Operating Instructions

3.2.2 Locking principle
Overview
The met
hod of locking depends on the safety locking device variant selected. There are
two variants:
•
Power to lock
•
Power to release
Important information
DANGER
Haz
ard due to lack of effectiveness of the protective device
For power to lock variants only: In the event of a voltage drop, the locking device
unlocks regardless of whether the dangerous state of the machine has ended.
b
Do not use the safety switch in applications in which the dangerous state cannot
be ended immediately (stopping/run-down time).
Power to lock
•
L
ock loc
king device: voltage at locking device input
•
Unlock locking function: no voltage at locking device input
If voltage is interrupted, the locking device is unlocked and protective device can be
opened immediately.
Power to release
•
Lock loc
king device: no voltage at locking device input
•
Unlock locking device: voltage at locking device input
If the voltage is interrupted, the locking device retains its last state (bistable coil). If the
locking device was locked before, the protective device cannot be opened. If the locking
device was not locked before, the protective device can be opened.
Only the power to release variants have a mechanical unlocking mechanism.
3.2.3 OSSD
Output signal switching device: signal output for the protective device, which is used for
s
toppin
g the dangerous movement.
An OSSD is a safety switching output. The functionality of each OSSD is tested periodi‐
cally. OSSDs are always connected in pairs and must undergo dual-channel analysis for
safety reasons. An OSSD pair is formed from 2 OSSDs that are connected and analyzed
together.
3.2.4 Switching behavior of the OSSDs
Overview
The saf
ety locking device is available in variants for protecting people or for process
protection. The variants differ with regards to the switching behavior of the OSSDs:
Variants for people protection (locking monitoring)
OSSDs go into the ON state as soon as the following requirements are all fullfilled.
•
Mo
vable ph
ysical guard is closed.
•
Locking device is locked.
•
There is a valid signal at the inputs In1 and In2.
3 PRODUCT DESCRIPTION
10
O P E R A T I N G I N S T R U C T I O N S | flexLock 8020562/2021-04-30 | SICK
Subject to change without notice
Review version 2021-04-30