BPA Definitions - A

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A

See ampere.

AAC

All-aluminum conductor. See conductor.

AAHX

See air-to-air heat exchanger.

abatement

Reducing the degree or intensity of, or eliminating pollution or noise.

AC

See alternating current.

ACE

See area control error.

ACH

See air changes per hour.

acid deposition

The process of nitrogen and sulfur oxides in the atmosphere coming into contact with water resources, plant and animal life, and components of the electric power system. May be in the form of rain, snow, or particulates.

acid rain

Rain that contains nitrogen and sulfur oxides, usually with pH of 4 to 7.

acquisition

The term commonly used at BPA for purchase of power. BPA is prohibited by law from owning a power project and its facilities. See resource acquisition.

acquisition of land rights

The land rights acquired by BPA can range from full fee title to perpetual non-exclusive easement to short-term permits and depend on the type of facility being installed.

acre-foot

The volume of water that will cover a one-acre area to a depth of one foot; often used to describe a quantity of storage in a reser-voir; one acre-foot equals 1233 cubic meters (325,000 gallons) of water.

ACSR

Aluminum conductor steel reinforced. See conductor.

Act

See Pacific Northwest Electric Power Planning and Conservation Act.

action level

1) In various regulatory programs, the point at which a response is called for. 2) In the Federal Superfund program for cleanup of hazardous waste, the existence of a contaminant concentration in the environment high enough to warrant action or trigger a response under the Superfund Amendments and Reauthorization Act of 1986 or the National Oil and Hazardous Substances Contingency Plan.

active power

See real power.

active solar system

Mechanical devices and an external energy source, in addition to solar energy, used to collect, store, and distribute thermal energy.

active storage

See storage.

actual computed requirements

See computed requirements.

A/D

See analog-to-digital converter.

administrator

The chief executive officer of BPA, appointed by the Secretary of the U.S. Department of Energy.

admittance

The reciprocal of electrical impedance; admittance is expressed in the same units as conductance (mhos) and impedance in the same units as resistance (ohms).

advance energy

See energy.

advance funding

See trust fund.

aeolian vibration

A wind-induced conductor vibration (up and down) having small amplitudes but may have high vibration speeds. Also spelled eolian.

aerial mile marker

A sign installed on the first tower or structure in each mile of each transmission line and located on both faces of the uppermost part of the structure as an aid to the aerial observer in identifying the structure numbers.

aerial warning signs

Signs installed on the uppermost part of a steel tower or wood pole structure to designate it as a flight hazard to aircraft oper-ators; BPA uses four signs: 1) Danger, to indicate any dangerous condition; 2) Static, to indicate overhead ground-wire crossing ahead; 3) Airport; 4) Detour, to advise pilot to avoid area ahead, such as a turkey or mink farm. Sign types 1, 2, and 3, have white letters on a red background; sign type 4 has black lettering on a yellow background.

AFUDC

See allowance for funds used during construction.

AGC

See automatic generation control.

air basin

A defined area in which air-borne pollutants tend to circulate and mix together.

air changes per hour (ACH)

The movement of a volume of air in one hour; if a house has one ACH, it means that all of the air in the house will be replaced in one hour.

air pollution

See pollutant.

airshed

A geographically isolated volume of air, usually above and/or downwind from industrial activity, that bears pollutants away for dilution and dispersal.

air-to-air heat exchanger (AAHX)

A device that exchanges indoor air with outdoor air, warming or cooling the incoming air with the air being exhausted.

airway lighting

Lights installed on structures according to Federal Aviation Administration regulations to designate flight hazards during darkness.

airway marker ball

A colored ball, usually orange, gloss white, or gloss yellow, attached to the conductors or overhead ground wire on a transmission line to increase their visibility. Also called aviation marker ball.

airway marking

The painting of transmission line structures according to Federal Aviation Administration regulations to designate flight hazards during daylight.

airway obstruction light

At BPA, a neon light mounted on transmission and radio towers in accordance with Federal Aviation Administration regulations to designate a flight hazard.

alevin

Embryonic fish.

all-aluminum conductor (AAC)

See conductor.

allocated assets

The allocation of asset costs to customer groups or market segments.

allocation factor

In ratemaking, a measure of electric power usage that apportions respon-sibility for the use of resources or services among customer classes, usually expressed as a percentage.

allowance for funds used during construction (AFUDC)

The interest on debts issued to finance construction work-in-progress, normally financed through borrowing and eventually paid by ratepayers after projects are completed and placed in service.

alluvial fan

A low cone-shaped deposit of material laid down by a swift-flowing stream as it enters a plain or an open valley.

alpha particle

A positively charged particle, emitted by certain radioactive materials, made up of two neutrons and two protons bound together, hence identical with the nucleus of the helium atom; the least penetrating of the three common types of radiation (alpha, beta, gamma), it is stopped by a sheet of paper. Not dangerous to plants, animals or humans unless the alpha-emitting substance has entered the body.

alternating current (AC)

An electric current or voltage that reverses direction of flow periodically, as contrasted to direct current, and has alternately positive and negative values. Most electricity used in the U.S. today is alternating current.

aluminum conductors steel reinforced

See conductor.

alumoweld

Conductor made from aluminum-covered steel. Stranded conductor of alumoweld is commonly used for overhead ground wire.

ambient air quality

The normal or average prevailing quality of the surrounding air in a given area in terms of the type and amounts of various air pollutants present.

ambient noise level

The normal or average background noise level (usually recorded in decibels) within a given area for a certain period of time during the day.

ambient temperature

1) The temperature of the air surrounding an object or person, such as the temperature inside a room. 2) The temperature of the surrounding cooling medium, such as gas or liquid, which comes into contact with the heated parts of electrical equipment and into which the heat of the equipment is dissipated.

American Public Power Association

A national service organization representing more than 1,750 local, publicly owned electric utilities.

ammeter

An electrical instrument, with a scale usually graduated in amperes, placed in a circuit to measure the magnitude of electric current.

amortisseur winding

A low-impedance winding consisting of conductors embedded in the pole shoes of a synchronous machine, such as a generator, and connected together at the ends of the poles. Used to oppose rotation or pulsation of the magnetic field of the machine with respect to the poles. Also called damping winding.

amortization

The repayment to the U.S. Treasury by BPA of principal on the Federal investment in the Federal Columbia River Power System (FCRPS), which includes BPA bonds and appropriations, and Army Corps of Engineers and Bureau of Recla-mation appropriations that are part of the FCRPS.

ampacity

Current-carrying capacity, expressed in amperes, of a conductor or cable under stated thermal conditions.

ampere (A)

A unit of measurement of electric current, which is the rate that electrons flow in a wire; one ampere is 6.023 x 1023 electrons per second. The measurement is similar to gallons per minute of water in a pipe.

amplifier

A device for increasing the power associated with a phenomenon without appreciably altering its quality and in which an input signal controls power from a source independent of the signal and delivers an output that bears some relationship to, and is generally greater than, the input signal.

amplitude

The absolute value of the maximum displacement from a zero value during one period of an oscillation. The maximum deviation of an alternating current from its average value during its cycle.

amplitude modulation

The process whereby the amplitude of one electrical quantity is varied in accordance with some selected characteristic of a second quantity, not necessarily electrical (for example, in microwave voice communications, a wave oscillating at the relatively low frequency of sound would be used to vary the amplitude of a continuous high-frequency transmitted carrier wave).

aMW

See average megawatts.

anadromous

Species of fish that hatch and initially grow in freshwater, migrate to and mature in the ocean, and return to freshwater as adults to spawn (such as salmon or steelhead trout).

analog-to-digital converter (A/D)

A device that converts analog information into one of many digital formats.

anchor

A device that stabilizes a transmission structure with respect to the ground.

guy anchor

Normally a metal plate buried in the ground to which an anchor rod is attached.

swamp anchor

Buried logs that brace a wood pole; used in marshy and swampy terrain; also called swamp brace or brace anchor.

anchor rod

Metal rod that forms the connection between the guy anchor and guy wire.

annual storage reservoir

See reservoir.

annunciator

A visual signaling device indicating one or more conditions that exist or have existed in an associated circuit and which usually requires personal attention.

annunciator relay

See relay.

anode

The electrode by which current enters a mercury arc or solid-state valve (thyristor) in the conversion from alternating current to direct current. Current flow is from anode to cathode.

antenna

A device for radiating or receiving electromagnetic waves.

apparent power

See voltamperes.

appliance saturation

A percentage reflecting the number of customers in a given customer class who own a particular type of energy-using equipment.

appropriation

The statutory authority that allows a Federal agency to incur financial obligations. The U.S. Army Corps of Engineers and Bureau of Reclamation also use Federal appropriations to finance their generating projects. BPA does not receive appropriations. See borrowing.

aquatic biota

The plant and animal life of a water body, considered as a total ecological entity.

arc

The discharge of electricity through air or other gas occurring across a gap or set of electrodes.

arcing

The process of current flowing across a gap, such as fault current flowing across an insulator string that flashed over due to a lightning surge.

area control error (ACE)

A number determined in the regulation of the power output of electric generators within a control area (automatic generation control) indicating how much the generation in a power system area deviates from load. The total ACE is subdivided into a schedule of station control errors and transmitted to power plants for the readjustment of specific generators.

Area offices

The offices that serve as BPA’s main contact with its customers in four areas — Puget Sound, Lower Columbia, Upper Columbia, and Snake River. Also see District offices.

armor rod

Protective helically formed wires wrapped around conductor to prevent damage at point of support; also used to repair minor conductor damage.

ASC

Average system cost. See costs.

asset efficiency ratio

The quotient that results from dividing total operating expenses by allocated assets. This ratio measures the relationship between operating assets and their cost of operations.

associated project costs

Payments to the U.S. Treasury for: Bureau of Reclamation operation and maintenance, loan interest, and principal on loans; Corps of Engineers operation and maintenance; and the Federal Energy Regulatory Commission portion of the coordination agreement for downstream benefits realized at non-Federal dams.

assumed energy date

The anticipated date of operation of a resource, allowing for average planning and construction times.

assured access

See intertie access.

assured capability

See capability.

assured delivery

Firm transmission service provided by BPA under a transmission contract to wheel power covered by a contract between a scheduling utility and a Southwest utility.

assured operating plan

The studies that determine the operating rules for the three Columbia River Treaty projects in British Columbia, Canada. See operating plan.

assured system capacity

See capacity.

attainment area

A geographic region where the concentration of a criteria air pollutant does not exceed national ambient air quality standards.

attenuation

In communication, a decrease in magnitude of a signal.

attenuator

A device for reducing the power level or the amplitude of a signal without introducing distortion. Commonly a combination of fixed or adjustable resistances.

audio frequency

Any frequency corresponding to a normally audible sound wave; can range roughly from 15 hertz to 20,000 Hz; frequently shortened to "audio" and used to refer to a device or group of devices intended to operate at audio frequencies.

authorization

The legislation enacted by Congress which sets up or continues the legal operation of a Federal program or agency indefinitely or for a specific period of time, or permits a particular type of obligation or expenditure within a program.

automatic circuit recloser

See circuit recloser.

automatic generation control (AGC)

The regulation of the power output of electric generators within a control area in response to changes in load, system frequency, and other factors to maintain the scheduled system frequency and interchanges with other control areas.

autotransformer

See transformer.

auxiliary relay

See relay.

availability charge

A fee, in a rate schedule or as negotiated, to ensure that a generating resource is capable of producing energy at a time or times it might otherwise be in a maintenance cycle or unavailable.

availability factor

The ratio of the time a piece of equipment or a unit is ready for or in service to the total time interval under consideration.

available water

Water that is not dedicated or reserved for other purposes. For power purposes, water that is not already dedicated for irrigation, navigation, municipal, or other use.

average annual growth rate

A measure of change that takes into account the compounding of change that takes place over time. Similar to compound interest paid on a savings account.

average annual megawatts (aMW)

See average megawatts.

average cost pricing

In electric utility usage, the pricing of the service to recover the total costs associated with that service.

average energy

The total power produced over a period of time divided by the number of hours in the period of time. Can be expressed in kilowatthours/day, megawatthours/month or average megawatts.

average megawatts (aMW)

The unit of energy output over a year, equivalent to the energy produced by the continuous operation of one megawatt of capacity over a period of time; also an average of one million watts transferred over a period of time (often a year, thus average annual megawatts).

average system cost (ASC)

See costs.

average system cost benefits

Benefits received by participating utilities for the purpose of reducing the retail rates of residential and small-farm customers. The benefit is computed as the difference between a utility’s ASC and BPA’s priority firm rate and then multiplied by the qualified residential and small-farm load.

average system cost methodology

The method used to compute and pay for a utility’s average transmission and production-related costs for the purpose of an exchange of power between BPA and a utility under section 5(c) of the Pacific Northwest Electric Power Planning and Conservation Act.

aviation marker ball

See airway marker ball.

avoided cost methodology

A method used to determine the payments from utilities to qualifying facilities (QFs) that produce or cogenerate power under the Public Utility Regulatory Policies Act. The utility pays the QF an amount based on the costs for power the utility avoids by purchasing power from the QF.

avoided costs

See costs.

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