Study of partial discharge charge evaluation and the associated uncertainty by means of high frequency current transformers

High frequency current transformers (HFCT) are widely used in partial discharge field and laboratory tests. Using these devices as sensors in partial discharge cable tests brings some advantages, namely: high degree of insulation, relatively good sensibility and the possibility of broadband measures. This paper analyzes the fundamentals of HFCTs measurements from the point of view of charge evaluation. Three different procedures for charge evaluation and the associated uncertainty are presented for partial discharge measurements in cables by means of HFCTs. Experimental and simulation data are presented and the associated uncertainty is calculated.