CMC_ANS_10002_ENU.pdf

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OMICRON Page 1 of 11

Application Note

Power Transformer Vector Group andTurns Ratio Testing with CMC 256plus/356

AuthorStephan Geiger | [email protected]

DateOct 21, 2010

Related OMICRON ProductsCMC 256plus, CMC 356

Application AreaPower Transformers

KeywordsCMC, Transformer, Vector Group, Turns Ratio, Bushings

Versionv2.21

Document IDANS_10002_ENU


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OMICRON 2012 Page 2 of 11

Content

1 Introduction ..................................................................................................................................... 3

2 Safety Instructions PLEASE READ CAREFULLY........................................................................ 4

3 Operating & Connection Instructions............................................................................................. 5

4 Additional Information .................................................................................................................... 9

5 Pictures ...........................................................................................................................................10

Please use this note only in combination with the related product manual which contains several important safetyinstructions. The user is responsible for every application that makes use of an OMICRON product.

OMICRON electronics GmbH including all international branch offices is henceforth referred to as OMICRON.

OMICRON 2010. All rights reserved. This application note is a publication of OMICRON.

All rights including translation reserved. Reproduction of any kind, for example, photocopying, microfilming, opticalcharacter recognition and/or storage in electronic data processing systems, requires the explicit consent of OMICRON.Reprinting, wholly or in part, is not permitted.

The product information, specifications, and technical data embodied in this application note represent the technicalstatus at the time of writing and are subject to change without prior notice.

We have done our best to ensure that the information given in this application note is useful, accurate and entirelyreliable. However, OMICRON does not assume responsibility for any inaccuracies which may be present.OMICRON translates this application note from the source language English into a number of other languages. Anytranslation of this document is done for local requirements, and in the event of a dispute between the English and a non-English version, the English version of this note shall govern.


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1 Introduction

This Application Note (Version 2.0) replaces all prior published documents that contain transformertesting with CMC Test Sets.

Before performing the transformer test, carefully read the safetyinstructions in this document together with those for the CMC Test Setand in the CP GB1 manual.

Do not operate the CMC Test Set until the safety instructions in each ofthe operating manuals have been observed and are fully understood.

The CMC Test Set should only be operated by trained personnel. Anymaloperation can result in damage to persons or property.

Use only the supported 'CM_TR_VG Test Utility V2.03.xls' Excel File fortesting the transformer!

The MS Excel tool 'CM_TR_VG Test Utility V2.03.xls' is provided with this Application Note

The original idea and prototype of this tool was developed by Alectrix (Pty) Ltd, South Africa.

Supported tests:

> Testing of Vector Group (VG)

> Measurement of Transformer Turns Ratios (TR)

> Measurement of Magnetizing Current

Supported CMC Test Sets:

> CMC 256-6; CMC 256plus> CMC 356 (with ELT-1 option)

Required software license:

> CMEngine


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2 Safety Instructions PLEASE READ CAREFULLY

1. The CM_TR_VG.XLT MS Excel macro provides a useful application to broaden the range ofapplications for the CMC Test Set. Note that the CMC Test Set is not designed to be used in anoutdoor/ open substation environment and hence suitable precautions against rain, heat etc. should betaken. Also the CMC Test Set is not intended to be used in a high voltage environment hence whenconnecting and disconnecting the unit to a power transformer special precaution must be taken. Byusing this Excel utility, the user accepts all responsibilities and risks.

2. Before using the CM_TR_VG.XLT MS Excel macro, carefully read the following safety and operatinginstructions.

3. Always adhere to the safety regulations applicable to the testing of power transformers as well astesting in live substations as stipulated by your company, your country and/or international safetyregulations.Testing and measuring with the CMC Test Set must comply with the relevant national and internationalsafety standards listed below:

- EN 50191 (VDE 0104) "Erection and Operation of Electrical Equipment"

- EN 50110-1 (VDE 0105 Part 100) "Operation of Electrical Installations"- IEEE 510 "IEEE Recommended Practices for Safety in High-Voltage and High-Power Testing"

4. Ensure that the power transformer is properly switched OFF, de-energized and isolated (visualinspection!) before connecting any test leads.Important: Switching off the high voltage in a substation and the grounding procedure is theresponsibility of the utility personnel!Five Safety Rules:1) Disconnect completely2) Secure against re-connection3) Verify that the installation is dead4) Carry our grounding and short-circuiting5) Provide protection against adjacent live parts

5. Testing with the CM_TR_VG.XLT MS Excel macro and the CMC Test Set should be performed only by

authorized and qualified personnel. Clearly establish the responsibilities in advance of any testing!6. Ensure that the housing of the CMC Test Set is properly connected to the substation earth potential via

the earth stud on the back of the CMC Test Set.

7. Ensure that all of the transformer's terminals do not carry any voltage potential (physicalmeasurement with a voltage meter!) before connecting any test leads. During a test, the CMC Test Setmust be the only power source for the transformer under test.

8. The test leads and clamps must be securely attached to the bushings of the transformer and the CPGB1 grounding boxes. Do not stand adjacent to or directly underneath a connection point because theconnection clamps may fall off and touch you. This is a physical and an electrical hazard.

9. Before connecting or disconnecting any of the test leads between the CMC Test Set and the powertransformer, ensure that the CMC Test Set is completely switched OFF (i.e. power switch is OFF).Never connect or disconnect any test leads while the outputs are active.

10. When connecting cables to the sockets, use wires with 4 mm safety "banana" connectors and plastichousing.

11. When the red warning light on the front panel of the CMC Test Set is lit, all test leads must be regardedas hazardous and should not be touched in any way.

12. Make sure to connect the voltage injection always to the high voltage winding and the voltagemeasurement to the low voltage winding of the transformer. Incorrect connections are potentially life-threatening and, at the very least, may damage the equipment. Therefore first check the wiring byinjecting only 50 V.


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3 Operating & Connection Instructions

1. Follow the five safety rules as described in the Safety Instructions. Connect the windings to ground!

2. Connect the CMC Test Set to the CP GB1 grounding box and the transformer as shown inFigure 1. The current clamps should be connected at binary inputs 2, 4 and 5. Place the current clampson the primary side leads going to the grounding box/transformer! The connection cables provided byOMICRON must be used to connect the leads to the CP GB1 grounding box. Furthermore the leadsfrom the CMC Test Set and the leads to the transformer must be attached to the same connectionclamp at the CP GB1 grounding box. Each cable must be attached to a single plug socket on theconnection clamp (see Figure 2).

Figure 1: Wiring diagram


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Figure 2: How to connect to the grounding box

3. Remove all grounding connections of the terminals except one per winding. Use Neutral (N) for thegrounding connection if accessible.

4. Pair the PC with the CMC Test Set by using the Test Set Associationlink from theTest Universe start page.(Note: This does not apply to a CMC256-6 with an LPT port).

5. Select the 'TR Test' sheet and click on Edit Test Object Parameters. Now match the transformerparameters with the test sheet parameters and return to the 'TR Test' sheet.


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6. Click on the 'Output ON/OFF' button in the Control Panel. The line to line test voltage defined will beapplied to the HV terminals of the transformer.

7. The LV Voltages, HV magnetizing current (open circuit current) and the phase angle of the LV voltagesrelative to the HV applied voltage on phase A will be measured and updated with a one second refreshrate. Before you start the test, for the measurement of the HV magnetizing current, define the ratio and

range of the clip-on ammeter in the Test Object Parameters. In addition place the clip-on ammeters onthe HV leads going to the transformers HV terminals.

8. Select Keep Results for Tapto record the measured values, the measurement will automatically moveto the next tap.

9. Tap the transformer to the next tap position and again select Keep Results for Tap. Repeat thisprocess until all taps were tested.

10. The tap changer can be tapped automatically by selecting the function in Test Object Parametersandwiring the binary output 1 of the CMC Test Set across the raise or lower push button in the tap changercontrol box (refer to the tap changer drawings for clarification). The binary output will pick up for 2seconds after the Keep Results for Tapbutton is selected.

11. The CMC Test Set outputs will automatically switch OFF once all the taps have been tested and themeasurement results are all displayed (Figure 2).

Figure 2: Test results

12. The vector diagram can be viewed once all the taps have been tested on the 'Vector Group' sheet; thescale is 'per unit' (Figure 3).

Figure 3: Measured vector group


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13. Save the test file with a unique name after completion!14. Please note that for personal safety and to safeguard the equipment the voltage injected must be

applied to the high voltage side of the transformer.15. Before disconnecting the transformer under test, ground all transformer connections!16. This macro works for an English operating system / Excel, i.e. decimal point is a dot, not a comma. If the

PCs regional setting is not set to English please change your regional options (Figure 4).

Figure 4: Regional and Language Options

17. The CM_TR_VG macro has been tested with Microsoft Excel 2003 and Excel 2007 underWindows XP and Windows 7.


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4 Additional Information

To connect the CMC test Set to the transformer the following accessories are recommended. However, theCP GB1 grounding boxes mustbe used in order to ensure absolute safety to personnel and to preventequipment damage as a result of high voltages:

> 2x CP GB1 grounding box VEHZ0672

> 2xMeasurement cable set(2.5 mm) 6x10m VEHK0619

> 12x Connection clamp VEHZ0610

For safety reasons first ground theconducting part of the transformer,then connect the clamps and cables tothe transformer. Finally connect to the

CMC Test Set!

> 1x Grounding cable(GR/YE) 1 x 6 m, 6 mm2with connection clamp VEHK0615

> 3x Current Clamp VEHZ4000


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5 Pictures

Figure 5 & 6: Transformer test conducted at the OMICRON Development Center with the Excel Test Utility


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OMICRONis an international company serving the electrical power

industry with innovative testing and diagnostic solutions. The application of

OMICRON products provides users with the highest level of confidence in

the condition assessment of primary and secondary equipment on their

systems. Services offered in the area of consulting, commissioning,

testing, diagnosis, and training make the product range complete.

Customers in more than 140 countries rely on the company's ability to

supply leading edge technology of excellent quality. Broad application

knowledge and extraordinary customer support provided by offices in

North America, Europe, South and East Asia, and the Middle East,

together with a worldwide network of distributors and representatives,

make the company a market leader in its sector.

Europe, Middle East, Africa

OMICRON electronics GmbH

Oberes Ried 1

6833 Klaus, Austria

Phone: +43 5523 507-0

Fax: +43 5523 507-999

[email protected]

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Suite 2006, 20/F, Tower 2

The Gateway, Harbour City

Kowloon, Hong Kong S.A.R.

Phone: +852 3767 5500

Fax: +852 3767 5400

[email protected]

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Houston, TX 77046, USA

Phone: +1 713 830-4660

+1 800-OMICRON

Fax: +1 713 830-4661

[email protected]

For addresses of OMICRON offices with customer servicecenters, regional sales offices or offices for training,

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