Two-Hand Operation/Synchronism - Siemens SIRIUS 3SK1 Manual

Safety systems - General information
4.3 Basic terminology
4.3.10

Two-hand operation/synchronism

Synchronous sensor operation is a special form of simultaneity of sensors.
In this case, it is not sufficient for sensor contacts 1 and 2 to be switched to the closed state
at different times, they must be closed within 0.5 seconds.
Synchronism of sensors is required, in particular, in the case of two-hand operation of
presses. This ensures that the presses only become active when the sensors are operated
simultaneously with both hands. This minimizes the risk of the operator getting a hand in the
press.
When 3SK1 safety relays are used, you can achieve applications up to type IIIc in
compliance with EN 574 (applications up to PL e/Cat. 4 in compliance with EN 13849-1 or
SILCL 3 in compliance with IEC 62061).
Note
In the delivery state of 3SK1 safety relays, monitoring of time synchronism is deactivated.
Time synchronism can be activated using the following adjustable parameter for 3SK112
Advanced and 3SK122 Advanced:
• Jumper T1/PAR (NO/NC evaluation)
• DIP switches (1) Autostart
• DIP switches (3) 2 x single-channel
Note
The 3SK1 Advanced safety relays exclusively support two-hand control units with two NO
contacts.
Note
The two-hand circuit must be marked in compliance with EN 574. You can find information
on determining the response time in the section entitled Response times (Page 194).
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SIRIUS 3SK1 safety relays
Manual, 06/2018, A5E02526190021A/RS-AD/004