Maintenance Work Order Classification
The preceding examples used only the count of corrective maintenance work orders. Additional insights can be gained from understanding the specific maintenance done under each work order. Classification of corrective maintenance work orders into meaningful categories serves to more precisely associate breakers to the maintenance they have required. The EPRI maintenance template includes breaker work order classifications in four high-level categories as shown in Figure 2-4.
- “Gas Calls” include work addressing gas containment subsystems
- “Mechanism” covers work addressing mechanism components
- “Others” encompasses all other work orders addressing circuit breaker functional failures
- “CM Not Specified” denotes work orders with not enough information to classify
Extracting useful information from the work order descriptions and assigning them into meaningful bins is time and labor-intensive. EPRI is evaluating the use of Natural Language Processing as a means to make the process more efficient. See Applying Advanced Analytics to Improve Substation Asset Management and Maintenance: Assessing and Applying Natural Language Processing To Analyze Unstructured Text Records. EPRI, Palo Alto, CA: 2021.3002021202.
The effort put into classifying work orders yields potentially valuable insights into breaker maintenance.
For example, Figure 2-5 provides a breakdown of all corrective maintenance work orders over a ten-year period for eight utilities’ fleets of SF6 breakers. One observes that Gas Calls constitute 40-55% of the CM work orders for most of the utilities represented, that is, almost half of the corrective maintenance was for adding gas or fixing gas leaks.
Another observation is that for Utility B, Not Specified accounts for about 25% of maintenance records. This is because a number of work order descriptions were blank or lacked sufficient information to put into a classification for this utility.
In addition, Utility J’s Gas Call percentage is significantly lower than for the other utilities. It’s possible that Utility J is very effective in containing gas leaks, but may also be experiencing a high percentage of other maintenance issues in the Other CM category. This indicates that further exploration is needed to understand what is driving the Utility J results.
All these observations are potentially useful insights and also point to avenues for further investigation.