Siemens 3VA1 100 A Manual page 151

The diagram below uses the example of an ET200S to illustrate the conventional method of
connecting the electronics-compatible auxiliary switch AUX, the trip alarm switch TAS and
the motor operator MO320 to a distributed I/O unit.
Further information about contact reliability can be found at the end of this chapter.
Auxiliary switches AUX
The purpose of auxiliary switches is to signal the position of the main contacts of the molded
case circuit breaker. The contacts of the auxiliary switch open and close simultaneously with
the main contacts of the molded case circuit breaker.
Leading changeover switches LCS
Leading changeover switches signal the opening of the main contacts with a lead time of 20
ms in advance of circuit breaker trips and are thus used for load shedding, for example.
Trip alarm switches TAS
Trip alarm switches signal every circuit breaker trip, regardless of the cause of the trip. The
trip alarm switches are operated whenever the molded case circuit breaker switches to the
TRIP position.
3VA molded case circuit breakers
Manual, 04/2015, A5E03603177010-02
Accessories
4.2 Internal accessories
151