Safety Integrated - Industry - Siemens

Safety Door with Spring-Loaded 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 the voltage
applied to a magnet in the safety position switch is removed.
This type of interlock is referred to as spring-actuated 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 applied to the magnet is removed by resetting a
failsafe digital output channel of the ET 200S; this channel is
linked to the magnet. The other way, the magnet is supplied
with voltage to be able to open the safety door by setting this
output.
Fail-Safe digital
output module
F-DO
Safety position switch with
lock engagement
(interlocked with spring force)
Magnet
G_FB_XX_084
The diagram below illustrates the concept of safety door monitoring:
N
N
N
N
N
Start
"Machine"
stop?
Y
F-DO="1"
Start request
Y
Release?
Y
Position switch:
Door closed?
Y
Hinge switch:
Door closed?
Y
F-DO="0"
Monitoring
unlocking
OK?
Y
"Machine"
starts
N
F-DO="0"
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.
Functional Example No. AS-FE-I-002-V10-EN 179
N
N
N
N
Y
"Machine"
stop
G_FB_XX_083
Ex. No.
2