PEC电气工程专业英语证书考试-Electricity GlossaryAac - abbreviation for alternating currentactive power - see real poweralternating current - an electrical current which reverses direction repeatedly due to a change in voltage which occurs at the same frequency. Often abbreviated AC or ac.alternator - an electric generator designed to produce alternating current. Usually consists of rotating parts which created the changing magnetic field to produce the alternating current.American National Standards Institute - a private organization that coordinates and/or approves some US standards, particularly those related to the electrical industry. Abbreviated ANSI.American Wire Gauge - A standard measure which represents the size of wire. The larger the number, the smaller the wire. Abbreviated AWG.ampacity - the maximum continuous current that a conductor can carry without overheating above its temperature rating.Ampere - electric current produced by one volt applied across a resistance of one ohm. It is also equal to the flow of one coulomb per second. Named after French physicist Andre M. Ampre 1836.ambient temperature - the surrounding temperature.Ampere-hour - the flow of electricity equal to one ampere for one hour. Commonly used to rate the capacity of batteries.analog - a measuring or display methodology which uses continuously varying physical parameters. In contrast, digital represents information in discrete binary form using only zeros and ones.apparent power - the mathematical product of voltage and current on ac systems. Since voltage and current may not be in phase on ac systems, the apparent power thus calculated may not equal the real power, but may actually exceed it. Reactive loads (inductance and/or capacitance) on ac systems will cause the apparent power to be larger than the real power.AWG - abbreviation for American Wire Gauge. Bbattery - a group of two or more cells connected together to provide electrical current. Sometimes also used to describe a single cell which converts chemical energy to electrical current.battery cycle life - the number of discharge and recharge cycles that a battery can undergo before degrading below its capacity rating.battery self-discharge - the gradual loss of chemical energy in a battery that is not connected to any electrical load.black start - refers to certain electric utility generating units that can start upon demand without any outside source of electric power. These are often combustion turbines that have stationary battery banks to provide backup power to energize all the controls and auxiliaries necessary to get the unit up and running. In the event of an large area-wide blackout, these units are critical to restoring the utility grid. Most utility generating units do not have black start capability.bonding - an electrical conducting path formed by the permanent joining of metallic parts. Intended to assure electrical continuity and the capability to safely conduct any likely current. Similar to bonding jumper or bonding conductor.branch circuit - the conductors between the last overcurrent protective device and the outlets or loads. Ccapacitor - a device that stores electrical charge usually by means conducting plates or foil separated by a thin insulating layer of dielectric material. The effectiveness of the device, or its capacitance, is measured in Farads.cell - a single device which converts chemical energy into electrical current. Sometimes also referred to as a battery.charge rate - the rate at which a battery or cell is recharged. Can be expressed as a ratio of battery capacity to current flow.circuit breaker - a device designed to open a circuit either by manual action or by automatic action when current exceeds a value longer than permitted. A circuit breaker can provide overcurrent protection.conductor - usually a metallic substance capable of transmitting electricity with little resistance. The best conductor at normal temperature ranges is silver. The most common is copper. Some other recently discovered substances called super conductors actually have zero resistance at extremely low temperatures.continuous load - a sustained electrical load current for three hours or more.Coulomb - the practical unit of electric charge transmitted by a current of one ampere for one second. It is the charge carried by 6.2418 x 1018 electrons. Named for the French physicist Charles A. de Coulomb 1806.current - the flow of electricity commonly measured in amperes.cycles-per-second - a measure of the frequency in an ac electric system. Abbreviated cps or cycles. Now replaced with the unit Hertz. Ddc - abbreviation for direct current.decibel - a logarithmic measure of the ratio of two quantities. Abbreviated dB. For electrical power, 1 dB = 10 x log10 P1/P2. For electric voltage or current, 1 dB = 20 x log10 E1/E2.