Download NERC Terms-Glossary of Terms Used in NERC Reliability Standards Exam Questions and Answers and more Exams Electrical Engineering in PDF only on Docsity!
Standards Exam | Actual Questions and Answers Latest Updated
NERC Terms-Glossary of Terms Used in NERC Reliability
2025 /202 6 (Graded A+)
Adjacent Balancing Authority - ✔✔A Balancing Authority whose Balancing Authority Area is interconnected with another Balancing Authority Area either directly or via a multi-party agreement or transmission tariff. After the Fact - ✔✔A time classification assigned to an RFI when the submittal time is greater than one hour after the start time of the RFI. Area Control Error (ACE) - ✔✔The instantaneous difference between a Balancing Authority's net actual and scheduled interchange, taking into account the effects of Frequency Bias, correction for meter error, and Automatic Time Error Correction (ATEC), if operating in the ATEC mode. ATEC is only applicable to Balancing Authorities in the Western Interconnection. Arranged Interchange - ✔✔The state where a Request for Interchange (initial or revised) has been submitted for approval. Automatic Generation Control - ✔✔Equipment that automatically adjusts generation in a Balancing Authority Area from a central location to maintain the Balancing Authority's interchange schedule plus Frequency Bias. AGC may also accommodate automatic inadvertent payback and time error correction. Balancing Authority (BA) - ✔✔The collection of generation, transmission, and loads within the metered boundaries of the Balancing Authority. The Balancing Authority maintains load-resource balance within this area. Base Load - ✔✔The minimum amount of electric power delivered or required over a given period at a constant rate. Blackstart Resource - ✔✔A generating unit(s) and its associated set of equipment which has the ability to be started without support from the System or is designed to remain energized without connection to
the remainder of the System, with the ability to energize a bus, meeting the Transmission Operator's restoration plan needs for real and reactive power capability, frequency and voltage control, and that has been included in the Transmission Operator's restoration plan. Bulk Electric System - ✔✔All Transmission Elements operated at 100 kV or higher and Real Power and Reactive Power resources connected at 100 kV or higher. This does not include facilities used in the local distribution of electric energy. Bus-tie Breaker - ✔✔A circuit breaker that is positioned to connect two individual substation bus configurations. Cascading - ✔✔The uncontrolled successive loss of system elements triggered by an incident at any location. Cascading results in widespread electric service interruption that cannot be restrained from sequentially spreading beyond an area predetermined by studies. Cogeneration - ✔✔Production of electricity from steam, heat, or other forms of energy produced as a by-product of another process. Confirmed Interchange - ✔✔The state where no party has denied and all required parties have approved the Arranged Interchange. Contingency - ✔✔The unexpected failure or outage of a system component, such as a generator, transmission line, circuit breaker, switch or other electrical element. Contingency Reserve - ✔✔The provision of capacity deployed by the Balancing Authority to meet the Disturbance Control Standard (DCS) and other NERC and Regional Reliability Organization contingency requirements. Control Center - ✔✔One or more facilities hosting operating personnel that monitor and control the Bulk Electric System (BES) in real-time to perform the reliability tasks, including their associated data centers, of: 1) a Reliability Coordinator, 2) a Balancing Authority, 3) a Transmission Operator for transmission Facilities at two or more locations, or 4) a Generator Operator for generation Facilities at two or more locations.
Firm Transmission Service - ✔✔The highest quality (priority) service offered to customers under a filed rate schedule that anticipates no planned interruption. Flowgate - ✔✔1.) A portion of the Transmission system through which the Interchange Distribution Calculator calculates the power flow from Interchange Transactions. 2.) A mathematical construct, comprised of one or more monitored transmission Facilities and optionally one or more contingency Facilities, used to analyze the impact of power flows upon the Bulk Electric System. Forced Outage - ✔✔1. The removal from service availability of a generating unit, transmission line, or other facility for emergency reasons.
- The condition in which the equipment is unavailable due to unanticipated failure. Frequency Bias - ✔✔A value, usually expressed in megawatts per 0.1 Hertz (MW/0.1 Hz), associated with a Balancing Authority Area that approximates the Balancing Authority Area's response to Interconnection frequency error. Frequency Deviation - ✔✔A change in Interconnection frequency. Frequency Error - ✔✔The difference between the actual and scheduled frequency. (FA - FS) Host Balancing Authority - ✔✔1. A Balancing Authority that confirms and implements Interchange Transactions for a Purchasing Selling Entity that operates generation or serves customers directly within the Balancing Authority's metered boundaries.
- The Balancing Authority within whose metered boundaries a jointly owned unit is physically located. Implemented Interchange - ✔✔The state where the Balancing Authority enters the Confirmed Interchange into its Area Control Error equation. Inadvertent Interchange - ✔✔The difference between the Balancing Authority's Net Actual Interchange and Net Scheduled Interchange. (IA - IS)
Interchange - ✔✔Energy transfers that cross Balancing Authority boundaries. Interchange Authority (IA) - ✔✔The responsible entity that authorizes implementation of valid and balanced Interchange Schedules between Balancing Authority Areas, and ensures communication of Interchange information for reliability assessment purposes. Interchange Schedule - ✔✔An agreed-upon Interchange Transaction size (megawatts), start and end time, beginning and ending ramp times and rate, and type required for delivery and receipt of power and energy between the Source and Sink Balancing Authorities involved in the transaction. Interchange Transaction - ✔✔An agreement to transfer energy from a seller to a buyer that crosses one or more Balancing Authority Area boundaries. Interchange Transaction Tag or Tag - ✔✔The details of an Interchange Transaction required for its physical implementation. Interconnection Reliability Operating Limit (IROL) - ✔✔A System Operating Limit that, if violated, could lead to instability, uncontrolled separation, or Cascading outages that adversely impact the reliability of the Bulk Electric System. Interconnection Reliability Operating Limit Tv (IROL Tv) - ✔✔The maximum time that an Interconnection Reliability Operating Limit can be violated before the risk to the interconnection or other Reliability Coordinator Area(s) becomes greater than acceptable. Each Interconnection Reliability Operating Limit's Tv shall be less than or equal to 30 minutes. Interruptible Load or Interruptible Demand - ✔✔Demand that the end-use customer makes available to its Load-Serving Entity via contract or agreement for curtailment. Joint Control - ✔✔Automatic Generation Control of jointly owned units by two or more Balancing Authorities. Load - ✔✔An end-use device or customer that receives power from the electric system.
On-Peak - ✔✔Those hours or other periods defined by NAESB business practices, contract, agreements, or guides as periods of higher electrical demand. Open Access Same Time Information Service (OASIS) - ✔✔An electronic posting system that the Transmission Service Provider maintains for transmission access data and that allows all transmission customers to view the data simultaneously. Open Access Transmission Tariff (OATT) - ✔✔Electronic transmission tariff accepted by the U.S. Federal Energy Regulatory Commission requiring the Transmission Service Provider to furnish to all shippers with non-discriminating service comparable to that provided by Transmission Owners to themselves. Operating Procedure - ✔✔A document that identifies specific steps or tasks that should be taken by one or more specific operating positions to achieve specific operating goal(s). The steps in an Operating Procedure should be followed in the order in which they are presented, and should be performed by the position(s) identified. A document that lists the specific steps for a system operator to take in removing a specific transmission line from service is an example of an Operating Procedure. Operating Reserve - ✔✔That capability above firm system demand required to provide for regulation, load forecasting error, equipment forced and scheduled outages and local area protection. It consists of spinning and non-spinning reserve. Operating Reserve - Spinning - ✔✔The portion of Operating Reserve consisting of:
- Generation synchronized to the system and fully available to serve load within the Disturbance Recovery Period following the contingency event; or
- Load fully removable from the system within the Disturbance Recovery Period following the contingency event. Point of Delivery (POD) - ✔✔A location that the Transmission Service Provider specifies on its transmission system where an Interchange Transaction leaves or a Load-Serving Entity receives its energy. Point of Receipt (POR) - ✔✔A location that the Transmission Service Provider specifies on its transmission system where an Interchange Transaction enters or a Generator delivers its output.
Point to Point Transmission Service (PTP) - ✔✔The reservation and transmission of capacity and energy on either a firm or non-firm basis from the Point(s) of Receipt to the Point(s) of Delivery. Pro Forma Tariff - ✔✔Usually refers to the standard OATT and/or associated transmission rights mandated by the U.S. Federal Energy Regulatory Commission Order No. 888. Purchasing-Selling Entity (PSE) - ✔✔The entity that purchases or sells, and takes title to, energy, capacity, and Interconnected Operations Services. Purchasing-Selling Entities may be affiliated or unaffiliated merchants and may or may not own generating facilities. Ramp Rate or Ramp - ✔✔(Schedule) The rate, expressed in megawatts per minute, at which the interchange schedule is attained during the ramp period. (Generator) The rate, expressed in megawatts per minute, that a generator changes its output. Rating - ✔✔The operational limits of a transmission system element under a set of specified conditions. Reactive Power - ✔✔The portion of electricity that establishes and sustains the electric and magnetic fields of alternating-current equipment. Reactive power must be supplied to most types of magnetic equipment, such as motors and transformers. It also must supply the reactive losses on transmission facilities. Reactive power is provided by generators, synchronous condensers, or electrostatic equipment such as capacitors and directly influences electric system voltage. It is usually expressed in kilovars (kvar) or megavars (Mvar). Real Power - ✔✔The portion of electricity that supplies energy to the load. Real-time - ✔✔Present time as opposed to future time. (From Interconnection Reliability Operating Limits standard.) Receiving Balancing Authority - ✔✔The Balancing Authority importing the Interchange. Regulating Reserve - ✔✔An amount of reserve responsive to Automatic Generation Control, which is sufficient to provide normal regulating margin.
Scheduling Path - ✔✔The Transmission Service arrangements reserved by the Purchasing-Selling Entity for a Transaction. Sending Balancing Authority - ✔✔The Balancing Authority exporting the Interchange. Sink Balancing Authority - ✔✔The Balancing Authority in which the load (sink) is located for an Interchange Transaction and any resulting Interchange Schedule. Source Balancing Authority - ✔✔The Balancing Authority in which the generation (source) is located for an Interchange Transaction and for any resulting Interchange Schedule. Special Protection System (Remedial Action Scheme) - ✔✔An automatic protection system designed to detect abnormal or predetermined system conditions, and take corrective actions other than and/or in addition to the isolation of faulted components to maintain system reliability. Such action may include changes in demand, generation (MW and Mvar), or system configuration to maintain system stability, acceptable voltage, or power flows. An SPS does not include (a) underfrequency or undervoltage load shedding or (b) fault conditions that must be isolated or (c) out-of-step relaying (not designed as an integral part of an SPS). Also called Remedial Action Scheme. Spinning Reserve - ✔✔Unloaded generation that is synchronized and ready to serve additional demand. Stability Limit - ✔✔The maximum power flow possible through some particular point in the system while maintaining stability in the entire system or the part of the system to which the stability limit refers. Supervisory Control and Data Acquisition (SCADA) - ✔✔A system of remote control and telemetry used to monitor and control the transmission system. Surge - ✔✔A transient variation of current, voltage, or power flow in an electric circuit or across an electric system.
System Operating Limit (SOL) - ✔✔The value (such as MW, MVar, Amperes, Frequency or Volts) that satisfies the most limiting of the prescribed operating criteria for a specified system configuration to ensure operation within acceptable reliability criteria. System Operating Limits are based upon certain operating criteria. These include, but are not limited to:
- Facility Ratings (Applicable pre- and post-Contingency equipment or facility ratings)
- Transient Stability Ratings (Applicable pre- and post-Contingency Stability Limits)
- Voltage Stability Ratings (Applicable pre- and post-Contingency Voltage Stability)
- System Voltage Limits (Applicable pre- and post-Contingency Voltage Limits) System Operator - ✔✔An individual at a control center (Balancing Authority, Transmission Operator, Generator Operator, Reliability Coordinator) whose responsibility it is to monitor and control that electric system in real time. Thermal Rating - ✔✔The maximum amount of electrical current that a transmission line or electrical facility can conduct over a specified time period before it sustains permanent damage by overheating or before it sags to the point that it violates public safety requirements. Tie Line - ✔✔A circuit connecting two Balancing Authority Areas. Time Error - ✔✔The difference between the Interconnection time measured at the Balancing Authority(ies) and the time specified by the National Institute of Standards and Technology. Time error is caused by the accumulation of Frequency Error over a given period. Time Error Correction - ✔✔An offset to the Interconnection's scheduled frequency to return the Interconnection's Time Error to a predetermined value. Total Transfer Capability (TTC) - ✔✔The amount of electric power that can be moved or transferred reliably from one area to another area of the interconnected transmission systems by way of all transmission lines (or paths) between those areas under specified system conditions. Transmission - ✔✔An interconnected group of lines and associated equipment for the movement or transfer of electric energy between points of supply and points at which it is transformed for delivery to customers or is delivered to other electric systems.
