Correction of power transformer no-load losses, measured under nonsinusoidal voltage waveforms

Abstract

A method to calculate the iron losses in power transformers with highly distorted supply voltages is introduced. The appearance of small loops inside the main hysteresis loop is analysed and a method is proposed that takes into account the relative height of the small loops, as well as the position of the small loops inside the main loop. The percentage of hysteresis and eddy current losses in the total no-load loss is evaluated. Results obtained by means of different methods of calculation are compared to the 50/50 criterion. This method is proposed for correcting the no-load losses measured in transformer tests when the applied voltage is highly distorted. An experiment corroborates the corrective method proposed