ABSTRACT. Partial discharge (PD) phenomena often result in serious faults in insulation. They may lead to electrical breakdown and cause loss of revenue to repair and replace the damaged part of the electrical equipment due to lack of precise and early detection of PD occurrence. PD measurements are important diagnostic tools to monitor the insulation condition of a device. Filtration in a PD measuring system is essential to eliminate or reduce noise pulses from affecting the measurement value. The device that is widely used nowadays is a high pass filter (HPF). In this project, an alternative filter device is established and studied, which is an impedance matching circuit (IMC). The aim of this project is to build an IMC in a PD measuring system for filtration purposes. The IMC is then measured to observe its characteristics and performance as a filter device in a PD measuring system. By measuring the number of PD occurrences and magnitude of PD on an insulation sample, the outcomes of PD obtained in the measurement system of impedance matching circuit are compared with those in high pass filter. From the tests, it was observed that IMC shows a smaller number of false PD occurrences and higher individual PD magnitude of each occurrence compared to HPF. Thus, the PD can be observed clearly even at smaller supply voltages by using IMC and breakdown of insulation can be avoided.
KEYWORDS. Partial discharge (PD), Impedance matching circuit (IMC), High pass filter (HPF).
