Primary Differential Pulse Method for Partial-Discharge Detection of Oil-Immersed Inverted Current Transformers

This paper proposes the primary differential pulse method (PDPM) for the live partial-discharge (PD) detection of oil-immersed inverted current transformers. The PDPM is based on the differential current measurements that are taken at the high-voltage side of the current transformer under test. The proposed technique overcomes the problem of an internally grounded test tap and identifies the internal PD based on the polarities of current pulses. The PDPMdetection system is composed of current sensors, a data-acquisition module, a fiber-optics-based data-transmission module, and an operation mechanism with an insulating rod. The testing results prove that the designed system is effective for the live PD detection and can also effectively differentiate between PD and outside interference for oil-immersed inverted current transformers.