SIRIUS 3RT2 contactors/contactor assemblies 
  2.4 Configuration 
SIRIUS Innovations 
System Manual, 01/2011, A8E56203870002-03 
117 
Application area  Description and suitable contactor versions 
Contactor assemblies 
Operation of a motor in 
two directions of 
rotation 
(3RA23 reversing 
contactor assembly) 
 
Contactor assembly for operation of a three-phase motor in two directions of rotation. 
  3RA23 reversing contactor assemblies 
 
Starting three-phase 
motors with reduced 
starting current peaks 
(3RA24 contactor 
assembly for star-delta 
(wye-delta) start) 
 
Contactor assembly for reducing the starting current and starting torque when starting three-
phase motors. 
  3RA24 contactor assemblies for star-delta (wye-delta) start 
 
 
2.4.2  Drive system/Coil selection 
The 3RT2 power contactors and 3RH2 contactor relays can be supplied with drives for all 
standard AC and DC coil voltages. In addition, 3RT2 power contactors of size S0 are 
available with electronic UC drives, which feature an extended operating range (helping to 
reduce variance) and have lower closing and holding powers, which enable less power to be 
consumed in the control cabinet. The UC drive can be operated with either AC or DC 
voltage. This is facilitated by control electronics with an upstream DC drive.  
 
  AC and DC drives  Electronic drive (UC drive) 
Control voltage  AC control or DC control  UC control 
Operating range  0.8 to 1.1 x U
S
1)
  0.7 to 1.3 x U
S
 
Coil surge 
suppressor 
Optional (integrated in coupling relays)  Integrated 
Preferred 
voltages 
  24 V 
  110 V 
  220/230 V 
  21 to 28 V 
  95 to 130 V 
  200 to 280 V
2)
 
Reduced variance 
  30 versions for AC control 
  15 versions for DC control 
3 versions for the entire AC/DC range 
Coil power
3)
: 
  Switch-on 
  Holding 
AC coil 
  65 VA 
  8.5 VA 
DC coil 
  5.9 W 
  5.9 W 
AC mode 
  6.5 VA 
  1.26 VA 
DC mode 
  6.7 W 
  0.8 W 
1)
  For further details, refer to the chapter titled "Technical data". 
2)
  At 280 V: high limit = 1.1 x U
S
. 
3)
  Example: contactor (size S0), 7.5 kW, 24 V.