Large power transformer direct-current resistance fast testing method

Abstract

The invention discloses a large power transformer direct-current resistance fast testing method used for testing the direct-current resistance of a large power transformer. The magnetomotive force produced by transformer residual magnetism of a winding is utilized, the magnetomotive force is eliminated and utilized in a short-circuit manner, demagnetization is implemented rapidly and simply, the residual magnetism in the same direction with the next measurement is retained, and the charging time for testing the next winding is shortened; when the method is applied to a direct-current resistance testing assistant device, the direct-current resistance can be tested simply and rapidly, the testing time is shortened greatly, and the testing difficulty is lowered greatly.

Description

technical field [0001] The invention relates to a method for quickly testing the DC resistance of a large-scale power transformer, in particular to a method for testing the DC resistance with a fixed measurement sequence in a delta connection mode. Background technique [0002] With the continuous increase of the capacity of the national grid, more and more large-capacity power transformers are connected to the grid, and the parameter testing work before the on-site transformer is put into operation is becoming more and more heavy, especially for large-capacity power transmission and transformation above 500KV. The DC resistance parameter test of a large power transformer, because its low-voltage side is connected in a delta manner, the windings cannot be opened, and the test time for measuring the DC resistance with constant current charging is very long, ranging from tens of minutes to a long time. Therefore, people use the method of increasing the test current and the cap...

AI Technical Summary

Problems solved by technology

as follows figure 1 As shown, when ab(a+,b-) is measured and ac(a+,c-) is measured, due to the influence of remanence, the direction of the remanence generated in the c winding is opposite to the direction of the magnetic field that the c winding needs to be saturated during the ac measurement. At this time, it will take a long time to quickly apply the same test current in reverse and saturate the charge, and the test instrument is often unable to output quickly due to capacity limitations; also when the ac(a+,c-) measurement is completed, measure bc (b+, c-), the direction of the remanence generated by the b winding is opposite to the direction of the magnetic field that the b winding needs to saturate during the bc measurement. Although the measurement time is reduced compared with the traditional wiring method, it is still longer

Images