94. Circuit Breaker Condition Monitoring for Substations

A circuit breaker (CB) is one of the most commonly used primary electrical apparatus in today's complex and largely networked power systems. The basic function of the breaker is to disconnect the faulty part from the rest of the system. Presently, periodic maintenance is carried out as per the maintenance plan of the utility or industry. This could be based on the number of operations or on a period interval and is independent of the magnitude of current handled by the breaker. With introduction of intelligent devices like IEDs and intelligent switchgear it is possible to continuously monitor different parameters of the circuit breaker. The electrical and mechanical wear of the breaker can be monitored and when the parameters exceed the threshold limits specified, corrective measures could be initiated. Alarms can be initiated to indicate when CB maintenance is needed, specifically when monitored values are not in line with the set values. This paper proposes a circuit breaker monitoring functionality integrated with the protection and control IEDs deployed in a substation environment. Circuit breaker wear can be estimated based on the parameters available to the IED. This paper also discusses limitations of such functionality and the methods used to arrive at reasonable estimates of wear. Product features are presented in the context of a generic HV/EHV three phase circuit breaker. However, the methods can be extended further to any type of circuit breaker currently used in the field. A general guideline for parameterization of this functionality is also presented along with a discussion on the suitable IEC 61850 logical nodes.