Design of Loop Antenna as Partial Discharge Sensor on Metal-Enclosed Power Apparatus

This paper discusses the development of loop antenna as a partial discharge (PD) sensor in power apparatus. The loop antenna detects electromagnetic waves emitted by PD. The advantage of using this method is that the PD measurements can be done without turning off the test object (on-line testing). PD testing is carried out with several loop antennas. The number of loop antenna turns is varied to determine the optimal loop antenna design for PD detection and measurement. The design of loop antenna for PD measurement is in the frequency range up to 100 MHz. The design of loop antenna is made in the form of circle with diameter of 9.55 cm. Each loop antenna has 4, 7, 10, and 30 turns. The loop antennas testing by vector network analyzer shows that the number of turns of the loop antennas affects the characteristics of antenna parameters such as return loss, bandwidth, and VSWR. The PD measurements result show that low bandwidth leads to low amount of PD measured. The use of metal box reduces the sensitivity of the loop antenna at a fixed distance. The optimum design of loop antenna has 10 windings.