A novel ring-shaped fractal antenna for partial discharge detection

This paper presents the development and application of a novel ring-shaped hybrid fractal antenna to the detection of partial discharge in inverter-fed low voltage drives. Partial discharge is known both as the source and indication of degradation in the winding insulation that is subjected to repetitive impulse voltage with short rise-time (high dv/dt) from PWM-controlled inverters. The partial discharge causes erosion of insulation thin magnet wire which results in premature failure and affects the reliability of low voltage electrical machines. The hybrid fractal antenna presented in this paper exhibits a wide bandwidth which covers the frequency spectrum (∼0.3−3GHz)and features a ring-shape geometry which enables it to be embedded within the a machine end-winding and have ideal directivity in all direction across the cross-section.