SIRIUS 3RU2/3RB3 overload relays   
5.6 Mounting 
  SIRIUS Innovations 
508  System Manual, 01/2011, A8E56203870002-03 
5.6  Mounting 
5.6.1  Mounting options 
Mounting options for the 3RU21 
3RU21 thermal overload relays are matched to 3RT contactors in terms of their electrical 
and mechanical features. As a result, direct mounting can be achieved easily. Alternatively, 
the devices are suitable for stand-alone assembly.  
Mounting options for the 3RB30/3RB31 
3RB30/3RB31 solid-state overload relays are suitable for space-saving, direct mounting onto 
3RT contactors as well as for stand-alone assembly. 
5.6.2  Minimum clearances and mounting position 
Minimum clearance 
A minimum lateral clearance of > 6 mm must be maintained from grounded parts. 
Mounting position for 3RU21 thermal overload relay 
The diagrams below illustrate the permissible mounting positions for contactor mounting and 
stand-alone assembly in the case of 3RU21 thermal overload relays.  
Table 5- 13  Permissible mounting positions for the 3RU21 
Overload relay, stand-alone assembly  Contactor + overload relay 
,
H
[ ,
,
H
[
,
H
[
rr
 
 
The set value is 1.1 times the motor current for a mounting position in the hatched area. 
Mounting position for 3RB30/3RB31 solid-state overload relay 
For 3RB30/3RB31 solid-state overload relays any mounting position can be chosen as 
required.