Passive Safety up to SIL3/PLe – A Cost-effective Alternative

Passive safety is becoming increasingly important as a cost-effective alternative for achieving machine safety. With conventional functional safety solutions, one must have a safe – and therefore expensive – output for each actuator. This allows all actuators to be safely switched off individually.


In practice, often only whole groups of actuators need to be safely switched off at the same time. This enables passive safety with only one safe output per group. All outputs can also be additionally switched on/off and controlled individually for operation purposes.


With ASi, the supply principle of passive safety is achieved by laying the profile cables separately. This excludes the possibility of external power supply to the actuators when the supply is switched off.


Fig.: Application examples for passive safety

Advantages of Passive Safety with Bihl+Wiedemann

  • Safety up to SIL3/PLe: The yellow ASi profile cable and the black profile cable for auxiliary power can easily be laid separately – even in the modules. Connected actuators supplied through AUX are therefore safely switched off when the auxiliary power is switched off.
  • Lower hardware costs: Safety-related disconnection of actuator groups can be achieved with just one safe output.
  • Sensor systems can always be read off: The yellow ASi cable provides the sensors with communication and power even in the event of a switch-off.
  • Efficient power supply: The black profile cable transmits 16 A or 20 A – thus significantly more power than typical M12 round cable solutions.
  • Low wiring costs: Thanks to profile cables and piercing technology, ASi reduces wiring costs by up to 68 percent compared to other fieldbus systems.

For more information on passive safety with Bihl+Wiedemann, please visit our website.

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