SIRIUS 3RT2 contactors/contactor assemblies
2.7 Accessories
SIRIUS Innovations
172 System Manual, 01/2011, A8E56203870002-03
Surge suppressor Suitable for
Control
voltage
Overvoltage
is limited ...
Effect Advantages/disadvantages Preferred
application
Advantag
es
Energy absorption
Non-critical
dimensioning
Simple
implementation
Varistor
AC/DC To varistor
voltage
OFF-delay
becomes only
slightly longer
(2 to 5 ms)
Disadvan
tages
Attenuation only
above U
VDR
Suitable for
most standard
applications,
e.g. in the
SIMATIC
environment
Advantag
es
RF attenuation
Well suited to AC
voltage
Attenuation
independent of
levels
RC
elements
AC/DC According
to
dimensionin
g
OFF-delay
remains
unchanged
Rates of rise of
voltage are
attenuated
Disadvan
tages
High inrush current
Sensitive to
harmonics
With critical
operating times
1)
The drop-out speed falls to zero once or twice for a few milliseconds:
● Safe drop-out is always ensured during current-free switching.
● When switching with a current present, the contacts are subjected to a higher thermal
load. This can lead to an overload when switching at the high current limit.
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