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Glossary - L

For your convenience, this page contains an alphabetically organized list of terms, definitions and common acronyms used in the electric utility industry.

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Term/Acronym Definition
LASL Low Ancillary Service Limit
LDL Low Dispatch Limit
LEL Low Emergency Limit
LFC Load Frequency Control
LMP Locational Marginal Price
LPC Low Power Consumption
LRL Low Reasonability Limit
LRS Load Ratio Share
LSE Load Serving Entity
LSL Low Sustained Limit
Late Payment Payments due to ERCOT by Invoice Recipients that are not received by the due date and time.
Level I Maintenance Outage See Outage
Level II Maintenance Outage See Outage
Level III Maintenance Outage See Outage
Load The amount of energy in MWh delivered at any specified point or points on a system.
Load Frequency Control (LFC) The deployment of those Generation Resources that are providing Regulation Service to ensure that system frequency is maintained within predetermined limits and the deployment of those Generation Resources that are providing Responsive Reserve Service when necessary as backup regulation. LFC does not include the deployment of Responsive Reserve by Load Resources when deployed as a block under EEA procedures.
Load Profile A representation of the energy usage of a group of Customers, showing the Demand variation on an hourly or sub-hourly basis.
Load Profile ID The Load Profile designation string that contains, the Load Profile Type Code, the Weather Zone Code, the Meter Data Type Code, the Weather Sensitivity Code, and the Time-Of-Use Schedule Code. An example of all Load Profile IDs are located in the Load Profiling Guide, Appendix D, Profile Decision Tree.
Load Profile Models Processes that use analytical modeling techniques to create Load Profiles.
Load Profile Segment A sub-classification of a Load Profile Group. High Winter Ratio (HWR) is an example. Together, the Load Profile Group and the Load Profile Segment form the Load Profile Type.
Load Profile Type A classification of a group of Customers having similar energy usage patterns and that are assigned the same Load Profile.
Load Profiling The set of processes used to develop and create Load Profiles.
Load Profiling Methodology The fundamental basis on which Load Profiles are created. The implementation of a Load Profiling Methodology may require statistical Sampling, engineering methods, econometric modeling, or other approaches.
Load Ratio Share The ratio of an Entity’s AML to total ERCOT AML for an interval.
Load Resource A Load capable of providing Ancillary Service to the ERCOT System and/or energy in the form of Demand response and registered with ERCOT as a Load Resource.

Load Serving Entity (LSE)

An Entity that sells energy to Customers or Wholesale Customers and that has registered as an LSE with ERCOT.  LSEs include Competitive Retailers (which includes REPs) and NOIEs that serve Load and ELSEs.

Load Zone A group of Electrical Buses assigned to the same zone under Section 3.4, Load Zones. Every Electrical Bus in ERCOT with a Load must be assigned to a Load Zone for Settlement purposes. A NOIE Load Zone is a type of Load Zone.
Load Zone LMP See Locational Marginal Price
Locational Marginal Price (LMP)

The offer and/or bid-based marginal cost of serving the next increment of Load at an Electrical Bus, which marginal cost is produced by the DAM process or by the SCED process.

Hub LMP

The price calculated for a Hub for each SCED interval according to the formula in Section 6.6.1.5, Hub LMPs, using LMPs at the Electrical Buses included in the Hub.

Load Zone LMP

The price calculated for a Load Zone for each SCED interval according to the formula in Section 6.6.1.4, Load Zone LMPs, using State Estimator (SE) Load data and LMPs at the Electrical Buses included in the Load Zone.

Low Ancillary Service Limit (LASL) A dynamically calculated MW lower limit on a Resource to maintain the ability of the Resource to provide committed Ancillary Service.
Low Emergency Limit (LEL) The limit established by the QSE describing the minimum temporary unsustainable energy production capability of a Resource. This limit must be achievable for a period of time indicated by the QSE but not less than 30 minutes.
Low Power Consumption (LPC) For a Load Resource, the limit established by the QSE, continuously updated in Real-Time, that describes the minimum sustained power consumption of a Load Resource. The LPC shall be a non-negative number in MW.
Low Sustained Limit (LSL) Low Sustained Limit (LSL) for a Generation Resource

The limit established by the QSE, continuously updatable in Real-Time, that describes the minimum sustained energy production capability of a Resource.

Low Sustained Limit (LSL) for a Load Resource

The limit calculated by ERCOT, using the QSE-established LPC.