SIVACON 8PS - Configuring with LX system
Configuration Manual, 10/2011, A5E02194899-02
201
Glossary
A
The manufacturers of low-voltage switchgear and controlgear assemblies specify rated
values in compliance with DIN EN 60439-1. These rated values apply to specified operating
conditions and characterise the suitability of a switchgear assembly. The rated values must
always be referred to when combining equipment or configuring switchgear and controlgear
assemblies.
Rated short-time withstand current (I
cw
) DIN EN 60439-1; 4.3
As the rms value of the short-circuit current, the rated short-time withstand current
characterises the thermal strength of a switchgear and controlgear assembly circuit under a
transient load. The rated short-time withstand current is normally determined for a duration of
1 s; deviating time values must be specified. The rated short-time withstand current is
specified for the trunking and/or main busbars of a switchgear and controlgear assembly.
Rated peak withstand current (I
pk
) DIN EN 60439-1; 4.4
As the peak value of the impulse current, the rated peak withstand current characterises the
dynamic strength of a circuit in a switchgear and controlgear assembly. The rated peak
withstand current is specified for the trunking and/or main busbars of a switchgear and
controlgear assembly.
Rated conditional short-circuit current (I
cc
) DIN EN 60439-1; 4.5
The conditional rated short-circuit current corresponds to the uninfluenced short-circuit
current that a circuit in a switchgear and controlgear assembly, protected by a short-circuit
protective device, can carry without damage (for a certain time). The conditional rated short-
circuit current is therefore specified for tap-off units and/or infeeds with circuit-breakers, for
example.
Rated impulse withstand voltage (U
imp
) DIN EN 60947-1; 4.3.1.3
This is a measure of the strength of the air paths in the interior of the switchgear in relation to
transient overvoltages. Suitable switchgear can be used to ensure that deactivated parts of a
system cannot transmit overvoltages from the line on which they are used.
Rated current (I
n
) (of a circuit-breaker) DIN EN 60947-2; 4.3.2.3
The current that is identical, for the circuit-breaker, to the rated continuous current and the
conventional thermal current.
➜ Rated uninterrupted current
