Electromagnetic Sensing of Partial Discharge in Air-insulated Medium Voltage Switchgear

The importance of detecting accurately the partial discharge in high voltage power industry becomes obvious as the infrastructure ages. In this work electromagnetic sensing for detecting the electromagnetic radiation, associated with partial discharge, in an air-insulated medium voltage switchgear (Type D24-121114 of Driescher) is used. The study relies on Finite Element Method as implemented in High Frequency Structure Simulator. The partial discharge is approximated by Gaussian source. Coaxial patch antenna is employed for electromagnetic sensing. This transducer is optimized to have highest efficiency in the frequency band of interest, for partial discharge detection, of 800 MHz to 900 MHz. The antenna is placed in the switchgear system and its ability to sense partial discharge in the air-insulated switchgear is addressed. The optimized location in the switchgear system of the antenna for an efficient sensing is presented. The current density induced in the electromagnetic sensors by the radiation emitted from the partial discharges is used as an indicator of efficient radiative coupling. As repetitive partial discharge leads to the failure of the air-insulated switchgear, this method provides a sensitive method for pre-fault detection.