Why CB requires maintenance? On-line power circuit breaker monitors are widely used today by maintenance groups for real-time reporting of breaker operating conditions. These monitors provide an effective means to predict and prevent breaker misoperations and failures. With the availability of real-time data, scheduled maintenance procedures are giving way to cost-effective reactive maintenance plans to reduce maintenance costs and out-of-service time. The value of historic operating data goes beyond the immediate and obvious need to assess breaker reliability. Time-stamped breaker operating data provide valuable operations intelligence to enhance delivery reliability and improve power quality The advent of Online Circuit Breaker Condition Monitors has allowed Operations and Maintenance Engineers to apply reliability centered (RCM), predictive (PdM), and just-in-time (JIT)maintenance techniques to circuit breakers. These breaker condition monitors examine select breaker operating characteristics, which are used to alarm for JIT maintenance and provide trending data input to RCM and predictive maintenance programs. Symptoms of wear, possible failure, and failure that can be detected by on-line monitoring can be placed into four general categories

  • Contact Wear: Damage from excessive interrupting duty, which is cumulative. Catastrophic failures have occurred under this circumstance.
  • Dielectric Compromise: Contaminated oil, worn baffles, nozzle ablation, and other items that cause excessive arc duration. These situations cause a longer clearing time, which may gradually increase to infringement on the breaker failure time.
  • Mechanism Problems - Mechanical issues such as worn parts, “frozen” linkages, faulty latches, and pneumatic or hydraulic system malfunctions. These problems may either gradually develop (degradation), or suddenly develop from a component failure.
  • Control Circuit Failure - Shorted coils, open coils, open or shorted circuits. These problems may either develop suddenly, as in a short circuit from wire abrasion or open circuit from termination failure, or gradually, as in insulation breakdown in a coil leading to a short.