ISO Generation Maintenance Program Glossary of Terms

Capacity Unavailability Factor CUF The percentage of lost capability due to planned outages, maintenance outages, scheduled outage extensions, forced outages, and planned or unplanned restrictions on capability (Derate).

Derate - Placing a temporary restriction on the capability of a Generating Asset to allow continued Availability of the Generating Asset. Derated Capability may be the result of equipment failures or degradation, approaching limits, such as emission control limits, or any other reason deemed necessary by the generating asset owner to ensure continued safe and legal operation of the generating asset.

Generator - The seller of Energy or Ancillary Services produced by a generating unit.

Generating Asset) - A generating device that has a metered output, or an administratively defined group of generating devices, that may or may not have individual metered outputs, but are aggregated for performance measurement.

Generating Asset Class- An administrative grouping of generating assets based on certain attributes, typically for the purpose of defining applicable maintenance practices or performance standards.

NERC ----The North American Electric Reliability Council or any successor thereto.