Trip Coil Signature Analysis and Interpretation for Distribution Circuit Breaker Condition Assessment and Diagnosis

A circuit breaker may be considered an ‘active link’, used to make and break an electrical circuit under conditions of varying severity. In the event of a circuit fault the circuit breaker must respond within tens of milliseconds in order to prevent damage to connected plant and safeguard personnel. As such, a circuit breaker will remain idle for the bulk of its lifetime, only being called into action periodically to interrupt load or fault current. This makes the circuit breaker one of the most safety critical, yet most unpredictable plant items on the power network. In addition, circuit breaker maloperations account for a significant proportion of Customer Minutes Lost (CMLs), Customer Interruptions (CIs), plant replacement costs and safety issues. Conflicting regulatory and economic pressures to improve the performance, reliability and longevity of these, and other major plant items while reducing maintenance costs have forced many utilities to reassess their asset management and maintenance strategies [1]. This has led to significant investment in novel condition monitoring technologies, which in turn precipitate the need for new methods of analysing and interpreting new forms and increasing volumes of plant data.