Drives and Controls Magazine
Electronic cable-pull switch is ‘the world's most advanced’
Published:  15 May, 2017

Rockwell Automation has developed what it claims is the world’s first solid-state cable-pull emergency-stop device, which uses a microprocessor-based technology to monitor and compensate for any thermal expansion or sagging of the trip-wire.

Traditional cable-pull switches are prone to nuisance trips and can be unreliable because of temperature-related changes in the cable tension. A patented rope-monitoring system in the new Allen-Bradley Guardmaster Lifeline 5 cable-pull switch compensates automatically for thermal expansion and cable sag.

“Because the Lifeline 5 cable-pull switch is a solid-state switch, there is no mechanical wear that is often associated with traditional switches,” says Rockwell’s product manager, Steve Tambeau. “That means increased uptime and more reliable safety function over a longer duty cycle.”

The new switch provides constant access to the E-stop function, allowing operators to prevent machine hazards with a simple pull of the attached cable. LED indicators help to tension the cable for quick, precise set-ups, while also providing switch status and diagnostics during operation, simplifying maintenance and troubleshooting.

Rockwell Automation's microprocessor-based cable-pull E-stop is designed to reduce nuisance trips

The switch is available in IP66 die-cast aluminium or IP67 stainless-steel housings. The aluminium model offers an optional built-in E-stop button.