Evidence of Partial Discharges in the Dielectric Liquid using Electro-Optic Probes

The conventional electrical method of partial discharge (PD) measurement is widely used by several utilities for assessing the quality of insulators. However, its implementation is often limited in the presence of excessive electromagnetic interferences. To overcome this problem, different research teams have been experimenting and investigating alternative PD detectors that are immune to electromagnetic interferences. This paper outlines one such method and presents partial discharge detection using an electro-optic (EO) probe. The work presented here makes use of a needle-barrier plane-configured device under test, filled with a dielectric liquid. The results thus obtained from the electro-optic probe are compared with those obtained from the conventional electrical method. The detection of PD events is found to be reproducible with the EO probe. The phase-resolved partial discharge (PRPD) pattern and the mean partial discharge inception voltage (PDIV) obtained from the EO probe are found to be comparable to those obtained from the electrical method. Also, the PD waveforms acquired from the EO probe are analyzed and have been discussed in this paper. The results show that the electro-optic probe can be a promising alternative for PD detection for a dielectric liquid under a high divergent electric field, without altering the high voltage set-up.