助磁法接线方式对变压器直阻测试的影响

The Wiring Mode's Influence on DC Resistance Testing of Transformer Based on Magnetic Circuit Method

为了缩短直流电阻测试时间,在测试大型变压器低压绕组时常用到"助磁法"。文中分析了采用助磁法时不同接线方式对铁心剩磁的影响,选择了一种比较理想的接线方式。该接线方式优化了测试时施加的充电电流和电压激励方向,使铁心中的磁通方向与测试某相绕组后铁心中的剩磁方向尽可能一致,合理利用铁心中的剩磁对被试绕组的测试进行"助磁",采用该接线方式测试低压绕组时铁心中总磁通变化绝对值最小。以某500 k V变电站主变为例,对其低压绕组直流电阻进行测试,将所有接线方式的测试结果进行对比,结果证明了所选接线方式可以一定程度上缩短测试时间,提高工作效率。

In order to shorten the testing time of DC resistance,the magnetic circuit method is usually used in the test of lowvoltage winding DC resistance of large transformer. The influence on remaining magnetic in the core of different wiring modebased on magnetic circuit method is analysed,and a more ideal wiring model is selected. The wiring model optimizes thedirection of charging current and voltage excitation during the test,so as to make the magnetic flux direction in the core asconsistent as possible with the remaining magnetic after testing onephase winding,and make reasonable use of the remainingmagnetic in the core to assist magnetic to the trial windings. A 500 kV transformer substation′s main transformer is used as anexample to compare the test results of all wiring modes,the results prove that the selected wiring method can shorten the testingtime to a certain extent,and improve the working efficiency.