Mie12110-t2000 Introductory Guide

DATE: 20/04/2011

DOC.MIE12110 REV.4

T 2000

INTRODUCTORY GUIDE

DOC. MIE12210 Rev. 4 Page 2 of 86

REVISIONS SUMMARY VISA N PAGE DATE 1 All 25/04/2006 Issued Lodi.

2 39 to 43 8/06/2006 Added the Calibration chapter

Lodi

3 All 23/11/2009 Minor corrections Lodi

4 71, 72 20/4/2011 Modified for the firmware revision 1.40

Lodi


SHORT FOREWORD .......................................................................................................5

INTRODUCTION ................................................................................................................6

1 TEST SET DESCRIPTION AND USE ...................................................................9

1.1 THE FRONT PANEL..................................................................................................... 9 1.2 THE POP-UP MENU.................................................................................................. 12

1.2.1 Transformers selection.................................................................... 13 1.3 POWER-ON................................................................................................................ 18 1.4 OUTPUTS DESCRIPTION AND HAZARDOUS SITUATIONS.......................... 20

1.4.1 Main current and voltage outputs ........................................... 20 1.4.2 HV voltage output ............................................................................... 22 1.4.3 Hazardous situation summary .................................................. 23

1.5 CURRENT GENERATION ......................................................................................... 24 1.6 OPTIONAL THERMAL PRINTER ............................................................................. 27 1.7 PROTECTIONS .......................................................................................................... 27

2 TRANSFORMERS TESTING FUNDAMENTALS .......................................... 30

2.1 CURRENT TRANSFORMERS ................................................................................... 30 2.2 REMANENCE .............................................................................................................. 31 2.3 HIGH CURRENT TESTS .......................................................................................... 31 2.4 WINDING RESISTANCE TEST.............................................................................. 31

3 WHATS INSIDE? ...................................................................................................... 33

3.1 PHYSICAL DESCRIPTION...................................................................................... 33 3.2 DETAILED FUNCTION DESCRIPTION................................................................. 37

3.2.1 Main output transformer, XTF10350 (5) ............................ 37 3.2.2 Main front board PWA11411 (17) ............................................ 38 3.2.3 TRANSFORMERS board PWA21412 (83)............................... 38 3.2.4 CONV-T 3000 board PWA21401 (16)..................................... 39 3.2.5 INTE ON-OFF T 3000 board PWA11410 (7) ....................... 40 3.2.6 MICR T1000 board PWA41300 (15)........................................ 40

4 THE HELL, IT DOESNT WORK.......................................................................... 42

4.1 INTRODUCTION ....................................................................................................... 42 4.2 ERROR MESSAGES.................................................................................................. 42 4.3 TROUBLE SHOOTING ............................................................................................. 46 4.4 AT POWER-ON DOES NOT TURN ON ................................................................. 47 4.5 NO OUTPUT FROM THE MAIN CURRENT AND VOLTAGE............................... 48 4.6 THE AC VOLTAGE MEASUREMENT IS NOT STABLE ...................................... 48 4.7 PROBLEMS DURING UPGRADE ............................................................................ 48 4.8 FALSE ALARM OF MISSING GROUND CONNECTION .................................... 49


4.9 THE DISPLAY BACKLIGHT DOES NOT TURN ON OR THE DISPLAY DOES NOT OPERATE ....................................................................................................... 49 4.10 A 110 V RATED TEST SET WAS POWERED AT 220 V.............................. 51 4.11 THE TEST SET DOES NOT COMMUNICATE WITH THE PC ........................ 53 4.12 FAULT ON THE 10 V OR 600 V EXTERNAL MEASUREMENT..................... 55 4.13 FAULT ON THE 10 A EXTERNAL MEASUREMENT ......................................... 65 4.14 FAULT ON THE REAL TIME CLOCK................................................................... 69 4.15 THE ENCODER IS BROKEN ................................................................................ 70 4.16 UPGRADE TO FIRMWARE REVISION 1.40 .................................................... 71 4.17 THE FAULT CANNOT BE FIXED ......................................................................... 73

5 CALIBRATION............................................................................................................. 77

5.1 INTRODUCTION ...................................................................................................... 77 5.2 CALIBRATION PROCEDURE ................................................................................ 77 5.3 T 2000 OUTPUT CALIBRATION......................................................................... 79

5.3.1 OUTPUT CURRENTS CALIBRATION ............................................ 79 5.3.2 OUTPUT VOLTAGES CALIBRATION ............................................. 80

5.4 EXTERNAL INPUT CURRENTS......................................................................... 82 5.5 EXTERNAL INPUT VOLTAGES ........................................................................ 84

APPENDIX 1 SPARE PARTS LIST ........................................................................ 86


SHORT FOREWORD

Dear T 2000 user, I often wondered why the users 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 T 2000 manual in three: specification, with all performance details; application manual, with instructions about how to use it one its operation is understood; introductory guide, with the device description and basic information. The idea is that you may read once the device description, while you need application examples more than once; so, why not to split the manual in three? The only exception to this organization is next page: it reminds to be cautious when using these test sets. We are on the field since more than 50 years, and no injury has ever been reported; yet, your kids want you back home after work. Have a good work with T 2000! Primo Lodi Q&A Manager


INTRODUCTION

T 2000 allows performing all the test to be performed on current and voltage transformers. The following table lists the tests that can be performed on CT and VT.

N. TEST OF

TEST DESCRIPTION

1 CT Ratio, Voltage mode 2 CT Ratio, polarity and burden 3 CT Burden; secondary side 4 CT Excitation curve 5 CT Winding or burden resistance 6 CT Voltage withstand 7 CT Polarity by impulses 8 VT Ratio; polarity 9 VT Burden, secondary side 10 VT Ratio, electronic transformers 11 VT Voltage withstand 12 VT Secondary over-current protection 13 PT Ratio per TAP 14 PT Resistance of Tap Changer

contacts 15 PT Tap Changer dynamic resistance

test 16 R Ground resistance and resistivity

With external options, T 2000 can test: . With the High IDC module, up to 400 A: contact resistances, in the micro-Ohm range; . With the high current booster: primary tests, up to 2000 A; . With the very high current booster: primary tests, up to 4000 A. The basic T 2000 function is to generate current and voltages, as requested by the type of test to be performed, that is selected on the LCD screen by means of the multi-function knob. Test results are kept in memory, and can be transferred to a PC at a later time, along with settings.


The instrument contains one generator with many outputs: High AC current; Low AC current; Low DC current; Current impulses; High AC voltage; Low AC voltage; Low DC voltage. All outputs are adjustable and metered on the large, graphic LCD display. With the multi-purpose knob and the LCD display it is possible to enter the MENU mode, that allows to set many functions, that make T 2000 a very powerful testing device, with manual and semi-automatic testing capabilities, and with the possibility to transfer test results to a PC via the RS232 interface. These results can be recorded, displayed and analysed by the powerful TDMS software, which allows creating a data base of test results for all the plant. The ease of operation has been the first goal of T 2000: this is why the LCD is graphic, and so large. With it, the dialogue in MENU mode is made easy. Besides, all T 2000 outputs relevant to the selected test are continuously measured, and output values are displayed, with no extra effort to the operator. Additional features are: . Two meters, current and voltage, with independent inputs, and with High and Low inputs each, allow measuring CT or VT outputs or any other source; . The optional thermal printer gives the immediate printout of the CT saturation curve; . An auxiliary contact, that follows START and STOP inputs, allows simulating the circuit breaker. At power-on, there is a message asking to wait for the self diagnosis is completed. After this, the following menu is displayed.


The desired operation is accessed by the multi-function wheel. The following chapters explain how to operate with the above selections. NOTE: WINDOWS is a trademark of MICROSOFT inc.


1 TEST SET DESCRIPTION AND USE

In this chapter we describe the test set and inform about the operations that are common to relay or transformers testing.

1.1 THE FRONT PANEL


The following list includes the key components inside T 2000. 1) Supply socket and main supply fuse, rated T5A, incorporated in the supply socket. 2) Power-on switch, with light. 4) Emergency push-button with lock-in. 5) Main outputs transformer. 6) Main outputs adjustment. 7) INTE ON-OFF printed circuit board; code YWA11410. 8) Earth socket. 11) Back panel board ; code YWA11413. 12) High output current measurement transformer. 13) Output sockets for high current output. 15) Microprocessor board, code YWA41300. 16) Converter board code YWA11401. 17) Front panel board; code YWA11411. 22) MENU control knob, with switch. 23) Display. 25) Serial interface connector. 26) Main current outputs measuring transformer. 27) Main current output sockets. 28) High Voltage enable key. 29) Variable transformer home position switch. 44) 800 A range selection light. 45) 40 A or 25 V range selection light. 46) 10 A or 90 V range selection light. 49) ON + TIME light: current is generated and time metered until STOP is detected. 50) OFF light: no current generation. 51) ON light: current is generated. 52) OFF + TIME light: current is removed and time metered until STOP is detected. 53) Main AC voltage selection light. 54) Main DC current or current impulses selection light. 55 and 56) START and STOP push-buttons. 57) Push-button for the selection of main output. 58) HV voltage on light. 60) Main AC voltage safety sockets. 61) Main DC current or current impulses safety sockets. 67) External current meter safety sockets.


68) External voltage meter safety sockets. 69) 25 mA metering input protection fuse. 70) 10 V measurement input connector. 80) Transformer protection thermal switches. 81) Serial interface supply transformer. 82) Electronic power switch (SCR). 83) TRANFORMERS board for the auxiliary supplies, PWA11412. 84) HV output measurement transformer. 85) Fan. 86) Primary circuit breaker. 87) HV opening relay. 88) HV output current meter. 89) Input current meter. NOTE: the connector to the 10 V input (70) can be removed only acting on the connector body. DONT PULL THE CABLE, AS YOU COULD DAMAGE IT!


1.2 THE POP-UP MENU

The following is the list of features that are menu selected. The menu is operated by means of the control knob marked MENU, that incorporates a switch. The menu is entered pressing the knob and selecting the item moving the knob. Once the item has bee found and programmed, pressing the arrow the menu moves back of one step, so that other programming can be performed; else, selecting ESC the menu returns to the main window. The first display is the following.

Next screens depend upon the type of selection: . For transformer tests, there is a dedicated screen for each type of test: only relevant parameters are displayed and recorded. . Other selections: Resistance, Results, Preferences, Test header. Any setting can be saved to and recalled from the memory. Up to 10 settings can be stored and recalled; setting no. 0 is the default one, and pops up at power-on. Settings are permanently stored in the memory; new settings can be written to the same address after confirmation. For normal mode operation it is possible to recall the standard setting, that cannot be modified. During the test, test results can be stored in the memory (up to 500 results may be stored). At the end of test, settings and test results can be transmitted to a PC provided with TDMS. The software allows saving test results, examining them and so on. The specification of TDMS is given in a separate document.


When the PC is connected, settings can also be created and transferred into T 2000 using TDMS.

1.2.1 Transformers selection

With this selection, the choice is: CT; VT; PT. After entering the final selection, the operator can input the relevant parameters, still by using the multi-function knob: turning it allows changing the parameter; pressing it makes it possible to go to next parameter. Once all parameters are set, it is possible to start the test and execute it. Test time is kept to the minimum to avoid the excess of heating. The following table summarizes all tests and the corresponding performances.


TEST OF

TEST DESCRIPTION

INPUT DATA

CONN. OUT

CONN. IN

MEASUREMENTS

CT N. 1

Ratio Voltage mode

- I primary; - I secondary (nominal values) - Voltage output - Voltage input

High/Low V AC to CT secondary

CT primary to low or high Vin

1) High / Low VAC out; 2) Low V in; 3) Polarity; 4) Actual ratio; 5) Ratio error %; and excitation curve, if selected

CT N. 2

Ratio, polarity and burden

- I primary; - I secondary (nominal values); - Clamp Y/N; - Clamp ratio; - Voltage input.

High I AC to CT primary

CT secondary to high I in; (Low Iin with Clamp); CT secondary to Vin low or high.

1) High I AC out (primary); 2) I in (secondary); 3) Nominal ratio; 4) Actual ratio; 5) Ratio % error; 6) Polarity 7) VA rating 8) Power factor;

CT N. 3

Burden, secondary side

- IN secondary (nominal value); - Voltag

Low I AC to CT burden

CT burden to Vin

1) I out (secondary); 2) V out (secondary); 3) Phase V-I out (secondary); 4) Power factor; 5) VA rating;


e input. - Current output

CT N. 4

Excitation curve

- Voltage output - I nom secondary - VA rating - Accuracy class - Overload - Internal loss - Standard (IEC, ANSI)

High V AC to CT secondary

1) High V AC out; 2) I out of High V AC; 3) Iout-Vout curve; 4) Current at knee, IKm; 5) Voltage at knee, VKm

CT N. 5

Winding or burden resistance

- Temperature compensation Y/N - Ambient and target temperatures

Low I DC to CT burden or winding

CT burden to Vin

1) Low I DC out; 2) V of lowI DC out; 3) Resistance; 4) Compensated resistance

CT N. 6

Voltage withstand

- Max High V AC ; - Max I test - Tmax

High V AC to: Primary and secondary;

1) High V AC out; 2) I out of High V AC ; 3) Elapsed Time


CT N. 7

Polarity by impulses

Low IDC to CT primary

CT sec. to Iin

1) I DC out; 2) I secondary; 3) Polarity

TEST OF

TEST DESCRIPTION

INPUT DATA

CONN. OUT

CONN. IN MEASUREMENTS

VT N. 8

Ratio; polarity V primary in kV; V secondary; Connection LL, LN for primary and secondary (nominal values)

High V AC to VT primary

VT secondary to V in

1) High VAC (primary) 2) V in (secondary); 3) Phase shift ; 4) Actual ratio; 5) Ratio error %; 6) Polarity

VT N. 9

Burden, secondary side

- V secondary (nominal value) - Connection LL, LN - Voltage output - Voltage input

Low V AC to VT burden

VT burden to V in (if enabled)

1) V out (secondary); 2) I out (secondary); 3) Phase V-I ; 4) Power factor; 5) VA rating

VT N. 10

Electronic Voltage Transformers

- V primary; - V secondary; - Connection LL,



1) High VAC (primary) 2) V in (secondary); 3) Actual ratio; 4) Ratio error %; 5) Polarity


LN for primary and secondary (nominal values)

VT N. 11

Voltage withstand

- Max High V AC; - Max I test; - Test duration.

High V AC to Primary and secondary;

1) High V AC out; 2) I out of High V AC ; 3) Elapsed Time

VT N. 12

Over-current protection

- I Trip - Output current

Low I AC to VT protection

1) I out (secondary) 2) I trip

PT N. 13

Ratio per Tap - V primary in kV; - V secondary; - Connection LL, LN for primary and secondary



1) High V AC out; 2) I of High V AC; 3) Phase V-I 4) V in; 5) Actual ratio; 6) Ratio error %.

PT N. 14

Resistance of Tap Changer contacts

- Temperature compensation Y/N - Ambient and target temperatures

Low I DC

V in 1) I DC out; 2) V of IDC out; 3) Resistance; 4)Compensated resistance

PT N. 15

Dynamic tap changer test

- Time base

Low I DC

V in 1) I DC out; 2) V of IDC out;


- trigger level

3) Resistance; 4) Resistance waveform

R Grid N. 16

Resistance or resistivity of earthing grid

- Output voltage - Input voltage

Low V AC to auxiliary spike

V input from measurement spike(s)

1) Output voltage 2) Output current 3) Input voltage 4) Ground resistance or Ground resistivity

1.3 POWER-ON

At first, be sure that the main control knob (6) is turned (rotated) to the zero position (complete counter-clockwise). The reason is that the current generator is actually a high current voltage generator. If the output is connected to the load (typically low impedance), as soon as the test is started, a very high current can circulate in the circuit. Next, connect the mains supply cable to the instrument and then to the supply. The power supply must be made of three wires: phase, neutral and ground. It is also intended that the neutral will have a low voltage with respect to ground (20 V maximum). If you need an extension cable, use a cable where the copper cross section of 6 sq. mm. minimum: this serves to prevent heating and voltage drops, that would cause also a reduction of the performances. Power-on T 2000: the test set checks if it is connected to the ground; if not, it alerts the operator with the following message.

All operations will be inhibited until the ground is available; power-off, connect to the ground and then power-on again. Usually the grounding connection is provided by the power supply cord; if the ground connection is not available at the power outlet, connect T 2000 to ground using the yellow/green cable with crocodile


provided. The connection to water pipes or to a big metal frame will do. NOTE: this protection checks the voltage between phases and ground; at least one of them (the neutral) must have a low voltage with respect to the ground. This means that T 2000 cannot be powered by two phases of a 220 V (or 110 V) three-phase supply (127 V or 63.5 V phase to neutral). If you are in this situation, and you are sure that the ground is there, you can over-ride the alarm as follows: . Press the > key; . The alarm will show up again; . Press the > key four times in all: the message will disappear, and you can continue. T 2000 diagnostic tests also the voltage supply value: if it exceeds the limits of 20%, one of the following messages will be displayed.

If the ground is connected, the following message is displayed.

During this time, a diagnostic sequence controls: . Key microprocessor board components; . Auxiliary supply voltages. If something is wrong, the operator is alerted by one of the following messages.


At the end of it, default selections are active; T 2000 is in the OFF state. If some selection keys are pressed at power-on, the following message warns the operator to release them.

After power-on, the following control lights turn on (default situation): . TEST OFF (50); . MENU SELECTION: 40 A SOCKET (45). To operate the test set it is necessary to perform the pop-up menu selections. During operation, if something goes wrong the test set protections intervene; usually, the operator is alerted by a message.

1.4 OUTPUTS DESCRIPTION AND HAZARDOUS SITUATIONS

1.4.1 Main current and voltage outputs

The first thing to be understood is that all main outputs are generated by a sole transformer, and are adjusted by knob (6); as a consequence: . It is impossible to adjust separately the AC current and the AC voltage; . The output selection does not open the unselected outputs; . Only one connection should be made to main outputs. In particular, if there are two connections to output sockets (27) and (13), the displayed current value is meaningless, currents will divide as a function of the burden. The situation of zeros is the following: . There are three independent zero: 800 A; 3000 V; all other main outputs; . The zero of low current outputs is in common with the 250 V AC output, but it is not directly connected to the zero of the DC current output, as there is a rectifying bridge between them. DO NOT CONNECT THESE ZERO BETWEEN THEM: this would cause a short-circuit on one of the rectifying diodes.


The only exception to the above is the HV output: it is not connected if it is not selected. However, when HV is selected, if a load is connected to the main AC current or AC voltage or DC current, as HV is adjusted these outputs will generate in a not controlled way. Coming to the characteristics of main supplies, the following applies. . The quality of the waveform is depending upon the quality of the voltage supply. Please do not blame T 2000 for distorted waveforms! . Current outputs are generated by a voltage transformer with low voltage and high current ratings. As a consequence, the current is a function of the load: you cannot pre-set the current value by adjusting knob (6). These outputs are not hazardous, as voltage is low; however, current capability is high; so, take care not to touch both conductors with a ring, watch or metal tool: it would heat-up very quickly. . AC voltage can be dangerous, as the range is 250 V: do not touch both ends. . DC current is low voltage and current limited; so, it is not dangerous. . Do not generate high power for a long while. If you are overloading the output, the test set will cut it off after a while, according to the table in the cover; in hot weather, the thermal protection could intervene, cutting the operation for a long while. Besides, repeating tests in overload conditions reduces the life of the components. . If in a plant being build up the AC supply is missing, sometimes a stand-by generator or a DC to AC converter can be used. In this instance, the quality of the supply can be very poor, to the point that it could be impossible to perform tests. In particular, if a DC to AC converter is used, it must be generating a real sinusoidal waveform: cheaper converters generate a trapezoid shaped waveform. This can also be the problem if a filter is used on the mains.


1.4.2 HV voltage output

Coming now to the HV output, IT IS VERY DANGEROUS; so, please take the maximum care when using it. . Never leave connection cables connected, even if the output is unused. T 2000 HV connectors are suited for HV isolation; instead, connection cables have at their ends some accessible clip-on crocodiles. It is true that HV is disconnected when not used; however, there is a relay that performs this, and if the relay fails, you have HV on your leads while performing other tests. . Connect the cable to the test device before enabling the HV test. Here again, a mistake is always possible. DO NOT CONNECT THE TEST DEVICE WHEN OUTPUTS ARE ACTIVE! . If possible, do not connect to ground any of HV voltage outputs. The high voltage generator has both sockets not connected to ground. In this situation, the accidental contact of the operator with either output would be of no consequence; this means that the operation would be safer. The connection of one side of the output to ground reduces the safety margin. The contact to ground of the other lead would cause a short circuit to the HV output, with immediate disconnection of the test set. Much worse, the accidental contact of the operator with the other lead would submit him to the high voltage, WITH NO PROTECTION FROM THE TEST SET. This is why an isolated operation is STRONGLY RECOMMENDED WHENEVER POSSIBLE. The recommendation does not apply to the isolation test, where one of the two leads must be grounded. During this test the above recommendations apply, so, take special care. The HV is generated only while the START button (56) is pressed: this is an additional safety feature. The operator will have both hands occupied: one for the knob (6), the other for the button (56); however, this is much safer than starting the HV generation, and then forgetting it in the ON state.


When the connection is performed, connect the crocodile first, then connect the cable to the HV connectors. The HV connector is made of a moving body, a threaded part on which is located a nut: see sketch. You cannot remove the connection pulling the cable: it is necessary to act on the body. If, for safety reasons, you do not want that the connection is removed, it is possible to lock the moving body with the nut. After this, the connector cannot be removed, until the nut is unscrewed to its former position.

1.4.3 Hazardous situation summary

The following table summarizes the most hazardous situations discussed above. Please consider this list, and check the situation in case of doubt. SITUATION CAUSE OF RISK CONTROL Long generation of outputs

Possible danger of over-heating components, specially with high ambient temperature

Check burden and duration

HV cables connected while not

Risk to the user if the isolation relay fails

No HV cable

THREAD

NUT

BODY


used High AC voltage output connected to ground

In this situation, if the operator touches the other terminal, he would be subject to a mortal voltage: it is necessary to be extremely cautious.

Ground connection

Connection while the output is active

In this situation there is voltage on the connection cables: there is the risk of being hit touching them.

The test set must be OFF

Disconnection while the output is active

The inductive load would cause a very high voltage spike.

The test set must be OFF

Connection to a live wire

The connection can be dangerous to the test set.

Test before connecting

1.5 CURRENT GENERATION

If the following current limits and time duration of main current outputs are trespassed, the generation is interrupted, and the operator is warned by an alarm message. HIGH AC CURRENT CURRENT OUTPUT

A

OUTPUT POWER

VA

ON TIME

s

OFF TIME min

100 600 STEADY - 150 800 15 min 30 200 1000 4 min 15 400 1600 15 5 600 2000 5 3 800 2000 1 2

With the T 2000E model, the performance is the following. CURRENT

A MAX

POWER VA

MAX ON

TIME s

OFF TIME min

MAX TOTAL LOAD mOhm

LOAD W/O

CABLES mOhm

POWER W/O

CABLES VA

100 850 CONT. - 86 80 800


150 1200 15 min 30 55 49 1100 200 1550 4 min 15 39 33 1320 300 2050 15 5 23 17 1530 400 2400 15 5 15 9 1440 600 2600 5 3 7 1 360 800 2100 1 2 3 - -

LOW AC CURRENT RANGE A AC

CURRENT OUTPUT

A

OUTPUT POWER

VA

LOAD TIME

s

RECOVERY TIME min

40 12 300 STEADY - 18 15 min 30 24 4 min 15 36 800 15 5 48 5 3 60 1000 1 2

10 5 400 STEADY - 7.5 15 min 30 10 800 60 15 15 30 10 20 1000 15 5

This generator serves for the test of VT protections, where low current is necessary. The procedure is the following. . At first, be sure that the main control knob (6) is turned (rotated) to the zero position (complete counter-clockwise). . Power-on T 2000. . Select by the push-button (57) the measurement on the desired output sockets (13), according to the maximum current to be generated: the LED turns on; the AC voltage value is displayed. . Connect the device to be tested to sockets (13). Consider that for tests of 40 A up it is necessary to connect the relay by a wire having at least a cross section of 10 sq. mm; for lower currents, a cross section of 2.5 sq. mm can be used. . Press ON and adjust the output current to the desired value with knob (6). . After you have started the test, if the burden is a short circuit made of a short cable, you measure at zero knob position a current that usually is less than 3% of the range. This value does


not influence at all the measurement of the current you are generating: it is not an error of the measurement instrument. . There is also another possible problem: the desired current cannot be reached. If it is impossible to reach the desired value, this is because the burden is too high. Very often the problem comes from connection wires; so, to perform the test it is necessary either to shorten them, or to increase the cross section (or both). Note that the test starts and stops as the current passes the zero.

1.6 FILTERING HEAVY BURDEN DISTORTION WITH THE FT1000 OPTION

Some very old electromechanical relays may have very inductive loads, which change in value during the test. As the test set current output is the ratio of applied voltage divided by the burden impedance, the inductance change causes current changes. The optional FT1000 opposes to such changes, and smoothes them away. The option includes an inductor, which adds to the burden, but stabilizes the current. The connection schematic is the following one (case of 10 A).

First of all, Select the operating frequency at 50 Hz or 60 Hz. Next, all you have to do is to connect FT1000 in series to the T2000 selected output: the FT1000 range shall be the same or greater than the one of T2000. You can now perform tests as usual.

FT1000 RELAY

I1

IN

C 10A


1.7 OPTIONAL THERMAL PRINTER

The optional thermal printer allows to print the selected test result. The connection is performed via the RS232 interface, using the serial cable provided. To get the printout, select the desired result and reach for the printer icon on the screen by means of the multifunction selector: the screen is printed.

1.8 PROTECTIONS

- If the test set is not connected to the ground, the test set does not allow for power generation, and warns the operator with the above diagnostic message. - If the power supply value is not within 20% of the nominal, the test set does not allow for power generation, and warns the operator with the above diagnostic message. - Fuse on the mains supply: if open, the power-on switch does not turn on. - At power-on, a diagnostic sequence controls: . Key microprocessor board components; . Auxiliary supply voltages. If something is wrong, the operator is alerted by the above diagnostic messages. - Emergency pushbutton: if pressed, main transformer primary circuit is open; all main outputs are removed. In this instance, the following message is displayed.

After pressed, the pushbutton stays in the emergency position until released by rotating it; as it is, the message disappears. - The high voltage output has the following protections: . HV outputs are disconnected when not used; . It is possible to access HV generation only in some tests; otherwise, the access is inhibited;


. Confirmation key: if not turned ON, the HV output is not generated. If the key is turned ON while T 2000 is generating other outputs, the generation is interrupted, and the following message is displayed:

. When a suitable test is selected, the test set informs the operator when the HV key should be turned ON:

. It is impossible to start generating the HV unless the adjustment knob is at zero; in this instance, the following message is displayed.

. The HV output is generated only until the START (H.V.) button is pressed: releasing the button interrupts immediately the generation. The test has to be started over again. Note that this feature applies only to HV generation: for all other generations, a single touch on START is enough. - The transformer under test cannot be left with some remaining magnetization. On some tests (like the saturation curve test), if the test is broken during the generation, and the output has not been adjusted to zero prior to stop, the following message is displayed.

In this instance, the operator has to start again the test, slowly reach the same test value and slowly decrease to zero. - Thermal (NTC) sensor on the main and auxiliary transformers. In case of over-temperature, the following message is displayed. It is necessary to power-off and wait until T 2000 cools down.

- Thermal sensor on the T 2000 inside. If T 2000 is too hot, the following message is displayed. It is necessary to power-off and wait until T 2000 cools down.


- Thermal sensor on the T 2000 inside. If T 2000 is too cold, the following message is displayed. The low temperature affects the display operation.

- If maximum time duration of power transformer generators are trespassed (see the table in the Specifications chapter), the generation is interrupted, and the operator is warned by the following message.

Pressing the knob, T 2000 displays the pause time duration:

- The main AC voltage source is protected against overloads. In this instance, the following message is displayed.

- The main DC current source is protected against over-voltages, that could be caused by the load inductance. In addition, the output is automatically kept to zero as test stops, so that any residual energy on the external load is discharged: during this time, the following message is displayed.

- The 20 mA measurement input is protected by fuse (69), rated F63mA, against wrong connections.


2 TRANSFORMERS TESTING FUNDAMENTALS

Many of tests explained in this manual involve high voltage and/or current, and should be performed by experienced personnel, familiar with the peculiarity or dangers that may exist during test setup and procedures. While some dangers have been pointed out, it is impractical to list all necessary precautions.

2.1 CURRENT TRANSFORMERS

Most used current transformers have no primary winding, as the primary is made of the primary conductor passing once through the center of a toroidal core to perform its function. Since the secondary winding is uniformly distributed about the core and only a single primary turn is used, essentially all magnetic flux is linked to the secondary winding, and there is essentially no leakage flux; this means also that the leakage reactance is negligible. CTs of this type are classified C type per ANSI/IEEE C57.13-1978, indicating that ratio correction at any current can be calculated once the burden, the secondary winding resistance and the excitation characteristics are known. With this type of CTs the same standard states that all tapped sections shall be so arranged that the ratio can be calculated from the excitation characteristics. Measuring the burden of the CT is important because the data allows verifying the accuracy of the transformer itself. The internal burden is the resistance of internal windings plus connection cables, and can be measured. Also the external burden can be measured, both as resistance and as impedance. For the correct measurement of the external burden, please consider the following notes. . All relays and other devices should be connected before the measurement, on the correct tap. . If a parallel CT exists, it should be disconnected. . The burden of electromechanical relays can be quite high, particularly with ground protection relays.


2.2 REMANENCE

All transformers with iron cores have the problem of residual magnetization. The core materials are subject to hysteresis: if a current through the transformer is interrupted, the flux density does not become zero while the current is zero. If the current interrupted is high, or if it is a DC current, remanence can be substantial, and can even be higher of the saturation knee. When the current is next energized, the flux change will start from the remanent value, and if the flux change is in the direction of the remanence, a large part of the cycle may find the transformer being saturated. When this occurs, much of the primary current is required for excitation, while the secondary current is significantly reduced, and distorted on alternate half cycles. The condition can be corrected by demagnetizing the current transformer. This is performed by selecting the saturation curve test, and applying to the secondary winding a voltage that should be starting from zero and then slowly increased until the saturation knee is passed; then, slowly decreasing (10 seconds) the voltage down to zero. The amount of saturation depends upon the value of the interrupted current: the higher the value the higher the saturation degree.

2.3 HIGH CURRENT TESTS

The high current generator is actually a low voltage, high current voltage generator. As a consequence, the voltage output is safe: touching conductors during the test would not be hazardous. However, there are two hazards to be considered: . Touching the high current leads with a metal object, such as the ring, watch, chain, would cause an extremely high current to the object, that would quickly increase its temperature: this would cause severe burns to the operator. . The high current generates high heat, specially at clamps: do not touch the cable without gloves, after a long test or an high current test.

2.4 WINDING RESISTANCE TEST


Usually transformers are used at 50 Hz, so their inductance is very low, as it is due to magnetic field losses. When the winding resistance is tested, we apply a DC current to a load that is heavily inductive, in the order of hundred or thousand of Henry. The T 2000 generator is actually a voltage generator, with a resistor in series and one in parallel to the load. With this type of load, the time constant for the current to reach its maximum is in the order of seconds, possibly minutes. For the sake of measuring the resistance it is not important that the current is perfectly stable; however, this gives the idea of the fact that if the adjustment knob is moved quickly, the current does not follow, and continues to grow until its asymptotic value. All this is when the current is increased: more important to be considered is what happens when the current has to be decreased to zero. When the resistance is measured, and the test should be stopped, T 2000 does not accept the stop command, and awaits for the knob to be adjusted to zero. The movement should be slow enough to allow for the magnetic energy stored into the transformer to be dissipated into the parallel resistor; when the knob is at zero, T 2000 accepts the STOP command, but keeps on measuring the current, and shows a message until it is decreased to zero. The load can be disconnected only after the message is disappeared; however, for added safety, you can short circuit the winding prior to remove the connections. Do not remove the connection while the test is on, or until the message is not disappeared: interrupting the circuit with a non dissipated magnetic energy would generate an over-voltage on the connection lead in your hand, that can be in the order of thousand of Volts: this is hazardous for you and can damage T 2000.


3 WHATS INSIDE?

3.1 PHYSICAL DESCRIPTION

The test set is contained in a housing, to which it is fixed by means of nine (also rubber feet) screws that are located below it: see the following picture.

After removal, the test set is shown in the following picture.

MOUNTING SCREWS


The mechanical components are: . The front plate, on which are mounted: the VARIAC transformer, all interfacing components and the front board; . The base plate, on which are mounted all other components; . Five legs on the corners keep together the two plates. The following is the list of the most important components. 5) Main outputs transformer, XTF10350. 6) Main outputs adjustment VARIAC. 7) INTE-T 3000 printed circuit board; code YWA11410. 11) Back panel board ; code YWA11413. 15) Microprocessor board, code YWA41300. 16) Converter T 3000 board, code YWA21401. 17) Front panel board; code YWA11411. 26) High current measuring transformer, XTF20062. 29) Variable transformer home position switch.


80) Low currents measurement transformer, XTF20059. 81) Serial interface supply transformer, XTF10357. 82) Power SCRs to control the test start-stop. 83) TRANFORMERS board for the auxiliary supplies, PWA11412. 84) HV output measurement transformer, XTF20049. 85) Fan. 86) Primary circuit breaker. 87) HV opening relay. 88) HV output current meter, XTF20059. There is a main board mounted just below the front panel, and a number of components mounted on the bottom panel. The arrangement of the main components mounted on the bottom panel is shown in the figure and pictures below.


On the upper corner are mounted the control cards: they are: MICRO-T1000, PWA41300; CONV T 3000, PWA21401; INTE-T 3000, PWA11410, TRANSFORMERS, PWA11412. They are connected to the back-panel PWA11413, and to the front panel via three flat cables. The first three cards are kept in place by the piece of aluminium sheet on the right. If a board is failing, it is necessary to remove the two screws. The last board, TRANSFORMERS, is kept in place by the screw on the front, as shown: it must be removed for card replacement.

On the bottom are also mounted the following components: 5) Main outputs transformer, XTF10350. 81) Serial interface supply transformer, XTF10357 (below the control cards). 82) Power SCRs to control the test start-stop. 84) HV output measurement transformer, XTF20049.


86) Primary circuit breaker. 87) HV opening relay. On the front panel are mounted the following components: 6) Main outputs adjustment VARIAC. 17) Front panel board; code YWA11411. 29) Variable transformer home position switch. The upper part of the test set, after opening, is shown in the following picture.

3.2 DETAILED FUNCTION DESCRIPTION

The following is the list of the most important boards: for each board is provided the explanation of the key functions performed.

3.2.1 Main output transformer, XTF10350 (5)

The main output transformer (5) has the following secondary windings. For connections, see the schematic at the end of this manual.


VOLTAGE V

POWER VA

PURPOSE

6 600 800 A output (1 s maximum); 100 A steady

250+ 90+ 25+ 9

125 450 300 45

0.5 A steady 10 A output (60 s maximum); 5 A steady 40 A output (60 s maximum); 12 A steady 5 A DC output steady (same common)

3000 600 0.2 A steady: isolated from other outputs.

3.2.2 Main front board PWA11411 (17)

The board includes many different circuits: START/STOP contacts filters. Back-light supply and contrast adjustment. Push-buttons. LEDs. Control and discharge of the filter capacitor for the main DC

voltage generation. Serial interface. Reduced power selection relay. Auxiliary relay. Transformer and shunt for the auxiliary AC voltage and current

measurement. The board includes also three isolated circuits for the

measurement of: 600 V external input; I external inputs (25 mA and 10 A); internal auxiliary DC V supply.

All circuits have: gain selections; high accuracy amplifiers; high accuracy isolated op amps.

Analog outputs are taken to CONV-3000, for the ADC conversion.

At the end of the document are given the mounting layout and the connectors disposition.

3.2.3 TRANSFORMERS board PWA21412 (83)

The board hosts a pair of transformers, that generate all the auxiliary voltages that serve to supply the circuits that have to be


isolated among them, and also the auxiliary + 5 V for all logic circuits, and 15 V for all analog circuits. The board includes a number of fuses. The following table summarizes: the fuse name, he fuse value, the circuit supplied. FUSE NAME

RATING (A) CIRCUIT SUPPLIED

F1 0.75 + 5 V AUXILIARY SUPPLY F2 2 + 5 V AUXILIARY SUPPLY F3 0.75 + 15 V AUXILIARY SUPPLY F4 0.75 - 15 V AUXILIARY SUPPLY F5 2 HIGH VOLTAGE RELAYS F6 2 AUXILIARY RELAY F7 0.75 START INPUT SUPPLY F8 2 GENERAL SUPPLY CIRCUIT BREAKER F9 0.75 STOP INPUT SUPPLY All fuses are of the SMD type. The following figure shows the fuses location, on the bottom side of the board.

3.2.4 CONV-T 3000 board PWA21401 (16)

TASK 1: to convert all analog measurement signals (the above

+ main I + main V AC + main V DC + auxiliary V AC) into digital


signals. This is performed by two 12-bit, 4 channels each parallel ADC converters.

TASK 2: to generate a squared waveform in phase with the mains input, and to square the AC current and voltage signals for the phase meter. Three circuits with amplifiers, limiters, comparators perform this task.

TASK 3: to generate a sinusoidal waveform, with controlled frequency and amplitude, that will be passed to the auxiliary AC voltage amplifier (10). This is made by the local micro DSP processor that generates the inputs for two DACs, that control the amplitude and the waveform, at 10 kHz.

On the board is located a set of 8 switches; their meaning is summarized in the following table. Dip number

Meaning

1 OFF 2 OFF 3 OFF 4 OFF 5 T2000 model: ON = T2000 6 T2000 model: ON = T2000 7 1200 V model: ON = 1200 V 8 Force download : OFF =no , ON = force download

3.2.5 INTE ON-OFF T 3000 board PWA11410 (7)

TASK 1: to detect the START and STOP inputs closed open

situation via two isolated constant current generator circuits, with wet/dry selection and opto-isolated logic output.

TASK 2: to drive the ON-OFF of the test set. There is the circuit that drives the power SCR pair (mounted on the back plate). SCR characteristics: 1200 V AC; 50 A steady; 200 A peak.

TASK 3: diagnostic circuits of the main auxiliary supplies.

3.2.6 MICR T1000 board PWA41300 (15)

The microprocessor board is the same as the one of the DRTS family, but without the two PLAs. It is controlling the test set


operation, test and results handling and the communication with the PC, but not the AC waveform generation, that is controlled by a dedicated slave microprocessor.


4 THE HELL, IT DOESNT WORK

4.1 INTRODUCTION

Sometimes, when my ears whistle, I wonder if it is because of some of my customers being angry at us because the test set doesnt work: according to Murphys law, when it was most necessary. We at ISA do our best efforts to filter the so-called infant mortality of electronic components prior to delivery of all our test sets; and this after extensive testing of prototypes and pre-production units. Yet, sometimes faults occur, because everything dies, including electronic components; so, please, before shooting at us, see if the following instructions can serve you to fix the problem. If not, e-mail us the problem, not forgetting to mention the units serial number: our business is to minimize your downtime. My e-mail address is: [email protected] Last, our experience is that our test sets withstand very heavy duty cycles for long wiles, if correctly used; most problems arise because of: . Voltage or current neutral is connected to earth; . Severe spikes on the mains (spikes are not always so kind to respect standard limits); . Transit, with the associated drops and thermal cycling; . Errors, such as the connection to live wires, or generating current on a short circuit with the handle completely turned to the maximum current. Please mention in your e-mail how did the fault occur: this serves us for our continuous improvement program.

4.2 ERROR MESSAGES

The test set performs a number of tests at power-on and during the generation. The following table lists all the messages, and the corrective action.


A) TESTS AT POWER-ON (and runtime) ERROR MESSAGE CONSEQUENCE CORRECTIVE

ACTION EMERGENCY The test set is

blocked. The EMERGENCY key is locked: press and rotate it, so that it is released.

Test set not connected to ground; power off and correct

The test cannot proceed

Connect the test set to ground using the dedicated socket and ground cable.

Power supply too low! Power off and correct

The message is repeated twice; then the test can proceed

Correct the supply. A slightly reduced voltage causes the corresponding reduction in maximum current and power; a very low voltage can damage the test set.

Power supply too high! Power off and correct

The test cannot proceed

Correct the supply, as there is the risk to damage the test set.

Diagnostic error + 15 V auxiliary supply

If the error is not confirmed it is possible to continue; else, the test cannot proceed (NOTE 1)

Try some power on off; if persists, three steps: . Check the fuses; . Try to replace the CONV board; . Return the test set.

Diagnostic error - 15 V auxiliary supply


Try some power on off; if persists, three steps: . Check the fuses; . Try to replace the CONV board; . Return the test


set. Diagnostic error NV memory access


Fault in the MICR board: replace it

Test results corrupted

It is necessary to erase corrupted data to continue

Using the menu, erase all results

Invalid test result data

It is necessary to erase invalid data to continue

Using the menu, erase all results

B) RUNTIME TESTS ERROR MESSAGE CONSEQUENCE CORRECTIVE

ACTION The test lasted too long. Test set is pausing

Tests are blocked for the specified duration

Wait until the message disappears

Pause. Residual time XXX seconds

If you try to restart before the above message disappears, the test set informs you about the residual time

Wait until the message disappears

V AC overload: reduce voltage or burden

Generation is stopped Reduce voltage or burden of main AC voltage

IAC output connection error

Generation is stopped The test set is sensing two burdens on main IAC and VAC: remove one of them

Transformer over temperature: cool down lasts 15

Generation is stopped (NOTE 1)

The main transformer temperature is


minutes too high because of heavy loads or very long test duration: wait until it cools down

T2000 is too hot: power off for 15 minutes


The test set temperature is too high because of heavy loads or very long test duration: wait until it cools down

T2000 is too cold: let it warm-up


The test set temperature is too low: let it powered-on until it heats up

10 V external input too high!

Measurement is stopped

Connect the input to the 600 V sockets

600 V external input too high!

Measurement is stopped

The input cannot exceed 600 V AC.

NOTE 1: Sometimes the alarm is false, i.e. the fault is in the diagnostic circuits (they also can fail), and the test set is OK. In this case, you can proceed by pressing the buttons and the control wheel at power on. There will be no confirmation message, and diagnostic faults will be ignored until you power-off the test set. TAKE CARE, because this operation skips ALL faults, and the test set is no more providing alarms in case of too long test duration during high current generation: MAKE THESE TESTS AS SHORT AS POSSIBLE!


4.3 TROUBLE SHOOTING

In case of malfunctioning, the following table lists the more likely types of faults, and the correction. Following paragraphs give more details about the corrections. SYMPTOM POSSIBLE CAUSE CORRECTION Problems after transport

Heavy shock Open T 3000 and check for loose boards or connections

At power-on does not turn on

Mains supply fuse open

The fuse is located in the power supply plug, in the small drawer. Replace it.

At power-on does not turn on

Mains fuse is OK See paragraph 4.4.

The variable transformer gets very hot as soon as the test set is powered-on

The INTE board is faulty

Replace INTE

A knob cannot be moved

The knob was badly pushed, and it touches the front panel

Remove the plastic cap on front of the knob. Un-tighten the nut: the knob can be moved. Put a small thickness below the knob, and lock the nut.

It is impossible to measure the 20 mA range

The input was overloaded; the PTC protection is not restored

Wait 15 minutes before trying again.

Measurements are completely false

The microprocessor has lost its correction factors

Go to the calibration procedure and repeat it.

Current and voltage are not generated

Fault of the INTE board

See paragraph 4.5

The AC voltage measurement is not

To be located See paragraph 4.6


stable Problems after UPGRADE

Repeat the procedure

See paragraph 4.7

False alarm of missing ground

To be located See paragraph 4.8

The display backlight does not turn on

Fault of the backlight converter

See paragraph 4.9

A test set rated 110 V was supplied at 220 V

Fault of some protection fuses

See paragraph 4.10

I cannot continue the test with the High IDC module

The thermal sensor is intervened.

Wait for the module to cool down.

4.4 AT POWER-ON DOES NOT TURN ON

If at power-on T 3000 does not turn on, and the mains fuse is OK, the fault is likely to be located in the AC voltage amplifier board (30): in its turn, the fault loads too much the supply transformer, and there is no auxiliary supply for the test set. To verify it, disconnect the auxiliary AC voltage amplifier; power-on and verify: if the test set powers-on, replace the amplifier. If necessary, repeat the same test on the DC voltage module (9). If necessary, disconnect also the white, 2-way connector going to INTE board, that drives the output transformer, and repeat the same test. On the edge of the CONV board are mounted a number of ring-shaped test points. They carry the key auxiliary supplies, which operate the test set. The arrangement of the test points is the following.


If any of these voltages is missing, the test set cannot operate: it is necessary to find out if it is a problem of blown fuse, or repair the auxiliary voltage circuit.

4.5 NO OUTPUT FROM THE MAIN CURRENT AND VOLTAGE

This is the case when you can start the test, but no output is generated from the main current and voltage outputs. In this situation the fault is located in the INTE ON-OFF board (7), that is located in the boards pack. The replacement is very fast: just follow the instructions above for the opening of T 3000 and board replacement.

4.6 THE AC VOLTAGE MEASUREMENT IS NOT STABLE

First of all, check that there is no unplugged connector or broken wire. Next, it is necessary to understand if the problem is in the measurement or if the output is actually unstable. To this purpose, connect the output to an AC voltage meter and verify the reading. If it is unstable as well, the problem is in the amp lifier; otherwise, it is in the measurement circuit. In the first instance, amplifier, we have to verify if the problem comes from the adjustment potentiometer. To this purpose, proceed as follows: . Go to the menu and select PREFAULT + FAULT; . In the PREFAULT mode, the output voltage is adjusted by the multi-function knob, and not by the potentiometer: please verify the output. If it is stable, the problem is located in the adjustment knob. If it is unstable, it can be located on the AP/50 amplifier, or on the CONV board. The problem when replacing CONV is that, as it hosts the measurement circuits, after replacing it, it is necessary to repeat the calibration. It is up to you if you want to receive the replacement boards or to deliver the test set to us. In the second instance, the fault is in the measurement, we have to replace the CONV board, with the problem explained above.

4.7 PROBLEMS DURING UPGRADE


If during the Upgrade operation the power went off, and the test set is no more operational, to recover the situation proceed as follows. - Remove (or unlock a little) the metal bar that fixes the two aluminium columns. - Remove the pack MICRO + CONV. - Open the pack MICRO + CONV. - Change the position of the mini-dip switch N. 8 on the CONV board (it is OFF; it must be set ON). - Insert again all the boards. - Turn on the test set. - At this point , the instrument should be connect to your PC. Execute the firmware download. Verify that the new firmware version appears; if yes, you have to turn off and set the dipswitch N. 8 to OFF (as it was initially).

4.8 FALSE ALARM OF MISSING GROUND CONNECTION

The test set includes a circuit that senses if it is connected to ground. The test circuit compares the voltage of both supplies, and verifies that the ground connection has a voltage is close to one of them. This is good for the normal case of the supply being made of Phase and Neutral: the neutral voltage is about the same as the ground. However, if you have a phase to phase supply, the circuit fails: it tells that there is no ground even when the ground is there. In this instance, after you are sure of the ground connection, it is possible to over-ride the protection: at power-on, keep pressed the arrow closest to the knob and the knob.

4.9 THE DISPLAY BACKLIGHT DOES NOT TURN ON OR THE DISPLAY DOES NOT OPERATE

1. The display backlight does not turn on. The backlight is supplied by a DC to DC converter that is mounted on the main board, that is mounted below the front panel. If the backlight does not turn on, the converter is likely to be faulty. The replacement is a bit hard, but not impossible. . Remove T 3000 from the container. . The converter is mounted as shown in the design below.


. First of all, verify that the connector is correctly fit, and that wires are not loose. Then, re-solder the converter to the main board: we once had a case of poor soldering. . If this is not enough, it is necessary to replace the converter. To this purpose, it is necessary to gain access to soldering points by removing the C shaped spacer that is located just before the converter. 2. The display does not operate. In this situation, verify the following. . The three FLATSTRIP cables from the control board back panel to the main board could be not completely fit in, as they are rather hard: check it. . Verify the voltages on the test points of the CONV board, as explained above. If some voltage is missing, remove the TRANSFORMER board PWA11412 and verify the fuses as explained here below. . The display is connected to the main front board via a number of pins, located in the center of the display: verify that there is no dirt causing a short circuit between them. . If everything is OK, there is also the possibility that the MICR or the TRANSFORMER boards are faulty: replace them.


. If changing the MICR board the fault is still there, it is necessary to return the test set to ISA for the replacement of the display, that involves a difficult labor.

4.10 A 110 V RATED TEST SET WAS POWERED AT 220 V

If the test set has been supplied with the wrong supply (230 on 115 V; 380 V on 230 V), the operation is the following. . First of all, remove the MOV voltage suppressor located below the mains supply, see the picture.

. Next, replace the fuses on the mains supply plug (in the small drawer). . Power-on: usually, the test set is OK. . If the display does not turn on, or the supply is not on, remove the transformer board PWA11412, and locate on it nine SMD fuses: see the picture.


. Check that they are not open; in case, remove the faulty one, and replace it by a short-circuit. The following table summarizes the fuse rating and the generated supply. FUSE RATING SUPPLY F1 0.375 A + 5 V F2 2 A + 12 V F3 0.75 A + 15 V F4 0.75 A - 15 V F5 2 A CB 3 kV F6 2 A RELAY 3 kV F7 0.75 A START INPUT F8 2 A POWER-ON CB F9 0.75 A STOP INPUT


Other fuses are located on the main board below the front panel. Of these, there are three fuses located just below the display: their location is sketched here below.

Fuse ratings are: F6: 2 A; F5 and F4: 0.375 A. After having replaced the faulty fuses, power-on again and try to generate: if you cannot, also the INTE ON-OFF board has been damaged, and needs to be replaced. After this, please perform a complete check of the test set performances.

4.11 THE TEST SET DOES NOT COMMUNICATE WITH THE PC

The serial interface is supplied via a dedicated, small transformer that is located below the TRANSFORMER board (7): see the mounting sketch. We have had a run of weak transformers, that cause the loss of connection. To verify the transformer: . Just below the serial I/F connector, on the big board, there is an AMP type connector, white, two wires. . Remove it, power-on, and measure the voltage on the pins: it must be around 8 V AC.

SUPPLY TRANSF.

F6

F5

F4


If you measure zero, this means that the transformer is faulty, and needs to be replaced.

If you measure 8 V AC, then the problem is in the circuit. First of all, refer to the schematic of the serial I/F circuit at the end of the document. Next, locate these components on the big board after the front panel: they are mounted just after the serial I/F connector.


U80 is mounted on a DIP socket; you should verify that between pins 15 and 16 of U80 (0 on pin 15) there should be + 5 V DC. . If + 5 V is not available, then verify: fuse F12, rectifying bridge D63, series regulator U79. . If + 5 V is OK, try to replace U80, MAX232CPE. . If the communication is wrong after replacing U80, the test set has to be returned, because the intervention is complicated.

4.12 FAULT ON THE 10 V OR 600 V EXTERNAL MEASUREMENT

The repair involves four steps: . Dismounting the front panel and the main board from the rest of the test set; . Testing the circuit and replacing the faulty components; . Re-assembling the test set; . Final test. 1) Dismounting the front panel and the main board from the rest of the test set. The process is made of:


. Unplugging all the connectors from the upper part to the lower part; . Unsoldering the connection wires; . Unscrewing the wires to the VARIAC; . Unscrewing the two high current cables from their sockets. The following pictures have been taken on a T 3000, so, on T 2000 two connectors and two boards (auxiliary AC and DC supplies) are missing. On the following picture is shown the lower T 3000 side.

Connectors to be removed are all those going to the main board and coming from the lower part of the instrument, and the three screw connections to the VARIAC: please mark them, in order to avoid errors when the cabling is restored. The fast-on connections to the front power supply plug are not to be removed. Mark connectors with the same number of pins: the length should avoid confusion, but it is safer to have an additional reference.


The following picture shows the detail of two more wires to disconnect.

The two black wires, connected to the HV relay with FAST-ON, are to be unfastened. These wires are connected to the HV sockets; one of them enters a CT transformer that measures the HV output current. The CT transformer is tied to the lower part; so, it is necessary to remove the wire through it. Please note the path of these wires, as it is to be repeated EXACTLY THE SAME as the test set is re-assembled: this path is critical because of inductions from the HV voltage. Next picture shows the connectors on the right side.


It is necessary to disconnect the connectors, as shown, and to unsolder all the wires shown. About this, PATE CARE TO MARK THEM, IN ORDER TO ENSURE THE SAME SEQUENCE WHEN THEY WILL BE SOLDERED BACK. Next picture shows the upper side of the test set.


Arrows show the two high current wires, to be unscrewed, and the connectors to remove. Next picture shows the detail of three flat cable connections to remove: take care as they are hard to remove and fit, but the body is a bit fragile.


Last, as all connections have been removed, remove the front panel and mother board from the rest, by unscrewing the screws shown in the next picture.


After removing these screws, the support legs will remain attached to the front panel, so that it can be moved without damaging the components. Take care when you unscrew, in case some connection was not removed. 2) Testing the circuit and replacing the faulty components First of all, refer to the attached circuit schematic, that shows the failing circuit. The first thing is to verify if there is some component burnt or physically damaged. The circuit is located on the mother board, near to the measurement sockets: please refer to the following mounting drawings. In particular, we suspect that the failing component is U68: have a close look at it. There is a possibility that the gas discharger D49 is in short circuit, or that zeener diodes TZ9 and TZ10 are in short circuit: please verify.


Components of the voltage measurement circuit.


Power supply of the voltage and current measurement circuits. If there is some damaged component, try to replace it; test also if fuses marked F8 and F9 are open; in case, replace them.


After this, it is necessary to verify if the measurement circuit is operational. To this purpose, it is necessary to power-on the test set; this can be done as follows: . Connect to the power supply the connectors J10 (lower side of the test set) and J18 (see mounting schematic above), using the two extension cables provided; . Remove the three flat cables from the lower part, replace them with the three longer cables provided, and connect them to the upper part. Power-on: the display shows the starting message, as usual. Select Relays, and then the two voltage measurement inputs: they should display zero. . If the measurement is zero, apply the voltage to one input, and verify that the measurement is correct; then repeat on the other. If everything is OK, the repair is finished. . If the measurement is not zero, it is necessary to perform other tests. First thing, we should verify that the auxiliary DC supplies, + 5 V_MV, + 15 V_MV and 15 V_MV, are correct. To this purpose, refer to the test point TP19, shown above: it is the zero of these voltages. Then, measure that the voltage on fuses F8 and F9 is 17.5 V AC nominal: this ensures that the transformer is OK.

. If one or both voltages are zero, temporarily remove fuses F8 and F9, as necessary, power-on and measure again the voltage.

IF ONE OR BOTH OUTPUTS on the transformer side ARE ZERO, THEN THE FAULT COMES FROM THE TRANSFORMER ITSELF. The recovery of such a fault implies removing the transformer from the main board: in this case, please inform us immediately.

If voltages are OK on the transformer side, then there is a short-circuit on some component. In this instance, replace all the ICs of the circuit, and try to power-on again: the short-circuit should be disappeared. If not, it is necessary to look at the schematic, and try removing all components that could cause the short-circuit.

. If AC voltages are OK, please verify the DC voltages between TP19 and: U69 pin 4 (+15 V); U69 pin 11 (-15 V); U61 pin 1 (+ 5


V). If some is missing, either there is a short circuit (in this instance remove all ICs we have delivered, and try again), or the corresponding series regulator is broken (very unlikely). Once AC and DC voltages are OK, if the measurement is still wrong, replace all ICs we have delivered; if still the measurement is wrong, it is necessary to follow the circuit schematic to locate the fault. Key components are: . PGA204AU, U68: it is a programmable gain amplifier. The gain is set by the microprocessor, as a function of the input amplitude; . OPA2477, U69, is a dual 477 op amp; . MAX312CSE, U70, is a four way analog switch; . HCPL7800, U61, is a fixed gain isolation amplifier. 3) Re-assembling the test set The re-assembling will be performed the other way round with respect to the dismounting; so: . Remove the two extension cables; . Replace the long flat cables with the original ones; . Screw in place the front panel; . Solder and screw wires; . Fit back the connectors; . Re-locate the HV cable, AS IT WAS BEFORE. 4) Final test Once the test set is restored, power-on again and verify that all outputs are correctly operational.

4.13 FAULT ON THE 10 A EXTERNAL MEASUREMENT

The measurement of the external 10 AC current is performed by means of a toroidal current transformer, located just below the input sockets. In case of fault: . Withdraw the test set from the container; . Check that there is a short circuit between 10 A and IN sockets: if not, the short-circuit wire was unsoldered (because of too high current: solder it back, through the toroidal CT; . If the short circuit is there, look at the CT and verify that there is no broken or disconnected wire on the secondary side. If the CT is broken, ask for the replacement;


. If there is no apparent damage to the CT, it is necessary to verify that it is correctly operational. To this purpose, open one of the secondary wires, and put in series a current ammeter. The transformer ratio is 1 A/ 5 mA; so, when you input 1 A, you should measure 5 mA on the secondary. If not, the CT is damaged and needs to be replaced. . If the CT is OK, then there is a faulty component. In the following, are given the schematic of the related circuit and the mounting diagram: the arrows show the points where the secondary wires are soldered.


If you are tooled to replace them, ask for the components: we will change the operational amplifier U46A; then, if necessary, the


analog switch U38. If neither of these components is faulty, it is advisable to return the test set for repair. The procedure to open T 3000 to gain access to the control board is described in the above paragraph. If you cannot perform this maintenance, you should return the test set.


4.14 FAULT ON THE REAL TIME CLOCK

The T 3000 internal clock is generated by a component mounted on the big front panel; it is supplied by a non-rechargeable battery, that should last 10 years or more. If the test set does not keep the date and time, the cause should be the battery being dead too soon. The location of battery BT1 is shown below.


To replace it, it is necessary to withdraw T 3000 from the container, and to open the test set in two, as explained in 4.13: this allows you to access the component. Remove the battery and replace it with the new one.

4.15 THE ENCODER IS BROKEN

In this instance, it is necessary to have some skill and patience. The procedure is the following. . You have in your hands the new encoder: it must replace the faulty one. This means that you have to dismount the old one, to unsolder the five wires coming from it and going to the front panel board, solder them to the new one, mount it. . The first problem is that it is necessary to gain access to the faulty encoder. If you look at it, it is surrounded by other components: no access. It is necessary to remove the DC voltage generator board. See the picture below.


. Now you have room enough to operate. Remove the encoder: the five wires going to it are long enough to allow you keeping it in your hand. . Unsolder the wires from the front panel, and then from the encoder, and solder them back to the encoder. . The encoder has five pins in all: mount the new encoder, and solder wires to the front panel, as shown in the sketch here below (seen from the rear). . At the end of soldering, power-on and check that it is correctly operational. After this, complete the mounting of the test set.

4.16 UPGRADE TO FIRMWARE REVISION 1.40

From the test set S/N 15668, delivered on September, 2008, the test set includes the STOP input. Starting from firmware revision 1.40, the test set has been added the capability of testing current relays. The feature can be enabled by moving a DIP switch that is located on the CONV board. The procedure to modify the switch position is the following. 1. Open the test set, removing the screws on the bottom. 2. Locate the MICR + CONV boards, and remove the two screws that keep them in place.

ENCODER


Boards are also kept in place by a rod that tightens the guides. Un-tighten the nut shown above and below.

3. Remove the two boards: MICR is above. Remove the screws that keep boards together. On the bottom right corner of CONV board is located a DIP SWITCH set.

NUT TO BE UN-TIGHTENED

NUT TO BE UN-TIGHTENED


4. Set switches as shown in the picture above, and restore the situation. Dont forget to tighten the rod! At power-on, you will find an additional selection: relay tests.

4.17 THE FAULT CANNOT BE FIXED

If the fault is too hard to be fixed, you have to deliver it back to your agent. We have encountered problems caused by a poor packing of instruments that have been delivered us for calibration or repair. In order to avoid such inconveniences, please apply the following procedure. First of all, compile the following form, and attach it to the instrument. Please do not forget to compile it. With the instrument should come the mains supply cable, and the serial interface cable. The users manual originally delivered with the test set is not necessary.


Cover the instrument itself with a polyester film, in order to protect it against dust and foam. The instrument should be protected by anti-shock foam having a minimum thickness of 5 cm ON ALL SIDES. Use a new carton box as a container. On the box apply the UP and the FRAGILE labels. In the box the instrument will be placed horizontal or standing; not upside down. If the set is heavier than 20 kg it is better to use also a pallet: this ensures that the box will not be packed upside down. Last but not least, do not declare an high value for customs: this expedites clearance of the good and lowers fees.


INSTRUMENT RETURN FORM

DATE _________________ AGENT ________________ COUNTRY ______________ TYPE OF INSTRUMENT ___________________ SERIAL NO. ___________________________ INSTRUMENT RETURNED FOR: CALIBRATION ____ REPAIR ____ In case of repair, please specify the following. DATE OF FAULT _______________________ REPORTED BY E-MAIL, PHONE ___________ COMPANY ___________________________ USERS REFERENCE ____________________ FAULT DESCRIPTION ______________________________________________________________________________________________ ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


HOW DID IT OCCUR ______________________________________________________________________________________________ _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ LOCAL ANALYSIS OR ATTEMPTS TO REPAIR _______________________________________________ _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ RECOMMANDATIONS AND NOTES _______________________________________________ __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


5 CALIBRATION

5.1 INTRODUCTION

T 2000 does not need to be calibrated, as metering circuits employ high stability components. It is suggested to check the unit every 2 years, by comparing T 2000 measurements to external meters. Tests should be performed with an high accuracy multi-meter, that should guarantee a maximum AC measurement error of 0.1%, both for voltage and current. Besides, as such multi-meters do not have current ranges greater than 2 A, for the test of the high current ranges it is necessary a class 0.1 measurement Current Transformer. The adoption of lower-class instruments may cause false interventions, that introduce errors into the test set. At the end of the test, if deviations are not acceptable it is possible to enter the calibration mode, as explained in the followings.

5.2 CALIBRATION PROCEDURE

The calibration mode is accessed by pressing push-buttons < and > at the meantime, and powering on T 2000. The windows that opens up allows for first selections. The operating mode is the following: . Select the range to be calibrated. Calibrated ranger are checked. . Set to zero the adjustment knob. . With no output, ad just the off-set. . Press > to go ON. The external meter measures the output; T 2000 displays its measurement. . There are two adjustment parameters: COARSE and FINE. Go to the COARSE adjustment, and modify it until the T 2000 measurement is greater than the one displayed by the external meter. Reduce the COARSE adjustment until T 2000 measurement is less than the external one, and save the coarse adjustment. . Now, go to the FINE adjustment, and modify it to the best match with the external meter (the difference should be less than 0.2% of the reading).


. Press the multifunction knob to confirm. T 2000 continues to generate: it is possible to check that the measurements match. If necessary, it is possible to re-enter the same range and repeat the adjustment; else, go to the next range: T 2000 goes OFF. . Take now the output to the value to be tested, to verify for the linearity of the measurement. If the measurement has a negative error, go back to range adjustment, reduce the COARSE adjustment parameter and increase the FINE one. . Go to next range, and so on, until the calibration is completed. . Once coarse and fine adjustments are performed, it is possible to correct the off-set readings. This is performed selecting the range without generation, correcting the reading and pressing set. Dont perform the offset calibration before the coarse adjustment, because the offset would be modified. . At the end of off-set calibration, it is necessary to verify the full scale reading: in case you find some (minor) deviation, adjust it, acting on fine only. Take care because on some ranges there are more adjustments to be performed on the same range (this is provided in order to null the linearity error:

- EXT I, 20 mA: 2 calibrations on the AC range, 4 calibrations in the DC range;

- EXT I, 10 A: 4 calibrations in the DC range; - EXT V, 10 V: 2 calibrations on the AC range, 4 calibrations

in the DC range; - EXT V, 600 V: 2 calibrations on the AC range, 4 calibrations

in the DC range; - MAIN I DC: 2 calibrations in the DC range.

These calibrations are performed with Coarse and Fine on the range setting; for other settings, only the Fine adjustment is performed. DC adjustments are: the range, positive; 20% of the range, positive, 20% of the range, negative, 80% of the range, negative. During these adjustments, the display shows the input to be applied (for instance, 10.66 mA on the 20 mA DC, nominal range). The actual applied value should deviate from the displayed one by no more than 5%.


The program alerts if a scale is not calibrated. At the end of the session, all parameters are saved in the non volatile FLASH EPROM.

5.3 T 2000 OUTPUT CALIBRATION

The internal measurements calibration is performed by generating the following current and voltage outputs. For each output range there is a number of measurement scales, that are separately adjusted: during the use T 2000 automatically selects the best scale. This increases the measurement accuracy.

5.3.1 OUTPUT CURRENTS CALIBRATION

NOTE: the current output from the main AC voltage is also calibrated. OUTPUT SOCKET

CONTROL

300 V AC; current measurement (Mis_IAC_main)

Range Calibration value

Notes

0.008 A 5 mA Output 300 Vac Main ; series resistor 1000 Ohm



0.199 A 140 mA Output 300 Vac Main ; series resistor 100 O

Mie12110-t2000 Introductory Guide

Documents

current transformers

main current

transformers board pwa21412

board pwa21401

board pwa11411

board pwa11410

outputs description

issued lodi