Siemens SENTRON 3VL System Manual page 85

Mounting rail connection
The appropriate safety clearances must be observed. Terminal covers or phase barriers are
available for the front connecting bars. Circuit breakers cannot be removed from the plug-in
socket in the "On" position. The circuit breaker will switch to the "tripped" position if attempts
are made to remove it in the "ON" position.
Withdrawable version
SENTRON VL circuit breakers can be used as withdrawable devices. They can be
connected on either the front or the back. Safety covers are provided and are required for
final installation.
In the connected position, the circuit breaker is completely engaged, and all contacts -
supply, outgoing and auxiliary contacts - are connected to the guide frame. The circuit
breaker is ready for operation.
Note
Safety interlock
A safety interlock prevents the circuit breaker from being removed when it is switched on.
The safety interlock causes the circuit breaker to switch off so that the arc which occurs
inside the circuit breaker when current flows can be extinguished.
3VL molded-case circuit breakers
System Manual, 03/2009, 110 0110 - 02 DS 01
Installing/mounting
7.1 Installation methods
85