The evaluation of quality of transformer oil by measuring capacitance

Abstract

Transformer oil plays an important role to keep transformer active and operate efficiently. It keeps transformer cool and works as an insulator between transformer windings and body. Due to arcing, corona discharge, low-energy sparking, severe overloading, pump motor failure and overheating in the insulating system are some of the possible mechanisms of degradation of transformer oil. This problems can increase water content, decrease dielectric strength, increase acidity or neutralization number(NN), increase or decrease interfacial tension (IFT) out of a specific range(40 to 50 dyne/cm), decrease quality index system (QQIN), and rapid increase in the amount of combustible gases, which can decrease the transformer life time and quality of service to consumer. There are several methods to identify and solve this problem. If this problem go in severe condition, it is not possible to solve without replacing by new one. May be there are different methods to check this problem but no specific method to check without taking oil outside the transformer. These methods are very expensive and time consuming. That’s why; our objective is to identify this problems as well as transformer condition without taking the oil outside by measuring the capacitance of the transformer.