Safety Integrated - Industry - Siemens

Safety Door with Magnetic Engagement in Category 4
acc. to EN 954-1
Automation Function
Description of the functionality
Interlocking devices with guard locking are mechanical or
electrical devices which only enable operation of a machine if
the door is closed and guard locked. Interlock and guard locking
is maintained until the risk of injury caused by hazardous
machine functions or motions is excluded. This monitoring is
usually performed by overspeed trips or standstill monitors. In
this example, motion/stoppage of a machine is simulated by a
NO contact.
In this example, an actuator installed on the door moves form
fit into a safety position switch with locked engagement. During
the potential hazard (machine in RUN), the actuator is held
(and thus the door guard locked) by the fact that voltage is applied
to a magnet in the safety position switch. This type of interlock
is referred to as magnet-field lock.
If the safety position switch fails, the safety function is maintained
by the hinge switch (also detects the opened safety
door). This ensures that the requirements of the
EN 954 : 1996 standard (Category 4) are met which prescribes
redundant installation of all safety-relevant parts for
position monitoring of the safeguard (here: Safety door).
The voltage is applied to the magnet of the safety position
switch via a failsafe digital output module (F-DO) of the ET
200S.
The diagram below illustrates the concept of safety door monitoring:
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Start
"Machine"
stop?
J
F-DO="0"
Start request?
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Release?
J
Position switch:
Door closed?
J
Hinge switch:
Door closed?
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F-DO="1"
Monitoring
unlocking
OK?
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"Machine"
starts
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F-DO="1"
Position switch:
Door closed?
Hinge switch:
Door closed?
Monitoring
locking
OK?
Stop request?
Note
In this example, no real machine is controlled; the concept
of a safety door monitoring with guard locking (on
sensor side) is shown. If you want to additionally integrate
a real machine or other actuators, you can of
course use the parameters described in the corresponding
STEP 7 as basis.
For calculating the max. reaction time of your F-system please
use the Excel file (Cotia table), which is available for S7 Distributed
Safety V 5.3. This file is available on the internet:
http://support.automation.siemens.com/WW/view/en/
19138505
Functional Example No. AS-FE-I-003-V10-EN 193
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"Machine"
stops
G_FB_XX_096
Ex. No.
3