Siemens SIRIUS 3RT Manual page 301

Surge suppressor Suitable
for
Control
voltage
RC AC/DC
elements
Suppressor AC/DC
diode
The drop-out speed falls to zero once or twice for a few milliseconds:
1)
● 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.
SIRIUS - SIRIUS 3RT Contactors/Contactor assemblies
Manual, 09/2017, A5E03656507120A/RS-AE/006
Overvoltage Effect
is limited ...
According
OFF-delay
•
to
remains
dimensioning
unchanged
Rates of rise
•
of voltage are
attenuated
Breakdown
Rate of rise of
•
voltage U
the voltage is
BR
not reduced
Additional
•
drop-out
delay is too
low
(1 to 5 ms)
Advantages/disadvantages
Advantages
RF attenuation
•
Well suited to AC
•
voltage
Attenuation
•
independent of
levels
Disadvantages
High inrush
•
current
Sensitive to
•
harmonics
Advantages
Non-critical
•
dimensioning
Simple design
•
Protected against
•
reverse polarity
Short pick-up
•
time
Disadvantages
Attenuation only
•
above the
breakdown
voltage U
Accessories
9.4 Surge suppressor
Preferred
application
With critical
operating times
Suitable for
most standard
applications,
e.g. in the
SIMATIC
environment
BR
301