![]() ![]() There were no design tools available to analyze and check the impulse stress at various parts of the winding. Digital recorders came in the late 1980s. So impulse testing was a laborious process. To analyze recordings, one had to wait till the films were chemically washed in a dark room attached to the test lab. The oscillographs of applied voltage and neutral current were filmed using high-speed cameras. Impulse test shall not be done on any of the units involved in this order.” Customer did not want impulse test to spoil his transformer, but did not mind it done on some other’s transformer! The fear of impulse test was so much that there was no question of repeating the test on a unit already impulse tested.ĭetection of minor failures (inter disc or inter turn) during the impulse testing was very difficult. ![]() Those days, there was a clause in some of the transformer specifications - “Manufacturer shall submit a type test report of the impulse test conducted on a similar transformer supplied by him earlier. ![]() Very few manufacturers had the facilities to conduct the test in-house. A) Impulse testing of transformers involves applying short duration voltage surges ( in micro seconds) to windings to make sure transformer will withstand travelling wave surges from transmission lines during thunder storm and lightning. Half a century back, impulse testing was a type test for transformers, done on the first unit of the order only. ![]()
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