SAVANNAH DISTRICT

 

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Abbreviations and Glossary

Glossary:

 

Acre-foot (AF)

 

The volume of water require to over one acre to a depth of one foot. 1 acre-foot= 43,560 cubic feet or 326,000 gallons.

 

Capacity

 

The load for which a generator, turbine, transformer, transmission circuit, apparatus, station or system is rated. Capacity is also used synonymously with capacity.

 

Circuit Breaker

 

Any switching device that is capable of closing or interrupting an electrical circuit.

 

Confluence

 

The combining of two streams.

 

Conservation
 Pool

 

Usable storage in reservoir for hydropower, recreation, water quality, fish and wildlife management, navigation, and water supply purposes; designed to be filled during normal and high flow periods for use during low flow periods.

 

Cubic Feet per 
 Second (cfs)

 

1cfs=450 gallons per minute (gpm)

 

Demand

 

The maximum amount of electrical energy that is being consumed at a given time.  This demand varies throughout different seasons and times of the day.           

 

Discharge

 

The rate of water flow through, over, or around water control facilities.  The rate of flow is measured by stream gauge, or calculated from predetermined rating tables.  The term may be applied to the rate of flow from each individual source (such as a particular turbine), or to the algebraic summation from all individual sources (which would be the total rate of flow).  Total discharge is synonymous with outflow.

 

Drawdown

 

The distance that the water surface elevation of a storage reservoir is lowered from a given or starting elevation as a result of the withdrawal of water to meet some project purpose(s), such as power generation or creating flood control space.

 

Drought
 Contingency
 Plan

 

Detailed drought management plan that addresses current water conditions in the Savannah River Basin, and serves as a baseline for future

 

Drought
 Indicators

 

Mechanisms which reflect drought conditions and severity.  Drought indicators consist of hydrologic indicators such as streamflow, rainfall, reservoir storage levels and groundwater levels, meteorological indicators such as rainfall, and human activity indicators, which include navigation cutbacks and reduction in hydropower generation.

 

Drought
 Response

 

A response network consists of trigger levels and appropriate management action.  Triggers are predetermined standards reflecting drought intensity which induce responses.

 

Effluent

 

Waste material discharges into the environment.

 

Flood Control
 Pool

 

Storage above the conservation pool elevation designed to store floodwater and reduce flooding downstream.

 

Flow

 

The amount of water passing a given point within a given period of time.

 

Forebay

 

The impoundment immediately above a dam or hydroelectric plant intake structure.  The term is applicable to all types of hydroelectric developments (e.g. storage, run-of-river, and pumped-storage).

 

Generating Unit

 

A single power producing unit, comprised of a turbine, generator, and related equipment.

 

Generation

 

The act or process of producing electricity from other forms of energy.  Also, the amount of electric energy so produced.

 

Generator

 

The electrical equipment in power systems that converts mechanical energy to electrical energy.

 

Governor

 

The device which measures and regulates turbine speed by controlling wicket gate angle to adjust water flow to the turbine.

 

Guide Curve

 

(also known as Rule Curve or Target Pool Levels).  Guides established to regulate and manage optimum pool elevations for yearly operations at impoundments.  Rule curves can be designed to regulate storage for flood control, hydropower production, and other operating objectives, as well as a combination of objectives.

 

Hydroelectric
 Plant

 

An electric power plant that uses water to generate power.

 

Hydropower
 Power

 

The energy that is produced from water.

 

Impoundment

 

A confined body of water such as a reservoir or lake.  Typically created by a dam to store water that is released to meet to maintain authorized purposes

 

Inflow

 

The rate of water flow into a reservoir or forebay during a specified period.

 

Kilowatt (kW)

 

The electric unit of power, which equals 1,000 watts or 1.341 horsepower.

 

Kilowatt hour
 (kWh)

 

Unit for measuring electric energy consumption or generation over time; it equals one kilowatt of power applied for one hour of time.  A typical home uses about 800 kilowatt hours per month. 

 

Load

 

The amount of electric power consumed/delivered at a given point.

 

Megawatt(mW)

 

Unit of electric power, used for measuring rate of producing or consuming electric energy.  One megawatt = 1,000 kilowatts or 1 million watts.  A megawatt is equal to 1,341 horsepower. 

 

Meteorological 
 Conditions

 

Atmospheric phenomena and weather of a region.

 

Minimum
 Discharge

 

The minimum flow that must be released from a project to meet environmental or other non-power requirements.

 

Minimum Pool
 Level

 

The lowest elevation to which the pool is to be drawn.

 

Multi-Purpose
 Reservoir

 

A reservoir planned to be used for more than one purpose.

 

Normal Pool
 Level

 

The elevation to which the reservoir surface will rise during ordinary conditions.

 

Outage

 

The period during which a generating unit, transmission line, or other facility is out of service.

 

Peak Demand
 Month

 

The month, or months, of highest power demand.

 

Peaking Plant

 

A powerplant which is normally operated to provide power during maximum load periods.

 

Penstock

 

A conduit (or tube) that carries water from the reservoir to the turbine in a hydroelectric plant.

 

pH

 

The condition represented by a number, used to express both acidity and alkalinity on a scale whose values run from 0 to 14 with 7 representing neutrality, and numbers less than 7 increasing acidity.

 

Powerplant

 

A generating station where prime movers (such as turbines), electric generators, and auxiliary equipment for producing electricity are located.

 

Pumped Storage

 

A hydropower facility that has reservoir pumps which also serve as generators, installed in the dam.  During the night, when cheap surplus power is available, the pumps are run to pump water from a lower reservoir to an upper reservoir (upstream).  During mid-day, when valuable peaking power is needed, the units are reversed and water is released back to the lower reservoir to generate electricity.

 

Releases

 

A determined amount of water that is allowed to pass through or discharged from a dam.

 

Reregulation
 Structure

 

Peaking power plants generally release water only a few hours per day.  A reregulation structure is a smaller dam located downstream that is capable of storing the intermittent slugs of water and releasing a continuous flow.

 

Rule Curve

 

Same as “Guide Curve.”

 

Streamflow

 

The rate at which water passes a given point in a stream, usually expressed in cubic feet per second.

 

Switchyard

 

An assemblage of electrical equipment for the purpose of tying together two or more electric circuits through switches, selectively arranged in order to permit a circuit to be disconnected or to change the electric connection between the circuits.  In a hydroelectric project, the switchyard is the point at which the energy generated at the project is connected to the distribution system.

 

Tailrace

 

The area below a dam; the channel that carries discharged water away from a dam.

 

Thermally
 Stratify

 

During the warm months of the year, the sun heats the upper layers of the lake.  Since the warm water rises, the surface of the lake continues to warm while the bottom layer stays cold.  During the winter months, the upper layers of the lake are cooled.  The warmer water on the bottom rises, causing destratification, or “turnover”, of the lake.

 

Transformer

 

An electromagnetic device used to change the electricity from the generator to usable voltage levels.

 

Transmission
 Line

 

The high voltage lines that carry electricity from the hydropower plant to the electric distribution system.

 

Triggering
 Mechanism

 

An indicator that is put in place to indicate the need to initiate or terminate a specific action before a crisis occurs.  At the action levels, the trigger elevation will initiate a series of actions that will culminate in the reduction of releases from the projects.

 

Turbine

 

Large blades that are turned by the force of water pushing against it; is connected to the generator.

 

Voltage

 

The force which causes the current to flow through an electrical conductor.

 

Watt

 

Basic unit of electrical power that is produced at one time, or rate of doing work.  The rate of energy transfer equivalent to one ampere flowing under a pressure of one volt at unity power factor.  One horsepower is equivalent to approximately 746 watts.

 

Wheeling

 

The transfer of power and energy from one utility over the transmission system of a second utility for delivery to a third utility, or to a load of the first utility.

 

Wicket Gates

 

Adjustable vanes that control the amount of water that can enter the turbine.

 


ABBREVIATIONS:

 

AF

 

acre-feet

 

cfs

 

cubic feet per second

 

cu

 

cubic

 

ft

 

foot, feet

 

gal

 

gallons

 

gph

 

gallons per hour

 

gpm

 

gallons per minute

 

km

 

kilometer

 

kv

 

kilovolt

 

kva

 

kilovolt-amperes

 

kWh

 

kilowatts per hour

 

m

 

meter

 

mgd

 

million gallons per day

 

mi

 

mile

 

MWH

 

Megawatts per hour

 

MSA

 

Metropolitan Statistical Area

 

NGVD

 

National Geodetic Vertical Datum

 

rpm

 

revolutions per minute

 

SAD

 

South Atlantic Division

 

SEPA

 

Southeast Power Administration

 

sq

 

square

 

WES

 

Waterways Experiment Station

 

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