Siemens SIRIUS 3SK1

When using a 3SK1 safety relay with instantaneous and time-delayed contacts, the two following
safety notes must always be observed:
NOTICE
In the event of external faults such as:
• Cross-circuit fault
• Short circuit to ground
• Current-source short circuit
and to access the con󹪝guration mode for copying a delay time after a reset, the following
device behavior must always be taken into account:
The outputs of stop category 0 switch instantaneously, while the outputs of stop category 1
have a time delay.
The sequence cannot be interrupted.
Exception: Switching o󹪜 the power supply.
NOTICE
Saving the starting command:
1. If the safe state is restored during the time delay, (e.g. the protective door is closed) and the
START button is actuated, the safety-related outputs switch to the active position
immediately after the delay time has elapsed.
The actuation of the START button is saved.
The OFF-delayed enabling contacts or outputs of the 3SK112-CB4 safety relays (relay and
semiconductor outputs) cannot be retriggered. This means that if an OFF command in the
sensor circuit is canceled before the delay time has elapsed, the delay time still elapses in
full length. If a start command has been issued during this time or if autostart has been set,
after this time has elapsed the OFF-delayed enabling contacts switch o󹪜 brie󹪞y and switch
on again immediately with the instantaneous enabling contacts (start command is saved).
2. If a sensor is actuated at an input expansion within the system con󹪝guration, the entire
system is disconnected. If the START button on the basic unit is then pressed while the
sensor on the input expansion is actuated (for instance, if the protective door is open), the
command will be saved by the basic unit. This results in an automatic start of the system
once the sensor at the input expansion is reset (for example, a protective door is closed
again). This system response is identical in the system con󹪝guration for all 3SK1 basic units.
For additional notes/explanations on this topic, see the following FAQ (https://
support.industry.siemens.com/cs/ww/en/view/103655974)
NOTICE
Observe the following in the case of protective doors with tumblers:
If the voltage Us is disconnected on devices with time-delayed outputs between switching the
instantaneous outputs and the time-delayed outputs, the delay time expires when the voltage
Us is restored, and the time-delayed contacts change their switch positions.
Con󹪝guration / operation
9.2 Explanation of the device's functions
SIRIUS 3SK1 Safety Relays and 3RQ1 Positively-Driven Coupling Relays
178 Equipment Manual, 05/2021, A5E02526190021A/RS-AE/005