PD pattern of various defects measured by TEV sensor

Partial Discharge (PD) is one of symptom that occur due to defect on the high voltage insulation system. PD measurement is needed to monitor the condition of equipment and avoid the failure. This paper deals with PD measurement by using Transient Earth Voltage (TEV) sensor. Applying a given voltage around 2 to 6 kV to artificial defects placed in a metal box produces PD. PD occurring inside the metal box would emits electromagnetic (EM) wave in wide frequency that propagates and leaks to the outside exciting the surface current on the metal wall and then producing transient earth voltage (TEV) as a result of current and impedance of the material. TEV sensor is mounted on the surface of the metal box to detect TEV signal representing PD inside. Then, TEV signals can be measured by an oscilloscope to obtain partial discharge pattern. The results revealed that each defect has own characteristic that differs from each other. PD with larger magnitude generated higher of TEV signal. Based on experimental results, PD measurements using TEV sensors, can be further developed, not only for measuring PD magnitude, but also can obtain a phase resolved PD pattern. Therefore, it can be used to estimate the type of PD that occurs in the equipment.