Analysis of Partial Discharge Characteristics of Olive and Castor Oil as Dielectric Medium for HV Applications

Abstract

Mineral oils are preferred liquid insulating medium for high voltage power apparatus applications for a long period. However, the search for alternate insulating oil comes in mind of researchers because the mineral oil is non-biodegradable, toxic in nature and non-renewable. Recent times, many research works are being carried out to replace mineral oil with suitable vegetable oil. Partial discharge characteristics play a vital role in determining the long term electrical insulation strength of liquid dielectric medium. However, reports on partial discharge characteristics of vegetable oils, such as extra virgin olive oil and castor oil are scanty. To confirm the suitability of extra virgin olive oil and castor oil as a high voltage insulating medium, it is important to carry out in-depth analysis about their partial discharge activity and characteristics. In this paper, partial discharge tests were performed on extra virgin olive oil and castor oil at different electrode configurations as per IEC test procedures. Partial discharges such as corona discharge and surface discharge activities were simulated in the laboratory experimental setup and the results were compared with the conventionally used mineral oil. Partial discharge inception voltage and phase resolved partial discharge (PRPD) pattern of olive oil and castor oil were evaluated and compared with the mineral oil. Time/frequency map and repetition rate analysis of PD signals were performed. PD source identification was carried out using fuzzy inference engine. Results show that olive oil and castor oil has better PD characteristics than mineral oil and it could be used as an alternate for mineral oils for high voltage insulation applications.