Feedback Circuit; Stop Category 0 - Siemens SIRIUS 3SK1 Equipment Manual

With 3SK1 semiconductor devices, the signaling circuits are always implemented as NO circuits.
This means that when the safety function is triggered, or a fault is detected, the signaling circuits
will open.
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 safety-related outputs can only be activated if
the feedback circuit is closed.
Note
When 3SK1 expansion units are used on 3ZY12 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.
Ensuring electrical safety and safety function
The normally closed contact of 3RQ12. is designed for a voltage of 24 V DC. If higher voltages
occur, electrical safety cannot be ensured due to the voltage clearance distances. If the 3RQ12.
is integrated in a system with a device connector, the feedback circuit is routed via the device
connector; connection of external voltage is not necessary and not permitted. Connecting
external voltage can bypass the safety function.
4.3.6 Stop category

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
Time-delayed shutdown of safety-related outputs in accordance with Stop category 1 is not
ensured under all operating states.
In the case of some internal device faults, and when disconnecting the supply voltage, these
safety-related outputs are switched off instantaneously .
SIRIUS 3SK1 Safety Relays and 3RQ1 Positively-Driven Coupling Relays
Equipment Manual, 05/2021, A5E02526190021A/RS-AE/005
DANGER
Safety systems - General information
4.3 Basic terminology
45