Siemens SENTRON 3VL System Manual page 64

Functions
5.2 Voltage protection
Leading auxililary switch for switching from "OFF" to "ON" (leading NO contact)
Application example:
If the circuit breaker is equipped with an undervoltage release, and the leading auxiliary
switch is installed in the rotary operating mechanism, the leading NO contacts make it
possible to supply the undervoltage release with power before the main contacts can be
closed.
Leading auxiliary switch for switching off (leading NC contact)
Application example:
In applications with thyristors, it is necessary to reset the power electronics of the converter
before the main circuit is switched off.
Circuit breakers with leading auxiliary switches create a leading signal that enables selective
deceleration of the thyristor.
Designation of the auxiliary switches and the alarm switches in the circuit breaker, and designation of
the connecting cables
MLFB
3VL9400-2AB00/01
3VL9400-2AD00/01
Cable designations
MLFB
3VL9800-2AC00/01
3VL9800-2AE00/01
Cable designations
64
Pos. 1
NC
NC
HS1/2
Pos. 1 Pos. 2
NC NO
NC NO
HS1/2 HS3/4
System Manual, 03/2009, 110 0110 - 02 DS 01
Pos. 2 Pos. 3
NO -
NO NO (AS)
HS3/4 AS
Pos. 3 Pos. 3
NC NO
- NO (AS)
HS5/6 HS7/8 or AS
3VL molded-case circuit breakers