ERIFY NOMINAL VALUES
This is the case when you have the settings, typically: line angle, 0°, 90°, and you want to test them. Your R-X plane is blank.
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Now, on the “Network” selection, you can program the first set of test parameters: the former paragraph deals about it. Next, go to “Test selection”, and select “Verify nominal values”: the selection is the following.
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You have to arm yourself with patience, and to program the settings. Once the first programming for one (or more) fault is performed, click on OK: the following message is displayed.
Now you can proceed adding tests at different angles on the same fault(s), and then changing faults and programming again fault angle and fault values, until all your settings have been input. Select the “Test” window: it will display like this.
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SETTINGS TO BE TESTED
NOMINAL VALUES
PRESS START FOR THE TEST
To the right, dots correspond to your settings; the table on the left summarizes the details. Pressing Start, all selected points are verified, in the programmed order, until all results have been obtained. When you are happy with your test results, press “Store all tests”: you can save test results in the location you want. 2.7 S EARCH THE R/X CHARACTERISTIC
You want to know more about the distance relay characteristic, but you don’t know its shape, or you don’t want to spend time designing it. In this case, you can t ake advantage of the “Search R/X characteristic” selection. First steps are as above; then, go to the “Test selection” window, and select “Search R/X characteristic”: the window becomes the following.
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PROGRAM SEARCH ANGLES
As you see, there is no characteristic curve on the R-X diagram: instead, there are a number of lines, that are those along which zone limits will be looked for. Thanks to our clever search algorithm, the test will not take too long: after first test results, we “learn” where settings are, and next tests are much faster. The time is a function of the tolerance you have programmed in “Network”; so, program no less than 2%!. You can change angles at will: the program accepts any step angle, but the default is a reasonable compromise. Press Start: the program will start looking for zone 1 at the first test angle, then zone 2 and so on, until it is finished. The following is a test result obtained on an ABB REL511. As you can see, lines are not perfectly straight, because of minor differences around the zone limit; however, the shape is clear, and zone limits are correct, both forwards and backwards.
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2.8 S OME MORE GENERAL FUNCTION SELECTIONS
The first selection we will consider is verify blinders. Blinders are lines, at a certain angle, which are normally used in distance relays to clearly separate the forward zones from the reverse. They are normally used with quadrilateral characteristics. Example of blinders is in the graph here on the right hand side. The test can be performed either with or without a nominal characteristic.
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If the nominal characteristic is available, the programs detects all blinders for each individual zone and type of fault. Then they are presented in a table where the user must select the blinders to be checked. For the example above, the table on the right is processed. Select the blinder to test: just double click on the Check column of the one you want to test Unselect a previous selection… just double click again As you may see, in order to help you choose the right blinder, the selection is made according to: Zone number Type of fault Blinder angle The user must choose which digital contact is associated with the blinder search, as different fault types may trigger different contacts. IF THE NOMINAL CHARACTERISTIC IS NOT AVAILABLE YOU HAVE TO ENTER THE BLINDER VALUES BY YOURSELF. Zone nr: Select the
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zone number (this will establish the maximum testing time) Test at: Select the Impedance value for the test… it must be within the above Zone number selection. Fault type: single phase, phase to phase… Blinder location: here you select the relative blinder o value the position o O and the zone number
this is the maximum acceptable error in degrees when searching for blinders. When all selection are done, press ok to confirm and prepare the test table.
Max Error:
The button Set digital Inputs contact page.
opens the Digital Inputs
The second function is the “Automatic zone test (Z / t)”. With this selection, the window is the following.
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TEST VALUES
You better select the Z-t window: now it shows the following.
TEST VALUES
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Dots mark the fault impedances where the time response will be tested. Pressing Start, tests are performed, and test results are displayed, until the last result is obtained.
The last selection we wish to mention is the menu choice “Show waveform.
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First select here
then here
Voltages and currents waveforms that the instrument generated in order to reproduce the test are displayed.
has
The window has two cursors, that are positioned with the right and left click of the mouse. When cursors are located on the fault,
