5
Operating Instructions
Safety Switch STM…
Correct use
Safety switches series STM are interlocking devices
with guard locking solenoid (type 2). The actuator
has a low coding level. In combination with a movable
guard and the machine control, this safety compo-
nent prevents the guard from being opened while
a dangerous machine function is being performed.
This means:
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Starting commands that cause a dangerous ma-
chine function must become active only when the
guard is closed and locked.
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The guard locking must not be released until the
dangerous machine function has ended.
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Closing and locking a guard must not cause auto-
matic starting of a dangerous machine function.
A separate start command must be issued. For
exceptions, refer to EN ISO 12100 or relevant
C-standards.
Devices from this series are also suitable for process
protection.
Before the device is used, a risk assessment must
be performed on the machine, e.g. in accordance
with the following standards:
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EN ISO 13849-1
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EN ISO 12100
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IEC 62061
Correct use includes observing the relevant require-
ments for installation and operation, particularly
based on the following standards:
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EN ISO 13849-1
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EN ISO 14119
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EN 60204-1
Important!
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The user is responsible for the proper integration
of the device into a safe overall system. For this
purpose, the overall system must be validated,
e.g. in accordance with EN ISO 13849-2.
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If the simplified method according to section 6.3
of EN ISO 13849-1:2015 is used for determining
the Performance Level (PL), the PL might be re-
duced if several devices are connected in series.
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Logical series connection of safe contacts is
possible up to PL d in certain circumstances.
More information about this is available in
ISO TR 24119.
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If a product data sheet is included with the prod-
uct, the information on the data sheet applies
in case of discrepancies with the operating
instructions.
Safety precautions
WARNING
Danger to life due to improper installation or due
to bypassing (tampering). Safety components
perform a personnel protection function.
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Safety components must not be bypassed,
turned away, removed or otherwise rendered
ineffective. On this topic pay attention in partic-
ular to the measures for reducing the possibility
of bypassing according to EN ISO 14119:2013,
section 7.
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The switching operation must be triggered only
by actuators designated for this purpose.
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Prevent bypassing by means of replacement
actuators. For this purpose, restrict access to
actuators and to keys for releases, for example.
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Mounting, electrical connection and setup only
by authorized personnel possessing special
knowledge about handling safety components.
CAUTION
Danger due to high housing temperature at ambi-
ent temperatures above 40 °C.
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Protect switch against touching by personnel or
contact with flammable material.
Function
The safety switch permits the locking of movable
guards.
In the switch head, there is a rotating cam that is
blocked/released by the guard locking pin.
The guard locking pin is moved on the insertion/
removal of the actuator and on the activation/
release of the guard locking. During this process
the switching contacts are actuated.
If the cam is blocked (guard locking active), the
actuator cannot be pulled out of the switch head. For
design reasons, guard locking can be activated only
when the guard is closed (prevention of inadvertent
locking position (faulty closure protection)).
Position monitoring of the guard and monitoring
of interlocking are performed via two separate
switching elements (see Fig. 1).
SK ÜK
E1
E2
Fig. 1: Function of safety switch STM
The safety switch is designed so that fault ex-
clusions for internal faults in accordance with
EN ISO 13849-2:2013, Table A4, can be assumed.
Guard lock monitoring
All versions feature at least one safe contact for
monitoring guard locking. The contacts are
opened when guard locking is released.
Door monitoring contact
All versions additionally feature at least one door
monitoring contact. Depending on the switching
element, the door monitoring contacts can be
either positively driven (contacts ) or not posi-
tively driven.
The door monitoring contacts are actuated when
the guard is opened.
Version STM1
(guard locking actuated by spring force and released
by power-ON)
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Activating guard locking: close guard; no voltage
at the solenoid
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Releasing guard locking: apply voltage to the
solenoid
The spring-operated guard locking functions in ac-
cordance with the closed-circuit current principle. If
the voltage is interrupted at the solenoid, the guard
locking remains active and the guard cannot be
opened directly.
If the guard is open when the power supply is
interrupted and is then closed, guard locking is
activated. This can lead to persons being locked
in unintentionally.
Version STM2
(guard locking actuated by power-ON and released
by spring force)
Important!
Use as guard locking for personnel protec-
tion is possible only in special cases, after
strict assessment of the accident risk (see
EN ISO 14119:2013, section 5.7.1)!
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Activating guard locking: apply voltage to the
solenoid
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Releasing guard locking: disconnect voltage from
the solenoid
The magnetically actuated guard locking operates in
accordance with the open-circuit current principle. If
the voltage at the solenoid is interrupted, the guard
locking is released and the guard can be opened
directly!
Switching states
The detailed switching states for your switch can
be found in Fig. 4. All available switching elements
are described there.
Guard open
STM1 and STM2:
The safety contacts and are open.
Guard closed and not locked
STM1 and STM2:
The safety contacts are closed. The safety
contacts are open.
Guard closed and locked
STM1 and STM2:
The safety contacts and are closed.
Selection of the actuator
NOTICE
Damage to the device due to unsuitable actuator.
Make sure to select the correct actuator (see
table in Fig. 6).
Additionally pay attention to the door radius and
the mounting options (see Fig. 5).
The following versions are available:
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Actuator S for safety switches without insertion
funnel.
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Actuator L for safety switches with insertion funnel.
Manual release
Some situations require the guard locking to be
released manually (e.g. malfunctions or an emer-
gency). A function test should be performed after
release.
More information on this topic can be found in the
standard EN ISO 14119:2013, section 5.7.5.1. The
device can feature the following release functions:
Auxiliary release
In the event of malfunctions, the guard locking can
be released with the auxiliary release irrespective
of the state of the solenoid.
The contacts are opened when the auxiliary
release is actuated. A stop command must be
generated with these contacts.
Actuating auxiliary release
1. Unscrew locking screw.
2. Using a screwdriver, turn the auxiliary release
to in the direction of the arrow.
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Guard locking is released.
Important!
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The actuator must not be under tensile stress
during manual release.
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After use, reset the auxiliary release and screw in
and seal the locking screw (with sealing lacquer,
for example).
