Electric Glossary

Electric glossary: provides practical definitions for terms used in the electric utility industry.

For definitions of terms used in the gas utility industry, please see our Natural Gas Glossary.


A

Assets - Items of value owned by or owed to a business.

B

Backup Generation Service - An optional service for customers with demands greater than or equal to 75 kW who wish to enhance their distribution system reliability through contracting with the company for the use of portable diesel or gas-fired backup generators. The service provides for backup generation if customers should ever experience a distribution-related outage.

Base energy all kWh charge. Charge applied to all energy (kWh) used by time-of-use customers, no matter when it is used.

Base Load Generation - Those generating facilities within a utility system that are operated to the greatest extent possible to maximize system mechanical and thermal efficiency and minimize system operating costs.

Base Load Unit/Station - Units or plants that are designed for nearly continuous operation at or near full capacity to provide all or part of the base load. An electric generation station normally operated to meet all, or part, of the minimum load demand of a power company's system over a given amount of time.

Base Rate - That part of the total electric rate covering the general costs of doing business unrelated to fuel expenses.

Block Rates - See Rates, Block.

C

Capacity - The load for which a generating unit, generating plant or other electrical apparatus is rated either by the user or by the manufacturer.

Circuit (Electric) - A conductor or a system of conductors through which electric current flows or is intended to flow. Wires.

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

Conduit - A duct designed to contain underground cables, conductors, wires.

Conjunctive Billing - The combination of the quantities of energy, demand or other items of two or more meters or services into respective single quantities for the purpose of billing, as if the bill were for a single meter or service.

Connection Charge - An amount to be paid by a customer in a lump sum or in installments for connecting the customer's facilities to the supplier's facilities.

Cooperative (Cooperatively-Owned Electric Utility) - A group of persons organized in a joint venture for the purpose of supplying electricity to a specified area. Such ventures are generally exempt from federal income tax laws. The Rural Electric Service (RES, formerly the Rural Electrification Administration or REA) financed most cooperatives.

Cooperative, Rural Electric (Coop) - A consumer-owned utility established to provide electric service in rural parts of the U.S. Consumer cooperatives are incorporated under the laws of the 46 states in which they operate. A consumer cooperative is a nonprofit enterprise, owned and controlled by the people it serves. These systems obtain most of their financing through insured and guaranteed loans administered by the Rural Electric Service and from their own financing institution, the National Rural Utilities Cooperative Financing Corporation.

Customer Charge - An amount to be paid periodically by a customer for electric service based upon costs incurred for metering, meter reading, billings, etc., exclusive of demand or energy consumption. MGE bills out the customer charges in dollars per day.

Customer Maximum 15-Minute Demand - See Demand, Customer Maximum 15-Minute.

D

Decommissioning - The removal of a nuclear facility from service and the reduction of residual radioactivity to a level that permits the release of the property for unrestricted use and termination of the Nuclear Regulatory Commission (NRC) license.

Degree-Day - A unit measuring the extent to which the outdoor mean (average of maximum and minimum) daily dry-bulb temperature falls below or rises above an assumed base. The base is normally taken as 65 degrees Fahrenheit for heating and for cooling unless otherwise designated. One degree-day is counted for each degree below (deficiency heating) or above (excess cooling) the assumed base, for each calendar day on which such deficiency or excess occurs.

Example 1: Cooling Degree-day - Assume the maximum and minimum outdoor temperature was 80 degrees Fahrenheit and 60 degrees Fahrenheit. The outdoor mean would be 70 degrees Fahrenheit. The base is 65 degrees. Since 70 degrees are 5 degrees greater than (in excess of) 65 degrees, there are 5 cooling degree-days for this day.

Example 2: Heating Degree-day - Assume the high was 32 degrees Fahrenheit and the low was 10 degrees. The mean is 21 degrees. Since 21 is 44 degrees lower (deficient) than the 65 degree base, there are 44 heating degree-days for this day.

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 (MGE uses 15 minutes). The primary source of "demand" is the power-consuming equipment of customers.

Demand, Annual Maximum - The greatest demand that occurred during a prescribed demand interval (15 minutes) in a calendar year. See also Demand, Customer Maximum 15-Minute.

Demand, Annual System Maximum - The greatest demand on an electric system during a prescribed demand interval in a calendar year.

Demand, Average - The demand on, or the power output of, an electric system or any of its parts over any interval of time, as determined by dividing the total number of kilowatt-hours by the number of units of time in the interval.

Demand, Billing - The demand upon which billing to a customer is based, as specified in a rate schedule or contract. It may be based on the contract year, a contract minimum or a previous maximum and, therefore, does not necessarily coincide with the actual measured demand of the billing period.

Demand Charge - That part of the charge for electric service based upon the electric capacity (kW) consumed and billed on the basis of billing demand under an applicable rate schedule.

Demand, Coincident - The sum of two or more demand that occur in the same demand interval.

Demand Costs - Costs that are related to and vary with power demand (kW), such as fixed production costs, transmission costs and a part of distribution costs.

Demand, Customer Maximum 15-Minute - The greatest rate at which electrical energy has been used during any period of 15 consecutive minutes in the current or preceding 11 billing months. See also Demand, Annual Maximum.

Demand, Instantaneous Peak - The demand at the instant of greatest load, usually determined from the readings of indicating or graphic meters.

Demand Interval - The period of time during which the electric energy flow is averaged in determining demand, such as 60-minute, 30-minute, 15-minute, or instantaneous. MGE typically uses 15-minute demands for most demand-billed rate classes.

Demand, Maximum - The greatest demand that occurred during a specified period of time such as a billing period.

Demand, Maximum Monthly 15-Minute - The greatest rate at which electrical energy has been used during any period of 15 consecutive minutes in the billing month.

Demand, Maximum On-Peak 15-Minute - The greatest rate at which electrical energy has been used during any on-peak period of 15 consecutive minutes in the billing month.

Demand, Noncoincident - The sum of two or more individual demand that do not occur in the same demand interval.

Demand Rates - See Rates, Demand.

Demand Reading - Highest or maximum demand for electricity an individual customer registers in a given interval (15 minutes) during the month or billing period. The metered demand or billing demand reading sets the demand charge for the month or billing period.

Depreciation - Charges made against income to provide for distributing the cost of depreciable plant less estimated net salvage over the estimated useful life of the asset in such a way as to allocate it as equitably as possible to the period during which such services are obtained from the use of the facilities. Among the factors to consider are: wear and tear, decay, inadequacy, obsolescence, changes in demand and requirements of public authorities.

Dispatch, Dispatching - The operating control of an integrated electric system to:
Assign generation to specific generating plants and other sources of supply to effect the most reliable and economical supply as the total of the significant area loads rises or falls.
Control operations and maintenance of high-voltage lines, substations and equipment, including administration of safety procedures.
Operate the interconnection.
Schedule energy transactions with other interconnected electric utilities.

Distribution - The act or process of delivering electric energy from convenient points on the transmission system (usually a substation) to consumers. 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. 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 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 Service - The network of wires and equipment that carries electric energy from the transmission system to the customer's premises. The costs to support, operate and maintain this local delivery system are included here in MGE's rates and are usually priced in cents per kilowatt-hour for energy-only customers and in dollars per kilowatt for demand-billed customers.

E

Economic Dispatch - The start-up, shutdown and allocation of load to individual generating units to effect the most economical production of electricity for customers. See also Dispatching.

Electricity Service - In MGE's rates, this is the network of generating plants, wires and equipment needed to produce or purchase electricity (generation) and to deliver it to the local distribution system (transmission). Priced in cents per kilowatt-hour for energy-only customers and in dollars per kilowatt and in cents per kilowatt-hour for demand-billed customers.

Energy Charge - That part of the charge for electric service based upon the electric energy (kWh) consumed or billed.

Energy Costs - Costs, such as fuel, related to and vary with energy production or consumption.

Energy, Electric - As commonly used in the electric utility industry, electric energy means kilowatt-hours.

Energy, Off-Peak - Energy supplied during periods of relatively low system demand as specified by the supplier. For MGE, this is from 9 p.m. to 10 a.m., Monday through Friday, all holidays, and all weekends.

Energy, On-Peak - Energy supplied during periods of relatively high system demand as specified by the supplier. For MGE, this is from 10 a.m. to 9 p.m., Monday through Friday, excluding holidays.

Energy, On-Peak 1. Energy supplied during periods of relatively high system demand as specified by the supplier. For MGE, this is from 10 am to 1 pm, Monday through Friday, excluding holidays.

Energy, On-Peak 2. Energy supplied during periods of relatively high system demand as specified by the supplier. For MGE, this is from 1 pm to 6 pm, Monday through Friday, excluding holidays.

Energy, On-Peak 3. Energy supplied during periods of relatively high system demand as specified by the supplier. For MGE, this is from 6 pm to 9 pm, Monday through Friday, excluding holidays.

Energy, Primary - Energy available from firm power.

Energy, Secondary or Supplemental - Energy available from nonfirm power.

Expense - Actual or expected cash outflows or incurrence of liabilities that result from the ongoing operation of a company.

F

Federal Energy Regulatory Commission (FERC) - An independent agency created within the Department of Energy (October 1, 1977), FERC is vested with broad regulatory authority. Virtually every facet of electric and natural gas production, transmission and sales conducted by private, investor-owned utilities, corporations or public marketing agencies was placed under FERC purview through either direct or indirect jurisdiction if any aspect of their operations were conducted in interstate commerce. As successor to the former Federal Power Commission (FPC), the FERC inherited practically all the FPC's interstate regulatory functions over the electric power and natural gas industries.

Firm Obligation - A commitment to supply electric energy or to make capacity available at any time specified during the period covered by the commitment.

Fixed Costs - Costs that do not change or vary with usage, output or production.

Flat Rates - See Rates, Flat.

Fuel Cost Adjustments - A provision in a rate schedule that provides for an adjustment to the customer's bill if the cost of fuel at the supplier's generating stations varies from a specified unit cost.

G

Generation, Generating Plant Electric Power - The large-scale production of electricity in a central plant. A power plant consists of one or more units. Each unit includes an individual turbine generator. Turbine generators (turbines directly connected to electric generators) use steam, wind, hot gas or falling water to generate power.

Gigawatt (gW) - One gigawatt equals one billion (1,000,000,000) watts, one million (1,000,000) kilowatts, or one thousand (1,000) megawatts.

Gigawatt-Hours (gWh) - One gigawatt-hour equals one billion (1,000,000,000) watt-hours, one million (1,000,000) kilowatt-hours, or one thousand (1,000) megawatt-hours.

Government (Government-Owned Electric Utilities and Agencies) - When used in statistical tables to indicate class of ownership, it includes municipally owned electric systems and federal and state public power projects. Cooperatives and investor-owned utilities are not included in this grouping.

Green Power, Green Pricing - Optional service choices that feature renewable fuels such as wind or solar, usually priced at some form of premium.

H

Holding Company (Electric Utility) - Usually means a corporation (parent company) that directly or indirectly owns a majority or all the voting securities (such as common stock) of one or more electric utility companies that are located in the same or contiguous states. The Securities Exchange Commission (SEC), as administrator of the Public Utility Holding Company Act of 1935, defines a holding company as "any company which ... owns, controls ... ten percent or more of the outstanding voting securities of a public utility company."

I

Independent Power Facility - A facility, or portion thereof, that is not in a utility's rate base. In the past, such a facility could sell only to electric utilities for resale to ultimate customers as a wholesale transaction. Today, laws are changing to allow these plants to sell directly to ultimate customers as retail transactions or retail wheeling.

Independent Power Producer (IPP) - Any person who owns or operates, in whole or in part, one or more new independent power production facilities.

Inflation - A general rise in prices. An increase in a particular price may or may not be inflationary, depending on how it affects other prices and on how promptly it brings to market additional supplies of the product.

Interruptible Power - See Power, Interruptible.

Inverted, Inverted Block Rate Design - A rate design for a customer class for which the unit charge for electricity increases as usage increases.

Investor-Owned Utilities (IOUs) - Those utilities organized as tax-paying businesses usually financed by the sale of securities in the free market, and whose properties are managed by representatives regularly elected by their shareholders. IOUs, which may be owned by an individual proprietor or a small group of people, are usually corporations owned by the general public. IOUs' stock normally is sold on an exchange such as the New York Stock Exchange or NASDAQ.

J

Joint Ownership - A contractual method for financing large facilities (usually generating plants) whereby two or more companies share all costs from the outset, both capital and expenses and, in turn, share the output or benefits in proportion to their investment. For example, MGE owns Columbia jointly with Alliant Utilities-WPL.

K

Kilowatt (kW) - One kilowatt equals 1,000 watts.

Kilowatt-Hour (kWh) - This is the basic unit of electric energy equal to one kilowatt of power supplied to or taken from an electric circuit steadily for one hour. One kilowatt-hour equals 1,000 watt-hours.

L

Lifeline Rates - See Rates, Lifeline.

Load Curve - A curve on a chart showing power (kilowatts) supplied, plotted against time of occurrence, and illustrating the varying magnitude of the load during the period covered.

Load Factor - The ratio of the average load in kilowatts supplied during a designated period to the peak or maximum load in kilowatts occurring in that period. Load factor, in percent, also may be derived by multiplying the kilowatt-hours (kWh) in the period by 100 and dividing by the product of the maximum demand in kilowatts and the number of hours in the period. Example: Load Factor Calculation - Load Factor = kilowatt-hours/hours in period/kilowatts. Assume a 30-day billing period or 30 times 24 hours for a total of 720 hours. Assume a customer used 10,000 kWh and had a maximum demand of 21 kW. The customer's load factor would be 66 percent ((10,000 kWh/720 hours/21 kW)*100).

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. Many utilities, MGE included, encourage load management by offering customers a choice of service options with various price incentives.

Load Shifting - Involves moving load from on-peak to off-peak periods. Popular applications include use of storage water heating, storage space heating, cool storage and customer load shifts to take advantage of time-of-use or other special rates.

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.

M

Marginal Price - The payment required to obtain one additional unit of a good.

Market Value - The current or prevailing price of a security or commodity as indicated by current market quotations, and therefore the price at which additional amounts presumably can be purchased or sold.

Maximum Monthly Demand - See Demand, Maximum.

Maximum Monthly 15-Minute Demand - See Demand, Maximum Monthly 15-Minute.

Maximum On-Peak 15-Minute Demand - See Demand, Maximum On-Peak 15-Minute.

Megawatt (MW) - One megawatt equals one million (1,000,000) watts.

Megawatt-hour (mWh) - One megawatt-hour equals one million (1,000,000) watt-hours.

Minimum Charge - A provision in a rate schedule stating that a customer's bill cannot fall below a specified level. For example, the electric energy charge may be 6.4 cents per kilowatt-hour (kWh), the customer charge may be $4, with a minimum monthly charge equal to the customer charge. In this case, a customer would be billed for $4 if usage were anywhere between zero and 62 kWh. However, even though the minimum charge may be stated in terms of a customer charge, a minimum charge differs from a customer charge in that charges for energy consumed are added to a customer charge, whereas a minimum charge ensures that the bill for energy consumed does not fall below a certain amount, even if little or no energy is consumed. A minimum charge is similar to a customer charge because it is designed to recover fixed costs of services such as meter reading, billing and facilities maintenance. Although this charge does not generally recover the full cost of these services, it does give the customer a price signal that these costs do exist.

Monthly Maximum Demand - See Demand, Maximum Monthly 15-Minute.

Monthly Maximum 15-Minute Demand - See Demand, Maximum Monthly 15-Minute.

Municipally-Owned Electric System - An electric utility system owned and operated by a municipality usually, but not always, providing service within the boundaries of the municipality.

N

Network - A system of transmission or distribution lines so cross-connected and operated as to permit multiple power supply to any principal point on it.

Nonfirm Power - See Power, Nonfirm.

North American Electric Reliability Corporation (NERC) - 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.

O

Off-Peak Energy - See Energy, Off-Peak.

On-Peak 1 - See Energy, On-peak 1

On-Peak 2 - See Energy, On-peak 2

On-Peak 3 - See Energy, On-peak 3

On-Peak Energy - See Energy, On-Peak.

On-Peak Maximum 15-Minute Demand - See Demand, Maximum On-Peak 15-Minute.

P

PCBs (Polychlorinated biphenyls) - A group of toxic, persistent chemicals used in transformers and capacitors.

Phase Service, Single - See Single-Phase Service.

Phase Service, Three - See Three-Phase Service.

Power, Firm - Power or power-producing capacity intended to be available at all times during the period covered by a commitment, even under adverse conditions.

Power, Interruptible - Power made available under agreements that permit curtailment or cessation of delivery by the supplier.

Power, Nonfirm - Power or power-producing capacity supplied or available under an arrangement that does not have the guaranteed continuous availability feature of firm power. Power supplied based on the availability of a generating unit is one type of such power.

Primary Discount - In MGE's rates, the primary discount provision is available to customers who can take delivery of electrical energy at primary distribution voltage levels. The transformer equipment discount is also available to customers taking primary voltage service who own their own transformers and transformer equipment.

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.

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.

Production - The act or process of generating electric energy.

Public Benefits Fee (PBF) - A charge, a form of tax, created by the Wisconsin State Legislature to fund the "Utility Public Benefits" fund. The money in the fund to be used to provide energy assistance to income-qualified households, to expand state energy conservation and efficiency programs and to encourage the development of renewable energy sources.

Public Utility District - A political subdivision (quasipublic corporation of a state), with territorial boundaries embracing an area wider than a single municipality and frequently covering more than one county for the purpose of generating, transmitting and distributing electric energy.

R

Radial - An electrical circuit arranged like rays, radiating from or converging to a common center. An electric circuit that is not looped.

Rate Case - The process in which a utility appears before its regulatory authority to determine the rates that can be charged to customers.

Rate Class - A group of customers identifies as a class subject to a rate different from rates of other groups.

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

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

Rates, Block - A certain specified price per unit is charged for all of any part of a block of such units, and reduced/increased prices per unit are charged for all or any part of succeeding blocks of such units, each such reduced/increased price per unit applying only to a particular block or portion thereof.

Rates, Demand - Any method of charge for electric service that is based upon, or is a function of, the rate of use, or size, of the customer's installation or maximum demand (expressed in kilowatts) during a given period of time like a billing period.

Rates, Flat - The price charged per unit is constant, does not vary due to an increase or decrease in the number of units.

Rates, Lifeline - A standard definition does not exist. Advocates of lifeline rates generally propose a low or reduced flat rate applicable to the first several hundred kilowatt-hours consumed monthly by each residential customer or a special group of residential customers. Revenue loss because of charging the low lifeline rates may be recovered by raising rates for consumption by residential customers consuming beyond the lifeline level and/or by increasing rates for nonresidential classes.

Rates, Seasonal - Rates vary depending upon the time of year. Charges are generally higher during the summer months when greater demand levels push up costs for generating electricity. All MGE rate classes are seasonal. MGE has summer and winter seasonal rates. Summer rates are effective from June 1 through September 30. All other times of the year winter rates are effective.

Rates, Step - A certain specified price per unit is charged for the entire consumption, the rate or price depending on the particular step within which the total consumption falls.

Rates, Time-of-Use - Prices for electricity that vary depending upon what time of day or night a customer uses it. Time-of-use rates are designed to reflect the different costs an electric company incurs in providing electricity during peak periods when electricity demand is high and off-peak periods when electricity demand is low. MGE has four time periods defined in its time-of-use services: off-peak, on-peak 1, on-peak 2, and on-peak 3. On-peak 1 is weekdays, 10 am to 1 pm. On-peak 2 is weekdays, 1 pm to 6 pm. On-peak 3 is weekdays, 6 pm to 9 pm. All other time weekdays, all weekends and holidays are off-peak. Whether customers benefit from time-of-use rates depends on the percentage of total consumption used during on-peak periods. Generally, customers who use less than 30% to 36% of their total consumption during on-peak periods may benefit from these rates. However, individual analysis of electricity usage habits is required to see if a time-of-use service would be of potential value.

Rates, Unbundled - The process of itemizing the rates for specific services that used to be covered under one rate.

Regulated Utility - Utilities are distinguished as being a class of business "affected with a deep public interest" and therefore subject to regulation. Public utilities are further distinguished in that in most jurisdictions it is considered desirable for them to operate as controlled monopolies. As such, they are obligated to charge fair, nondiscriminatory rates and to render safe, reliable service to the public on demand. In return, they are generally free from substantial direct competition and are permitted, although not assured of or guaranteed to get, a fair return on investment.

Reliability - The guarantee of system performance at all times and under all reasonable conditions to assure 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.

Requirements Service - Service that the supplier plans to provide on an ongoing basis.

Reserve Margin - The difference between net system capability and system maximum load requirements (peak load or peak demand).

Retail - Sales of electric energy to ultimate customers.

Retail Wheeling - An arrangement in which retail customers can purchase electricity from any supplier as opposed to their local utility. The local utility would be required to allow the outside generating company to wheel the power over the local lines to the customer. Wisconsin does not currently allow retail wheeling.

S

Seasonal Rates - See Rates, Seasonal.

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

Service, Customer's - That portion of conductors usually between the last pole or manhole and the premises of the customer served.

Service Drop - The overhead conductors between the electric supply, such as the last pole, and the building or structure being served.

Service Entrance - The equipment installed between the utility's service drop, or lateral, and the customer's conductors. Typically consists of the meter used for billing, switches and/or circuit breakers and/or fuses, and a metal housing.

Service Lateral - The underground service conductors between the street main and the first point of connection to the service entrance conductors.

Single-Phase Service - 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.

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

Step Rates - See Rates, Step.

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

Submetering - Remetering of purchased energy by a customer for distribution to his tenants through privately owned or rented meters.

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.

Summer Peak - The greatest load on an electric system during any prescribed demand interval in the summer (or cooling) season. For MGE the summer period is from June 1 through September 30. All other times of the year winter rates are effective.

Summer Rates - See Rates, Seasonal.

T

Tariff - A schedule of prices or fees.

Tariff Schedule - A document filed with the regulatory authority(ies) specifying lawful rates, charges, rules and conditions under which the utility provides service to the public.

Three-Phase Service - 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.

Time-of-Day Rates - See Rates, Time-of-Use.

Time-of-Use Rates - See Rates, Time-of-Use.

Transformer - An electromagnetic device for changing the voltage level of alternating-current electricity.

Transmission - The act or process of transporting electric energy in bulk from a source or sources of supply to other principal parts of the system or to other utility systems.

Transmission Access - The ability of third parties to use transmission facilities owned by others (wheeling utilities) to deliver power to another utility.

U

Ultimate Customers (Consumers) - Those customers purchasing electricity for their own use and not for resale.

Unbundled Rates - See Rates, Unbundled.

Unbundling - Itemizing some of the different services a customer actually receives and charging for these services separately.

V

Variable Costs - Costs that change or vary with usage, output or production. Example: Fuel costs.

W

Weatherization - A set of measures designed to reduce heat gain and/or heat loss (and thereby energy consumption). Common weatherization measures are weather stripping, ceiling and wall insulation, and storm windows and doors.

Wheeling Service - The use of the transmission facilities of one system to transmit power and energy by agreement of, and for, another system with a corresponding wheeling charge.

Wind Energy/Wind Generation - Electricity generated through wind-powered turbines.

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