Machine Design

PLC makes Olympic slopes safe

The Pilz PSS 3000 continuously monitors critical functions and elements such as two 600-hp cable motors, gondola grips, doors, and wind speed and direction.

Getting to the top of downhill ski runs at the Winter Olympics in Salt Lake City will be safer, thanks to a safety-control system from Pilz Automation Safety, Canton, Mich. Ski-lift manufacturer Doppelmayr, Golden, Colo., used the PSS 3000 safety system PLC to monitor a variety of variables and conditions on the gondolas that take skiers and spectators to the top of the mountain.

The system works by reading inputs from the safety switches on the towers, cable motors, gondola cable grips, and gondola doors. Inputs are sent to three different processors, each from a different manufacturer, ensuring that all three cannot fail from a similar system fault. The processors check each other as well as the inputs so that the output port activates only if it gets the same result from all three processors.

Processors watch cable-motor current for increases, which could signal a malfunction. The system also monitors the cable grips that keep the gondola attached to the cable, checking grip force as part of preventive maintenance.

Included in the system are sensors for wind speed and direction. This lets the system slow or stop the cables when high winds come at a critical angle.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.