SIRIUS 3RU2/3RB3 overload relays 
  5.10 Technical data 
SIRIUS Innovations 
System Manual, 01/2011, A8E56203870002-03 
537 
5.10.1.3  Equipment 
Table 5- 35  Equipment on 3RU21 and 3RB20/3RB31 overload relays 
Feature  Description  3RU21  3RB30/3RB
31 
RESET function 
  Enables manual or automatic resetting of the relay 
✓  ✓ 
Remote RESET function 
  Enables remote resetting of the relay 
✓ 
(by means 
of separate 
module) 
✓ 
(3RB31 only 
with 
24 V DC) 
TEST function for auxiliary contacts 
  Allows easy checking of function and wiring 
✓  ✓ 
TEST function for electronics 
  Allows checking of the electronics 
--  ✓ 
Status display 
  Indicates the current operating state 
✓  ✓ 
Integrated auxiliary contacts 
(1 NO + 1 NC) 
  Allow the load to be disconnected in the event of 
an irregularity 
  Can be used to output signals 
✓  ✓ 
5.10.1.4  Configuration of load feeders 
Table 5- 36  Configuration of load feeders 3RU21 and 3RB30/3RB31 
Feature  Description  3RU21  3RB30/3RB
31 
Short-circuit-proof up to 100 kA at 
690 V 
(in conjunction with the appropriate 
fuses or the appropriate motor starter 
protector) 
  Provides optimum protection of the loads and 
operating personnel in the event of short circuits 
due to insulation faults or faulty switching 
operations 
✓  ✓ 
Electrical and mechanical matching 
to 3RT2 contactors 
  Simplifies configuration 
  Reduces connection outlay and costs 
  Enables stand-alone assembly as well as space-
saving direct mounting 
✓  ✓ 
Spring-loaded connection system for 
main circuit 
  Enables fast connections 
  Ensures that connections are vibration-resistant 
  Enables maintenance-free connections 
✓  ✓ 
Spring-loaded connection system for 
auxiliary circuits 
  Enables fast connections 
  Ensures that connections are vibration-resistant 
  Enables maintenance-free connections 
✓  ✓