ANCP0902 VT Ratio Measurement With 12kV

Application NoteVT Ratio Measurement with 12kV

AN CP0902 Application Note

2

Manual Version: ANCP0902.AE.1

OMICRON electronics 2009. All rights reserved.

This Application Note is a publication of OMICRON electronics GmbH.

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

The product information, specifications, and technical data embodied in this Application Note representthe technical status 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, accurateand entirely reliable. However, OMICRON electronics does not assume responsibility for anyinaccuracies which may be present.

The user is responsible for every application that makes use of an OMICRON product.

OMICRON electronics translates this Application Note from the source language English into a numberof other languages. Any translation of this Application Note is done for local requirements, and in theevent of a dispute between the English and a non-English version, the English version of this manualshall govern.

3Contents

Contents1 Using this Document . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

1.1 Operator Qualifications and Safety Standards. . . . . . . . . . . . . . . . . . . . . . . . . . . 51.2 Conventions and Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.3 Related Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.4 Safety Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2 Safety Instructions for Connecting the CPC 100 to the Test Setup . . . . . .92.1 Before Starting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

3 Test Setup and Manual Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114 Template Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

ANCP0902 Application Note

4

5Using this Document

1 Using this DocumentThis Application Note describes how to execute a VT Ratio measurement by using the CPC 100 and the CP TD1 as the power source up to 12 kV. The CPC 100 delivers an output voltage with a maximum of 2 kV. Sometimes it is required to measure the VT Ratio with higher voltages to have more accurate results.

With the CPC 100 and theCP TD1, it is possible to generate voltages up to 12 kV and to measure the ratio in two steps.

Reading the AN CP0902 Application Note alone does not release you from the duty of complying with all national and international safety regulations relevant to working with the CPC 100 and the CP TD1.

1.1 Operator Qualifications and Safety StandardsWorking with high voltage is extremely dangerous. The VT Ratio measurements described in this Application Note must be carried out only by qualified, skilled and authorized personnel. Before starting to work, clearly establish the responsibilities. Personnel receiving training, instructions, directions, or education on the measurement setup must be under constant supervision of an experienced operator while working with the equipment.

The operator is responsible for the safety requirements during the whole test. Before performing tests using high voltage, read the following:

Do not perform any test without having carefully read the CPC 100 User Manual.

Read in particular all safety instructions and follow them. Do not use the test equipment without a good connection to ground. Pay attention to the national and the international standards for the safe

operation of high-voltage test equipment (EN 50191, IEEE 510 and others).


6

1.2 Conventions and Symbols UsedIn this document, the following symbols indicate paragraphs with special safety relevant meaning.

1.3 Related DocumentsThe following documents complete the information covered in this Application Note:

1.4 Safety RulesBefore starting a measurement, read the safety rules in the CPC 100 User and Reference Manual and the CP TD1 Reference Manual carefully and observe the application-specific safety instructions in this Application Note when performing measurements to protect yourself from high-voltage hazards.

Symbol DescriptionPersonal injury or severe damage to objects possible.

Equipment damage or loss of data possible.

Title DescriptionCPC 100 User Manual Provides basic information on the CPC 100

test system and relevant safety instructions.CPC 100 Reference Manual Provides detailed hardware and software

information on the CPC 100 test system including relevant safety instructions.

AN CP0711: Test Templates General information about working with templates for the CPC 100.

CP TD1 Reference Manual Provides basic information on the CP TD1 and relevant safety instructions.

7Using this Document

GeneralAlways observe the five safety rules:

Disconnect completely Secure against re-connection Verify that the installation is dead Carry out grounding and short-circuiting Provide protection against adjacent live parts

Caution: Never touch any terminal without visible ground connection!


8

9Safety Instructions for Connecting the CPC 100 to the Test Setup

2 Safety Instructions for Connecting the CPC 100 to the Test Setup

2.1 Before StartingMake sure that both the CPC 100 and CP TD1 are properly grounded and that the VT is disconnected from the line.

Beware of nearby parallel systems which are not disconnected. They can induce hazardous loads in floating segments of a substation. Always touch the leads and terminals with a grounding hook first.


10

11

Test Setup and Manual Performance

3 Test Setup and Manual PerformanceTo find the VT Ratio, two different measurements have to be performed. Afterwards, the ratio has to be calculated with the results of each measurement.

Measurement 1 Measurement 2The first measurement covers the complex resistance of a capacitance or a resistance.

Note: Use a resistor or a capacitor (values see below) and an appropriate test voltage.

The second measurement covers the complex resistance of R or C in series to a voltage transformer.

Note: Use the same resistor or capacitor as for Measurement 1 and a test voltage of up to 12 kV.

The voltage in Measurement 1 should be similar to the expected low voltage (LV) in Measurement 2 (HV Out / VT Ratio). As the passive device is not completely independent from the voltage, there might be minor losses in accuracy if the voltage in Measurement 1 is different to the low voltage in Measurement 2.

R = 1 k to 10 k (Please consider the power of the resistor as P = U/R)

C = 100 nF to 1 F (U > Test Voltage)

The voltage on the low-voltage side should be similar to the voltage in the first test (for example 100 V). The passive device remains the same as in Measurement 1.


12

Figure 3-1 Setup 1 Figure 3-2 Setup 2 Connect C or R according to Figure 3-1 Choose the TanDelta-PF test card Select combined measurement Z and Mode

UST-A Select the voltage, for example 100 V

Connect C or R and the VT according to Figure 3-2Use any low-voltage winding of your VT. Leave other low-voltage windings open.

The ground connection (X) of the VT has to be connected to the CP TD1 ground. This connection is important for the test.

Choose the TanDelta-PF test card Select combined measurement Z and the

Mode UST-A Select the voltage, for example 12 kV

Results Measurement 1:

The result of the first test is the value of the complex resistance of the passive device, for example Z1 = 998.0 and Angle1 = 0.15.

Results Measurement 2:

The result of the second test is the value of the complex resistance of the passive device multiplied with the VT Ratio, for exampleZ2 = 998.0 k and Angle2 = 0.25.

Overall ResultsOverall results are calculated as follows:

Ratio = Z2/Z1 = 1000:1Angle = Angle2 - Angle1 = 0.1

(accuracy: approx. 0.2% and 0.1)

Measurement 1 Measurement 2

13

Template Usage

4 Template UsageBy using our template for the VT Ratio measurement the test cards are preconfigured and the calculation is done automatically in the Exce file. The test cards can be customized if the configuration does not fit your personal needs.

Measurement 1 has to be performed once; Measurement 2 has to be performed for each phase (A, B, C).

You find the template and the Excel template enclosed to this Application Note.

First of all, transfer the template (VT_Ratio_TD1.xmt) to your CPC 100.All four measurements are prepared in the template. Z (C or R) is the test card relating to "Measurement 1". Z+VT (A)...(C) are the test cards relating to "Measurement 2". Only the first measurement in each card is used for the calculation of the VT ratio.

Figure 4-1 Test card for the complex resistance of C or R


14

Perform the measurements Save your measurement results on the CPC 100 Open the Excel template VT Ratio with TD1.xlt Transfer the file to your computer or load the file directly from the CPC 100

to the Excel template Open the "Welcome" sheet and load the results to the Excel template

You will find the results of your measurements on the "Report" sheet in the Excel file.

Insert all relevant information (Tester, Manuf., Serial No., etc.) in the "Report" sheet. To get the deviation to the nominal ratio of the VT it is unavoidable to type in the primary and the secondary voltage (see nameplate) of your transformer.

The template is now ready to be customized for any personal needs.

1 Using this Document1.1 Operator Qualifications and Safety Standards1.2 Conventions and Symbols Used1.3 Related Documents1.4 Safety Rules

2 Safety Instructions for Connecting the CPC 100 to the Test Setup2.1 Before Starting

3 Test Setup and Manual Performance4 Template Usage