Authors: Daniel Cooper, P.E., Alan Robbins and Debra Roby

Entities that are included on the NERC Compliance Registry as either a Generator Owner (GO) or Transmission Owner (TO) should be preparing for changes in the NERC Reliability standards FAC-008 and FAC-009. The changes will require at least some modifications to the registered entity's FAC-008 (Facility Ratings Methodology) documents.

Effective as of January 1, 2013, the present FAC-008-1 and FAC-009-1 Standards will be replaced by a much more detailed FAC-008-3 Standard. The new FAC-008-3 Standard will also include the requirement to share ratings with other interconnected or affected parties. All registered GOs and TOs will need to revise their facility ratings documents to comply with FAC-008-3 by January 1, 2013. To the extent a registered entity's equipment rating procedures are not compliant with the revised FAC-008-3 Standard, those procedures will need to be revised and new equipment ratings derived and communicated to other entities prior to January 1, 2013.

The changes were driven by at least three factors:

(1) A recognition that the FAC-008-1 Standard and the FAC-009-1 Standard could result in two separate but similar compliance documents;

(2) The need to allow for separate rating methodology requirements for generator facilities and for transmission facilities; and

(3) A desire to have more detail in the standard to make compliance requirements more clear.


Highlights from the new FAC-008-3 include:

There are now separate requirements for Generator equipment and for Transmission equipment, as well as some requirements that explicitly apply to both Generator and Transmission equipment.

Generators and Associated Interconnect Equipment:

The Standard contains criteria for documenting how generator ratings are determined. Documentation must include:

  • Assumptions used in determining the rating (ambient conditions, run time, any corrections, etc.)
  • Any design, construction or operating factors that are considered in or affect the rating determination
  • A general rule that the generator rating can't exceed the rating of the most limiting piece of equipment for the generator and its interconnection

The Standard also contains criteria for the rating methodology for generator interconnect equipment (breakers, meters, PTs and CTs, buswork, etc.)

Transmission Equipment

The Standard contains separate criteria for the rating methodology used for transmission equipment.  These criteria require the following items be included in the methodology:

  • Discussion of whether ratings are based on manufacturer data, industry standards (IEEE, etc), or operating performance restrictions
  • Explanation of the assumptions, design criteria, and/or methods used to identify equipment ratings.
  • A general rule that the rating of any assemblage or grouping of equipment can't exceed the rating of the most limiting piece of equipment in the assemblage or grouping.
  • A discussion of the process used to determine the normal, short term emergency, long term emergency, and drastic action limits for the equipment.

Communicating Ratings

The new FAC-008-3 contains a broad requirement to share equipment ratings with affected or interconnected parties, replacing the FAC-009 Standard.

The Standard includes a new requirement that effectively gives affected entities, such as the Reliability Coordinator, connected Transmission Operator (TOp) or Generator Operator (GOp), Planning Authority or Transmission Planner the ability to comment on (question) any equipment rating provided by a GO or TO. Any such comment must be answered by proposing a new rating or explaining why the original rating is valid.

The new Standard also allows affected entities to request information on the most limiting element affecting a rating as well as the second and third most limiting elements. In practice, requests for information on the second and third most limiting elements should be rare except for extremely critical elements or elements that are central to serious SOLs or IROLs.

Finally, all registered TOs and TOps should be aware there are a number of other changes relating to the TO and TOp functions that will go into effect later this year (PER-003-1) or in 2013 (PER-005-1, EOP-001-1, EOP-005-2, EOP-006-2, and EOP-008-1). Some of these changes are significant. Any entity that is listed on the NERC Compliance Registry as a TO or TOp should become familiar with the revised Standards and take active measures to ensure the entity is compliant within the deadline specified for each respective revised Standard.