Online monitors keep transformers in service

The trend toward a deregulated global electricity market is raising utility cost consciousness. An important aspect of cost savings is equipment investment for the power transmission system, and power transformers are among the most expensive elements of a high voltage power system. Cost savings can be realized through a delay in the procurement of transformers and a reduction in maintenance effort. Monitoring systems for power transformers can help to achieve these aims. They provide detailed information about the transformer's condition and help minimize the probability of an unexpected outage. Monitoring systems open the possibility for extending the operating time of power transformers, reduce the risk of expensive failures, and provide potential in changing the maintenance strategy. Online monitoring methods including temperature measurement, gas-in-oil analysis and partial discharge measurement are discussed. New concepts in on-line monitoring including sensors, hardware and software are also discussed.