Test methods

Končar PowerTransformers Ltd.

TEST METHODS FOR POWER TRANSFORMERS

QT No: xx-yy
Page : 1 / 2

TEST METHODS FOR POWER TRANSFORMERS Contract number: XXXXXXX Transformer type: 0 XXX 000 000 – 000

TESTING POWER TRANSFORMERS Test procedures and equipment used for the testing of large power transformers at Končar Power transformers are dealt with in the following Sections. The electricalcharacteristics and dielectric strength of the transformer are checked by means of measurements and tests defined by standards. The tests are carried out in accordance with IEC Standard 60076, Power transformers, unless otherwise specified in the contract documents.
CONTENTS

Item 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20.

Title Summary of dielectric testsMeasurement of voltage ratio and check of connection symbol Measurement of winding resistance Impedance and load loss measurement Measurement of no-load loss and current Induced overvoltage withstand test Partial discharge measurement Separate-source voltage test Operation tests on on-load tap-changer Measurement of the zero-sequence impedance Capacitance and the insulation power factor measurementInsulation resistance measurement Measurement of the electric strength of the insulating oil Temperature rise test Lightning impulse test Test with the lightning impulse chopped on the tail Switching impulse test Measurement of acoustic sound level Measurement of higher harmonics in magnetizing current Tightness (leakage) test

ID KPT-QTPT 001E KPT-QTPT 002E KPT-QTPT 003E KPT-QTPT 004E KPT-QTPT 005EKPT-QTPT 006E KPT-QTPT 007E KPT-QTPT 008E KPT-QTPT 009E KPT-QTPT 010E KPT-QTPT 011E KPT-QTPT 012E KPT-QTPT 013E KPT-QTPT 014E KPT-QTPT 015E KPT-QTPT 016E KPT-QTPT 017E KPT-QTPT 018E KPT-QTPT 019E KPT-QTPT 020E

issue 08.2003. issue 08.2003. issue 08.2003. issue 08.2003. issue 08.2003. issue 08.2003. issue 08.2003. issue 08.2003. issue 08.2003. issue 09.2003. issue 11.2004. issue 09.2003. issue08.2003. issue 11.2004. issue 08.2003. issue 09.2003. issue 09.2003. issue 09.2003. issue 08.2003. issue 09.2003.

Prepared by:

Approved by:

F. Juraković
Issue: 08.2003. 09.2003. 06.2004. 11.2004.

I. Šulc
03.2006. 07.2006.

KPT-QT.001E, izdanje 08.2003.

Končar PowerTransformers Ltd.

TEST METHODS FOR POWER TRANSFORMERS

QT No: xx-yy
Page : 2 / 2

Item 21. 22. 23. 24.

TitleFRA measurement Core insulation measurement Power consumption of cooling system Measurement of transferred surges

ID KPT-QTPT 021E KPT-QTPT 022E KPT-QTPT 023E KPT-QTPT 024E

issue 06.2004. issue 03.2006. issue 03.2006. issue 07.2006.

Issue :

08.2003.

09.2003.

06.2004.

11.2004.

03.2006.

07.2006.

KPT-QT.001E, izdanje 08.2003.

Končar PowerTransformers Ltd.

SUMMARYOF DIELECTRIC TESTS

KPT-QTPT 001E Page: 1 / 4

1.

SUMMARY OF DIELECTRIC TESTS

The Basic rules for insulation requirements and dielectric tests are summarized in table 1 (IEC 60076-3). Levels of standard withstand voltages, identified by highest voltage for equipment Um of winding are given in tables 2, 3 and 4. The choice between the different levels of standard withstand voltage inthese tables depends on the severity of over voltage conditions to be expected in the system and on the importance of the particular installation.

Tests Category of winding Highest voltage for equipment Um

kV
Uniform insulation Um≤72,5 72,5170 kV) a long duration induced voltage test including observation of partial discharges, should be specified as a routine test (see table 1 in KPT-QTPT001E). A three-phase transformer shall be tested preferably in a symmetrical three-phase connection (see Fig. 6-2a) or in some cases in a single-phase connection that gives voltages in the line terminals according to Fig.6-2b (successively applied to all three phases).

U
U U
U -0,5U -0,5U

G G a) b)

Fig. 6-2

A three-phase transformer supplied from the low-voltage winding side with a...