SIRIUS 3RU2/3RB3 overload relays 
  5.10 Technical data 
SIRIUS Innovations 
System Manual, 01/2011, A8E56203870002-03 
541 
Type  3RU21 16  3RU21 26 
Size  S00  S0 
Width  45 mm  45 mm 
Current setting  A  0.11 to 0.16 to  
11 to 16 
1.8 to 2.5 to  
34 to 40 
Power loss per device (max.)  W  3.9 ... 6.6  3.9 ... 6 
Short-circuit protection 
  With fuse without contactor 
See "Selection and ordering data" in Catalog 
LV 1 N SIRIUS Innovations 
  With fuse and contactor 
See the chapter titled "Motor starter protectors (Page 379)" 
Protective separation between main and 
auxiliary courrent paths 
acc. to IEC/EN 60947-1 
V  440 
5.10.2.3  Conductor cross-sections main circuit 
Table 5- 40  Technical data for the main circuit connection, 3RU21 overload relays 
Type  3RU21 16  3RU21 26 
Size  S00  S0 
Width  45 mm  45 mm 
Connection type  Screw connection 
  Connection screw 
M3, Pozidriv size 2  M4, Pozidriv size 2 
  Operating tool 
∅ 5 to 6  ∅ 5 to 6 
  Tightening torque 
Nm  0.8 to 1.2  2 to 2.5 
  Conductor cross-sections (min./max.), 1-wire or 2-wire connection possible 
- Solid  mm
2
  2 x (0.5 to 1.5)
1)
 
; 2 x (0.75 to 2.5)
1) 
 
2 x (0.5 to 4)
1) 
 
2 x (1 to 2.5)
1) 
 
2 x (2.5 to 10)
1) 
 
- Finely stranded with end sleeve 
(DIN 46228 Part 1) 
mm
2
  2 x (0.5 to 1.5)
1) 
 
2 x (0.75 to 2.5)
2)
 
2 x (1 to 2.5)
1)
 
; 2 x (2.5 to 6)
1) 
; max. 1 x 10 
 
- AWG cables, solid or stranded  AWG  2 x (20 to 16)
1)
 
; 2 x (18 to 14)
1) 
2 x 12 
2 x (16 to 12)
1)  
2 x (14 to 8)
1)
 
Connection type  Spring-loaded connection 
  Operating tool 
∅ 3.0 x 0.5 ∅ 3.5 x 0.5 
  Conductor cross-sections (min./max.) 
- Solid  mm
2
  1 x (0.5 to 4)  1 x (1 to 10) 
- Finely stranded without end sleeve  mm
2
  1 x (0.5 to 2.5)  1 x (1 to 6) 
- Finely stranded with end sleeve 
(DIN 46228 Part 1) 
mm
2
  1 x (0.5 to 2.5)  1 x (1 to 6) 
 
- AWG cables, solid or stranded  AWG  1 x (20 to 12)  1 x (18 to 8)