Design of UHF-Overvoltage Sensor and Measurement Under Superimposed Voltage

Abstract-Insulation performance of epoxy surface in GIS systems is influenced by the applied superimposed voltage of AC and overvoltage. The simultaneous measurement of the partial discharges (PDs) and applied voltage can help to evaluate the condition of GIS equipment more accurately. A novel composite sensor for PD UHF signals and overvoltage measurement is proposed to realize the simultaneous detection. The effective height of the composite sensor is calculated with FDTD model and the preliminary optimization is carried based on it. The effectiveness of the composite sensor is tested on an epoxy surface discharge model under of AC voltage, lightning impulse and superimposed voltage. Experiment results show that the extra PDs are excited by the superimposed LI and the proposed sensor is capable to detect the voltage waveform and PD signals under the superimposed condition.