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Glossary
LOW VOLTAGE SWITCHGEAR AND CONTROL GEAR
Circuit Breaker
A switching device capable of making, carrying and breaking currents
under normal circuit conditions and also making, carrying for a
specified time, and breaking currents under specified abnormal circuit
conditions such as those of short circuit.
Disconnector
A mechanical switching device which, in the open position, complies
with the requirements specified for the isolating function.
Enclosure
A part providing a specified degree of protection against certain
external influences and a specified degree of protection against
approach to or contact with live and moving parts.
Fuseboard
A enclosure containing bus-bars, with fuses, for the purpose of
protecting, controlling or connecting more than one outgoing circuit
fed from one or more incoming circuits. (Also known as a Distribution
Fuseboard).
Fuse Combination Unit
A combination of a mechanical switching device and fuses in a composite
unit.
Isolation
Function intended to cut-off the supply from all or a discrete section
of the installation by separating the installation or section from
every source of electrical energy for reasons of safety.
Integrally Fused Circuit Breaker
A combination, in a single device, of a circuit breaker and fuses,
one fuse being placed in series with each pole of the circuit breaker.
Short Circuit
The accidental or intentional connection, by relatively low resistance
or impedance, of two or more points in a circuit.
Short Circuit Current
An over-current resulting from a short circuit.
Switch (Mechanical)
A switching device capable of making, carrying and breaking currents
under normal circuit conditions which may include specified operating
overload conditions and also carrying for a specified time currents
under specified abnormal circuit conditions such as those of short
circuit.
Switch Disconnector
A switch which, in the open position, satisfies the isolating requirements
specified for a disconnector.
Switch Disconnector Fuse
A switch disconnector in which the poles have a fuse in series in
a composite unit.
Starter
The combination of all the switching means necessary to start and
stop a motor, in combination with suitable overload protection.
Short Circuit Protector Device
(SCPD) A device intended to protect a circuit or parts of a circuit
against short circuit currents by interrupting them.
Short Circuit Making Capacity
A making capacity for which prescribed conditions include a short
circuit at the terminals of the switching device.
Utilisation Category (For a switching device or fuse)
a combination of specified requirements related to the conditions
in which the switching device or fuse fulfils its purpose.
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