DANGER
H
azard due to lack of effectiveness of the protective device
In the case of non-compliance, it is possible that the dangerous state of the machine
may not be stopped or not stopped in a timely manner.
b
Make sure that the following control and electrical requirements are met so that
the safety light curtain can fulfill its protective function.
•
T
he external voltage supply of the safety light curtain must be capable of jumper‐
ing a brief power failure of 20 ms as specified in IEC 60204-1
•
The power supply unit must ensure safe isolation according to IEC 61140
(SELV/PELV). Suitable power supply units are available as accessories from SICK.
Further topics
•
"A
ccessories", page 139
4.4.1 Restart interlock
Overview
T
he 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 safety light curtain has an internal restart interlock.
Important information
DANGER
Hazard due to unexpected starting of the machine
The machine may not restart if the OSSDs switch to the ON state once the reset
pushbutton has been pressed. The control must ensure that the machine only restarts
if the machine start button is also pressed after the reset pushbutton.
b
Make sure that the machine can only restart once the reset pushbutton and start
button have been pressed in the specified order.
Principle of operation
Be
fore the machine can be restarted, the operator must reset the restart interlock.
Figure 26: Schematic representation of operation with restart interlock
T
he 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.
4 P
ROJECT PLANNING
48
O P E R A T I N G I N S T R U C T I O N S | deTec4 Ex II 3GD 8023872/18YZ/2021-01-14 | SICK
Subject to change without notice
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