Siemens Sentron 3VA Manual page 391

Motor operator actuation controlled via control cable and undervoltage release
S0
S1
S01
K1
U<
F1
L1
L2
This circuit is deployed in order to prevent no-load operation of the molded case circuit
breaker. The contact of auxiliary contactor K1 prevents no-load operation when the
undervoltage release "U<" is de-energized.
No-load operations subject the molded case circuit breaker to high stresses. If the
undervoltage release is de-energized, auxiliary contactor K1 has not picked up. The contact
in the ON circuit (control circuit) of the motor operator is thus not closed, that is, the molded
case circuit breaker cannot be switched.
This auxiliary contactor is not necessary when the undervoltage release is supplied
uninterrupted (e.g. pushbutton S01) from the same source as the motor operator itself
(e.g. contact 3).
3VA molded case circuit breakers with UL and IEC certification
Manual, 01/2019, L1V30435333-01
OFF (to be provided by customer)
ON (to be provided by customer)
Remote command (to be provided by customer)
Auxiliary contactor (to be provided by customer)
Undervoltage release (to be provided by customer)
Fuse in the control circuit (to be provided by customer)
Indicator light AUTO mode (to be provided by customer)
Indicator light MAN mode (to be provided by customer)
Technical specifications
6.1 Circuit diagrams
389