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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?

Published date: 04 April 2019

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. For the other safety relays not listed in this attachment, like XPSATR1153, XPSAR & XPSLCMUT1160, please consult their documentation on line.

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