Condition Based Maintenance
Preventive maintenance activities for circuit breakers have historically been performed on a periodic basis. This is common for some low voltage circuit breakers. However, for medium and high voltage circuit breakers, a condition based maintenance program may be warranted. The main purpose of the overhauls of circuit breakers is to replace worn components. Through condition based maintenance, it may be possible to delay an overhaul to when it is necessary.
Normally, a circuit breaker overhaul is required when a specified number of operations, full load fault interruptions, or a recommended time interval has passed. The time interval may be recommended by either FIST 4-1B or the manufacturer’s O&M manual. A manufacturer’s requirement to perform maintenance based on time and number of operations is based on an expected lifespan of the breaker seals and other consumable components. Using this method will often result in maintenance being performed long before the breaker components are in need of replacement.
Ideally, Reclamation should be using condition based maintenance practices to determine when an overhaul, or at least an inspection, is required. Therefore, an overhaul is performed when the components of the breaker are actually worn and prior to a breaker failure.
A typical condition based maintenance program uses diagnostic testing to estimate the condition of the circuit breaker. By analyzing the results of the diagnostic tests and comparing the results over time, trends can be found and decisions made that may trigger specific maintenance procedures. These decisions are not based on any one diagnostic test. It could take several different tests to verify the decision to perform the maintenance.
