Condition monitoring of high voltage circuit breakers

The advances made in microprocessor-based measuring equipment can be used to good effect to determine the condition of a circuit breaker. In essence a very effective condition monitoring tool is represented by a number of products that are now commercially available. These have the inherent ability to measure, record and analyse important parameters such as contact stroke, travel (i.e. "speedcurves") as well as trip and close coil current wave forms. By capturing this data and further processing, important issues having bearing on maintenance and reliability can be effectively addressed. Up to now the measurement of main contact timing has simply been confirming that parameters are "within specification". Moreover this timing measurement is only repeated over a period of years which does not permit early warning of a developing problem. By repeating measurements more regularly (for instance coincident with "trip testing") and creating a data base for each circuit breaker the mechanical behaviour can be closely monitored. Since breaker performance is largely influenced by mechanical factors, a data base of key related parameters will have a dramatic effect upon pre-empting incidents and determining the corrective action to be taken. In the interest of creating and effectively managing such a data base it is therefore of paramount importance that the appropriate measurement equipment and allied systems be "state-of-the-art" and that the data recorded is sensible, reliable and easily accessible.