Abstract In this paper, the long-time-no-load test and 100%-total-loss-load test are carried out on a extra high voltage (EHV) converter transformer, which is put into operation for 12 years and is defective. And the test principle, equipment parameters, and on-site implementation are investigated. The measurement result of long-time-no-load is less than 1.3% compared with the factory value, which shows there is no obvious defect in the transformer core. During the 100%-total-loss-load test, the local temperature rise is found abnormally (the local temperature reaches 92.2℃). The reason for the hot spot is that the performance of the top box edge bolt insulation cover is weakened, and overheating is caused by magnetic flux leakage. The installation of a drainage line is used to reduce eddy current loss. After the treatment, 12-hour 100%-total-loss-load test is conducted again. The temperature at the same location is reduced to 49.7℃, and the hot spot defect is obviously eliminated.
Pan Zhicheng,Deng Jun,Lu Chunyu等. The engineering application of on-site long-time-no-load test and 100%-total-loss-load test of extra high voltage converter transformer[J]. Electrical Engineering, 2020, 21(3): 125-129.
2020, Vol. 21 
