Dissolved Gases Analysis of canola-based ester oil under creepage discharge

Abstract

The objective of this work is to investigate the Dissolved Gases Analysis (DGA) of canola-based ester oil under creepage discharge. DGA is a reliable diagnostic tool used in power transformers to detect incipient faults developing inside the transformer. The detection of incipient faults enables early scheduling of preventative maintenance and hence prevention of transformer damage. Recently, natural ester oils have been introduced to power transformers as an alternative oil. The application of natural ester oils in power transformers requires a guideline for the application of DGA in this type of oil. The creepage discharges are generated by applying 28 kV to a needle-plane configuration configured at an acute angle. The dissolved gases result reveal that similar gases are generated in the ester and mineral oil while the quantity of dissolved gases is high in the ester oil than the mineral oil. The key dissolved gas was found to be hydrogen. The Duval's triangle and the IEEE key gas diagnostic technique correctly identify the fault while the IEC 60599 fails to identify the fault. The IEC 60599 requires modifications for use in transformers filled with canola oil.