Siemens SIRIUS 3RH Series, System Manual

Page: 145 / 786

SIRIUS 3RT2 contactors/contactor assemblies
2.4 Configuration
SIRIUS Innovations
System Manual, 01/2011, A8E56203870002-03
145
Switching off
During the switch-off of AC-operated contactors, the contactor may no longer switch off in
case of control circuit interruption due to an excessive line capacity of the control cable.
The following counter-measures can be taken:
●
Changed circuit topology to allow for the application of shorter control cables.
● Application of DC-operated contactors.
● Reduced control voltage.
● Application of a contactor whose magnet coil has a higher holding power.
● Parallel connection of an ohmic resistance for increased holding power.
Sizing of the parallel resistance Power of the additional resistance
5 LQ˖
S
&
/
3
LQ:
S
8
6
5
S
For reasons of cost effectiveness, P
P
should be lower than 10 W.
Table 2- 17 Calculation of the maximum cable length
For pushbutton switch control For maintained-contact operation
For pushbutton switch control with a three-core cable, a line
capacity of 0.6 μF/km (2 x 0.3 μF/km) should be expected.
For maintained-contact operation with a two-core cable, a
line capacity of 0.3 μF/km should be expected.
1/
/
(
(
&
&
1/
/
&
LQP
SHUP
,
ຘ6
+
6
ຘ 8
ຘ
LQP
SHUP
,
ຘ 6
+
6
ຘ 8
U
S
Rated control supply voltage in V
S
H
Holding power of the contactor in VA
U
S
Rated control supply voltage in V
S
H
Holding power of the contactor in VA