Signaling Circuit; Feedback Circuit; Stop Categories - Siemens SIRIUS 3SK1 Manual

4.3.4

Signaling circuit

A current signaling path provides a safety-related output signal. Signaling circuits can be
implemented with either NC or NO contact functionality.
With 3SK1 relays, the signaling circuits are always implemented as NC circuits. This means
that when the safety function is triggered, or a fault is detected, the signaling circuits will
always close.
4.3.5

Feedback circuit

A feedback circuit is used to monitor controlled actuators (e.g. relays or load contactors) with
positively driven contacts or mirror contacts. The enabling circuits can only be activated with
the feedback circuit closed.
Note
When 3SK1 expansion units are used on 3ZY1 device connectors with 3SK1 Advanced
basic units, it is not necessary to incorporate the expansion modules in the feedback circuit
wiring. This is implemented internally via the device connector.
4.3.6

Stop categories

Stop category 0
Non-controlled shutdown by immediately switching off the power to the machine's drive
elements.
Stop category 1
Controlled stopping where the energy feed is interrupted with a time delay, or is only
interrupted once standstill has been reached.
Note
The time-delayed shutdown of enabling circuits in accordance with Stop category 1 is not
guaranteed under all operating states.
In the case of some internal device faults, and when disconnecting the supply voltage, these
enabling circuits are switched off instantaneously.
3SK1 safety relays
Manual, 04/2013, A5E02526190021A/RS-AA/01
Safety systems - General information
4.3 Basic terminology
33