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3RW3 semiconductor motor control unit
SIRIUS System Manual
8-24
GWA 4NEB 430 0999-02b
8.3.3.3 Combining the 3RT contactor with the 3RU1 thermal overload relay and 3RW3 soft starter
Frame size of the
overload relay
The frame size selected for the overload relay should be large enough so
that it is just possible to set the current value calculated.
In the event of current values that are lower than can be set for the speci-
fied overload relay, the next smaller overload relay must be used.
Important
It is not permissible to mount the thermal overload relay under the contac-
tor/connecting lead/soft starter combination.
The overload relay must be integrated in the feeder before the contractor/
connecting lead/soft starter combination. The specified correction factors
apply only to this permissible mounting sequence.
Figure 8-11: 3RT+3RU1+3RW3 combination
Minimum clearance
For thermal reasons, a minimum clearance is necessary between the con-
tactor/overload relay combination and the soft starter, as is a minimum
length of the connecting leads.
The following table specifies the minimum clearances and minimum lengths
of the connecting leads for the various frame sizes:
Table 8-9: 3RW3 installation guidelines, minimum clearances/lengths
3RT
3RU1
Connecting
lead
3RW
3RT
3RU1
3RW
Rail 1:
Combination of 3RT1 contac-
tor and 3RU1 thermal over-
load relay
Rail 2:
3RW3 soft starter
Frame size
Minimum clearance bet-
ween rail 1 and rail 2
(center to center) in mm
Minimum length of the
connecting lead
in mm
S00
160
100
S0
200
150
S2
240
200
S3
300
250