Frequency Response of HV Test Transformers and the Associated Measurement Problems

This paper analyses the frequency response of HV test transformers. A single transformer or a cascade arrangement has been found to behave as a tuned filter with the peak frequencies between 150 Hz and 1 kHz well in the range of low-order harmonics. In consequence, the HV side presents distorted waveforms which cause more or less severe measurement errors, depending on the divider and the instrument used.