It has been a longstanding, standard practice for maintenance personnel to perform fluid quality tests such as dielectric breakdown voltage to confirm an acceptable fluid condition when returning or placing oil-filled circuit breakers into service. Some utilities have also used these screening tests to continue monitoring fluid condition of in-service Oil-filled circuit breakers (OCB’s). Further assessment of in-tank condition required removing the OCB from service for internal inspections. Contact resistance measurements, and other intrusive maintenance activity.
In 1996, TJ|H2b began to search for a diagnostic marker for the detection of a particular failure mode in one type of OCB. The outgrowth of that effort was the development of the world’s first fluid-based OCB condition assessment tool, Breaker Oil Analysis (BOA®). By the beginning of 1998, BOA® had been successfully applied to thousands of transmission and distribution breakers as well as to oil-filled switches. The cost benefits from using BOA® are primarily achieved through the reduction of unnecessary maintenance activities.
Using traditional ASTM methodology and particle profiling, condition codes are generated by evaluating the relationships among the test data. BOA® provides information about coke formation, contact deterioration, fluid degradation, and interrupter deterioration (baffles, arc chutes housing, etc.). Application of this diagnostic tool allows maintenance personnel to depart from traditional time-based maintenance practices by monitoring the condition of units to determine when maintenance becomes necessary. BOA® also provides a guide for the maintenance practices by monitoring the condition of units to determine when maintenance becomes necessary. BOA® also provides a guide for the maintenance to be performed by indicating when components reach the end of their useful life or when abnormal conditions threaten the life or operation of the circuit breaker.
BOA® has been extensively field-tested and has proven to enhance equipment reliability. No false negatives have occurred with the BOA® service, which means that no tanks that have been assessed have been found to be in a poorer condition than indicated. Conversely, false positives are not a concern because BOA® has been designed to address the residual contamination of tanks from prior maintenance activities. This can occur when the used oil is replaced in the unit after repairs are made or when the unit is insufficiently cleaned and flushed after maintenance.
Maintenance costs may be reduced by as much as ninety-two percent (92%) depending on the type of maintenance program currently being used. As an example, compare a six-year fixed-interval maintenance program to a condition-based program that results in an average maintenance interval of ten years. In this example, the annual average condition-based maintenance would be sixty percent of the maintenance performed using the fixed interval approach. Maintenance would be reduced by forty percent.