Siemens SIRIUS System Manual

3RT1/3RH1 contactors
SIRIUS System Manual
GWA 4NEB 430 0999-02b
3-75
Diode
Figure 3-58: Circuit with a diode (AC/DC operation)
This is what happens when a coil is disconnected that is connected to a
diode:
Advantages: No overvoltage occurs during disconnection. The diode block
becomes effective at 0.6 V.
Disadvantage: The diode can only be used for DC operation.
The break time of the contactor is considerably increased and amounts to 6
to 9 times the off-delay.
This increased break time can be used, if necessary, for control purposes,
such as for bridging brief interruptions in voltage.
Zener diodes (diode combinations) are available for shorter break times. The
break time then amounts to 2 to 6 times the off-delay.
Surge suppressors
The following surge suppressors are available for the 3RT1 contactors:
Table 3-28: Surge suppressor
Circuit with diode
(
DC o
p
eration
)
0
200
20
U
Sp
[V]
0
t [
µ
s]
U
Sp
= 0,6 V = U
SP
der Diode
^
Surge suppressor With LED
Without
LED
For S00 For S00 For S0 For S2, S3
Suppression diode
x x -- --
Diode combination:
suppression diode and Zener
diode
--xxx
Varistor
xxxx
RC element
--xxx

Siemens SIRIUS Specifications

General

Brand	Siemens
Model	SIRIUS
Category	Relays
Language	English