glossaary on autocad utility design

www.autodesk.com/autocadutilitydesign.com

AutoCAD®

Utility Design

2012

Glossary of Electric Industry Terms

This document contains commonly referenced transmission and distribution terms in an electric utility.

Contents

Introduction .................................................................................................................................................................. 2

Business Terms ........................................................................................................................................................ 2

Technical Terms ....................................................................................................................................................... 7

Resources and References ....................................................................................................................................... 14

ELECTRIC INDUSTRY GLOSSARY OF TERMS

2

Introduction The electric industry is generally broken into three categories:

Generation - production of electric power

Transmission - transfer of electricity from the generation source to the various substations along the way

Distribution - routing of electrical conductors to the consumer based on demand and location, typically to a

distribution substation that feeds a neighborhood or business.

Although there are terms defined that relate to generation, transmission and distribution, the primary purpose of these

terms is to help users understand the distribution system vernacular.

Business Terms

The following section contains terms that are commonly referenced in business discussions related to the electric

industry.

Advanced Metering

Infrastructure (AMI)

AMI refers to systems that measure, collect, and analyze energy usage— from advanced devices

such as electricity meters, gas meters, and/or water meters through various communication

media on request or on a predefined schedule.

AMI is different with regard to traditional automatic meter reading (AMR) in that it enables two-

way communications with the meter. Traditional systems that are only capable of meter readings

don't qualify as AMI systems.

Alternative Energy Alternative energy is a generic term that refers to any source of energy fuelled in ways that do not

use up natural resources or harm the environment. In some definitions, alternative energy refers

to energy that is not from fossil fuels. In other definitions the fuel source does not need to be

renewable, but is not a traditional source of energy—for example, compressed natural gas, solar,

hydroelectric, or wind.

Automatic Meter

Reading (AMR)

AMR is the technology of automatically collecting consumption, diagnostic, and status data from

energy metering and transferring that data to a central database for billing, troubleshooting, and

analyzing. AMR saves utility providers the expense of periodic trips to each physical location to

read meters. This timely information, coupled with analysis, can help both utility providers and

customers to better control the use and production of electric energy, gas usage, and water

consumption.

Cogeneration Cogeneration (also combined heat and power, or CHP) is the use of a heat engine or a power

station to simultaneously generate both electricity and useful heat.

Conventional power plants emit the heat created as a by-product of electricity generation into the

environment through cooling towers, flue gas, or by other means. CHP or a bottoming cycle

captures the by-product heat for domestic or industrial heating purposes, either very close to the

plant, or—especially in Scandinavia and eastern Europe—as hot water for district heating with

temperatures ranging from approximately 80° to 130°C. This is also called decentralized energy.

Computerized

Maintenance

Management System

(CMMS)

A CMMS software package maintains a computer database of information about an

organization’s maintenance operations. This information is intended to help maintenance workers

do their jobs more effectively (for example, determining which storerooms contain the spare parts

they need) and to help management make informed decisions (for example, calculating the cost

of maintenance for each piece of equipment used by the organization, which may lead to better

allocation of resources). The information may also be useful when dealing with third parties; if, for

example, an organization is involved in a liability case, the data in a CMMS database can serve


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as evidence that proper safety maintenance has been performed. Also referred to as the EAM

system in some case

Cooperatives

(COOP)

US specific term

Electric cooperatives are private, independent electric utilities, owned by the members they

serve. Democratically governed businesses, electric cooperatives are organized under the

Cooperative or Rochdale Principles, anchoring them firmly in the communities they serve and

ensuring that they are closely regulated by their consumers. Most are members of the National

Association of Rural Electric Cooperatives (NRECA).

Council of European

Energy Regulators

(CEER)

EU specific term

The Council of European Energy Regulators (CEER) is a not-for-profit association in which

Europe's independent national regulators of electricity and gas voluntarily cooperate to protect

consumer' interests and to facilitate the creation of a single, competitive, efficient and sustainable

internal market for gas and electricity in Europe

The Council of European Energy Regulators (CEER) is a not-for-profit association in which

Europe's independent national regulators of electricity and gas voluntarily cooperate to protect

consumer' interests and to facilitate the creation of a single, competitive, efficient and sustainable

internal market for gas and electricity in Europe.

CEER acts as a preparatory body for the European Regulators' Group for Electricity and Gas

(ERGEG). .

Customer Information

System (CIS)

See CRM (below). The term CIS is more commonly used in electric utilities. In addition to the

data contained in a CRM system, a CIS system typically incorporates customer billing

information.

Customer

Relationship

Management (CRM)

Customer relationship management (CRM) consists of the processes a company uses to track

and organize its contacts with current and prospective customers. CRM software is used to

support these processes; information about customers and customer interactions can be entered,

stored, and accessed by employees in different company departments. Typical CRM goals are to

improve services provided to customers, and to use customer contact information for targeted

marketing.

Distributed

Generation

Distributed generation describes electric power generation that is geographically distributed or

spread out across the grid, generally smaller in scale than traditional power plants and located

closer to the load, often on customers' property.

Distribution

Management System

(DMS)

A distribution management system (DMS) refers to a suite of application software that supports

electric system operations. DMS applications such as online distribution power flow require an

electric system model including connectivity, impedance, equipment, load distribution, and most

likely geographic coordinates for all components. A DMS is a ―smarter‖ OMS, and it supports

non-outage operating decisions in addition to outage scenarios.

Electric Utility An electric utility is an organization that is responsible for the installation, operation, or

maintenance of an electric supply system.

Energy Management

Systems (EMS)

An EMS system provides automatic control of the generation and monitoring of the transmission

and distribution systems. EMS applications assist the dispatcher in performing routine control

functions, in maintaining the security of the power network, and in reducing operational costs.

This application is critical to the operation of the power system and therefore has the highest

executive visibility.

Enterprise Asset

Management (EAM)

Enterprise asset management (EAM) means the whole life optimal management of the physical

assets of an organization to maximize value. It covers such things as design, construction,

commissioning, operations, maintenance, and decommissioning/replacement of a plant,

equipment, and facilities. Also known as Facilities Asset Management System (FAMS).


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Enterprise Resource

Planning (ERP)

Enterprise resource planning (ERP) is a companywide computer software system used to

manage and coordinate all the resources, information, and functions of a business from shared

data stores.

European Regulators’

Group for Electricity

and Gas (ERGEG)

EU specific term

ERGEG is the European Commission's formal advisory group of energy regulators. ERGEG was

established by the European Commission, in November 2003, to assist the Commission in

creating a single-EU market for electricity and gas. ERGEG's members are the heads of the

national energy regulatory authorities in the 27 EU Member States.

Green Power/Green

Pricing

Optional service choices that feature renewable fuels such as wind or solar, usually priced at

some form of premium.

Investor Owned Utility

(IOU)

Utilities owned by private investors, IOUs are generally subject to different regulations than

publicly owned utilities and co-ops, and they pay taxes as corporate citizens. These utilities are

usually regulated by the state’s Public Utilities Commission. IOUs are typically looking for ways to

reduce inefficiencies and save energy, and they recommend ways to do so to their consumers.

Material Management

System

This system is used to plan for and control the flow of materials in and out of the company. A

material items database may be accessed by many departments for multiple purposes. The main

subsystems are stores operations, materials planning, and purchasing.

Municipal Utilities

District (MUD)

US specific term

Municipal utility districts are similar to Public Utilities Districts (See PUDs) but are created by

private developers instead of governments.

North American

Electric Reliability

Corporation (NERC)

US specific term

Formed by the electric utility industry in 1968 to promote the reliability of their generation and

transmission systems. NERC develops and enforces reliability standards; assesses adequacy

annually via a 10-year forecast and winter and summer forecasts; monitors the bulk power

system; and educates, trains and certifies industry personnel. NERC is a self-regulatory

organization, subject to oversight by the U.S. Federal Energy Regulatory Commission and

governmental authorities in Canada.

Outage Management

System (OMS)

An OMS is used by operators of electric distribution systems to assist in the restoration of power.

At the core of a modern outage management system is a detailed network model of the

distribution system. By combining the locations of outage calls from customers, a rules engine is

used to predict the locations of outages. For instance, since the distribution system is primarily

tree-like or radial in design, all calls in a particular area downstream of a fuse could be inferred to

be caused by a single fuse or circuit breaker upstream of the calls.

Power Distribution Distribution is typically defined as that portion of the utility system between the distribution

substations and the consumers' service-entrance equipment.

Power Generation Generation is the process of creating electricity from other forms of energy. It is the first process

in the delivery of electricity to consumers. The other processes, electric power transmission and

electricity distribution, are normally carried out by the electrical power industry.

Power Transmission Transmission is the bulk transfer of high voltage electrical power to consumers. A power

transmission network typically connects power plants to multiple substations near a populated

area.

Primary Distribution/

Primary Distribution

Feeder

A primary voltage distribution circuit, usually considered to be between a substation or point of

supply and the distribution transformers, which supplies lower voltage distribution circuits or

consumer service circuits.


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Primary Voltage The voltage of the circuit supplying power to a transformer is called the primary voltage, as

opposed to the output voltage or load-supply voltage which is called secondary voltage. In power

supply practice, the primary is almost always the high-voltage side and the secondary is the low-

voltage side of a transformer, except at generating stations.

Public Utilities

Commission (PUC)

US specific term

A Public Utilities Commission (PUC) regulates privately owned electric, natural gas,

telecommunications, water, railroad, rail transit, and passenger transportation companies.

Public Utilities District

(PUD)

US specific term

A Public Utility District (PUD) is a special-purpose district or other governmental jurisdiction that

provides public utilities (such as electricity, natural gas, sewage treatment, waste

collection/management, wholesale telecommunications, and water) to the residents of that

district.

PUDs are created by a local government body, such as a city, county, or metropolitan service

area (two or more communities joining together for public utility purposes). Normally the districts

are nonprofit.

PUDs are often governed by a commission, which may be appointed or elected.

Radial An electrical circuit arranged like rays, radiating from or converging to a common center. An

electric circuit that is not looped.

Rate Case

A rate case is the formal process which industries that have the legal designation of public utility

are mandated to follow in order to set the rate at which they are allowed to charge consumers for

their service. Rate cases serve as one of the primary instruments of government regulation of

such industries.

Rate Level The electric price a utility is authorized to collect.

Rate Structure The design and organization of billing charges to customers.

Reliability Reliability generally describes the continuity (or guarantee) of system performance under all

reasonable conditions to customers ensuring constancy, quality, adequacy and economy of

electricity. It is also the assurance of the continuous supply of electricity for customers at the

proper voltage and frequency. Reliability depends both on the availability of sufficient generation

resources to meet demand and on the ability of the transmission and distribution system to

deliver the power.

Renewable Energy Renewable energy is energy generated from natural resources—such as sunlight, wind, rain,

tides and geothermal heat—which are renewable (naturally replenished). Renewable energy

production is growing quickly, often as a response to government requirements.

Smart Grid

(also known as Strong

Grid in China)

In principle, the Smart Grid is a simple upgrade of 20th century power grids, which generally

―broadcast‖ power from a few central power generators to a large number of users. The new grid

will be capable of routing power in more optimal ways to respond to a very wide range of

conditions, such as intermittent wind or solar generation or concentrations of plug-in electric

vehicles. These Smart Grid programs will enable fundamental changes in the efficiency of electric

transmission and distribution operations.

For every transmission and distribution project, utilities must adhere to rigorous design and

engineering standards. Many have pre-defined workflows and business processes in place that

help ensure quality and accuracy, as well as cost controls. Smart Grid projects, with their greater

emphasis on planning and delivering initiatives and projects faster and more economically, also

often include ambitious new environmental mandates and call for more sustainable design.


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Smart Grid Principles

(Europe)

Conceived as employing innovative products and services together with intelligent monitoring,

control, communication, and self-healing technologies.

Better facilitate the connection and operation of generators of all sizes and technologies.

Allow consumers to play a part in optimising the operation of the system.

Provide consumers with greater information and options for choice of supply.

Significantly reduce the environmental impact of the whole electricity supply system.

Maintain or even improve the existing high levels of system reliability, quality and security of

supply.

Maintain and improve the existing services efficiently.

Smart Grid Principles

(North America)

The modernization of the nation's electricity transmission and distribution system to maintain a

reliable and secure electricity infrastructure that can meet future demand growth and to achieve

each of the following:

Increased use of digital information and controls technology to improve reliability, security,

and efficiency of the electric grid.

Dynamic optimization of grid operations and resources, with full cyber-security.

Deployment and integration of distributed resources and generation, including renewable

resources.

Development and incorporation of demand response, demand-side resources, and energy-

efficiency resources.

Deployment of `smart' technologies (real-time, automated, interactive technologies that

optimize the physical operation of appliances and consumer devices) for metering,

communications concerning grid operations and status, and distribution automation.

Integration of `smart' appliances and consumer devices.

Deployment and integration of advanced electricity storage and peak-shaving technologies,

including plug-in electric and hybrid electric vehicles, and thermal-storage air conditioning.

Provision to consumers of timely information and control options.

Development of standards for communication and interoperability of appliances and

equipment connected to the electric grid, including the infrastructure serving the grid.

Identification and lowering of unreasonable or unnecessary barriers to adoption of smart

grid technologies, practices, and services

Supervisory Control

and Data Acquisition

(SCADA)

SCADA refers to an industrial control system: a computer system monitoring and controlling a

process. The process can be industrial, infrastructure, or facility based.

System Expansion The system expansion projects cater for the long-term (5 to 20 years) planning of generation and

transmission of power. System expansion applications typically provide a decision support

environment using a variety of options and strategies that are considered in the planning process

which usually involves large common data sets from multiple sources. Lengthy reports are

produced for internal documentation and regulation approval.

System Planning and

Analysis

This application area supports the short-term planning process and provides tools for analyzing

incremental expansion.

Tariff A tariff is a duty imposed on goods when they are moved across a political boundary.

Tariff Structure Electricity consumers are divided into classes of service or sectors (residential, commercial,

industrial, and other) based on the type of service they receive. Sectoral classification of

consumers is determined by each utility and is based on various criteria such as:

Demand levels

Rate schedules

Distribution voltage


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Accounting methods

End-use applications

Other social and economic characteristics

Utilities typically employ a number of tariffs. The alternative tariffs reflect consumers' varying

consumption levels and patterns and the associated impact on the utility's costs of providing the

service.

Work Management

System

A work management system is a software solution for organizing work assignments and tracking

each assignment throughout complicated workflow processes. The system also typically caters to

resource allocation, job estimation, and fulfillment timelines ranging from planning and

construction to maintenance and operational procedures.

Technical Terms

The following section contains terms that are commonly referenced in technical discussions related to the electric

industry.

Alternating Current Alternating current is an electric current in which the direction of flow is reversed at frequent,

regular intervals—usually 100 or 120 times per second (50 or 60 cycles per second or 50//60 Hz).

Blackout

A blackout refers to the total loss of power to an area and is the most severe form of power

outage that can occur. Blackouts which result from or result in power stations tripping are

particularly difficult to recover from quickly. Outages may last from a few hours to a few weeks

depending on the nature of the blackout and the configuration of the electrical network. See

Rolling Blackout

Brownout A brownout is a drop in voltage in an electrical power supply, so named because it typically

causes lights to dim. Systems supplied with three-phase electric power also suffer brownouts if

one or more phases are absent, at reduced voltage, or incorrectly phased. Such malfunctions are

particularly damaging to electric motors.

Circuit A conductor or a system of conductors through which electric current flows or is intended to flow

(wires).

Circuit Breaker Circuit breakers are used to interrupt circuits while current flows through them. Shown below are

air circuit breakers used to compress air so as to quench the arc when the connection is broken.

Oil circuit breakers are used to switch circuits and equipment in and out of a system in a

substation. They are oil-filled to provide cooling and to prevent arcing when the switch is

activated.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation_equipment/oil_ci

rcuit_breakers.html

Compatible Units

(CU)

Sometimes referred to as design units, compatible units is a design technique where parts,

materials, tools, and labor components are created as a reusable block or template for use in

repetitive components of a design. Compatible units are generally used to identify labor costs,

bills of materials, and so on, based on the physical design specifications created using a graphic

design tool.


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Conductor A substance or body that allows an electric current to pass continuously along it (a wire).

Conduit Conduits are hollow tubes running from manhole to manhole in an underground transmission or

distribution system. Conduits are ducts designed to contain underground cables, conductors,

and wires.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation_equipment/cond

uits.html

Cutover Switching from an old network system to a replacement system, cutovers cover the overlap from

when the new system is live until the old system has been shut down.

Demand The rate at which electric energy is delivered to or by a system, part of a system or a piece of

equipment. It is expressed usually in kilowatts at a given instant or averaged over any designated

period of time. The primary source of "demand" is the power-consuming equipment of

customers.

Design Layout The process of graphically drafting design specifications using a graphical design tool.

Distribution The act or process of delivering electric energy from convenient points on the transmission

system (usually a substation) to consumers.

Distribution Line One or more circuits of a distribution system either direct-buried, in conduit or on the same line of

poles or supporting structures, operating at relative low voltage as compared with transmission

lines.

Distribution

Substation

Located near end users, a distribution substation changes the transmission voltage to a lower

level for use by end users.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation.html#Distribution

Distribution System The network of wires and equipment that distributes, transports or delivers electricity to

customers. The delivery of electric energy to customers on the distribution service originates at a

distribution substation. Electric energy is carried at high voltages along the transmission lines.

For consumers needing lower voltages, it is reduced in voltage at a substation and delivered over

primary distribution lines extending throughout the area where the electricity is distributed. For

users needing even lower voltages, the voltage is reduced once more by a distribution

transformer or line transformer. At this point, it changes from primary to secondary distribution.

Distribution systems include lines, poles, transformers, and other equipment needed to deliver

electric owner to the consumer at required voltages.

Distribution

Transformer

Distribution transformers reduce the voltage of the primary circuit to the voltage required by

customers.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/distribution_system/distribut

ion_transformers.html

Elbows Elbows are devices that allow a utility technician to connect or disconnect a distribution line from

within a pad-mounted transformer.

Gigawatt (GW) A gigawatt (GW) is: (an enormous amount of power)


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One billion watts

One million kilowatts

One thousand megawatts

Guy Guy is a brace or cable fastened to the pole to strengthen it and keep it in position. Guys are

used wherever the wires tend to pull the pole out of its normal position and to sustain the line

during abnormal loads caused by sleet, wind, and cold. Guys counteract the unbalanced forces

imposed on the poles by dead-ending conductors; changing conductor sizes, types, and

tensions; or angles in the transmission or distribution line.

Handholes Handholes are small underground junction boxes.

High-Voltage

Underground Cables

High-voltage cables are designed to carry high-voltage current and are constructed in many

different ways, but are usually shielded cables. They are made with a conductor, conductor-

strand shielding, insulation, semi-conducting insulation shielding, metallic insulation shielding,

and a sheath.

Kilowatt-Hour (kWh) A kilowatt-hour (kWh) is one thousand watts acting over a period of 1 hour. The kWh is a unit of

energy. 1 kWh=3600 kJ.

Latency A measure of time delay experienced in a system, the precise definition of which depends on the

system and the time being measured. Latencies may have different meaning in different contexts.

Load Management Economic reduction of electric energy demand during a utility's peak generating periods. Load

management differs from conservation in that load-management strategies are designed to either

reduce or shift demand from on-peak to off-peak times, while conservation strategies may

primarily reduce usage over the entire 24-hour period. Motivations for initiating load management

include the reduction of capital expenditure (for new power plants), circumvention of capacity

limitations, provision for economic dispatch, cost of service reductions, system efficiency

improvements or system reliability improvements. Actions may take the form of normal or

emergency procedures.

Load Shedding See Rolling Blackout

Loop/Looped An electrical circuit that provides two sources of power to a load or to a substation so that if one

source is de-energized the remaining source continues to provide power.

Loss/Losses The general term applied to energy (kilowatt-hours) and power (kilowatts) lost or unaccounted for

in the operation of an electric system. Losses occur primarily as energy transformations from

kilowatt-hours to waste heat in electric conductors and apparatus.

Megawatt (MW) A megawatt (MW) is a unit of power equal to one million watts. MWe refers to electric output from

a generator. MWt refers to thermal output from a reactor or heat source (the gross heat output of

a reactor itself, which is typically three times the MWe figure).

Meter Meters are measuring devices of two types: indicating meters and recording meters. An

indicating meter shows on a dial the quantity being measured. A recording meter makes a

permanent record of the quantity being measured, usually by tracing a line on a chart or graph.

http://en.wikipedia.org/wiki/Electricity_meter

Network Network - A system of transmission or distribution lines so cross-connected and operated as to


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permit multiple power supply to any principal point on it.

Outage

An outage is a complete loss of voltage usually lasting from as short as 30 cycles up to several

hours (or in some cases even days). Outages are usually caused by the fault-induced operation

of circuit breakers or fuses. Some of these interruptions might be classified as permanent, while

others might be classified as temporary (momentaries).

Overhead

Transmission Lines

The majority of overhead transmission lines carry high-voltage, three-phase AC current.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/transmission_lines.html#Ov

erhead

Phase/Phasing

Electric power is generally transmitted as alternating current in a three-phase system: A, B, and

C. A three-phase system is generally more economical than others because it uses less

conductor material to transmit electric power than equivalent single-phase or two-phase systems

at the same voltage. Most households are served using a single phase, and as a result single-

phase loads should be distributed evenly between the phases of the three-phase system for

efficient use of the supply transformer and supply conductors.

Power Generation

Plant

A power generation plant is a source of electricity. It is most likely fossil fuel–powered (coal, fuel

oil, or natural gas) but could also be powered by nuclear, hydroelectric, a wind farm, or some

other alternative power source.

Power Transformers Power transformers raise or lower voltage as needed to serve the transmission or distribution

circuits.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation_equipment/powe

r_transformers.html

Primary Circuits Primary circuits are the distribution circuits that carry power from substations to local load areas.

They are also called express feeders or distribution main feeders.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/distribution_system/primary

_circuits.html

Pulling Tension Pulling tension is the limit of the force that can be exerted on a cable until it sees some damage.

This term is typically used when pulling conductors through underground conduits and ducts.

Recloser A recloser is a device that acts like a circuit breaker, but automatically resets after a few

moments. It is useful because many system problems are transient and automatically resolve

when the power is cut off for a moment.

Reconductoring Reconductoring refers to replacing the cable or wire on an electric circuit, typically a high-voltage

transmission line, usually to afford a greater electric-current-carrying capability.

Right of Way (ROW) ROW is a type of easement where a utility or government has the right to use another person’s

land for a stated purpose. The right of way allows utilities to build and travel over a said property

during construction and operation of its facilities.

Riser Terminal Pole

Dip

A riser comprises the components that move power from overhead to underground. Also known

as a Dip or Terminal Pole.


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Rolling Blackout A rolling blackout, also referred to as load shedding, is an intentionally-engineered electrical

power outage. Rolling blackouts are a last resort measure used by an electricity utility company

in order to avoid a total blackout of the power system. They are usually in response to a situation

where the demand for electricity exceeds the power supply capability of the network. Rolling

blackouts may be localized to a specific part of the electricity network or may be more

widespread and affect entire countries and continents. Rolling blackouts generally result from two

causes: insufficient generation capacity or inadequate transmission infrastructure to deliver

sufficient power to the area where it is needed.

Secondary Secondaries are the conductors originating at the low-voltage secondary winding of a distribution

transformer. Secondaries for residential service are three-wire single-phase circuits. They extend

along the rear lot lines, alleys, or streets past customers’ premises. The secondaries can be

overhead lines or underground lines.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/distribution_system/second

aries.html

Service Area Territory in which a utility system is required or has the right to supply electric service to ultimate

consumers.

Service Drop The overhead conductors between the electric supply, such as the last pole, and the building or

structure being served.

Services

The wire extending from the secondary or distribution transformer to a customer's location is

called a service. A service can be above or below ground. Underground services have a riser

connection at the distribution pole.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/distribution_system/service

s.html

Single Phase Service where the facility (e.g., house, office, warehouse, barn) has two energized wires coming

into it. Typically serves smaller needs of 120V/240V. Requires less and simpler equipment and

infrastructure to support and tends to be less expensive to install and to maintain.

Smart Meter

A smart meter is an advanced meter that identifies consumption in more detail than a

conventional meter—and optionally, but generally, communicates that information via some

network back to the local utility for monitoring and billing purposes.

Staking Sheet

US specific term

A part of the construction process, a staking sheet is the construction drawing and documentation

that is used to list type and location of units, poles, conductor spans, and so on. Its generation is

typically a time-consuming process, sometimes requiring trips to the site, redrawing, and manual

updates into several systems, especially when the design layout and work order system is not

automated or integrated.

Step Down To change electricity from a higher to a lower voltage

Step Down

Transmission

Substation

A step down transmission substation connects different parts of a grid and is a source for

subtransmission lines or distribution lines. The step-down substation can change the

transmission voltage to a subtransmission voltage. The subtransmission voltage lines can then

serve as a source to distribution substations. Sometimes, power is tapped from the

subtransmission line for use in an industrial facility along the way. Otherwise, the power goes to a

distribution substation.


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http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation.html#Step‐down

Step Up To change electricity from a lower to a higher voltage.

Step Up Transmission

Substation

A step up transmission substation receives electric power from a nearby generating facility and

uses a large power transformer to increase the voltage for transmission to distant locations.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation.html#Step‐up

Substation An assemblage of equipment for the purposes of switching and/or changing or regulating the

voltage of electricity. Service equipment, line transformer installations or minor distribution and

transmission equipment are not classified as substations.

Subtransmission

System/Lines

Subtransmission is the part of the utility system that supplies distribution substations from bulk

power sources, such as large transmission substations or generating stations. In turn, the

distribution substations supply primary distribution systems. Subtransmission has many of the

characteristics of both transmission and distribution in that it moves relatively large amounts of

power from one point to another, like transmission, and at the same time it provides area

coverage, like distribution.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/transmission_lines.html#Su

btransmission

Surges (Lightning or

Switching Surges)

A surge is a transient voltage or current which can have extremely short duration and high

magnitude. Typically, surges are caused by switching operations or lightning. Surges can be

generated by customers due to the switching of their own loads or may be caused by utility

switching operations (capacitors, breakers, and so on). Surges have always existed on power

systems, but it is only in recent years that they have received attention, mainly due to the

sensitivity of electronic devices like DVD players and personal computers.

Switches

Distribution systems have switches installed at strategic locations to redirect or cut off power

flows for load balancing or sectionalizing. Also, switches permit workers to repair damaged lines

or equipment and to complete upgrade work on the system.

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/substation_equipment/circui

t_switchers.html

Three Phase Service where the facility (e.g., manufacturing plant, office building, warehouse, barn) has three

energized wires coming into it. Typically serves larger power needs of greater than 120V/240V.

Usually required for motors exceeding 10 horsepower or other inductive loads. Requires more

sophisticated equipment and infrastructure to support and tends to be more expensive to install

and maintain.

Transformer An electromagnetic device that changes the voltage level of alternating-current by transferring

electrical energy from one circuit to another through inductively coupled conductors — the

transformer's coils. A varying current in the first or "primary" winding creates a varying magnetic

field in the core (or cores) of the transformer. This varying magnetic field induces a varying


13

electromotive force (EMF) or "voltage" in the "secondary" winding.

Transmission Circuit A set of conductors energized at voltages over 69,000 volts and transmitting large blocks of

electrical energy over relatively long distances is called a transmission circuit or transmission line.

Transmission circuits are constructed between transmission substations located at electric

generating stations or switching points in the electric system. Transmission circuits may be

overhead, with structures supporting conductors attached to insulators, or underground, with

conductors surrounded by insulation, shielding, and a sheath or a jacket to form a cable. The

distinguishing characteristics of transmission circuits are that they are operated at relatively high

voltages, transmit large blocks of electrical power, and extend over considerable distances.

Overhead Transmission Circuits Transmission lines or circuits are usually constructed for

economic and capability reasons. The lines extend for long distances in rural areas.

Underground Transmission Circuits In some areas of large cities, it is not practical or

permissible to build high-voltage overhead lines; in these cases transmission and distribution

circuits are installed underground.

Transmission

Substation

A transmission substation connects two or more transmission lines. The simplest case is where

all transmission lines have the same voltage. In such cases, the substation contains high-voltage

switches that allow lines to be connected or isolated for fault clearance or maintenance. A

transmission station may have transformers to control power flow between two adjacent power

systems.

Undervoltage See voltage drop.

Utility Vegetation

Management (UMV)

US specific term

It is generally accepted that the single largest cause of electric power outages occurs when trees,

or portions of trees, grow or fall into overhead power lines. Virtually every electric customer in the

US and Canada has, at one time or another, experienced a sustained electric outage as a direct

result of a tree and power line conflict. While this is a more common problem on distribution lines,

transmission tree-related outages are also experienced on a regular basis.

Electric utility companies actively work to mitigate these threats. In fact, Utility Vegetation

Management (UVM) programs represent one of the largest recurring maintenance expenses for

electric utility companies in North America. Utilities and regulators generally agree that keeping

trees and vegetation from conflicting with overhead conductors is a critical and expensive

responsibility of all utility companies concerned about electric service reliability and fire mitigation.

Voltage Drop A customer who experiences a long-duration (several seconds or longer) service or utilization

voltage less than the proper nominal operating low voltage limit can be considered to be

experiencing a voltage drop situation. Such a condition may be caused by a number of factors,

such as overloaded or poor house wiring, poor connections, and/or a voltage drop on the utility

system.

Voltage Regulator A voltage regulator is used relatively far from the substation to boost the voltage back to standard

line levels.

Voltage Sag A momentary dip of nominal voltage that lasts for a few seconds or less is classified as a voltage

sag. Voltage sags may be caused by faults on the transmission or distribution system or by the

switching of loads with large amounts of initial starting/inrush current (motors, transformers, large

dc power supplies). Voltage sags may be sufficiently severe, especially in the case of faults, to

cause sensitive loads (computers, DVD players, clocks, and so on) to operate incorrectly.

Wind Loading When installing transmission towers or electric poles, wind loading is taken into account to cater

for the effects of wind on structural design parameters such as maximum safe height.


14

Resources and References

Electric Power eTool Illustrated Glossary, US Department of Labor―Occupational Safety & Health Administration

Technical Publications

Lineman’s and Cableman’s Handbook, 11th Edition. McGraw-Hill Engineering, 2006.

Electric Power Systems: A Conceptual Introduction. Wiley-IEEE Press, 2006.

Standard Handbook for Electrical Engineers. McGraw-Hill Engineering, 1999.

Transmission & Distribution Electrical Engineering, 3rd Edition. Colin Bayliss, Newnes, 2007.

Autodesk is a registered trademark of Autodesk, Inc., and/or its subsidiaries and/or affiliates in the USA and/or other countries. All other brand names, product names, or trademarks belong to their respective holders. Autodesk reserves the right to alter product and services offerings, and specifications and pricing at any time without notice, and is not responsible for typographical or graphical errors that may appear in this document.

© 2011 Autodesk, Inc. All rights reserved.

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