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Magnefix MD4
991.184 G01 03
107
8.2 Abnormal
Operating conditions
Rated voltage, current, power
The voltage, current and power upon which the design
of the switchgear is based.
Short-circuit
An unintentional connection between two or more
electrical conductors, or between a conductor and
earth, in which extreme heat may be generated which
may damage the installation and its surroundings.
Short-circuit current
An electrical current which is higher, as a result of a
short-circuit, than the nominal current.
Arc
An electrical discharge, through the insulation, which
produces a short-circuit. In general, and in particular in
air-insulated installations, arcing may occur
unexpectedly and be of an explosive nature.
8.3 Equipment and the area surrounding it
Electrical installation
An assembly of electrical leads and the appliances to
which the leads are connected.
Switching and distribution unit, switchgear
A unit to protect or switch on or off, in one place, two
or more parts of an electrical installation.
Switchroom:
The location in which the switchgear is set up.
Working area:
A clearly designated part of the switchroom in which
work on the installation can be carried out safely.
Switch:
A device for the purpose of switching electrical
currents on and off.
Load-break switch:
A switch capable of safely switching on a short-circuit
current and switching off a nominal current.
Circuit-breaker:
A switch capable of safely switching on and switching
off a short-circuit current.
N
OTE
The vacuum circuit-breaker used in the protected
panel is a variant that can switch off
autonomously. Switching on is only possible when
the circuit is dead and the power is down.
Fuse:
An electrical appliance which is connected in series
with a circuit, and can interrupt the circuit safely by the
melting of an internal conductor immediately the
current in the circuit exceeds a specified value for a
specified time.
Cartridge fuse:
The replaceable part of a fuse which contains the
(fusible) conductor.