Quantitative Analysis of Rogowski CT Frequency Characteristics

Abstract

Partial discharges in power cables will generate small currents with low frequencies in the ground cords. In cable PD online monitoring systems, CTs are usually used to obtain such PD signals. In this paper, by derivations based on theories of wave propagation, the frequency characteristics of Rogowski CTs (RCTs) and the effects of transformer parameters (size, core material, etc.) on its pass band B, sensitivity H(jω0), the lower cutoff frequency fL is acquired. The feasibility of such derivations is verified by experiments. By conducting comparative experiments, the effect of the use of screening box and the way of coil winding on the performance of a current transformer is acquired. A feasible plan to improve the frequency characteristics of CTs is presented, in order to acquire more stable gain and better anti-interference ability within their pass band.