Monitoring a protective door up to PL e / SIL 3 with a fail-safe S7-1500 controller
Monitoring of the protective door position is designed according to EN ISO 13849‑1:2015 for requirements up to PL e and according to EN 62061:2005/A2:2015 for requirements up to SIL 3.
To ensure the required safety, the position of the protective door is monitored by two SIRIUS 3SE5 position switches. If one position switch fails, the second position switch still recognizes that the protective door is opened. The discrepancy monitoring in the controller detects a failure of one position switches and prevents that the system is switched on again until the error is eliminated.
In order to prevent failures of a common cause, position switches with different operating principles are used. In case of the position switch of position 1 the protective door position is detected via a separate actuator which is moved into the position switch when the protective door is being closed. The position switch of position 2 is provided with a swiveling lever which is actuated when the protective door is open.
In both position switches, a NC contact is evaluated each and assigned to the fail-safe digital input module. The controller detects cross-circuits between the two signals of the position switches.
Migration to TIA Portal V14
Replacing components by SIMATIC S7-1500 with central modules
Safety door, safety-switch, safety-door, safety switch