Glossary of terms used by utilities and their regulators electricity physics


It is not intended to be all-inclusive, but rather as an introduction in plain language to the meaning of some otherwise arcane sets of initials and combinations of words. They are grouped under headings indicating the context in which they usually are used.

A. Gas AGA Abbreviation for American Gas Association, the trade association of the gas distribution and transmission industry. Active Corrosion Continuing corrosion of pipeline facilities, which unless controlled, could result in leaks. Anode The positive pole or electrode of an electrolytic cell; anodes are attached to steel pipelines to prevent corrosion. Back fill The material used to refill a ditch or other excavation, or the process of doing so. Bar hold test surveys Leakage surveys made by driving or boring holes at regular intervals along the route of an underground gas pipe and

testing the atmosphere in the holes for the presence of gas with a combustible gas detector or other suitable device. Billing cycle The time interval during which all meters of a class or sub-class of customers are read. The reading of meters is

generally distributed over a period of time (one or two months). A billing cycle comprises the time from the date the first customer of the group is read until the last customer is read. Bottled gas Ordinarily butane or propane, or butane and propane mixtures, liquefied and bottled under pressure for domestic use. Bunker "C " or No. 6 fuel oil A heavy residual fuel oil used by ships, industry, and for large-scale heating installations. Calorimeter Devices used extensively in measuring the quantity of the heat content of natural gas. City gate Meter stations which serve as designated point(s) on a distribution system where the distributor takes delivery of its gas

a low-Btu fuel. High-Btu gas is similar to natural gas and will range in energy content from 900 to 1,000 Btu per cubic foot. Low-Btu gas may range as low as 200 Btu per cubic foot. Coincident demand The sum of two or more demands which occur in the same time interval. Combustible gas indicator (CGI) A portable instrument used in leak detection to determine accurately the methane content in a given area. Commodity charges The cost per unit volume of gas actually delivered to the buyer. The commodity charge is basically made up of the field purchase cost, the transmission costs that depend on the amount of gas transported, and a portion of the fixed costs of the transmission company. Common plant A plant used by a utility in rendering more than one type of service, such as electric and gas, i.e., a corporate headquarters, computer equipment. Compressed Natural Gas (LPG) Natural gas (or propane) that is compressed to a liquid state and is several times the atmospheric pressure. Compressor A machine which draws in air or other gas, compresses it, and discharges it at a higher pressure. A jet engine is

one form used in upgrading pressures for the transmission of gas. Truck mounted compressors are used in the distribution industry to operate equipment such as "jack hammers." Compressor station Any permanent combination of facilities which supplies the energy to move gas in transmission lines or into storage fields. Condensate The liquid resulting when a vapor is subjected to cooling and/or pressure reduction. Conjunctive billing The combining of the quantities of gas from two or more meters into a single quantity for the purpose of billing as