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Preventa XU - In which cases is it necessary to associate some safety interface with the XUSL4E or XUSL2E safety light curtain?

Normally the XUSL4E and XUSL2E safety light curtain can operate without any safety relay or any safety interface. It is the recommended stand-alone solution with the big advantages to reduce:
  • the response time of the machine,
  • the safety level of the solution, may be, because it contains only 2 components (light curtain & outputs) for the SIL (safety integrity level) or the PL (performance level) calculation, according to the IEC 62061 or to the ISO 13849-1 standard,
  • the maintenance operations,
  • the cost of the solution ...
However it can be necessary to add some safety interface in the following cases :
- function not integrated into the light curtain. Example muting function, time-delayed outputs for the OSSD's of the XUSL curtain ... Interface to use in such specific cases
  • muting function : 2 muting photoelectric sensors XPSLCMUT1160 muting relay or XPSMCM modular safety controller.
  • time-delayed output : XPSATR1153P/C for a 3s time delay maxi.
- combination of several XUSL curtains in the same safety processing unit like a safety PLC or a safety controller like the XPSMCM modular one.
- increase the OSSD number to switch off several independant safety chain solutions. Example of unit to select : XPSAR having 7 safety NO outputs.
- increase the OSSD breaking capacity to switch off big contactors through a safety relay having NO safety outputs able to break their coils.
- supply control relays or power contactors in AC voltage, instead of 24Vdc.

Attached our typical wiring diagrams of XUSL4E/2E light curtains showing the stand-alone solution, and some solutions using the XPS safety relays and the XPSMC/MCM safety controllers.
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