Glossary of Power Industry Terms


Access Charge
A fee imposed on seller to gain access to a utility’s transmission or distribution lines necessary to deliver power to a point of exchange or use.

The American Legislative Exchange Council is a national association of state legislators. who develop and promote free market policies. One of ALEC’s primary purposes is the development of model legislation to be used by its legislator members in the states.

Alternating Current (AC)
Current which varies from zero to a positive maximum to zero to a negative maximum to zero. a number of times per second. the number being expressed in cycles per second of Hertz (HZ)

A device for converting mechanical energy into electrical energy.

American Public Power Association (APPA)
A national service organization representing 2000 municipal and other state or local publicly owned electric utilities throughout the United States.

The strength or intensity of an electric current. measured in amperes (AMPS)

Ancillary Services
Services provided by a utility and other suppliers to a provider of generation which maintains the quality. safety loading. accounting and planning necessary to move generation from one point to another.

Avoided Cost
The cost that a utility is expected to incur for its customers in providing (generation) service to its customer. This is the price paid by utilities to cogenerators in many states.



Battery Charge Rectifier
A component which changes AC voltage from the battery charge windings (within the STATOR) to DC voltage. This voltage could be used to charge a battery.

Bilateral Contracts
A contractual system between a buyer and a seller to obtain generation and/or ancillary services of a given type, duration, timing and reliability over a contractual term.

Refers to a condition when all electrical power is disrupted to your area.

Bottleneck Facility
A point on the system, such as a transmission line, through which all electricity must pass to get to its intended buyers. If there is limited capacity at this point, some priorities must be developed to decide whose power gets through. It also must be decided if the owner of the bottleneck may, or must, build additional facilities to relieve the constraint.

Bonneville Power Administration. One of five federal power marketing administrations that sell low-cost electric power produced by federal hydro electric dams to agricultural and municipal users. BPA serves Idaho, Oregon and Washington as well as parts of Nevada and Wyoming.

Broker Systems
An electronic marketplace in which electric generation is priced and purchased.

Refers to a condition when the system voltage drops below acceptable levels causing lights to dim and potentially causing other electrical equipment to function improperly or to be damaged.

A conducting element, usually graphite and/or copper, which maintains sliding electrical contact between a stationary and a moving element.

Bulk Power Supply
Often this term is used interchangeably with wholesale power supply. In broader terms, it refers to the aggregate of electric generating plants, transmission lines, and related equipment. The term may refer to those facilities within one electric utility, or within a group of utilities in which the transmission lines are interconnected.

Buy Release
A secondary market for capacity that is contracted by a customer not using all of its capacity.

Buy Through
An agreement between utility and customer to import power when the customer’s service would otherwise be interrupted.



Captive Customer
A customer who does not have realistic alternatives to buying power from the local utility, even if that customer had the legal right to buy from competitors.

Cascade Failure
A failure mode wherein the failure of one component of a complex system causes other components of that system to fail; for example, in a system of standby emergency diesel generators that must be synchronized in AC parallel to operate, a failure mode on one generator could cause all of the other generators in parallel to fail.

The commonly used term for a rural electric cooperative. Rural electric cooperatives generate and/or purchase wholesale power, arrange for the transmission of that power, and then distribute the power to serve the demand of rural customers. Co-ops typically become involved in ancillary services such as energy conservation, load management and other demand-side management programs in order to serve their customers at the least cost. (All Co-ops do not necessarily generate electricity.)

Cogeneration (Cogen)
Generating electricity using a waste heat fuel source (full or partial) which comes from another industrial process.

Common Cause Failure
The simultaneous failure of more than one system component due to shared causes, often extraordinary events, such as natural disaster, human error, etc.

Computer Grade Power
Electricity meeting the Institute of Electrical and Electronic Engineers Standard 446-1987. This standard sets time and voltage intervals which electronic equipment must tolerate without malfunction.

A wire or cable designed for the passage of electrical current.

A contactor is an electrically operated switch usually used in control circuits and whose contacts are considered high amperage compared to a relay.

Contracts for Differences (CfD)
A type of bilateral contract where the electric generator seller is paid a fixed amount over time which is a combination of the short-term market price and an adjustment with the purchaser for the difference. For example, a generator may sell a distribution company power for ten years at 6 cents/kWh. That power is bid into PoolCo at some low cent/kWh value (to ensure it is always taken). The seller then gets the market clearing price from the pool and the purchaser pays the producer the difference between the PoolCo selling price and 6 cents/kWh (or vice versa if the pool price should go above the contract price).

The laminations in the generator constituting the magnetic structure thereof.

Cost Based Pricing
Electric service prices determined by adding the costs associated with serving an individual customer (or the average cost of serving a group of similar customers) to an allowed return on investment.

Cost of Service Studies
Technical engineering/accounting studies that allocate the total cost of providing electric service to groups of similar customers, based on energy usage, peak use timing, character of service, load factor, voltage, type of metering needed, etc.

The metal frame that surrounds and protects the generator/engine.

The flow rate of electricity.

One complete reversal of alternating current of voltage, from zero to a positive maximum to zero to a negative maximum back to zero . The number of cycles per second is the frequency, expressed in Hertz (HZ).



A regulatory process for determining the total revenue needed to cover the costs of a utility in which the actual or projected level of sales is disassociated (“decoupled”) from the revenues derived. Conservationists advocate such a process to discourage utilities from selling more energy to maintain adequate profit levels.

Demand Side Management (DSM)
1. Refers to measures taken by a utility to encourage conservation of electric usage or to reschedule electric usage for more uniform usage throughout the day or year. Such efforts are intended at minimizing the size and number of generating facilities or designing strategic load growth. 2. Planning, implementation, and evaluation of utility-sponsored programs to change the timing or reduce the amount of a customer’s energy consumption.

The elimination of regulation from a previously regulated industry or sector.

A solid state device which allows current to pass in one direction only. Since it allows only one half cycle of an alternating current pass, its out put will be unidirectional and it may be considered a rectifying element.

Direct Access
The ability of a retail customer to purchase commodity electricity directly from the wholesale market rather than through a local distribution utility. (See also Retail Competition.)

Direct Current (Dc)
An electric current flows in one direction only. DC is produced by chemical action (i.e. a storage battery) or by electromagnetic induction.

The functional separation of the vertically integrated utility into smaller, individually owned business units (i.e., generation, dispatch/control, transmission, distribution). The terms “deintegration”, “disintegration” and “delamination” are sometimes used to mean the same thing. (See also Divestiture.)

Distributed Generation
A distributed generation system involves small amounts of generation located on a utility’s distribution system for the purpose of meeting local (substation level) peak loads and/or displacing the need to build additional (or upgrade) local distribution lines.

The process of delivering electric power at lower voltages from central substations to the point of end use.

Distribution Utility (Disco)
The regulated electric utility entity that constructs and maintains the distribution wires connecting the transmission grid to the final customer. The Disco can also perform other services such as aggregating customers, purchasing power supply and transmission services for customers, billing customers and reimbursing suppliers, and offering other regulated or non-regulated energy services to retail customers. The “wires” and “customer service” functions provided by a distribution utility could be split so that two totally separate entities are used to supply these two types of distribution services.

1. Refers to the sale of a utility’s generation or transmission assets. 2. The stripping off of one utility function from the others by selling (spinning-off) or in some other way changing the ownership of the asset related to that function–most commonly associated with spinning-off generation assets so they are no longer owned by the shareholders that own the transmission and distribution assets. (See also Disaggregation.)

A machine for converting mechanical energy into electrical energy by electromagnetic induction. A generator.



Economic Efficiency
1. Measures the amount of output obtained for a given set of economic inputs. The most desirable economic efficiency is that which produces a given level of output using the fewest economic inputs. 2. A term that refers to the optimal production and consumption of goods and services. This generally occurs when prices of products and services reflect their marginal costs. Economic efficiency gains can be achieved through cost reduction, but it is better to think of the concept as actions that promote an increase in overall net value (which includes, but is not limited to, cost reductions).

Economic Long Run
The time period over which the value of a given set of economic inputs is recovered, which is often a function of both the physical life of the asset and its economic usefulness.

Economic Short Run
Any period less than the economic long run. During the economic short run, economists argue that price levels should cover all variable costs and make some or no contribution to fixed costs, but that full costs may not be recovered.

Economies of Scale
Economies of scale exist where the industry exhibits decreasing average long-run costs with size.

Edison Electric Institute. An association of electric companies formed in 1933 “to exchange information on industry developments and to act as an advocate for utilities on subjects of national interest.”

Electricity Consumers Resources Council. An association formed in 1976 of large industrial consumers of electricity. They work cooperatively for the development of coordinated and consistent policies affecting electric energy supply and pricing at the federal, state and local levels. ELCON members account for over five percent of all electricity consumed in the United States.

Electric Technologies
Processes and uses of electric service which increase productivity and decrease overall emissions. Examples of emerging electric technologies are laser cutting, microwave medical waste disposal, infrared paint drying processes, flash-bake cooking, etc.

Electro-Motive Force (EMF)
The force which causes current to flow in a conductor; in other words, the voltage potential.

Embedded Costs Exceeding Market Prices (ECEMP)
Embedded costs of utility investment exceeding market prices are: 1) costs incurred pursuant to a regulatory or contractual obligation; 2) costs that are reflected in cost-based rates; and 3) cost-based rates that exceed the price of alternatives in the marketplace. ECEMPs may become “stranded costs” where they exceed the amount that can be restored through the asset’s sale. Regulatory questions involve whether such costs should be recovered by utility shareholders and if so, how they should be recovered.

Engine Generator
An electric power generator driven by a natural gas or diesel reciprocating engine.

Environmental Externalities
Environmental costs associated with the provision of a good or service which may or may not be incorporated in the internal cost measurements of the provider. Such costs are sometimes imputed theoretically to represent unmeasured costs to society associated with the use of the good or service.

The Energy Policy Act of 1992 addresses a wide variety of energy issues. The legislation creates a new class of power generators, exempts wholesale generators (EWGs), that are exempt from the provisions of the Public Utilities Holding Company Act of 1935 and grants the authority to FERC to order and condition access by eligible parties to the interconnected transmission grid.

Efficiency Service Company. A company that offers to reduce a client’s electricity consumption with the cost savings being split with the company.

Exempt Wholesale Generator (EWG)
Created under the 1992 Energy Act, these wholesale generators are exempt from certain financial and legal restrictions stipulated in the Public Utilities Holding Company Act of 1935.



Federal Energy Regulatory Commission (FERC)
The Federal Energy Regulatory Commission regulates the price, terms, and conditions of power sold in interstate commerce and regulates the price, terms and conditions of all transmission services. FERC is the federal counterpart to state utility regulatory commissions.

FERC 888
FERC 888 promotes wholesale competition through open access and non-discriminatory transmission service by public utilities. Requirements of FERC 888 include the identification of stranded costs by public utilities and transmitting utilities for recovery, unbundling of costs, and separating marketing functions from transmission operations.

FERC 889
Requirements of FERC 889 include the creation of a nation-wide information sharing system. Open Access Same-Time Information System (OASIS) is a computer information system on the Internet created to allow utilities/power marketers to make reservations on transmission systems across the nation. This open access, information sharing site is scheduled to be operational January 1, 1997.

Financial Risk
The risks associated with making an investment; the probability of recovering that investment plus an appropriate return.

An energy storage system that stores energy in the form of a rotating mass. A flywheel system is a functional replacement for a bank of chemical batteries.

A forward is a commodity bought and sold for delivery at some specific time in the future. It is differentiated from futures by the fact that a forward contract is customized, non-exchange traded, and a non-regulated hedging mechanism.

Fuel Cell
An electrochemical device which, without combustion, converts the chemical energy of a fuel, usually hydrogen or a hydrogen-containing mixture, and oxygen, usually from the air, directly into electricity.

Full Power Outlet
Enables you to draw the full power of the generator out of one outlet.

Futures Market
Arrangement through a contract for the delivery of a commodity at a future time and at a price specified at the time of purchase. The price is based on an auction or market basis. Standardized, exchange-traded, and government regulated hedging mechanism.



Generation Company (Genco)
A regulated or non-regulated entity (depending upon the industry structure) that operates and maintains existing plants. The Genco may own the generation plants or interact with the short term market on behalf of plant owners. In the context of restructuring the market for electricity, Genco is sometimes used to describe a specialized “marketer” for the generating plants formerly owned by a vertically-integrated utility.

A general name for a device that converts mechanical energy into electrical energy. The electrical energy may be direct current (DC) or alternating current (AC).

A system of interconnected power lines and generators that is managed so that the generators are dispatched as needed to meet the requirements of the customers connected to the grid at various points. Gridco is sometimes used to identify an independent company responsible for the operation of the grid.

A connection, intentional or accidental, between an electrical circuit and the earth or some conduction body serving in the place of the earth.



Hedging Contracts
Contracts which establish future prices and quantities of electricity independent of the short-term market. Derivatives may be used for this purpose. (See also contracts for differences, forwards, futures, and options).

High density electronic load.



Idle Control
A system that controls the idle speed of the engine in direct relation to the electrical load.

Ignition Coil
A device used to supply DC voltage to the spark plugs

Independent Power Producer (IPP)
An entity which owns facilities to generate electric power for sale to utilities and end users.

Independent System Operator (ISO)
An independent management team set up to run transmission systems owned by two or more entities. Under the arrangement, owners retain title to their assets and the ISO runs the systems as a joint operation. The ISO files a single transmission tariff for the region, plans and schedules transmission outages, takes a lead role in transmission system planning, collects transmission charges and makes payments to the actual providers.

Integrated Resource Planning (IRP)
A process to control electric power planning through both demand-side management (to reduce the need or demand for electricity) and supply side management (to redistribute the types of needed electric generation among fuel types, location, etc.) to accomplish specified social and environmental goals.

Integrated Resource Planning Principles
The underlying principles of IRP can be distinguished from the formal process of developing an approved utility resource plan for utility investments in supply-side and demand-side and transmission resource costs and attributes outside of the basic provision (or reduction) for electric capacity and energy. These resources may be owned or constructed by any entity and may be acquired through contracts as well as through direct investments. Another principle is the incorporation of risk and uncertainty into the planning analysis. The public participation aspects for IRP allow public and regulatory involvement in the planning rather that the siting stage of project development.

Investor Owned Utility (IOU)
A utility operated by a public corporation in which ownership shares are held by individual investors who supply the capital in expectation of earnings on their investments.



A unit of electrical energy equal to the work done when a current of one ampere passes through a resistance of one ohm for one second



KiloVolt (kV)
A KiloVolt is 1000 Volts.

Kilowatt (KW)
A watt is a unit of power in the International System of Units (SI) that is required to do work at the rate of 1 joule per second. Kilo is from the metric system and means 1000. Therefore, a kilowatt is power required to do work at the rate of 1000 joules per second.

Kilowatt-hour (KWhr)
A Kilowatt-hour is the total number of kilowatts used in one hour, or 3,600,000 joules.

KVA refers to kilovolt-ampere and is the unit used to express apparent power. This unit of measure for power consumption is used for equipment that is not resistive such as motors, computers, and most non-incandescent lighting.



The electric power used by devices connected to an electrical generating system.

Load Following
1. The obligation of the wheeling utility to provide from its own generating sources any difference between the amount of power being wheeled and the instantaneous requirement of the customer receiving, or the supplier delivering the wheeled power. 2. Load following falls into two categories: (a) dedicating sufficient generating capacity to the automatic generator control (AGC) mode to allow them to follow load, and (b) monitoring mismatches between intended and actual interchanges between control areas, and transmitting control signals to AGC generators to minimize this mismatch. Both require a system to record mismatches (over-runs and under-runs). Load following is important because it helps maintain system frequency. Otherwise, if demand exceeded supply, generators would slow down; and if supply exceeded demand, generators would speed up. Both situations could result in an unstable situation which could lead to a widespread outage.



An alternator with permanent magnets used to generate current for ignition in an internal combustion engine.

Marginal Cost
In the utility context, the cost to the utility of providing the next (marginal) kilowatt-hour of electricity, irrespective of sunk costs.

Market-Based Pricing
Electric service prices determined in an open market of supply on demand under which the price is set solely by agreement as to what a buyer will pay and a seller will accept. Such prices could recover less or more than the full cost, depending upon what the buyer and seller see as their relevant opportunities and risks.

An agent for generation projects who markets power on behalf of the generator. The marketer may also arrange transmission, firming or other ancillary services as needed. Though a marketer may perform many of the same functions as a broker, the difference is that a marketer represents the generator while a broker acts as a middleman. (See also Power Marketers.)

Mid-continent Area Power Pool (MAPP)
MAPP is a voluntary organization of electric utilities committed to providing reliable and economical electric service to their customers. MAPP is one of nine Reliability Councils under the North American Electric Reliability Council (NERC). It is also a power pool where members engage in sales and purchases of power.

Motor Generator
An electric power generator driven by an electric motor. Motor generators can be used to condition, or “cleanup”, power from a “dirty” power source such as the electric utility grid or to convert electricity from one form to another. In the SurePower System, motor generators are used to convert DC power from the DC Link Bus to AC power. In the SurePower System, the motor generator also is configured to condition utility power if utility back up power is ever needed.

Municipal Utility (Muni)
A provider of utility services owned and operated by a municipal government.

The process by which a municipal entity assumes responsibility for supplying utility service to its constituents. In supplying electricity, the municipality may generate and distribute the power or purchase wholesale power from other generators and distribute it.



The National Association for Regulatory Utility Commissioners. An advisory council composed of governmental agencies of the fifty States, the District of Columbia, Puerto Rico and the Virgin Islands engaged in the regulation of utilities and carriers. The chief objective is to serve the consumer interest by seeking to improve the quality and effectiveness of public regulations in America.

The National Association of Utility Consumer Advocates. NASUCA includes members from 38 states and the District of Columbia. It was formed to exchange information and take positions on issues affecting utility rates before federal judges, Congress and the courts.

The National Conference of State Legislatures. A national advisory council which provides services to state legislatures by bringing together information from all States to forge workable answers to complex policy questions.

The Northern American Electric Reliability Council. An association for regional councils which provides coordination and planning.

Non-Utility Generators (NUGs)
Facilities for generating electricity that are not owned exclusively by an electric utility (less that 50%) and which operate connected to an electric utility system. Included are qualifying cogeneration and independent power productions facilities under Public Utility Regulatory Policies Act (PURPA) for 1978 (referred to as qualifying facilities, Qfs), facilities installed under the competitive bidding process, and other independent power producers (IPPs) that operate connected to the electric utility system.

A Notice of Proposed Rulemaking. A designation used by the FERC for some of its dockets.

Northeast Power Coordinating Council. A regional reliability coordinating council comprising the New England Power Pool, the New York Power Pool and the utilities of eastern Canada.

Northwest Regional Transmission Association. A sub-regional transmission group within the Western Regional Transmission Association.



Obligation to Serve
The concept embodied in the statutes of most States governing the retail or end-use provision of electric service in which a utility is required to serve all customers who request service at non-discriminatory prices. This obligation is rendered in return for the granting of exclusive rights to serve a geographic area at retail.

Generally refers to designated periods of relatively low system demand. NERC has defined these periods as 10 p.m. until 6 a.m., Monday through Saturday and all day Sunday.

Off-Peak Rate
Generally refers to the cost for power used during Off-Peak periods.

Unit of electrical resistance. One volt will cause a current of one flow through a resistance of one ohm.

Open Access
1. A term becoming generally applied to the evolving access to the transmission system for all generators and wholesale customers. (See FERC NOPR of March 1995.) 2. The use of utility’s transmission and distribution facilities on a common-carrier basis at cost-based rates.

Open Access Same-Time Information System (OASIS)
OASIS is a real-time information-sharing system that enables all buyers and sellers of electricity to access the transmission costs for all other buyers and sellers. This system is designed to ensure that transmission owners and their affiliates do not have an unfair advantage in using transmission to sell power. All utilities must use the OASIS on the Internet.

An option is a contractual agreement that gives the holder the right to buy (call option) or sell (put option) a fixed quantity of a security or commodity (for example, a commodity or commodity futures contract), at a fixed price, within a specified period of time. May either be standardized, exchange-traded and government regulated or over-the-counter, customized and non-regulated.



The maximum load consumed or produced by a unit or group of units in a stated period of time.

Peak Load or Peak Demand
The electric load that corresponds to a maximum level of electric demand in a specified time period.

Performance-Based Rate Making
A process by which a utility’s rates are set in such a way as to encourage certain behaviors considered to be in the public interest, as opposed to setting rates based on cost plus an allowed return on investment.

The uniform periodic change in amplitude or magnitude of an alternating current. Three phase alternating current consists of three different sine wave current consists of three different sine wave current flows, different in phase by 120 degrees from each other.

1. An entity in which the generating assets of all members are “pooled” and the participants obtain pooled average prices for power to meet their system needs. 2. PoolCo refers to a specialized, centrally dispatched spot market power pool that functions as a short-term market. It establishes the short-term market clearing price and provides a system of long-term transmission compensation contracts. It is regulated to provide open access, comparable service and cost recovery. A PoolCo would make ancillary generation services, including load following, spinning reserve, backup power, and reactive power, available to all market participants on comparable terms. In addition, the PoolCo provides settlement mechanisms when differences in contracted volumes exist between buyers and sellers of energy and capacity.

Power Marketers
Sales agents for electric power, typically not a part of a utility. Such entities contract with sellers and buyers as the middleman. Unlike brokers, power marketers take title to all power they transact. (See also Marketers.)

Power Transfer System
A system to safely wire your generator to your home’s electrical system.

Pricing Parity
Under regulated pricing, the process of setting the price to collect revenues from a given group or category of customers to equal the cost to serve the customer, including and allowed return on investment. By contrast, an absence of parity would indicate that the prices for one class of customers were less than the full cost and prices for another class of customers were more than the full cost, even though total prices for all classes together may equal the total cost for all classes.

Pricing Transparency and Liquiditynbsp;
In a fully functioning competitive market, price transparency would reflect an indifference to the identity of buyer and seller because the price would be entirely available to all buyers and sellers.

Probabilistic Risk Assessment
A mathematical science used to calculate the unavailability of complex systems. PRA allows both qualitative and quantitative evaluation of reliability, availability and accident scenarios.

Project Financing
An arrangement when a lender provides the needed capital to build a facility and the security for the lien is the value of the project itself, rather than the security being the full faith and credit of the owner of the project.

The Public Utility Holding Company Act of 1935. This act prohibits acquisition of any wholesale or retail electric business through a holding company unless that business forms part of an integrated public utility system when combined with the utility’s other electric business. The legislation also restricts ownership of an electric business by non-utility corporations.

The Public Utility Regulatory Policies Act of 1978, passed by the U.S. Congress. This statute requires States to consider the implementation of Utility Conservation Programs and create markets for cogenerators and small power producers who meet certain efficiency standards, including the requirement that States set the price of power the utilities must buy from such facilities based on avoided costs.



Qualifying Facility (QF)
Under PURPA, Qfs were allowed to sell their electric output to the local utility at avoided cost rates. To become a QF, the independent power supplier had to produce electricity with a specified fuel type (cogeneration or renewables), and meet certain ownership, size and efficiency criteria established by the Federal Energy Regulatory Commission.



Rated Speed
Revolutions per minute at which the set is designed to operate.

Rated Voltage
The rated voltage of an engine generator set is the voltage at which it is designed to operate.

Rear Bearing Carrier
The casting which houses the rotor bearing which supports the rotor shaft.

An electrical component that converts alternating current (AC) to unidirectional current (DC)

An electrically operated switch usually used in control circuits and whose contacts are considered low amperage, compared to a contactor.

The degree to which electric power is made available to those who need it in sufficient quantity and quality to be dependable and safe. The degree of reliability may be measured by the frequency, duration, and magnitude of adverse effects on consumer services.

Reserve Margin
The amount of installed generation which exceeds the operating generation capacity needed to meet the expected peak load of a given utility with a defined statistical probability. Standards vary from utility to utility, but most utility planners consider a 15-20 percent reserve margin essential for good reliability.

Opposition to the flow of current.

The changes being considered in the set of regulatory and statutory policies governing electric utilities in the U.S.

Retail Competition
The concept under which multiple sellers of electric power and services can sell directly to end-use customers. (See also Direct Access.)

Retail Market
A market in which electricity and other energy services are sold directly to the end-use customer.

Retail Wheeling
The process of moving electric power from a point of generation across one or more utility-owned transmission and distribution systems to a retail customer. (See also Direct Access.)

The rotating element of a generator.

A Regional Transmission Group. A voluntary organization of transmission owners, users and other entities interested in coordinating transmission planning, expansion, operation and use on a regional and inter-regional basis.

Rural Electric Cooperative Utility
An electric utility set up under the Rural Electrification Act of 1934 and owned by the customers of the utility itself. The original purpose of the Act was to provide electric power availability to rural customers who may not have received service because they were more costly to serve than the concentrated customers locally. (See also Co-op.)



Service Area Exclusivity
The concept embodied in the statutes of most States under which a utility is granted the right to be the exclusive provider of electric service in a given geographic area in return for the utility’s obligation to serve all customers with reliable service at fair and non-discriminatory rates.

Single Phase
An AC load, or source of power normally having only two input terminals if a load or two output terminals if a source.

Single Point of Failure
A component or location in a redundant system where a single, credible failure could lead to loss of electrical power to the critical load.

Spinning Reserves
1. The difference between the capability and actual output of generating units which are operating and connected to the electrical network. 2. The amount of unloaded generating capability, on units that are in the generating mode and connected to the interconnected system, which can be fully applied in 10 minutes.

Standby (Backup) Service
1. Service through a permanent connection not normally used but available in lieu of, or as a supplement to, the usual source of supply. 2. Generating and power quality assurance services provided by a supplier to customers who rely on service or equipment which may not be as available or reliable as needs dictate. Typically, standby or backup service is sold by a utility to another utility or generator, such as an industrial cogenerator, to assure continuation of service during maintenance and emergency outage.

Standby Power
A backup source of electrical energy (e.g. a diesel generator) that waits dormant until a control device triggers it to start operating.

The stationary part of a generator.

Stranded Benefits
Benefits associated with regulated retail electric service which may be at risk under open market retail competition. Examples are conservation programs, fuel diversity, reliability of supply, and tax revenues based on utility reserves.

Stranded Costs/Stranded Assets
Costs incurred by a utility which may not be recoverable under market-based retail competition. Examples are undepreciated generating facilities, deferred costs, and long-term contract costs.

Activities conducted on the utility’s side of the customer meter. Activities designed to supply electric power to customers, rather than meeting load through energy efficiency measures or on-site generation on the customer-side of the meter.

The Southwest Regional Transmission Association. A subregional Regional Transmission Authority (RTG) within the Western Regional Tranmission Authority (WRTA), and awaiting FERC approval.



A document, approved by the responsible regulatory agency, listing the terms and conditions, including a schedule of prices, under which utility services will be provided.

Time-of-Use (TOU) Rates
The pricing of electricity based on the estimated cost of electricity during a particular time block. Time-of-Use rates are usually divided into three or four time blocks per twenty-four hour period (on-peak, mid-peak, off-peak and, sometimes, super off-peak) and by seasons of the year (summer and winter). Real-time pricing differs from TOU rates in that it is based on actual (as opposed to forecasted) prices which fluctuate many times a day and are weather-sensitive, rather than varying with a fixed schedule.

Transition Costs
See Embedded Costs Exceeding Market Prices.

Turbine Generator
An electric power generator driven by a gas or steam turbine.



The separating of the total process of electric power service from generation to metering into its component parts for the purpose of separate pricing or service offerings.

(Uninterruptible Power Supply) A system designed to automatically provide power, without delay or transients, during any period when the normal power supply is incapable of performing acceptably. A UPS does not generate power and can operate only when a primary power source such as the electric utility grid is operating.



Vertical Integration
An arrangement whereby the same company owns all the different aspects of making, selling and delivering a product or service. In the electric industry, it refers to the historically common arrangement whereby a utility would own its own generating plants, transmission system and distribution lines to provide all aspects of electric service.

Vibration Mount
A rubber device located between the engine or generator and the cradle to minimize vibration.

The potential difference between two points.

Electrical potential difference expressed in volts.

Voltage Regulator
A component which automatically maintains proper generator voltage by controlling the amount of DC exitation to the rotor.



The Western Association for Transmission System Coordination.

Unit of electrical power. In DC equals volts times amperes. In AC equals effective volts times effective amps times power factor times a consistent dependent on the number of phases. 1 kilowatt = 1,000 watts.

Western Area Power Administration (WAPA)
WAPA markets and transmits reliable, low-cost electric power, provides related services and encourages energy efficient management in an environmentally sound manner to a service area covering 3.38 million square kilometers (1.3 million square miles). Western’s wholesale power customers provide service to millions of consumers in 15 western states (Arizona, California, Colorado, Iowa, Kansas, Minnesota, Montana, Nebraska, Nevada, New Mexico, North Dakota, South Dakota, Texas, Utah and Wyoming).

The transmission of electricity by an entity that does not own or directly use the power it is transmitting. Wholesale wheeling is used to indicate bulk transactions in the wholesale market, whereas retail wheeling allows power producers direct access to retail customers. This term is often used colloquially as meaning transmission.

Wholesale Competition
Rivalry between utilities and other electricity generators striving for the same market of bulk power for resale.

Wholesale Wheeling
The process of moving bulk power from a generator across one or more utility-owned transmission system to another utility for resale.

All the coils of a generator. Stator winding consists of a number stator coils and their interconnections. Rotor windings consist of all windings and connections on the rotor poles.

The Western Systems Power Pool. A FERC-approved industry institution that provides a forum for short-term trades in electric energy, capacity, exchanges and transmission services. The pool consists of approximately 50 members and serves 22 states, a Canadian province and 60 million people. The WSSP is headquartered in Phoenix, Arizona.

The Western States’ System Coordinating Council. A voluntary industry association created to enhance reliability among western utilities.

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