A partial discharge coupler for detecting partial discharges in a conductor includes a frequency dependent network, a differential amplifier and a frequency selective coupling component. The frequency dependent network includes a first filter component, a fuse component and a load component, typically coupled together in series with reference to a first ground. The first filter component filters the high voltage, low frequency alternating current signal carried by the conductor from the load component and passes high frequency partial discharge pulse signals to the load component. The frequency selective coupling component couples in series between the differential amplifier and the load component. The output of the differential amplifier is configured to provide an output that is isolated from the ground connection for communicating detected partial discharge signals to partial discharge test equipment.