Glossary For Low Voltage Switchgear & 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.