Abnormal Operating Conditions; Equipment And The Area Surrounding It - Eaton Magnefix MD4 User Manual

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.
Magnefix MD4
991.184 G01 03 107