Field experience with an on-line gas monitoring device for oil filled instrument transformers

Electrical breakdown in the paper oil insulation systems of high voltage oil filled apparatus can cause severe damage to the apparatus as well as to the surrounding equipment. These failures also cause a loss of revenue from unexpected interruptions. These factors led to requests from electric utilities for additional safety measures to monitor the health of the insulation systems in high voltage oil filled instrument transformers. The direction of these measures was to develop a monitoring device to detect the presence of gassing, an indication of a breakdown in the insulation system and then provide an alarm before the apparatus actually failed. An online gas detector was developed and introduced. The experience gained over the past 35 years has shown that this solution is minimizing the damage and the high costs associated with these types of failures