Application of Directional Couplers for Partial Discharge Measurement on HVDC GIS/GIL Test Setups

PD measurement at DC is one of the most challenging topics for HVDC GIS/GIL test setups. The metal-enclosed HVDC GIS/GIL under test are typically equipped with test bushings, which easily enable the testing with DC and impulse voltages. Based on the presence of test bushings the PD measurement is often influenced by external pulse shaped signals. The separation of PD and pulse shaped noise signals is difficult to perform, due to their similar characteristics in time and fre¬quency domain. Different methods for noise identification and rejection are known and under investigation for HVDC GIS/GIL test setups. The application of a directional coupler will be an easy, efficient and reliable method for the rejection of external pulse shape noise signals.