Glossary of electric industry, energy & cooperative terms

I

Incandescent Lamp
An electric lamp that emits light due to the glow of a heated filament.

Independent Power Producer (IPP)
A generation company that produces power to be purchased wholesale by electric utilities. Investor-Owned Utilities (IOUs) Utilities that issue common stock which is purchased by the public; also called privately-owned utilities (as opposed to electric cooperatives or municipal utilities). IPPs are entities that generate electricity as a by-product of another manufacturing process. For example, a company that generates large amounts of heat may use the heat to convert steam into electricity.

Independent System Operators
An independent, Federally-regulated entity that coordinates regional transmission in a non-discriminatory manner and ensures the safety and reliability of the electric system.

Industrial
The industrial sector is generally defined as manufacturing, construction, mining agriculture, fishing and forestry establishments Standard Industrial Classification (SIC) codes 01-39. The utility may classify industrial service using the SIC codes, or based on demand or annual usage exceeding some specified limit. The limit may be set by the utility based on the rate schedule of the utility.

Infiltration
Unwanted flow of air into a building through cracks around doors, windows, and other openings in the building envelope. Infiltration is generally accompanied by exfiltration (flow out of the building).

Insulation, Thermal
Any material high in resistance to heat transmission that, when placed in the walls, ceilings or floors of a structure, will reduce the rate of heat flow.

Insulator
Protective equipment that prevents conductors (wires) from making contact with one another or the support tower or pole. Porcelain and glass are most widely used insulating materials because of their nonconductive properties. The two most common insulator designs are the "cap and pin" and the suspension type. The amount of insulation varies depending on the voltage and location of the lines. For example, in Florida’s subtropical environment they must withstand high heat and humidity and, along the seashore, constant contamination from salt air.

Internet (Web) Terminology

Interruptible Load
Refers to program activities that, in accordance with contractual arrangements, can interrupt consumer load at times of seasonal peak load by direct control of the utility system operator or by action of the consumer at the direct request of the system operator. It usually involves commercial and industrial consumers. In some instances the load reduction may be affected by direct action of the system operator (remote tripping) after notice to the consumer in accordance with contractual provisions. For example, loads that can be interrupted to fulfill planning or operation reserve requirements should be reported as Interruptible Load. Interruptible Load as defined here excludes Direct Load Control and Other Load Management. (Interruptible Load, as reported here, is synonymous with Interruptible Demand reported to the North American Electric Reliability Council on the voluntary Form EIA-411, "Coordinated Regional Bulk Power Supply Program Report," with the exception that annual peakload effects are reported on the Form EIA-861 and seasonal (i.e., summer and winter) peakload effects are reported on the EIA-411).

Interruptible Rates
Rates lower than firm service rates, reflecting the fact that service can be interrupted to permit the utility t continue ton meet its firm service load.

Interruptible Service
Low priority service offers to customers under schedules or contracts which anticipate and permit interruption on short notice, generally in peak-load periods, to serve firm service customers and higher priority users.

Intermediate Load (Electric System)
The range from base load to a point between base load and peak. This point may be the midpoint, a percent of the peakload, or the load over a specified time period.

Internal Combustion Plant
A plant in which the prime mover is an internal combustion engine. An internal combustion engine has one or more cylinders in which the process of combustion takes place, converting energy released from the rapid burning of a fuel-air mixture into mechanical energy. Diesel or gas-fired engines are the principal types used in electric plants. The plant is usually operated during periods of high demand for electricity.

Investor-Owned Utility
Investor-Owned Utilities (IOUs) Utilities issue common stock which is purchased by the public; also called privately-owned utilities (as opposed to electric cooperatives or municipal utilities). In Florida, IOUs are regulated by the Public Service Commission.

Back to top

Page last updated: Tuesday, August 24, 2010