TPL-001-5.1 Spare Equipment Strategy

Transmission planning and modeling was identified as an area of focus in the 2026 ERO Enterprise Compliance Monitoring and Enforcement Program Implementation Plan (CMEP IP). Specifically, this focus pertains to large load integration, ensuring adequate transmission planning and modeling, and proper use of data mining and modeling data.

As the grid continues to evolve, the Electric Reliability Organization (ERO) Enterprise is modifying its resource adequacy studies to capture a broader range of System conditions. As part of TPL-001-5.1, Requirement 2 brings attention to entities’ spare equipment strategy. The Requirement states that when an entity’s spare equipment strategy could result in the unavailability of major transmission equipment that has a lead time of one year or more (such as a transformer), the impact of this possible unavailability on System performance shall be assessed. This analysis shall simulate the conditions that the System is expected to experience during the possible unavailability of the long lead time equipment.

A best practice is to document the criteria and methodology used to define major transmission equipment. This documentation must include the specific rationale for what is included or excluded. When documenting a spare equipment strategy, delineating roles and responsibilities will help ensure that the strategy is followed. Consider identifying personnel responsible for the following:

• Maintaining and communicating equipment inventory
• Tracking lead times
• Submitting requests
• Granting approvals

It is important to note that these responsibilities may vary depending on size and location of an entity. Larger entities may have site-specific roles and responsibilities, covering one or more substations. Regardless, entities should consider putting systems in place to track these reoccurring actions that need to be taken.

Entities should consider implementing internal controls focused on best practices such as:

• Conducting regular inspections and maintenance of major transmission equipment
  • Opportunity for a proactive approach
  • For in-use and spare equipment
  • May extend the useful life of equipment
• Utilizing tools intended to prompt
  • The backfilling of equipment
  • When equipment is due for inspection and maintenance

Regular field inspections may extend the useful life of in-use equipment, plus having a pulse on the overall health of the equipment may result in fewer in-service failures. Tracking the equipment’s age and health status may also help determine the periodicity of field inspection and maintenance needs.

When entities have major Transmission equipment that, according to their spare equipment strategy, has a lead time of one year or more, the impact of this must be accounted for in the entity’s annual Planning Assessment. Implementing an internal controls framework within the entity’s spare equipment strategy may help ensure that entities adequately follow their processes to achieve a more reliable Bulk Electric System.