Torque Proving with Safety PLC output

[bella]

Hello all,

I have an application with a PF755 and Guardlogix PLC that controls a lifting mechanism driven by a motor with a brake and encoder. I was wondering if it was possible to use a PLC output to control the setting and releasing of the brake depending of a status bit that I can get from the PF755 (through communication) instead of letting the drive do it through the optional output.

Thank you in advance.

 

[GaryS]

I would not do it that way
I would use am Electromotive drive
There are designed to just what you want
I have been using them for many years

 

[Keystone]

Allen-Bradley in their Knowlegbase has several good tech notes how to do Torq Proving with safety relays and a time delay safety relay. Your best option is to allow the drive to control the break. Have a safety relay (or safety PLC) give a fast stop command on fault then use the Safe Torq Off after the max stop time with a safety rated timer.
The drive is designed to control the brake and detect brake slip, if the drive controls the break. The 755 are good a vertical lift applications if break control and troq proving are done correctly.
I have an application where I am doing a similar application.

 

[Keystone]

Here is a link to the application tech note for Safety Relay and PowerFlex 755 Drive with Hardwired Safe Torque-off: Publication SAFETY-AT146A-EN-P - August 2015