A Real Time Monitoring of Breakdown Voltage of Transformer Oil for Condition Based Maintenance

The most obligatory part of electricity distribution system is transformer. With the increasing number of transformers due to the growth of consumer load, the number of failures of transformer is also increasing day by day which not only create inconvenience to users by the interruption of power supply but also increases both the capital and revenue loss of the power distribution companies (DISCOMS). Among the failures a significant numbers are premature failures. In some countries this rate of failure is more than 10%, where the acceptable range of failure is less than 3%. This high failure rate is a huge concern to all DISCOMS since they spent millions of dollars on repairing and replacement of distribution transformers. These premature failures also increase the value of system average interruption frequency index and system average interruption duration index. It is proven that most of the premature failures are insulation failures which can be reduced by using a real time monitoring system. In this paper, a new prototype was implemented to monitor the condition of transformer oil which will help the condition-based maintenance (CBM). Firstly, a prototype has been developed to record water content and relative humidity present in a live transformer. Whereas in the second phase, investigation was conducted on different transformers to witness the state of transformer oil and compare the resultant data with breakdown voltage of transformer oil of respective transformer.