a c potentiometer
An apparatus for the comparison of a.c. voltages. Balance requires both the magnitude and the phase angle of the unknown voltage to be balanced with the known voltage. This may be done either in cartesian form or in polar form
Absolute value
Value of an expression without regard to sign or phase angle.
accumulator
Storage battery or secondary cell for storing electricity.
Back flashover
Flash-over occurring from an object usually at earth potential to a line conductor due to the potential of the earthed object rising due to lightning.
Base load capacity
Capacity of generating equipment operated to serve loads 24-hours per day.
Bode plot
Semi-log plots of the magnitude and phase angle of a transfer function (or performance) against frequency.
Breeder reactor
A nuclear reactor which produces the same kind of fissile material as it burns. For example, a reactor using plutonium as a fuel can produce more plutonium than it uses by conversion of Uranium-238.
Bridge rectifier
A full-wave rectifier where the diodes are connected in a bridge circuit . This allows the current to the load during both the positive and negative alternation of the supply voltage. This is the most common type of rectifier circuit to produce a unidirectional voltage for an alternating input.
British thermal unit BTU
Quantity of heat required to raise the temperature of 1 pound of water through 1 oF. It is equal to 1054 joule or 251.98 calories.
Broadband communications
The result of utilities forming partnerships to offer consumers "one-stop-shopping " for energy-related and high-tech telecommunications services.
Buffer register
The register that holds digital data temporarily.
Busbar
A rigid conductor used for connecting together distributors or feeders.
Butterworth filter
A filter designed to produce a flat response up to the cut-off frequency.
cable
Conducting wire or wires separated and surrounded by a dielectric substance or insulation.
cable channel
An enclosure situated above or in the ground, ventilated or closed, and having dimensions which do not permit the access of persons but allow access to the conduits and/or cables throughout their length during and after installation. A cable channel may or may not form part of the building construction.
cable coupler
A means of enabling the connection or disconnection, at will, of two flexible cables. It consists of a connector and a plug.
cable ducting
An enclosure of metal or insulating material, other than conduit or cable trunking, intended for the protection of cables which are drawn in after erection of the ducting.
Cable tunnel
A corridor containing supporting structures for cables and joints and/or other elements of wiring systems and whose dimensions allow persons to pass freely throughout the entire length.