Challenges Associated with Implementation of HFCTs for Partial Discharge Measurements

The stochastic nature of partial discharge (PD) and the inability to directly detect charge displacement makes representative measurement of such events very challenging. High frequency current transformers (HFCTs) have been favored among sensors due to their non-invasiveness and wide bandwidth. Although simple in design, HFCTs for PD measurements need careful consideration to ensure suitability for their intended environment and task. Traditional phase resolved partial discharge analysis (PRPDA) does not impose strenuous requirements for measurements systems as pertinent analysis can be extracted from peak magnitude and power frequency phase information. However, detailed assessment examining waveform parameters from individual discharge pulses (such as DC PD) requires higher bandwidth, sensitivity, and noise suppression, as well as a clear understanding of the measurements system's influence on observed phenomena.