Monitoring The Position Of The Protective Door And Tumbler Function - Siemens SIMATIC ET200SP Function Manual

4.2.3

Monitoring the position of the protective door and tumbler function

The position of the protective door is monitored by a SIRIUS 3SF1 position switch. The
position switch detects the position of the protective door by a separate actuator. This moves
into the position switch when the protective door closes.
The SIRIUS 3SF1 position switch also contains an integrated tumbler which can keep the
protective door closed during operation and thus prevent entry into the danger zone. An
actuator mounted on the protective door moves into the positively-driven position switch
with tumbler. The SIRIUS 3SF1 position switch with tumbler used here has a spring-actuated
lock. This means that door is held shut in the de-energized state and the door is unlocked by
applying a voltage.
Operating principle: If the door is closed and no voltage is applied, a locking mechanism
moves into the separate actuator, which prevents the door from being opened. If a voltage is
applied, the locking mechanism is drawn out of the separate actuator by a solenoid, which
unlocks the tumbler.
Figure 4-2
The SIRIUS 3SF1 position switches are equipped with mechanical protection against incorrect
locking. This ensures that the door or locking mechanism can only be locked if the door is
closed.
The SIRIUS 3SF1 position switch has an integrated AS-i slave, in contrast to the 3SE5 standard
position switch.
Two contacts are evaluated internally in order to reach the required (SIL 2 or PL d) safety
level. If one of the contacts is defective, opening of the protective door is still detected by the
second contact. Failure of a contact is detected by a discrepancy monitor, which prevents a
renewed switch on until the fault has been rectified.
Safety engineering with AS‑Interface in the SIMATIC ET 200SP, including typical circuit diagram
Function Manual, 08/2020, A5E44991382002A/RS-AB/002
Position switch with tumbler
Circuit diagram example
4.2 Operating principle
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