Improvement of Performance of PD Detector by Modification of Pi-Attenuator Circuit and Ultrawide Band Amplifier

This paper deals with the improvement of performance of partial discharge (PD) detector by modification of Pi-Attenuator circuit and ultra wide band amplifier of impedance matching circuit. PD occurrence is the early indicator of power apparatus insulation failure. The detection method of this early symptom toward failure is indispensable. PD cause an electrical current in the ultra wide band (UWB) frequency up to several GHz. In order to obtain overall spectrum of PD signal, the bandwidth of PD measurement system should be wider than the bandwidth of PD signal. One of the methods to measure PD signals in UWB is by using impedance matching circuit (IMC) as a coupling device in the PD measurement system. The IMC consists of attenuator circuit and UWB amplifier. The impedance of the IMC should be the same as the impedance characteristic of the coaxial and the internal cables of the oscilloscope to optimize the power transfer generated by PD current. The performance of PD detector is improved by modification of pi-attenuator and wide band amplifier of IMC. The circuit design is conducted by simulation model using Advanced Design System 2014 (ADS2014) software to identify the circuit characteristics by performing S-parameter simulation.