Saturation of High-Frequency Current Transformers: Challenges and Solutions

When using high-frequency current transformers (HFCT) to measure partial discharges (PD) on power cables, core saturation caused by the 50 Hz operating of cable is a major problem. Saturation leads nonlinearity in transfer function HFCT sensor and significantly reduces its sensitivity PD signals. To avoid magnetic ensure linear operation thus maximum sensitivity, split ferrite can be used. However, finding right air gap length between two halves complicated task, as optimal depends several parameters should neither too small nor large. This article deals with problem detail presents solutions for determining cores. We present numerous measurements exemplary split-core HFCTs from three different materials. Based obtained data, we then derive mathematical functions describing these functions, validate an model. Using model, any material calculated few simple equations, speeding up design process. In this way, model improves computer-aided HFCTs. With length, does not saturate maximized. Our results show that online monitoring mainly amplitude changes load cable. Therefore, conventional constant practical. Instead, want develop improved active control future.