Siemens SIRIUS 3SK1 Manual page 16

Product-specific safety information
2.1 General safety notes
Safe functional extra-low voltage
The 3SK1 safety relays with a supply voltage of 24 V DC must be operated with safe
functional extra-low voltage (SELV, PELV). This means these modules must only be
subjected to a voltage of Um even in the event of a fault. The following applies for these
3SK1 safety relays: Um < 60.0 V.
You can find more detailed information about safe functional extra-low voltage in the data
sheets of the power supplies to be used.
Protection against electrostatic charge
When handling and installing 3SK1 safety relays, ensure that the components are protected
from being electrostatically charged. Changes to the system configuration and wiring are
only permissible while the supply voltage is switched off.
Connection of 3SK1 safety relays is only permissible when the power supply units (PELV
and SELV) are switched off.
Noise immunity / grounding
The following must be grounded in accordance with the regulations to ensure noise
immunity of the 3SK1 safety relays:
• PELV / SELV power supply units (please also note the documentation for the respective
Note
Cover the 3ZY12 device connector on the left-hand side using the cover supplied with the
device termination connector.
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WARNING
CAUTION
CAUTION
power supply unit in this regard).
SIRIUS 3SK1 safety relays
Manual, 06/2018, A5E02526190021A/RS-AD/004