4.4.1
Restart interlock
Overview
The restart interlock prevents the machine from automatically starting up, for example
after a protective device has responded while the machine is operating or after chang‐
ing the machine’s operating mode.
Depending on the regulations which apply at the place of installation, a restart interlock
may be required.
The protective device has an internal restart interlock. You must therefore implement a
restart interlock externally via the circuitry or the control if needed, e.g. in connection
with the SICK RLY3-OSSD2 / RLY3-OSSD3 safety relay.
Functionality
Before the machine can be restarted, the operator must reset the restart interlock.
!
§
"
$
Figure 13: Schematic representation of operation with restart interlock
The dangerous state of the machine (
!
) is brought to an end if the light path is inter‐
rupted (
"
) and is not re-enabled (
§
) until the operator presses the reset pushbutton
located outside the hazardous area (
$
). The machine can then be restarted.
Depending on applicable national regulations, a restart interlock must be available if it
is possible to stand behind the protective device. Observe IEC
60204-1.
4.4.2
External device monitoring (EDM)
Overview
The external switching elements (external device monitoring, EDM) must be inspected
in line with the regulations which apply at the place of installation or the required relia‐
bility of the safety function.
External device monitoring (EDM) monitors the status of downstream contactors.
Important information
NOTE
Because the multiple light beam safety device does not have integrated external device
monitoring, this must be implemented in the external control, if required.
Prerequisites
•
Positively guided contactors are used for shutting down the machine.
If the auxiliary contacts of the positively guided contactors are connected to the
external device monitoring, the external device monitoring checks whether the
contactors drop off when the OSSDs are switched off.
4
PROJECT PLANNING
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O P E R A T I N G I N S T R U C T I O N S | deTem4 Core
8020453/14Q7/2020-04-27 | SICK
Subject to change without notice
