6
Operating Instructions
Safety Switch STP-TW…AS1 (Twin)
Correct use
Safety switches series STP‑TW…AS1 are operated
as slaves on the safety bus AS‑Interface Safety
at Work and function as interlocking devices with
guard locking (separate actuator). The actuator has
a low coding level. In combination with a movable
safety guard and the machine control, this safety
component prevents the safety guard from being
opened while a dangerous machine function is
being performed.
This means:
f
Starting commands that cause a dangerous ma‑
chine function must become active only when the
safety guard is closed and locked.
f
The guard locking device must not be unlocked
until the dangerous machine function has ended.
f
Closing and locking a safety guard must not cause
automatic starting of a dangerous machine func‑
tion. 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:
f
EN ISO 13849‑1, Safety of machinery – Safety‑re‑
lated parts of control systems – Part 1: General
principles for design
f
EN ISO 12100, Safety of machinery – General
principles for design – Risk assessment and risk
reduction
f
IEC 62061, Safety of machinery – Functional
safety of safety‑related electrical, electronic and
programmable electronic control systems
Correct use includes observing the relevant require‑
ments for installation and operation, particularly
based on the following standards:
f
EN ISO 13849‑1, Safety of machinery – Safety‑re‑
lated parts of control systems – Part 1: General
principles for design
f
EN ISO 14119 (supersedes EN 1088), Safety of
machinery – Interlocking devices associated with
guards – Principles for design and selection
f
EN 60204‑1, Safety of machinery – Electrical
equipment of machines – Part 1: General re‑
quirements
Important!
f
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.
f
If the simplified method according to section 6.3
of EN ISO 13849‑1:2008 is used for determining
the Performance Level (PL), the PL might be re‑
duced if several devices are connected in series.
f
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.
f
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 personal protection function.
f
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.
f
The switching operation must be triggered only
by actuators designated for this purpose.
f
Prevent bypassing by means of replacement
actuators. For this purpose, restrict access to
actuators and to keys for releases, for example.
f
A complete safety‑oriented system generally
consists of several signaling devices, sensors,
evaluation units and concepts for safe shutdown.
The manufacturer of a machine or installation is
responsible for correct and safe overall function.
f
All safety precautions and requirements stated
in the operating instructions of the AS‑Interface
safety monitor used must be observed.
f
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.
f
Protect switch against touching by personnel or
contact with inflammable material.
Function
Safety switches series STP‑TW...AS1 (Twin) have
two actuator heads. They permit the simultaneous
locking or unlocking of two movable safety guards.
Both actuators must be inserted in order to activate
guard locking.
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 actuators 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
actuators cannot be pulled out of the switch head.
For design reasons, guard locking can be activated
only when the safety guard is closed (failsafe locking
mechanism).
Position monitoring of the safety guard and monitor‑
ing of interlocking are performed via two separate
switching elements (door monitoring contact SK and
solenoid monitoring contact ÜK).
When the safety guard is closed and guard locking
effective, each STP‑TW...AS1 transmits a switch‑spe‑
cific, unique safety code sequence with 8 x 4 bits
via the AS‑Interface bus. This code sequence is
evaluated by an AS‑Interface safety monitor. The
positively driven contact SK for door monitoring is
represented by the AS‑Interface input bits D0 and
D1. The solenoid monitoring contact ÜK is repre‑
sented by the AS‑Interface input bits D2 and D3.
The safety switch must be correspondingly config‑
ured in the AS‑Interface safety monitor (refer to the
operating instructions of the AS‑Interface safety
monitor used and the status table).
The safety switch is designed so that fault exclusions
for internal faults in accordance with EN ISO 13849
2:2013, Table A4, can be assumed.
Version STP-TW3…AS1
(guard locking actuated by spring force and released
by energy ON)
Important!
For the purpose of the protection of people against
dangerous over‑traveling movements, it can also
be necessary to switch the black AS‑Interface
cable (auxiliary power), which is connected to
the AS‑Interface distribution box and the switch,
via a standstill monitor or via the safe switch‑on
delay feature in a dual‑channel AS‑Interface safety
monitor (e.g. door locking for duration of the time
delay).
f
Activating guard locking: Close safety guard; no
voltage at the solenoid and/or clear AS‑Interface
output bit D0
f
Releasing guard locking: Apply voltage to the
solenoid and set AS‑Interface output bit D0
The spring‑operated guard locking functions in
accordance with the closed‑circuit current princi‑
ple. If voltage is interrupted at the solenoid, guard
locking remains active and the safety guard cannot
be opened directly.
If the safety guard is open when the power supply
is interrupted and the guard is then closed, guard
locking is activated. This can lead to persons being
locked in unintentionally.
Version STP-TW4…AS1
(guard locking actuated by energy ON and released
by spring force)
Important!
Use as guard locking for personnel protection is
possible only in special cases, after strict assess‑
ment of the accident risk (see EN ISO 14119:2013,
section 5.7.1)!
f
Activating guard locking: Apply voltage to the
solenoid and set AS‑Interface output bit D0
f
Releasing guard locking: Disconnect voltage from
the solenoid or clear AS‑Interface output bit D0
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 safety guard can be
opened directly!
Switching states
The detailed switching states and code sequences
for your switch can be found in the status table.
Selection of the actuator
NOTICE
Damage to the device due to unsuitable actuator.
Make sure to select the correct actuator (see
table in Figure 4).
Additionally pay attention to the door radius and
the fastening options (see Figure 5).
The following versions are available:
f
Actuator S for safety switches without insertion
funnel.
Manual release
Some situations require guard locking to be released
manually (e.g. malfunctions or an emergency). 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 half‑sequence is sent with the auxiliary release
actuated.