Monitored Start - Siemens SIRIUS 3SK1 Manual

4.3.9

Monitored start

For a monitored start, the device is started by operating the START button, but only after the
input image has been checked and a positive test of the safety relay has been conducted.
Contrary to the manual start, the monitored start evaluates a signal change of the START
button. This means that the START button cannot be bypassed (misuse). For PL e (ISO
13849-1) as well as SIL 3 (IEC 62061), the monitored start must be used in the case of
EMERGENCY STOP. For other safety sensors/functions, the necessity for a monitored start
command depends on the risk assesment.
If the START button is operated for more than 2 seconds, the 3SK1 basic unit detects a
wiring short-circuit in the START button and switches to the fault state (Device = green; SF =
flashing red; Out = flashing yellow; IN = off)
Note
In the delivery state of the 3SK1 safety relays, the start type is set to "Monitored start".
Figure 4-4
SIRIUS 3SK1 safety relays
Manual, 06/2018, A5E02526190021A/RS-AD/004
Start function "Monitored start"
Safety systems - General information
4.3 Basic terminology
37