Minimum level of system inertia necessary to ensure deployment of frequency responsive reserves.
Dynamic Line Ratings (DLRs)
A transmission facility rating that: (1) applies to a time period of not greater than one hour; and (2) reflects up-to-date forecasts of inputs such as (but not limited to) ambient air temperature, wind, solar heating intensity, transmission line tension, or transmission line sag.
Ambient-Adjusted Ratings (AARs)
A transmission facility rating that: (1) applies to a time period of not greater than one hour; (2) reflects an up-to-date forecast of ambient air temperature across the time period to which the rating applies; (3) reflects the absence of solar heating during nighttime periods where the local sunrise/sunset times used to determine daytime and nighttime periods are updated at least monthly, if not more frequently; and (4) is calculated at least each hour, if not more frequently.
Emergency Rating
A transmission facility rating that reflects operation for a specified, finite period, rather than reflecting continuous operation. An emergency rating may assume acceptable loss of equipment life or other physical or safety limitations for the equipment involved
Facility
A set of electrical equipment ratings that collectively operates as a single bulk electric system element (e.g., transformers, relay protective devices, terminal equipment, and series and shunt compensation devices)
Facility Rating
The maximum or minimum voltage, current, frequency, or real or reactive power flow through a facility that does not violate the applicable equipment rating of any equipment comprising the facility