Fundamentals of HV circuit breakers (applications, failure analysis and maintenance)

Research Objectives

Due to the deregulation of electricity markets, reliability, stability and availability of power systems must be improved in order to increase the competitiveness of electricity markets. In order to improve such aspects, power systems should be operated with minimal abnormal conditions and those conditions must be cleared as soon as possible.

Therefore, high voltage circuit breakers, designed to interrupt faulted conditions, have played an important role in power systems over 100 years since the first introduction of oil circuit breakers.

The maintenance programs of HV circuit breakers have been long performed by using the manufacture guidelines and experiences of operators. They have hardly been proved that they are really effective in terms of performance and costs.

With emerge of deregulation electricity markets, maintenance costs considered as the large part of operation costs of utilities should be reduced in order to keep competitiveness of utilities.

The failure database collected from utilities is deeply investigated to establish the probabilistic models. These models can represent the probability of failures and how the failures are developed during the lifetime of HV circuit breakers.

For instance, the treeing model of failures shows the distribution of failures from the first to the following failures in any subsequent years. The cascading reliability model is an extension of treeing model to investigate the reliability of HV circuit breakers after consecutive failures.

In addition, the application of the Markov model can represent how the components of HV circuit breakers fail.

The result of the investigation represents the severity ranking of failures, which is important for the asset managers to make decisions as to which failures must be intensively taken into account. The consequence of this analysis results in risk assessment of HV circuit breakers which can be used to design the asset management.

Other objectives of this work dealing with asset management are cost structure analysis and maintenance optimization. Cost structure analysis is able to breakdown the costs of HV circuit breakers with regard to the specifications and the components.

Consequently, it enables manufacturers to design the optimal HV circuit breakers based on this cost analysis.

The “when and how” to perform maintenance tasks of HV circuit breakers to increase the reliability are of interest and are included in maintenance optimization.