Harmonic response tests on distribution circuit potential transformers

Experimental data are presented that show the performances of distribution circuit potential transformers operating with nonsinusoidal waveforms. Four standard magnetic voltage transformers designed for 60 Hz power applications and rated from 7.2 kV to 20 kV were tested. Ratio correction factor and phase angle measurements were conducted at rated 60 Hz voltage with harmonic distortion levels at and below 8%. Test results indicate that potential transformers rated up to 20 kV experience errors of less than 5% at harmonic frequencies up to 3500 Hz when operating into typical induction watthour meter burdens. The phase angle response is essentially linear over the frequency range used to test the transformers, with a typical phase angle of about -10° at frequencies of approximately 3 to 3.5 kHz