Siemens SIRIUS 3RT Series System Manual page 140

SIRIUS 3RT2 contactors/contactor assemblies
2.4 Configuration
φ = switchover current factor = switchover current peak/starting current peak
The switchover current factor has a theoretical maximum value of 2.
Example measurements:
Favorable circuit: φ = 0.8
Unfavorable circuit: φ = 1.37
Note
See the main and control circuit wiring designs below; these depict the circuit diagrams for
contactor assemblies for star-delta (wye-delta) start with clockwise and counterclockwise
rotation according to the preferred wiring.
Main circuit
The diagram below shows the preferred main circuit wiring for a star-delta circuit, clockwise
and counterclockwise rotation.
Figure 2-16
140
Main circuit of the contactor assembly for star-delta (wye-delta) start
SIRIUS Innovations
System Manual, 01/2011, A8E56203870002-03