Patent ID: 8098072

Claim:
A partial discharge coupler for detecting partial discharges in a conductor carrying a high voltage alternating current signal, the partial discharge coupler comprising: a frequency dependent network having a first filter component, a fuse component and a load component, wherein: the first filter component is configured to filter the high voltage, low frequency alternating current signal carried by the conductor from the load component and to pass high frequency partial discharge pulse signals to the load component when the partial discharge coupler is installed between the conductor and a first ground; the fuse component is configured to provide overload protection to the partial discharge coupler if a signal through the fuse component exceeds a predetermined fuse condition; the load component defines a first node and a second node, the first node connected to the remainder of the network and the second node coupled to the first ground when the frequency dependent network is installed between the conductor and the first ground; a differential amplifier having a first differential input, a second differential input and an output, wherein: the second differential input of the differential amplifier is coupled to the second node of the load component, and the output of the differential amplifier is configured to provide an output that is isolated from the first ground connection for communicating detected partial discharge signals to partial discharge test equipment; and a frequency selective coupling component that is coupled in series between the first differential input of the differential amplifier and the first node of the load component configured to pass high frequency partial discharge signals to the differential amplifier, and to filter low frequency alternating current signals from the differential amplifier.