Consolidated Edison has put into practice the use of a circuit breaker maintenance ranking tool developed by the Electric Power Research Institute for its circuit breaker maintenance program. The tool uses algorithms that combine standard operating and maintenance information with breaker application and design data to provide information on a periodic basis about the equipment’s expected condition and its need for maintenance.
Con Edison has estimated the cost savings from this initiative to be about $3 million dollars per year. These cost savings were realized in 2009 and are expected to continue annually due to the extended time intervals between major maintenance inspections for the circuit breakers. Equipment reliability is expected to be maintained since the tool directs maintenance toward equipment most likely in need of maintenance. It also minimizes unnecessary maintenance inspections that were of little benefit to improving the condition of the equipment.
The EPRI-developed algorithms give a measure of a breaker’s relative condition as well as a measure of the relative applicability of specific maintenance actions. The condition measure helps categorize a breaker population for general maintenance considerations and for asset health and condition analysis. The applicability measure helps to trigger specific maintenance actions, such as diagnostic testing, reducing the reliance on time-based maintenance approaches.
With this tool, utilities can achieve the benefits of a condition-based circuit breaker maintenance program without additional costs by using data that has already been collected for other purposes. Thirteen utilities are participating in the research project and versions of the tool have been applied at several locations with success.
“The estimated cost savings we have realized from this process validated our pursuit of this approach,” said Matt Walther, asset management manager for Con Edison Substation Operations. “Using the data from the maintenance tool helps us to be more precise in the circuit breakers we choose to perform maintenance on. It really enables our team to focus limited resources on the right equipment thus improving productivity.”
Past Maintenance Processes Less Analytic
Typically, circuit breaker maintenance plans have been based on scheduled time intervals and have less to do with the particular breaker’s actual condition. This philosophy was adopted due to the limited amount of information that could be acquired regarding the condition of a circuit breaker. This approach served the industry well, but current concerns, including an aging infrastructure, limited maintenance resources, and increased demand for service reliability, have prompted maintenance and asset managers to investigate other approaches to circuit breaker maintenance decisions.
EPRI has been developing the required algorithms for the maintenance tool for a number of years. As it has evolved, variations of the tool have been demonstrated at several utilities with success. Those early maintenance programs have resulted in savings, reduced reliance on time-directed maintenance, achieved the benefits of a condition-based maintenance program and resulted in more effective allocation of maintenance resources. The tool has also helped create a consistent, documented methodology for maintenance decisions.
“This tool helps to convert data into useful information that can drive meaningful actions and hence enable risk based decisions” stated Bhavin Desai, senior project manager for EPRI’s Substation Program.
The EPRI tool allows the user to gather all of the information of the circuit breaker fleet from various sources (Historian and Computerized Maintenance Management System) and have them at the users’ finger tips. Since the tool is spreadsheet-based, the user can sort and group the breakers in various ways. This allows sorting by breaker type or voltage class, specific breaker model, etc. It enables the user to see trends and helps in the identification of specific problems within the breaker fleet.
Most utilities are being challenged to reduce operating costs without adversely affecting service levels. Utilities need to maintain their equipment in a reliable and safe manner with the capability to deliver desired levels of performance cost effectively. Taking an asset management approach can help them to be even more effective in managing their systems.
As this tool continues to evolve, it can help utilities be more precise in their predictions and lead them to establish maintenance programs that are effective and use minimal resources, compared to traditional maintenance approaches.
