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ISA T 2000 User Manual

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DATE: 18/11/2009
DOC.MIE11110
REV.5
T 2000
APPLICATION GUIDE

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  • Page 1 DATE: 18/11/2009 DOC.MIE11110 REV.5 T 2000 APPLICATION GUIDE...
  • Page 2 DOC. MIE11110 Rev. 5 Page 2 of 110 REVISIONS SUMMARY VISA PAGE DATE 25/04/2006 Issued Lodi. 42, 62-65 24/11/2006 Added the line Lodi impedance test, notes to PT ratio test 48 - 52 23/04/2007 Modified the dynamic Lodi TAP changer test 23-27 31/7/2007 Added the very high...

  • Page 3: Table Of Contents

    DOC. MIE11110 Rev. 5 Page 3 of 110 SHORT FOREWORD....................... 4 SAFETY AT WORK......................5 INTRODUCTION ........................ 9 1 TRANSFORMER TESTS APPLICATION EXAMPLES ..........10 1.1 C URRENT RANSFORMER TESTS ............... 11 1 .1.1. CT tests : ratio, polarity voltage mode ......11 1 .1.2.

  • Page 4: Short Foreword

    So, either the manual is actually of help, or I ignore it. This is why I decided to split the T 2000 manual in three: specification, with all performance details; application manual, with instructions about how to use it one its operation is understood;...

  • Page 5: Safety At Work

    DOC. MIE11110 Rev. 5 Page 5 of 110 SAFETY AT WORK The Product hereafter described is manufactured and tested according to the specifications, and when used for normal applications and within 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.
  • Page 6 DOC. MIE11110 Rev. 5 Page 6 of 110 Would the test set be used beyond these limits, the safety of the test set could be impaired. Mains supply characteristics are: . Voltage: 230 AC, 50-60 Hz; . Power consumption: 1 kW maximum without overload; 4 kW at 600 A (5 s).
  • Page 7 DOC. MIE11110 Rev. 5 Page 7 of 110 The connection to ground is provided through the mains supply cable; however, for added safety, the Product should be connected to ground using the dedicated socket. IF THE GROUND IS NOT AVAILABLE AT THE MAINS SUPPLY, CONNECT THE TEST SET TO GROUND USING THE DEDICATED SOCKET.
  • Page 8 THESE TYPES OF FAULT ARE NOT COVERED BY THE WARRANTY. The first hazard is very clear: while T 2000 is connected to the transformer to be tested, there must be no connection of the transformer itself to a voltage or current source. T 2000 outputs are protected against transient spikes, but not against such a situation.

  • Page 9: Introduction

    Rev. 5 Page 9 of 110 INTRODUCTION T 2000 allows performing all the test to be performed on current and voltage transformers. At power-on, there is a message asking to wait for the self diagnosis is completed. After this, the following menu is displayed.

  • Page 10: Transformer Tests Application Examples

    The description of why we operate this way and of which are test set features are given in the following chapters. So, read the following chapters the first time you use T 2000, and then, once learned about it, apply what you learned as follows.

  • Page 11: Current Transformer Tests

    DOC. MIE11110 Rev. 5 Page 11 of 110 The following paragraphs detail the operations following these selections. 1.1 C URRENT RANSFORMER TESTS When this selection is performed, the following screen is displayed. It is possible to select the tap number: this selection is reported in the available tests.
  • Page 12 DOC. MIE11110 Rev. 5 Page 12 of 110 measured also generating current; however, with this connection it is also possible to test the excitation curve. The following table explains the AC voltage output to be used as a function of CT parameters. Given: .
  • Page 13 DOC. MIE11110 Rev. 5 Page 13 of 110 NOTE: the drawing shows the output connection to 3000 V, and the input connection to 10 V. For the connection, use the following cables: A) Output connection, 3000 V: - N. 2 High voltage connection cables, 4 m long, 5 kV, with earth screen.
  • Page 14 N. 2 Clamps to connect low voltage or low current or measurements. HV cables shall be connected while T 2000 is powered-off. HV clamps shall have a minimum clearance of 20 mm with respect to all conductive surfaces, so to avoid discharges during operation.
  • Page 15 DOC. MIE11110 Rev. 5 Page 15 of 110 . The transformer ratio; . The percentage ratio error with respect to the nominal; . The polarity, as OK or KO. You will notice that the % error does not change as a function of the test voltage. When you are close to VSM/2, press SAVE: test result is saved, and voltage is removed.

  • Page 16: Ct Tests : Ratio, Polarity And Burden

    DOC. MIE11110 Rev. 5 Page 16 of 110 Having verified that there is no saturation, you can return and press SAVE to save the test result; then, slowly reduce the voltage: the test can be stopped only after knob (6) is in its zero position.
  • Page 17 DOC. MIE11110 Rev. 5 Page 17 of 110 test) to the primary side, and measuring the secondary current and voltage. The connection diagram is the following. For the connection, use the following cables:...
  • Page 18 DOC. MIE11110 Rev. 5 Page 18 of 110 A) Output connection, 800 A: - N. 2 High current connection cables, 100 sq. mm, 4 m long. Terminated on one side with the high current connector; on the other side, it is possible to use one of the following three connections.
  • Page 19 DOC. MIE11110 Rev. 5 Page 19 of 110 600 V input. The choice is performed considering the test current IP and the VA rating. Given: . KCT = CT ratio; . IP = primary test current; . VA = VA rating, compute: IS = IP / KCT VS = VA / IS...
  • Page 20 DOC. MIE11110 Rev. 5 Page 20 of 110 The screen shows: . The secondary current; . The secondary voltage; . The phase angle, in degrees, between current and voltage, with the voltage taken as the reference. Usually this angle will be negative, because the burden is inductive;...

  • Page 21: Ct Tests : Ratio, Polarity With Booster

    DOC. MIE11110 Rev. 5 Page 21 of 110 When you are satisfied with the result, press SAVE: test result is saved. Return to zero the adjustment knob (6). WHEN YOU DISCONNECT THE PRIMARY CABLES, PLEASE CONSIDER CURRENT TEST VALUE TEST DURATION.
  • Page 22 Purpose of the test is to measure the actual CT ratio and to verify its polarity, with a test current higher than the one available from T 2000. To this purpose, the external current booster option allows to get up to 2000 A. Note that with this test it is impossible to measure the burden, as it is in the former test.
  • Page 23 1000 A or 2000 A. Even if 1000 A are not much more than the 800 A that T 2000 can generate, the test duration with the booster is much longer than with T 2000. The...
  • Page 24 A) Output connection, 800 A: - N. 2 High current connection cables, 100 sq. mm, 1 m long, for the connection of T 2000 to the current booster. B) From the booster. The booster is provided with six, each 200 sq. mm.. There are two possibilities, according to the test current: - Test current up to 1000 A: use two cables 2 m long;...
  • Page 25 DOC. MIE11110 Rev. 5 Page 25 of 110 wrong result: the red socket (output or input) is the positive; with the clip-on transformer, look at the arrow or at the red mark (entering current). Now, input in the screen: . The primary and secondary current; .
  • Page 26 DOC. MIE11110 Rev. 5 Page 26 of 110 WHEN YOU DISCONNECT THE PRIMARY CABLES, PLEASE CONSIDER TEST DURATION. LONG, CONNECTION VICE AND CABLE CAN BE VERY HOT: USE PROTECTION GLOVES! If, during the test, you have no measurement from the current booster, this means that you have over-heated the module, and the thermal protection is intervened, cutting the measurement output.
  • Page 27 DOC. MIE11110 Rev. 5 Page 27 of 110 Purpose of the test is to measure the actual CT ratio and to verify its polarity, with a test current higher than the one available from T 3000. To this purpose, the external current booster option allows to get up to 4000 A, according to the number of transformers.
  • Page 28 DOC. MIE11110 Rev. 5 Page 28 of 110 . With more transformers, it is necessary to lift the transformers and operator with a lifter. Connection cables from the interposing module to the transformers are 20 m long, and allow reach any distance while leaving If instead the CT is located into a cabinet, disconnect the high current cables from the screw driven clamps, and connect them to the spring driven clamps, using a clamp per cable, then clamp...
  • Page 29 DOC. MIE11110 Rev. 5 Page 29 of 110 The following is the connection s chematic, for the case of four transformers and two turns.
  • Page 30 DOC. MIE11110 Rev. 5 Page 30 of 110 The following picture shows the option components in the case of a transformer only.
  • Page 31 DOC. MIE11110 Rev. 5 Page 31 of 110 The following picture shows the detail of the connection of the two cables to the clamp. The following picture shows the connection of the option to T 3000 and to the transformer under test (in the picture, there is an aluminium bar on a CT).
  • Page 32 DOC. MIE11110 Rev. 5 Page 32 of 110 The test is performed as follows. . Prior to all, remember that tests are demanding much current from the mains supply; so, connect to a suitable supply plug, rated 32 A for tests up to 2000 A and 63 A for higher currents. NOTE: with a 16 A rated sockets, the over-current protection will open at test start! .
  • Page 33 DOC. MIE11110 Rev. 5 Page 33 of 110 . Power-on the interposing module IM2000(the corresponding light turns on). . Power-on the test set. . Connect the AUX CONTACT test set output to the corresponding interposing module IM2000input. NOTE: if you connect AUX CONTACT before powering on the test set, at test set power on the interposing module IM2000breaker will close for a short time.
  • Page 34 DOC. MIE11110 Rev. 5 Page 34 of 110 For the sake of clearness, the above picture refers to the case of two turns: the pair of cable passes two times the transformers central hole. BEFORE STARTING TEST, VERIFY THAT SECONDARY CIRCUIT IS CLOSED: THE CT GENERATES HIGH VOLTAGE IF THE PRIMARY CURRENT IS INJECTED AND THE SECONDARY IS OPEN! Press the test start button (56), and adjust the primary current to...
  • Page 35 DOC. MIE11110 Rev. 5 Page 35 of 110 . A loss on the power supply cable, that does not provide the desired 230 V under load: look at the supply currents in the table below! N. OF N. OF TEST SUPPLY TRANS TURNS...

  • Page 36: Ct Tests : Burden, Secondary Side

    DOC. MIE11110 Rev. 5 Page 36 of 110 Keep the test duration as short as possible: if you exceed the above table, the test set stops automatically the test, and does not allow to proceed for 3 minutes. If test duration is less than the above, stop duration is proportionally reduced.
  • Page 37 DOC. MIE11110 Rev. 5 Page 37 of 110 The CT secondary is disconnected, and the selected T 2000 current output connected. For the connection, use the following cables: A) Output connection: - N. 2 Low current connection cables, 10 sq. mm, 4 m long.
  • Page 38 DOC. MIE11110 Rev. 5 Page 38 of 110 B) Input connection: - N. 2 measurement cables (to the 600 V measurement), or N. 1 cable for low voltage measurement connection, shielded, 4 m long (for the 10 V measurement; shown in the circuit diagram), plus N. 2 Clamps to connect the voltage measurement.

  • Page 39: Ct Tests : Excitation Curve

    DOC. MIE11110 Rev. 5 Page 39 of 110 1 .1.5. CT tests : excitation curve When this test is selected, the following menu is displayed. For the first parameter, standard, we have three choices: ANSI1 (no gap); ANSI2 (gap) or IEC, as they have the following definitions of the knee point (see std.
  • Page 40 DOC. MIE11110 Rev. 5 Page 40 of 110 The test voltage to be reached during the test is at least 2*VSM, so that the saturation knee is well designed. Then, select the voltage input range as a function of the test voltage and of the CT ratio.
  • Page 41 DOC. MIE11110 Rev. 5 Page 41 of 110 NOTE: the drawing shows the output connection to 3000 V. For the connection, use the following cables: A) Output connection, 3000 V:...
  • Page 42 N. 2 Clamps to connect low voltage or low current or measurements. HV cables shall be connected while T 2000 is powered-off. HV clamps shall have a minimum clearance of 20 mm with respect to all conductive surfaces, so to avoid discharges during operation.
  • Page 43 DOC. MIE11110 Rev. 5 Page 43 of 110 Please remember that if the test current is more than 0.2 A at 3000 V, the test duration will be limited, as per the following table. VOLTAGE CURRENT OUTPUT LOAD RECOVERY OUTPUT OUTPUT POWER TIME...
  • Page 44 DOC. MIE11110 Rev. 5 Page 44 of 110 NOTES: 1. In this test we saturate CT the magnetic material. The slow decrease of the voltage has the purpose of de-magnetizing it. If the return to zero is too fast, the CT saturation curve would be distorted.
  • Page 45 DOC. MIE11110 Rev. 5 Page 45 of 110...
  • Page 46 DOC. MIE11110 Rev. 5 Page 46 of 110 As you see, because of the saturation the knee is shifted. The first part of the curve is distorted because of the current necessary to de-magnetize the core: the sharp increase of the voltage is when the material has been de-magnetized.

  • Page 47: Ct Tests : Winding Or Burden Resistance

    DOC. MIE11110 Rev. 5 Page 47 of 110 In this instance, you have to start again the test, slowly reach the same test value and slowly decrease to zero. 1 .1.6. CT tests : winding or burden resistance When this test is selected, the following menu is displayed. Purpose of the test is to measure the CT burden in terms of Ohm, i.e.
  • Page 48 DOC. MIE11110 Rev. 5 Page 48 of 110 The CT secondary is disconnected, and the DC current output is connected to the winding (as shown) or to the burden. If the test is on the primary resistance, both ends of the primary should be grounded: this nulls the effect of the primary inductance.
  • Page 49 DOC. MIE11110 Rev. 5 Page 49 of 110 B) Input connection: - N. 1 cable for low voltage measurement connection, shielded, 4 m long, for the 10 V measurement, plus N. 2 Clamps to connect the voltage measurement. Prior to the test, you can select if the test result has to be compensated taking into account the temperature, and computed to a reference temperature (as specified for the CT).

  • Page 50: Ct Tests : Voltage Withstand

    DOC. MIE11110 Rev. 5 Page 50 of 110 You have to move the knob to zero, then press STOP; for some time, until the magnetization energy is not discharged and some current flows into the discharger, the following message is displayed: DO NOT PERFORM THE TEST WITHOUT THE PRIMARY SHORT - CIRCUIT: AT THE END OF THE TEST, THE TRANSFORMER WOULD...
  • Page 51 Rev. 5 Page 51 of 110 however, as T 2000 reaches only 3000 V, the test voltage is normally much less than the nominal voltage rating, so the test can be useful to measure the leakage current, at lower voltage.
  • Page 52 DOC. MIE11110 Rev. 5 Page 52 of 110 The CT secondary is disconnected, and the HV output is connected to the secondary and to the ground. For the connection, use the following cables: - N. 2 High voltage connection cables, 4 m long, 5 kV, with earth screen.
  • Page 53 HV cables shall be connected while T 2000 is powered-off. HV clamps shall have a minimum clearance of 20 mm with respect to all conductive surfaces, so to avoid discharges during operation.

  • Page 54: Ct Tests : Polarity By Impulses

    DOC. MIE11110 Rev. 5 Page 54 of 110 If, when the test START button (56) is pressed, the HV key is already ON, the following message is displayed: In this instance, press the STOP button (55), turn OFF the HV key (28), then press test START button (56).
  • Page 55 DOC. MIE11110 Rev. 5 Page 55 of 110 positive, following the positive edge: in this instance, test result will be shown as OK. Both impulses, positive and negative, will be displayed on the screen, so that you can decide, in case of doubt. A counter counts automatically the number of tests performed.
  • Page 56 DOC. MIE11110 Rev. 5 Page 56 of 110 For the connection, use the following cables: A) Output connection: - N. 2 Low current connection cables, 10 sq. mm, 4 m long. Terminated on one side with the current clamps. B) Input connection: - N.

  • Page 57: Voltage Transformers Tests

    DOC. MIE11110 Rev. 5 Page 57 of 110 1.2: V OLTAGE RANSFORMERS TESTS With the selection VOLTAGE TRANFORMERS TEST the following screen is opened. It is possible to select the tap number: this selection is reported in the available tests. 1.2.1: VT tests: ratio and polarity When this test is selected, the following menu is displayed.
  • Page 58 DOC. MIE11110 Rev. 5 Page 58 of 110 . The primary voltage, in kV, either Line to Line or Line to neutral; . The secondary voltage, in V, either Line to Line or Line to neutral. . The selected input measurement range. To this purpose, consider that the maximum test voltage VT is 3000 V, and can be much lower that the nominal primary voltage, VPN.
  • Page 59 DOC. MIE11110 Rev. 5 Page 59 of 110 A) Output connection: - N. 2 High voltage connection cables, 4 m long, 5 kV, with earth screen, terminated on both sides with HV connectors. - N. 2 Clamps for the HV connection. B) Input connection, voltage less than 10 V:...
  • Page 60 - N. 2 measurement cables. - N. 2 Clamps. HV cables shall be connected while T 2000 is powered-off. HV clamps shall have a minimum clearance of 20 mm with respect to all conductive surfaces, so to avoid discharges during operation.

  • Page 61: 2: Vt Tests: Burden, Secondary Side

    The applied voltage can be measured at the T 2000 output sockets; however, i f the test current is high and it is desired to increase the test accuracy eliminating the voltage drops along the connection cables, it is possible to measure the voltage drop on the burden, by enabling the external measurement input.
  • Page 62 DOC. MIE11110 Rev. 5 Page 62 of 110 A) Output connection: - N. 2 Low voltage connection cables. - N. 2 Clamps. IF DESIRED: B) Input connection, voltage less than 10 V: - N. 1 Cable for low voltage measurement connection, shielded, 4 m long, terminated on one side with the measurement connector, and on the other side with two 4 mm banana plugs.

  • Page 63: 3: Vt Tests: Ratio, Electronic Transformers

    C) Input connection, voltage more than 10 V: - N. 2 measurement cables. - N. 2 Clamps. Cables shall be connected while T 2000 is powered-off. If the test voltage is above 50 V, take the precautions so that conductors are not touched during the test.

  • Page 64: 4: Vt Tests: Voltage Withstand

    DOC. MIE11110 Rev. 5 Page 64 of 110 Purpose of the test is to measure the actual VT ratio, and to verify its polarity. This test is performed applying voltage to the primary side, and measuring the secondary voltage and phase angle.
  • Page 65 Page 65 of 110 sink. It is also possible to test the insulation between primary and secondary, and between primary and ground; however, as T 2000 reaches only 3000 V, the test voltage is normally much less than the nominal voltage rating, so the test can be useful to measure the leakage current, at lower voltage.

  • Page 66: 5: Vt Tests: Secondary Over-Current Protection

    DOC. MIE11110 Rev. 5 Page 66 of 110 1.2.5: VT tests: secondary over-current protection When this test is selected, the following menu is displayed. Purpose of the test is to verify the setting and the trip timing of the overcurrent protection that protects each phase of the TV secondary.
  • Page 67 DOC. MIE11110 Rev. 5 Page 67 of 110 The selected current output is connected to the VT burden, after having opened the secondary. Output connection: - N. 2 Low current connection cables. - N. 2 Clamps. The operator selects accordingly the current range for the test. There are two tests: .

  • Page 68: Power Transformers Tests

    DOC. MIE11110 Rev. 5 Page 68 of 110 . Protection timing: Set the knob a little higher than the position corresponding to the threshold, and start the test: as the current is interrupted, the timer displays the elapsed time. An automatic counter is increasing as you repeat the tests on the three phases.
  • Page 69 DOC. MIE11110 Rev. 5 Page 69 of 110 Prior to explain input parameters, let us discuss their definitions. In a PT, the ratio is defined as shown below. However, we have three cases of primary and secondary connections: 1. Yy (or Dd); 2. Yd; 3. Dy. Case 1: Types Yy or Dd The ratio is: t = VAB / Vab = VA / Va This is the case foreseen by the test set.
  • Page 70 DOC. MIE11110 Rev. 5 Page 70 of 110 In this case, the voltage is applied between A and N on the HV side, and it is measured between a and c on the secondary side. The measured ratio is therefore: T = VAN / Vac = (VAB / 1,732) / Vac = (VAB / Vac ) / 1,732 = t / 1.732, hence:...
  • Page 71 DOC. MIE11110 Rev. 5 Page 71 of 110 A) Output connection: - N. 2 High voltage connection cables, 4 m long, 5 kV, with earth screen. Terminated on both sides with HV connectors. - N. 2 Clamps for the HV connection. B) Input connection: - N.

  • Page 72: 2: Pt Tests: Resistance Of Ltc Contacts

    DOC. MIE11110 Rev. 5 Page 72 of 110 HV cables shall be connected while T 2000 is powered-off. HV clamps shall have a minimum clearance of 20 mm with respect to all conductive surfaces, so to avoid discharges during operation.
  • Page 73 This test is performed applying DC current to the PT primary, and measuring the corresponding DC voltage drop. This voltage can be measured at the T 2000 output sockets; however, if it is desired to increase the test accuracy eliminating the voltage drops along the connection cables, it is possible to measure the voltage drop on the burden, by enabling the external measurement input.
  • Page 74 DOC. MIE11110 Rev. 5 Page 74 of 110 The PT secondary is disconnected, and the DC current output is connected to the winding. PT secondary are short-circuited to ground: this nulls the effect of the primary inductance. For the connection, use the following cables: A) Output connection: - N.
  • Page 75 1%/s), press SAVE: test result is saved. Return to zero the adjustment knob (6). NOTE: T 2000 does not have a stable current source: it follows the mains variations. With slow changing mains values, the resistance measurement is stable enough, as it is the ratio, measured at the meantime, of voltage versus current;...

  • Page 76: 3: Pt Tests: Dynamic Ltc Test

    DOC. MIE11110 Rev. 5 Page 76 of 110 VERY IMPORTANT NOTICE: during the current adjustment, a current is induced into the primary loop, that is short-circuited: the induced current is a function of the current rate of change. For this reason, the test current MUST BE INCREASED VERY SLOWLY: the current is delayed with respect to the voltage.
  • Page 77 DOC. MIE11110 Rev. 5 Page 77 of 110 This test applies to the resistive LTC’s; it is performed applying DC current to the PT primary, and measuring the dynamic resistance change operator issues change command. connection diagram is the following.
  • Page 78 DOC. MIE11110 Rev. 5 Page 78 of 110 The PT primary is disconnected, and the DC current output is connected to the winding. PT secondaries are short-circuited to ground: this nulls the effect of the primary inductance. Also the other two primaries should be short-circuited. For the connection, use the following cables: A) Output connection: - N.
  • Page 79 DOC. MIE11110 Rev. 5 Page 79 of 110 B) Input connection: - N. 1 cable for low voltage measurement connection, shielded, 4 m long, for the 10 V measurement, plus N. 2 Clamps to connect the voltage measurement. The test is performed as follows. - First of all, move the tap changer all the way to the starting position: this will be recorded as test number one.
  • Page 80 DOC. MIE11110 Rev. 5 Page 80 of 110 nominal waveform cannot be observed, as it is masked by the L/R time constant of current growth. According to our experience, the selection time is usually very short, especially in high power transformer, when it is around 30 ms.
  • Page 81 DOC. MIE11110 Rev. 5 Page 81 of 110 2. Selection time about 30 ms; LTC fails.
  • Page 82 DOC. MIE11110 Rev. 5 Page 82 of 110 3. Selection time about 30 ms; L/R time constant very high; the resistance cannot be measured; LTC is OK.
  • Page 83 DOC. MIE11110 Rev. 5 Page 83 of 110 4. Same LTC as above; fault on this selection.

  • Page 84: Tests: Pt Ratio Test

    DOC. MIE11110 Rev. 5 Page 84 of 110 5. Same LTC as above; fault on this selection. 1.3.4 PT tests: PT ratio test • Connect low V to the transformer HV side phase 1 and 2. • Adjust the voltage of V1 to 100 V. •...
  • Page 85 DOC. MIE11110 Rev. 5 Page 85 of 110 value with respect to another, say Ea. This is normal because of the single-phase feeding. • The transformer ratio is: Type Dy (shown): 100 / (Ea * 1.73). Type Yd: 173 / Ea. Types Dd, Yy: 100 / Ea.

  • Page 86: Resistance Tests

    DOC. MIE11110 Rev. 5 Page 86 of 110 2 RESISTANCE TESTS With this selection, the following screen is displayed. 2.1 M ICROOHMMETER When this test is selected, the following menu is displayed. Purpose of the test is to measure at the uOhm level the resistance of the circuit breaker contacts, or any resistance of interest.
  • Page 87 DOC. MIE11110 Rev. 5 Page 87 of 110 to 10 mA, where 2 mA correspond to 0 A out, and 10 mA correspond to 400 A out. The voltage drop across the test item is measured in the meanwhile; the resistance is computed as the ratio of voltage versus current.
  • Page 88 With these cables it is possible to reach 400 A; however, if the test is performed at lower current, it is possible to increase the cable length by using the cables 4 m long included in T 2000, or even putting these cables in series, in order to obtain a total cable length of 6 m.
  • Page 89 DOC. MIE11110 Rev. 5 Page 89 of 110 test start, based upon the fact that the minimum measurement current is not sensed. The High IDC current module has a thermal protection: at the intervention, the measurement current is taken to zero, and the test interrupted.

  • Page 90: Earth Resistance

    DOC. MIE11110 Rev. 5 Page 90 of 110 2.2 E ARTH RESISTANCE When this test is selected, the following menu is displayed. Purpose of the test is to measure the soil resistance of systems, with the neutral isolated or connected to ground via an impedance, whose short-circuit current does not exceed 500 A, as per the IEC 80 standard.
  • Page 91 DOC. MIE11110 Rev. 5 Page 91 of 110 The connection diagram is the following.
  • Page 92 DOC. MIE11110 Rev. 5 Page 92 of 110 The voltage drop caused by the soil resistance of the system under test is measured between the connection to the system grounding (point A) and a voltage spike (point B), that shall be placed on the line between this point and the auxiliary earth.
  • Page 93 . Coupling with parallel lines, in case of overhead lines. This is why we do not recommend to use T 2000 in case of large substations. The last thing to be considered is the earth resistance of the auxiliary earth connection, that is realized by the auxiliary spike provided.
  • Page 94 DOC. MIE11110 Rev. 5 Page 94 of 110 RANGE OUTPUT OUTPUT OUTPUT LOAD RECOVERY CURRENT VOLTAGE POWER TIME TIME 10 A STEADY 250 V STEADY As you see, on the 10 A output it is possible to reach 5 A in continuous generation;...

  • Page 95: Soil Resistivity

    DOC. MIE11110 Rev. 5 Page 95 of 110 . A single-pole cable for the connection from the test set to the measurement reel, 4 m long, section 2.5 sq. mm. . A single-pole cable for the connection of the meter to the reference voltage probe, 50 m long, section 1 sq.
  • Page 96 DOC. MIE11110 Rev. 5 Page 96 of 110 The test is performed by applying the test current to two spikes inserted into the soil, and measuring the voltage drop across the soil in other two spikes, arranged as shown in the following connection diagram.
  • Page 97 DOC. MIE11110 Rev. 5 Page 97 of 110 the soil is homogeneous there will be no change in ? changing d; instead, if the soil is not homogeneous, for instance some earth above rocks, ? can change significantly with d. The resistivity ? is computed by the formula ? = 2 * p * R * d, (Ohm*m) Where d is in meters and R = V / I is computed from the measured...
  • Page 98 DOC. MIE11110 Rev. 5 Page 98 of 110 Once the result is achieved, press SAVE, slowly reduce to zero the current and repeat the test in the formerly defined points of the site to be verified.

  • Page 99: Line Impedance Tests

    DOC. MIE11110 Rev. 5 Page 99 of 110 3 LINE IMPEDANCE TESTS With this selection, the following screen is displayed. 3.1 L INE IMPEDANCE MEASUREMENT When this test is selected, the following menu is displayed. Purpose of this test is to measure the impedance of the line under test, in module and argument.
  • Page 100 - Open SU3000. Connect one side to ground, and the other side to two cables: one will go to T 2000, the other to the line to be tested. Note that until the SU3000 is OPEN, the switch is open, and there is no ground connection.

  • Page 101: Earth Impedance Measurement

    DOC. MIE11110 Rev. 5 Page 101 of 110 - Slowly increase the output voltage, and verify the corresponding line impedance ZL and argument. As the impedance is the ratio voltage versus current, its value should not change very much as the current is increased.
  • Page 102 DOC. MIE11110 Rev. 5 Page 102 of 110 The connection for this test is modified as shown in the following figure.

  • Page 103: Mutual Factor Measurement

    - Open SU3000. Connect one side to ground, and the other side to two cables: one will go to T 2000, the other to the line to be tested. Note that until SU3000 is OPEN, the switch is open, and there is no ground connection.
  • Page 104 DOC. MIE11110 Rev. 5 Page 104 of 110 If there are two parallel lines, it is important to measure the mutual factor, that is taken into account with KE in case of ground fault. Defining line 1 the one with the fault, and line 2 the parallel line, the computation formula is the following.
  • Page 105 DOC. MIE11110 Rev. 5 Page 105 of 110...
  • Page 106 - Open SU3000. Connect one side to ground, and the other side to two cables: one will go to T 2000, the other to the line 2. Note that until the device is OPEN, the switch is open, and there is no ground connection.

  • Page 107: Appendix: Dynamic Tap Changer Testing

    DOC. MIE11110 Rev. 5 Page 107 of 110 APPENDIX: DYNAMIC TA P CHANGER TESTING The test performed by T 3000 has the purpose of allowing the verification of the tap changer device: the following design shows a possible configuration of the power transformer and TAP changer..
  • Page 108 DOC. MIE11110 Rev. 5 Page 108 of 110 The voltage is changed by moving the cursor from one TAP to the next one. The problem with the changer is that it must cope with two opposite mandatory requirements: . During TAP change, the circuit must not be opened; and .
  • Page 109 DOC. MIE11110 Rev. 5 Page 109 of 110 Continuing with movements, the resistance variation is displayed in the following figure. The resistances of all taps can be measured with the static test; the dynamic test allows to verify that in any of the changes there is an open circuit or a short circuit.
  • Page 110 DOC. MIE11110 Rev. 5 Page 110 of 110 (parasitic) inductance that cannot be zero. When the resistance changes, the current changes with the time constant L/R. If this time constant is small, then the value of R can be measured; if it is big (as compared to the switching time), then R cannot be measured;...

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