Research on the effect of different connection test methods on frequency response of transformer windings

In order to comprehend the influence of different test methods on winding frequency response. A three-phase power transformer is taken as the test object, and the characteristics of winding frequency response under the proposed test methods in the existing standards are compared and analyzed through experiments. The following conclusions are drawn for the test transformer: During the test process, whether the untested winding ports are shorted will result in obvious deviation on the frequency response of the test winding, and different test methods affect different frequency bands. The frequency response curves of the test winding in the frequency range below 100 kHz and in the frequency range around 1 MHz are obviously affected by whether the untested winding ports are shorted. Injection port has obvious influence on inter-winding frequency response measurement. For this transformer, the major change will appear above 100 kHz. This method has certain superiority for fault diagnosis, such as the diagnosis for radial deformation and the judgment of faulty windings.