There are various ways in gas insulated switchgear(GIS) partial discharge detection each with advantages and disadvantages,but the joint testing method to choose several detecting ways can improve the accuracy of the partial discharge(PD) detection.The joint testing method adapted by SMEPC is described.Joint test method extractes information on UHF signals,ultrasound signals or high-frequency current signals,improves PD location accuracy and defect recognition accuracy.An instance of the joint testing metho...