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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® and conducting insulating oil analysis 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 and 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® insulating oil analysis, 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 breaker maintenance program currently being used to perform insulating oil testing and analyze the oil. 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. Breaker maintenance would be reduced by forty percent by using the Breaker Oil Analysis.
After performing a BOA® test on your breaker, you will receive a condition rating. The recommended sampling interval ranges from ‘immediately’ to ‘annually’, depending on the condition of your unit. Please refer to the scoring methodology or reach out to TJH2b for further explanation on recommended intervals.
BOA™ condition codes, in general, indicate the following+:
+Some variations of the recommended mitigations or retest intervals may occur at the discretion of the laboratory based on information provided. With breakers, we are dealing with a complex subject involving a number of variables. As such, general “rules of thumb” with regard to sampling intervals cannot be applied in every case. A number of other factors must be taken into consideration, such as:
As such, the appropriate action is up to the discretion of the Asset Manager who is best placed to take other influencing factors into account according to established internal procedures. Our codes and recommendations, while based on a vast amount of experience as well as guidelines published by IEEE and other standards bodies, are to be taken only as useful guides.
Breaker Oil Analysis (BOA®) includes a condition rating, diagnostics, and potential remediation actions where applicable. Upon receipt of the report from TJH2b, we recommend that results and diagnostics are reviewed promptly, following internal procedures. If further support is needed, TJH2b offers free, 24/7 consultation services to help you understand reports and provide guidance.
TJH2b recommends following the latest revision of ASTM D923 (Standard Practices for Sampling Electrical Insulating Liquids) or an equivalent standard in order to ensure consistent, high-quality sampling practices. TJH2b has developed a tool to help you meet the standard and take a proper, representative sample every time: Turbulent Flush Sampling System.
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