Accent Lighting: Directional lighting to emphasize a particular object or draw attention to a part of the field of view.
Acceptor: A dopant material, such as boron, which has fewer outer shell electrons than required in an otherwise balanced crystal structure, providing a hole, which can accept a free electron.
Accessible: (As applied to wiring methods) Capable of being removed or exposed without damaging the building structure or finish, or not permanently closed in by the structure or finish of the building.
Accessible: (as applied to equipment) Admitting close approach: not guarded by locked doors, elevation, or other effective means. (see Accessible, Readily)
Accessible, Readily: (Readily Accessible) Capable of being reached quickly for operation, renewal, or inspections, without requiring those to whom ready access is requisite to climb over or remove obstacles or to resort to portable ladders, chairs, etc.
Active solar heater: A solar water or space-heating system that moves heated air or water using pumps or fans.
Air mass: The ratio of the mass of atmosphere in the actual observer-sun path to the mass that would exist if the observer was at sea level, at standard barometric pressure, and the sun was directly overhead. Note: (sometimes called air mass ratio)
Alternating current: Electric current in which the direction of flow is reversed at frequent intervals: usually 100 or 120 times per second (50 or 60 cycles per second or 50//60 Hz).
ALARA: As Low As Reasonably Achievable, economic and social factors being taken into account. This is the optimization principle of radiation protection.
American Wire Gauge (AWG) The standard measurement to indicate wire diameter. The diameters of successive sizes vary geometrically in retrogression, (i.e.,the larger the number, the smaller the wire). Also known as the B&S Standard.
Ambient Temperature: The temperature of the air, water, or surrounding earth. Conductor ampacity is corrected for changes in ambient temperature including temperatures below 86°F. The cooling effect can increase the current carrying capacity of the conductor. (Review Section 310-10 of the Electrical Code for more understanding)
Ammeter: An electric meter used to measure current, calibrated in amperes.
Ampacity: The current-carrying capacity of conductors or equipment, expressed in amperes.
Ampere (A) : The unit of measurement of electrical current produced in a circuit by 1 volt acting through a resistance of 1 ohm.
Ampere-hour (Ah): Quantity of electricity or measure of charge. (1 Ah = 3600 C [Coulomb])
Apparent Power: The product of the voltage (in volts) and the current (in amperes). It comprises both active and reactive power. It is measured in “volt-amperes” and often expressed in “kilovolt-amperes” (kVA) or “megavolt-amperes” (MVA).
Armored Cable: A cable provided with a wrapping of metal, usually steel wires or tapes, primarily for the purpose of mechanical protection.
Attenuation: (l) The ratio of the input to output power levels in a network (transmission line) when it is excited by a matched source and terminated in a matched load. (2) Power loss in an electrical system.
Automatic circuit re-closer: A self-controlled device for interrupting and re-closing an alternating current circuit with a predetermined sequence of opening and re-closing followed by resetting,hold-closed, or lockout operation.
Autonomous system: A stand-alone Photovoltaic system that has no back-up generating source. May or may not include storage batteries.
Availability: Describes the reliability of power plants. It refers to the number of hours the turbines are available to produce power divided by the total hours in a year.
Electrical Definitions Letter B
Band gap: In a semiconductor, the energy difference between the highest valence band and the lowest conduction band.
Bare Conductor: A conductor not covered with insulating material.
Barrier energy: The energy given up by an electron in penetrating the cell barrier; a measure of the electrostatic potential of the barrier.
Base load: The minimum amount of electric power delivered or required over a given period of time at a steady rate.
Baseload Capacity: The generating equipment normally operated to serve loads on an around-the-clock basis.
Base power: Power generated by a utility unit that operates at a very high capacity factor.
Batteries: These are used in the substation control house as a backup to power the control systems in case of a power blackout.
Bonding Jumper: A bare or insulated conductor used to ensure the required electrical conductivity between metal parts required to be electrically connected. Frequently used from a bonding bushing to the service equipment enclosure to provide a path around concentric knockouts in an enclosure wall - also used to bond one raceway to another.
Boron (B): A chemical element, atomic number 5, semi-metallic in nature, used as a dopant to make p-semiconductor layers.
Breakdown Voltage: The voltage at which an insulator or dielectric ruptures, or at which ionization and conduction take place in a gas or vapor.
Bushing: An insulating structure, including a through conductor or providing a passageway for such a conductor, with provision for mounting on a barrier, conducting or otherwise, for the purposes of insulating the conductor from the barrier and conducting current from one side of the barrier to the other.
Bus Support Insulators: These are porcelain or fiberglass insulators that serve to isolate the bus bar switches and other support structures and to prevent leakage current from flowing through the structure. These insulators are similar in function of other insulators used in substations and transmission poles and towers.
