3.2.2
Locking principle
Overview
The method of locking depends on the safety locking device variant selected. There are
two variants:
•
Power to lock
•
Power to release
Power to lock
•
Locking the locking function: voltage at locking function input
•
Unlocking the locking function: no voltage at locking function input
If voltage is interrupted, the locking function is unlocked and movable physical guard
can be opened immediately.
DANGER
Hazard due to lack of effectiveness of the protective device
For power to lock variants only: In the event of a voltage drop, the locking function
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 release
•
Locking the locking function: no voltage at locking function input
•
Unlocking the locking function: voltage at locking function input
If the voltage is interrupted, the locking function retains its last state (bistable sole‐
noid). If the locking function was locked before, the movable physical guard cannot be
opened. If the locking function was not locked before, the movable physical guard can
be opened.
Only the power to release variants have an auxiliary release.
3.2.3
OSSD
Output signal switching device: signal output for the protective device, which is used for
stopping 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 safety 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 protecting people (locking monitoring)
OSSDs go into the ON state when the following conditions are all met.
•
Movable physical guard is closed.
•
Locking function is locked.
•
A valid signal is present 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
8020562/2022-07-07 | SICK
Subject to change without notice