mie11166-cba1000 application guide - user equipuserequip.com/files/specs/5683/isa cba 1000 manual_...

Istrumentazioni Sistemi Automatici S.r.l.

VIA BERGAMO 41 - 21020 TAINO (VA) - ITALY

OFFICES TEL. +39.0331.956081 - FAX +39.0331.957091

LAB: TEL. +39.0331.956483 -

E-MAIL [email protected]

WEB www.isatest.com

DATE: 12/12/2005 DOC.MIE11166 REV.1

APPLICATION GUIDE FOR THE

CIRCUIT BREAKER ANALYZER AND MICROOHMMETER

MOD. CBA1000

Doc. MIE11166 Rev. 1 of 30

REVISIONS SUMMARY VISA N PAGE DATE 1 All 12/12/2005 Preliminary issue Lodi.


SHORT FOREWORD ..................................................................................................................................................... 4

SAFETY AT WORK........................................................................................................................................................ 5

1 INTRODUCTION ......................................................................................................................................................... 7

2 CB TIMING TEST........................................................................................................................................................ 8

2.1 CONNECTION TO THE CIRCUIT BREAKER.................................................................................................................... 8 2.1.1 CB contacts. ...................................................................................................................................................... 8 2.1.2 Coil drivers ........................................................................................................................................................ 8 2.1.3 More than two chamber per phase ................................................................................................................... 9

2.2 TEST EXECUTION..................................................................................................................................................... 10 2.3 TEST RESULTS ANALYSIS......................................................................................................................................... 13

3 CB MOVEMENT OR ANALOG SIGNAL TEST.................................................................................................... 15

3.1 TRAVEL TRANSDUCER CONNECTION TO THE CIRCUIT BREAKER............................................................................... 15 3.2 PRESSURE TRANSDUCER CONNECTION TO CBA1000...............................................................................................18 3.3 ANALOG SIGNAL CONNECTION TO CBA1000 ........................................................................................................... 19

4 AUXILIARY CONTACTS TEST .............................................................................................................................. 21

5 TWO RECORDING TEST......................................................................................................................................... 22

6 STATIC RESISTANCE TEST ................................................................................................................................... 24

7 DYNAMIC RESISTANCE TEST .............................................................................................................................. 26

8 TWO GROUNDS TEST WITH DET1000 ................................................................................................................ 29


SHORT FOREWORD Dear CBA/1000 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 CBA1000 manual in three: specification, with all performance details; introductory guide, with the device description; application manual, with instructions about how to use it one 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? This manual deals with application examples: read through them, they will help you. Have a good work with CBA/1000! Primo Lodi Q&A Manager


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 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. Mains supply characteristics are:

.. From 85 to 265 V AC; 50-60 Hz,

.. From 100 to 350 V DC. . Power consumption: 100W maximum. The Product includes a rechargeable NI-Cd battery. In case of replacement, dispose it in the suitable containers. 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 the coil drivers.

. The symbol is located close to the ground socket.


. The symbol is located close to the mains supply socket, that incorporates the protection fuse. 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 check the situation in case of doubt. SITUATION CAUSE OF RISK CONTROL TEST SET NOT GROUNDED BEFORE ANY CONNECTION

Capacitor dividers take the case at 110 V; the unit is not protected against common mode noise. Heavy risk in case of fault during tests.

Ground connection on the dedicated socket; supply plug with ground.

CB NOT CLOSED AND GROUNDED ON BOTH SIDES, BEFORE CONNECTING THE MAIN CONTACTS

When floating, main poles can be at high voltage because of inductions. Heavy risk in case of connection error!

CB closed. Main poles grounding.

CB NOT GROUNDED ON ONE SIDE DURING TESTS

Heavy risk in case of wrong disconnector operation!

Main poles grounding on one side.

Connection sockets not isolated Contact to a live wire. If the optional cable set is not used, use safety connection sockets!

CB coils not disconnected from the circuit.

There can be voltage from the plant during tests: this could damage the test set.

CB coils disconnected.

Contact with the plant auxiliary supply.

The DC voltage can be higher than 50 V DC, hence very dangerous.

Connections to the DC supply must be protected.

Travel transducer does not have extra stroke

Damage of the travel transducer or joints because of extra stroke during tests

Verify Open and Close positions

CB in service before disconnecting it from CBA1000.

Danger of short-circuits on the test set. Disconnect CBA1000 prior to restoring. In case, use the PARK sockets for coil cables.

CLOSE THE CB AND CONNECT IT TO GROUND ON BOTH SIDES BEFORE DISCONNECTING

When floating, main poles can be at high voltage because of inductions. Heavy risk in case of connection error!

CB closed. Main poles grounding.

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. The connection to ground is provided through the mains supply cable or, when the test set is battery operated, it is connected to ground using the dedicated socket. In case of doubt, please contact your Seller. The Seller, and Manufacturer, declines any and all responsibility due to improper usage, or any usage outside the specified limits.


1 INTRODUCTION The circuit breaker analyzer and micro-Ohmmeter model CBA1000 is a two-in-one test set. When used as a circuit breaker analyzer, it allows the off-line testing of the characteristics of all modern MV and HV circuit breakers. When used as a micro-Ohmmeter, it allows measuring the contact resistance of the circuit breaker contact, or also of joints or other circuit parts. It allows also to perform the dynamic test of the contact resistance, that is to record and display how does the contact resistance change while it is closing: this allows detecting hidden defects, that are otherwise impossible to be diagnosed. Purpose of this manual is to guide you step by step, so that you can perform all key CB tests. It is understood that the user knows how to perform selections, as explained in the introductory manual.


2 CB TIMING TEST Purpose of the test is to verify the time delays of main contacts with respect to the coil open/close commands, and the timing spread of contacts. Test result will tell if timings are within the limits; the comparison with former test results will tell how much the CB has changed its timing because of the wear induced by operation, and how uniform has been the wear on the three phases. The test is performed connecting CBA1000 to the CB main contacts and coils, and then issuing the test commands. During the test, CBA1000 issues the coils Open – Close commands, and measures the corresponding contact timings. Test results are shown on the display.

2.1 CONNECTION TO THE CIRCUIT BREAKER

2.1.1 CB contacts. Before proceeding, apply the rules listed in the Safety at work chapter ! The first operation is to connect CBA1000 to CB contacts. To this purpose: . Use inputs A1, B1, C1, for phases 1, 2, 3 in case of single-chamber CB. . Use inputs A1-A2, B1-B2, C1-C2, for phases 1, 2, 3 in case of two-chamber CB. The selection is performed as follows: Menu > Breaker and auxiliary channel settings > Bre aker contacts > A1+B1+C1 or all RET During the connection, CB MUST BE CLOSED AND GROUNDED ON BOTH SIDES. If the optional cable kit has been purchased, the connection is performed using the three-conductors cables provided, one for each phase: conductors are marked A, B, C. Once the connection is performed, it is necessary to open the earth connection on one side, but THE OTHER SIDE MUST BE LEFT CONNECTED TO GROUND . Which socket (red, black, blue) should be connected to ground is not relevant. For the test of the pre-insertion resistor there is no further connection: you have to select it. Menu > Breaker and auxiliary channel settings > Pre -insertion resistor test > Enable RET If you don’t use the optional connection cables, they should be tied together, in order to minimize the interference cause by the electric field.

2.1.2 Coil drivers Next operation is to connect logic CBA1000 coil driver outputs to the CB coils. Before proceeding, coils must be DISCONNECTED FROM THE PLANT CIRCUITS , so that there is no interference during the test. The connection is made in two steps:


- First step: Connect one of the two sockets of all coil drive circuits to the auxiliary DC voltage supply of the plant; usually, the connection is performed to the positive of the auxiliary supply. Coil driver is bidirectional, so it does not matter to which socket the auxiliary voltage is connected. - Second step: connect the coil input to the corresponding CBA1000 sockets, considering that: . The Close coil is always one, and is to be connected to the socked marked C; . The Open coils command could be three phase: in this instance, connect it to THE SOCKET MARKED O1; . If the Open coils command is single phase, and if the four coils option is available, then connect the Open phase 1 coil to socket O1, the Open phase 2 coil to socket O2; the Open phase 3 coil to socket O3. If you don’t use the optional connection cables, the cross section should be enough for the coil drive current: at least 6 sq. mm, in order to minimize the current drop. NOTE: sockets O2 and O3 are always present, even if the four coils option is not available. NOTE: sockets marked PARK are not connected: prior to test, it is safer to fit the coil driving connections in these sockets, until everything is OK. At this moment, connections are as follows (case of: single chamber CB, with four Open coils).

2.1.3 More than two chamber per phase If you have more than two chambers per phase, you can split the test in three, testing one phase at a time: you can connect up to six chambers per phase. The alternative solution is to use two (or more; up to 4) CBA1000, taking advantage of the Master-Slave option (one Master, three Slave). The following connection refers to four chambers per phase, but up to 8 chambers can be tested (only one pole is shown).


One CBA1000 is the Master: this is the one to which are connected the coils. The Slave is the one that monitors the additional chambers: its Slave input is connected to the Master output of the Master CBA1000; besides, on the Slave unit(s) you have to select the Slave operation, as follows: Menu > Trigger options > External trigger RET Only CB contacts (and auxiliary CB contacts, analog input) are connected to the slave unit: NOT the coil drivers. At the end of tests, on the Slave unit the timings are referred to the Master’s trigger. The total test result can be glued using the software.

2.2 TEST EXECUTION Once connections are performed, next operation is to power-on CBA1000: the following screen is displayed.

At the end of self-diagnostic, the following screen is displayed.

On the front panel, breaker contacts LED’s will display the contacts status: Green = Main contact Closed, as it should be at this moment; RED = main contact Open. In case of discrepancy, correct the connection. This is the situation with a single-chamber CB.


On the first test, you have to input the tests header, as follows. Menu > Tests header RET Once test data are input, you can proceed with the test. As you are finished with a CB, don’t forget to input the new CB header. The test can be executed with a number of different values for the various available choices. At power-on, the default situation is presented: parameters selection can be read pressing the Set pushbutton. Set > Show current setup (RET) If these values match with what you want to do, you can immediately start the test; else, you can load a previously saved setting, or you can enter the menu, modify the desired parameters and then save the setting, before proceeding. For instance, if you want to modify the timing setting, act as follows: Menu > Recording options > Open to close delay > (v alue) RET And so on with other delays. At the end of timing programming, you can check your values pressing Help diagram: the following window is displayed.

Remember that he “Recording duration” must be bigger than “Pre-trigger” + “OC delay” + “CO delay” + the CB timings, so that no significant part of the test is lost. On the other side, it should not be too big, as it defines the test result dimension, hence the number of test results that can be kept in memory.


There are as many as 64 memory positions available for test settings; so, we suggest to prepare the desired ones using the software, possibly before leaving the office; when you are on site, you just load the desired setting, as follows. Set > Load setup > File selection RET Now, you are ready for the test. As you see, on the front panel there are two buttons in all: one selects the type of test; the other one starts the test. You don’t have to use the Menu selection to set the desired test. After power-on, the default selection is OCO; for instance, if you want to perform an O-C test, press the SEL button until the OC LED turns on: the test is selected.

Now, press the START button: the buzzer warns eight times that the test is about to start, then the test is performed. The LED above the pushbutton turns on until the test is over.

Breaker contacts LED’s turn red and green, as main contacts open and close: at the end of the test, green LED’s should follow the selection. On the display it is shown the test result.

You can examine it, and verify current peaks and diagram, main contact timing, pre-insertion resistor timing, by moving the two cursors (cursor selection is obtained checking on t1 or t2). If the result is OK, you can save it, and perform other tests; else, you can repeat it, ignoring the warning message about saving Saving the result is performed using the Res selection: Res > Save result > File name RET The following window is displayed:


It is possible to continue testing the same CB and saving results with different tests. It is also possible to recall the former result of the same CB, so that you can check for deviations in time; this is easily performed using the software. When the test on the CB is finished, before going to another one, remember to select Close at the end of test, prior to disconnect cables!

2.3 TEST RESULTS ANALYSIS The analysis of test results allows to measure the relevant CB contacts parameters. The first measurement is the delay between the Open (Close) coil command and the corresponding main contact Opened (Closed) position. The following figure shows the recording with an Open – Close command: delays are referred to coil commands. Other relevant measurements are the Open coil current and Close coil current: they are metered moving the cursors on the desired point. The coil current shape is also providing information on what does it happen as the coil actuator moves. At the beginning, the coil inductance is low, as there is a big gap on the actuator. At some moment, the actuator operates the mechanical latch that keeps the contact in the Closed position: from then, the actuator moves faster, and the inductance increases until the actuator reaches the end

OPEN DELAY CLOSE DELAY

OPEN COIL CURRENT

CLOSE COIL CURRENT

A1 B1 C1


of stroke. The inductance increase typically causes a momentary current decrease, that depends upon the actuator characteristics of inductance and speed. From this moment on, the current increase is defined by the R-L actuator characteristic, where L is the end-of-stroke actuator inductance, and R is the coil DC resistance. The maximum coil current is Imax = Vaux / R. When the CB contact is close to its Open position, the auxiliary contact cuts the Open coil current: this is (almost) the end of the CB stroke. All these timings can be compared to specs or to former test results. Another important measurement is the contact timing spread and the pole spread: the first one applies when there are two chambers per phase. Zooming on the contacts trip, it is possible to examine the details. Zooming even more, it is possible to verify if there are bounces on the contact: they are detrimental to contact life, and mean that the contact surface is worn.

MAXIMUM COIL CURRENT

TRIP LATCH OPENED

END OF STROKE

COIL CURRENT OPENING

CONTACTS TIME SPREAD

A1 A2 B1 B2 C1 C2

POLES TIME SPREAD

CONTACTS TIME SPREAD

POLES TIME SPREAD

A1

CONTACT BOUNCE


3 CB MOVEMENT OR ANALOG SIGNAL TEST In this instance, you want to test also the CB movement during tests, or you want to monitor some other analog signal. It is therefore necessary to perform some more connection to the CB.

3.1 TRAVEL TRANSDUCER CONNECTION TO THE CIRCUIT BREAKER Travel transducers are used for the purpose of having a better detail on the mechanical status of the CB. This is accomplished as follows: . Comparing the movement trace to CB Open and Close contacts, it is possible to verify if they act at the desired stroke positions, including tolerances; . Computing from the trace the corresponding speed and acceleration, it is possible to verify if CB limits are exceeded because of plays caused by wearing. . Also auxiliary CB contacts acting positions can be checked. The travel transducer is a potentiometer (pulse transducers are not foreseen); the cursor position corresponds to the pole position during the movement. There are two types of transducers: linear, with different strokes, and angular. The linear transducer is mechanically connected to the leverage that acts on poles by means of joints; the angular one is connected to the motor shaft. To solve the mechanical problems, the optional linear transducers are equipped with suitable connection hardware. The linear transducer is usually connected to a point that does not perform the same movement of the contact: usually, the movement is less that the one of the contact. This means that for both types of transducers it is necessary to know not only the contact nominal stroke, but also the nominal stroke of the transducer connection. As both types of transducers are potentiometers, it is necessary to supply them with a DC voltage, that is measured by CBA1000. This voltage is available on sockets (18): see the connection diagram.


The programming of the test is performed as follows. . First of all, install the transducer and connect it to CBA1000. During transducer installation, mount it so that there is some stroke after Open and Close positions (minimum 5% of the stroke): this is because during operation the CB shaft moves beyond the Open and Close positions at rest. If you don’t, the movement diagram would cut the extra stroke, and the transducer could be damaged. The following design shows the situation. . If you don’t use the optional connection cables, use the connector provided and make the connection cable using a shielded wire pair, wit the shield connected to the connector body. This serves to minimize interference on the measurement signal. . Enable the Analog input measurement, as follows: Menu > Analog channel/coils setting > Analog channe l > Enabled > Travel transducer > Label > 5 V >

CURSOR MAX. STROKE CLOSE OPEN MIN. STROKE

TRANSDUCER

100%

>5% >5%


. At this moment, the following window is displayed.

. The first set of data is referred to the transducer. You can select the type of transducer: degree for angular, mm or Inch for linear. Next you have to key in the nominal transducer stroke, that is the nominal stroke at the connection point, and the maximum transducer stroke that is the maximum movement of the transducer itself: it will be, for instance, 350° for an angular transducer, and 100 or 200 mm for a linear one. This information allows CBA1000 to translate the input voltage into the transducer position. Next, you have to inform about the supply voltage for the transducer. If it is the internal source, the test can continue; else, you have to key in the voltage, that must be accurately measured for an errorless test result. . The next set of data refers to the CB contact. You can select the unit of measurement, that can be feet, millimetres or inches; then, you have to input the nominal CB contact stroke. . Now, select TEST: this serves to measure the actual transducer stroke, hence the actual CB contact stroke. After checking, the following window is displayed.


. CBA1000 recognizes if the CB is open or closed, and displays the Close (or Open) transducer position, in the selected U.M. and in percentage of the total transducer stroke. Now, issue a command so that the CB goes to the opposite position, Open (or closed): the window displays the next position, and computes the actual transducer and CB contact strokes and the stroke percent error with respect to the nominal, that must match with the tolerance limits. . From this moment, CBA1000 is ready to display the CB contact movement in the selected U.M.: from these values, the software computes speed and acceleration. The analysis of test results allows to measure other relevant CB parameters. Next figure shows a typical movement diagram, after an Open – Close command. CBA 1000 computes the key parameters of the diagram, that are: CB reaction time (from the command to when the contact starts to move); “wipe” movement (from Closed to when contacts open; “damping time” (from the contact opening to the Open position); “over-travel” (the stroke beyond the reference Open or Closed positions), “rebound” (the stroke after the over-travel).

3.2 PRESSURE TRANSDUCER CONNECTION TO CBA1000 Pressure transducers measure the gas pressure as the CB is operated: watching this signal is useful as hidden problems could be revealed. Usually the transducer is mounted on the CB, and outputs a low voltage. The selection is performed as follows. . If you don’t use the optional connection cables, use the connector provided and make the connection cable using a shielded wire pair, wit the shield connected to the connector body. This serves to minimize interference on the measurement signal. . Enable the Analog input measurement, as follows: Menu > Analog channel/coils setting > Analog channe l > Enabled > Pressure transducer > . At this moment, the following window is displayed.

STROKE

CLOSE DELAY

OPEN COIL CURRENT

A1 B1 C1

CONTACT OPENS

OVER-TRAVEL BOUNCE

OVER-TRAVEL

REBOUND

CONTACT CLOSED

CONTACT OPENED

CB reaction time

WIPE

DAMPING TIME


. First of all, introduce the reference Label. . Then, you can select the type Unit of Measurement of the transducer. . Next, you have to key in the pressure when the voltage is 0 V (because usually it is not zero), and the pressure transducer constant, in V/U.M.: it will be, for instance, 0,1 V/Bar. This information allows CBA1000 to translate the input voltage into pressure. . From this moment, CBA1000 is ready to display the pressure, in the selected U.M.. The test execution is the same as for CB contacts test; in the result window, the CB pressure is displayed.

3.3 ANALOG SIGNAL CONNECTION TO CBA1000 The monitoring of other analog voltage can be executed; for instance, it could be interesting to watch: . Motors current or voltage; . Auxiliary DC-AC supply voltage. In this instance, the connection is performed to either of the voltage inputs, as CBA1000 monitors only the selected one. If you want to connect to the 5 V input, and don’t use the optional connection cables, use the connector provided and make the connection cable using a shielded wire pair, wit the shield connected to the connector body. This serves to minimize interference on the measurement signal. If you want to measure the motor current, and you don’t have the optional cable set, you should use a current to voltage clip-on meter, with a conversion constant of 1 V – 10 A. The selection is performed as follows. . Enable the Analog input measurement, as follows: Menu > Analog channel/coils setting > Analog input > Label > Voltage input range RET The test execution is the same as for CB contacts test; in the result window, the selected analog input is displayed.


The following figure shows the test of the auxiliary supply. NOTE: Do not exceed the input voltage limit of 350 V AC or 500 V DC.


4 AUXILIARY CONTACTS TEST In this instance, you need to test also some auxiliary contacts during tests. It is therefore necessary to perform some more connection to the CB. For instance, it can be useful to connect the CB Open and CB closed auxiliary contacts, and to verify at which point of the stroke they operate: this allows to know if mechanical tolerances are met. During this connection, please consider the following: . CBA1000 has two ISOLATED groups of two inputs each; so, it is possible to watch two types of contacts, for instance one polarized, and the other one voltage free. . If inputs are with voltage, the zero of the voltage must be connected to the black C socket. If contacts are more than two, connect both C sockets. . If inputs are without voltage, connect the contacts common to the black C socket. If contacts are more than two, connect both C sockets. The following figure shows the connection to one polarized contact.

After powering-on CBA1000, first of all select the type of input (dry or with voltage); then, check that the contact status displayed by LED’s on the front matches with the nominal one (light ON = Closed or With voltage), and correct if something is wrong. The selection is performed as follows. Menu > Auxiliary inputs The following window is opened.


Select auxiliary inputs as desired.

5 TWO RECORDING TEST This is a special test, that solves the problem of testing disconnectors, or any device that takes a long time to switch, after the command has been issued, or to test the “Pole discrepancy” protection, for single phase CB. The selection avoids to waste time recording all this delay while the contact is not yet closed (opened), as follows. Menu > Recording options > check “two recordings” The following window is displayed:

The test is split in three parts: . The first part, when the Open (Close) command is issued: of this part it is possible to select the duration, so that it is possible to record the coil current and the first reaction; . The second part, that can be any duration, during which CBA1000 does not record anything; . The third part, when the second action is occurring, and its duration. The following diagram shows the case of “Pole discrepancy”. At first, and Open command is issued; only one pole is opened; we monitor the Open coil current and the pole opening. Next, we program a pause, that is equal to the minimum Pole discrepancy intervention time, considering the


time tolerance. Next, we program the second time, that will be equal to two times the Pole discrepancy intervention time tolerance, so that we are sure to record the final CB opening. OPEN 1 CONTACT 1 CONTACTS 2, 3 Example: the nominal Pole discrepancy intervention time is 30 s; tolerance is ± 1 s. We will program: T1 = 0,5 s; Pause = 30 – 1 = 29 s; T2 = 2 s.

PAUSE MONITORED T2 MONITORED T1


6 STATIC RESISTANCE TEST This test serves to measure the contact resistance of the CB main contact, and also the resistance of any connection, joint or so. The test is performed applying an high current to the test object (if it is a CB contact it must be Closed), and measuring the voltage drop across it. The high current cables are connected to the high current sockets (19): they should have a cross section of 25 sq. mm, in order to minimize the voltage drop; besides, they should be twisted for the maximum possible length, in order to minimize the inductance. The measurement cable is connected to connector (16): if the optional cable set was not purchased, the cable should be two-wires, shielded: the shield is connected to the male connector provided. The measurement cable will be connected as close as possible to the joint or CB contact, after the current connections, so that the contact voltage drop is not affecting the measurement. Don’t connect to CBA1000 sockets, else we would measure the conductors resistance, that is much bigger than the contact or joint resistance. Also, don’t connect to the high current clips, as otherwise we would measure the clips contact resistance, that is also much bigger than the contact resistance.


The figure above shows the connection, with one pole grounded. However, during this test both ends can be grounded: the paralleling resistance of ground connections is in the range of 10 mOhm up, and it does not affect very much the measurement, that is in the range of 100 uOhm or less: if it is more than this, the CB contact is damaged and needs an intervention. In fact, with a nominal current is 1000 A, the contact resistance power dissipation is 1 W per uOhm: 1 mOhm means an 1 kW power dissipation. To execute the test, select: Menu > Static contact resistance The following window is opened:

. First of all, select the test current: for CB contact, it is 200 A. . Next, select the test mode. If the test is for CB contacts, select “Test on breaker phase” then specify the CB phase and contact under test. . Press START: the current is injected, the voltage drop measured, the corresponding resistance measured. Test current, voltage drop and resistance are displayed to the right. If the measurement is good, pressing on SAVE, the resistance is added to the summary table. . If the measurement is doubtful and the measurement is to be repeated, you should wait for about 1 minute, so that the capacitor is charged, and then press START again and repeat the test. . If the measurement is OK, select another phase or contact, move connections and continue until all contacts have been tested. Note that if you operate with the battery, as this test is power consuming, the maximum battery duration drops to one hour, with respect to the four hours when timing tests are performed.


7 DYNAMIC RESISTANCE TEST This test serves to verify CB main contact resistance change during actual operation: it is possible that contact resistance is good as the contact closes, but during the closing stroke some mechanical damage causes sudden openings or resistance changes that are detrimental to the CB contact. The test is performed connecting CBA1000 to the contact while it is open, then issuing a Close command: as soon as the contact closes, an high current flows through it, and the resistance profile change is displayed. Test result is the resistance profile during close: the contact resistance value is less accurate than the static measurement, but the additional information is the actual behaviour of the contact as it closes. The high current cables are connected to the high current sockets (19): they should have a cross section of 25 sq. mm, in order to minimize the voltage drop; besides, they should be twisted for the maximum possible length, in order to minimize the inductance, and should be as short as possible. This is very important, because cables inductance alters the first part of the recording. The measurement cable is connected to connector (16): if the optional cable set was not purchased, the cable should be two-wires, shielded; the shield is connected to the male connector provided. The measurement cable will be connected as close as possible to the joint or CB contact, after the current connections, so that the contact voltage drop is not affecting the measurement. Don’t connect to CBA1000 sockets, else we would measure the conductors resistance, that is much bigger than the contact or joint resistance. Also, don’t connect to the high current clips, as otherwise we would measure the clips contact resistance, that is also much bigger than the contact resistance.


The figure above shows the connection, with one pole grounded. However, during this test both ends can be grounded: the paralleling resistance of ground connections is in the range of 10 mOhm up, and it does not affect very much the measurement, that is in the range of 100 uOhm or less: if it is more than this, the CB contact is damaged and needs an intervention. In fact, with a nominal current is 1000 A, the contact resistance power dissipation is 1 W per uOhm: 1 mOhm means an 1 kW power dissipation. To execute the test, select: Menu > Dynamic contact resistance The following window is opened:


. First of all, select the test current: for CB contact, it is 200 A. . Next, select the test mode. If you want to test all CB contacts, select “Test on breaker phase” then specify the CB phase and contact under test. . Press START: the contact is closed, and this causes the current to be injected; current and voltage variations are recorded, and the corresponding resistance is measured point per point. The steady-state test current, voltage drop and resistance are displayed to the right; selecting “SHOW DIAGRAM”, the following window is displayed. . If the measurement is good, pressing on SAVE, the resistance is added to the summary table. . If the measurement is doubtful and the measurement is to be repeated, you should wait for about 1 minute, so that the capacitor is charged, and then press START again and repeat the test. . If the measurement is OK, select another phase or contact, move connections and continue until all contacts have been tested. Note that if you operate with the battery, as this test is power consuming, the maximum battery duration drops to one hour, with respect to the four hours when timing tests are performed.


8 TWO GROUNDS TEST WITH DET1000 As explained in the previous chapters, during the CBA1000 connection to main CB poles, CB must be closed, and grounded on both sides. Once the connection is preformed, one of the two ground connections must be removed, because otherwise the ground connection would shunt the CB contact test current, and the CB would appear always closed. There is a drawback about removing a grounding: it is that the operator IS NO MORE PROTECTED AGAINST AN HV BEING APPLIED TO THE OPEN S IDE : when the CB contact is open, that side is not grounded at all. DET1000 has been developed to allow to perform the test EVEN IF BOTH GROUNDS ARE CLOSED. The operating principle takes advantage of the fact that the ground connection has a resistance in the range of 10 – 20 mOhm, that is at minimum 50 times the CB contact resistance. DET1000 generates an higher current (10 A) than CBA1000 (50 mA or less) to detect the closed contact: the higher current allows to generate a voltage drop that is 100 mV up for the ground connection, and 50 times less for the closed CB contact.

To perform the test, you have to: . Connect CBA1000 to DET1000; . Connect DET1000 current outputs to CB main contacts, using the 10 m three-way cables; . Connect DET1000 measurement inputs to CB main contacts, using the 10 m 2-way shielded cables. Take care to connect these cables closer to the CB contact than the current ones; . Connect CBA 1000 to coils, auxiliary contacts, transducer; . Instruct CBA1000 that the option is present; . Issue an Open CB command: LED’s on the CBA front panel should show it OPEN. If not (LED’s show CB Closed), go to the threshold selection, and increase the threshold until contacts are sensed Open; . Now, issue a Close CB command: LED’s on the CBA front panel should show it CLOSED. If not (LED’s show CB Open), go to the threshold selection, and increase it until contacts are sensed Open. The possible cases for the threshold settings are summarized in the following table.

DET1000

10 A

GROUND CONNECTION RESISTANCES

VOLTAGE MEASUREMENT V IN


THRESHOLD LED CORRECTION HIGHER THAN OPEN LEVEL

ALWAYS CLOSED REDUCE THRESHOLD

BETWEEN OPEN AND CLOSED LEVELS

FOLLOW CB POSITION

NONE

LOWER THAN CLOSED LEVEL

ALWAYS OPEN INCREASE THRESHOLD

Now it is possible to perform tests as usual, operating on CBA1000.

mie11166-cba1000 application guide - user equipuserequip.com/files/specs/5683/isa cba 1000 manual_...

Documents