The PD Detector is an online partial discharge spot tester for HV assets. The instrument detects TEV signals generated by internal discharge in Air Insulated Switchgear (AIS), acoustic discharge generated by surface tracking or corona, high-frequency signal generated by cable partial discharge, and ultra-high frequency signal generated by internal discharge in Gas Insulated Switchgear (GIS). A mobile device receives data directly from the instrument for display and synchronization with a central server.