Testing capacity enhancement for Power Transformer at Manufacturer’s works Electrical Research & Development Association (ERDA) is a Not for Profit premiere testing laboratory providing testing solutions to the Indian Electrical Industry and Utilities. ERDA was established with the financial support of Council of Scientific and Industrial Research (CSIR), Government of India and the state Government of Gujarat. ERDA constantly strives to improve quality and reliability of equipment, materials and services for electrical industries, utilities and users of electricity. One of the biggest challenges faced by the Power Transmission companies (TRANSCOs) is the continuity and reliability of power supply. Transformers being the most important and critical component of T&D system, contribute significantly by playing the key role in the performance of grid. Hence, Transformers connected in Transmission and distribution system must have reliable and satisfactory operations. Operating temperature, losses or temperature rise of the transformers have a direct bearing of its life. Therefore, it is essential that transformers must be tested extensively before being put to service in the grid. Failure of a power transformer during operation or inefficient operation of the transformer will cause black out. Also the utility will have to incur the cost of replacing/repairing the transformer to provide services to its customer. Therefore, it is advisable to get power transformers tested by an NABL approved independent third party test agency. ERDA is NABL accredited to perform testing of power transformers at manufacturer locations by using dedicated test set ups. ERDA uses calibrated instruments for measurement at the manufacturer’s location. With the growing demand of the Utilities, ERDA has commenced providing onsite testing services for the Transformers. The major clientele includes MSETCL, UPPTCL, OPTCL, CSPTCL, AP Transco, MPPKVVCL, GETCO, UGVCL etc. The biggest leap with the new portable loss measurement system of ERDA is of stepping up our existing on-site testing scope from 100 MVA (220 kV) class to 500 MVA (400 kV) class. Details about maximum range of transformers that can be tested with this setup is mentioned below. Maximum Rating (MVA)
LV or tertiary winding
No-Load Loss
Load Loss
Temperature rise test
315 (400 kV class) – 3 Ø
Up to 66 kV
√
√
√
500 (400 kV class) – 3 Ø
Up to 66 kV
√
√
√
500 (765 kV class) – 1 Ø
Up to 66 kV
√
√
X
ERDA’s Portable Loss Measurement system
ERDA’s portable loss measurement system is an advanced measuring system that uses passive two stage compensated technology. The ||www.electricalmirror.net||
main advantage of a two stage compensated technology is that the effective burden is zero when feeding into another compensated CT. As a result the errors of the CT are effectively reduced to zero in both magnitude and phase. For voltage measurement three shielded gas filled (SF6) high voltage standard capacitors and three model voltage dividers are used for measuring the phase to ground voltage in each phase. It also uses two staged compensated current comparator to correct for both magnitude and phase errors with the divider. Following tests are possible to conduct at manufacturer works; Up to 500 MVA, 400 kV/66 kV Class, 3- Phase Power Transformers; - Measurement of Winding Resistance - Measurement of Turns Ration - Measurement of No Load Losses - Measurement of Load Losses and percentage impedance - Temperature rise test - Measurement of Zero-Sequence Impedance - Magnetic balance test - Induce Over Voltage Withstand Test - Separate Source Withstand voltage test
Up to 500 MVA, 765 kV/66 kV Class, Single - Phase Power Transformers; - - - - - - - - -
Measurement of Winding Resistance Measurement of Turns Ration Measurement of No Load Losses Measurement of Load Losses and percentage impedance Temperature rise test Measurement of Zero-Sequence Impedance Magnetic balance test Induce Over Voltage Withstand Test Separate Source Withstand voltage test EM || June 2021 ||
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