VFD Decel Time & Light Curtain Delay Off

[jtautomation]

Hey guys,

Our Powerflex VFD table is really close to the keyence light curtain. We are using AB PLC it isnt a safety PLC. Our VFD is hardwired.

My question is, because the decel time of the VFD is configurable on the front keypad and so is the light curtain delay off time doesn't this make it unsafe?

Is there anyway to lock down these settings?

 

[jholm90]

If your vfd isn't safety rated with some sort of safety inputs (i.e. red safety terminals on powerflex525) you cannot use the regular stop signal to make the area safe. Look into contactors on the motor side of the vfd and an operator indicator light to enter only after the vfd has stopped.

Basically you will have to hardware in a solution because it's not locked down from changes.. at least based on my previous inspection experiences.

 

[James Mcquade]

please post more specific details about your operation.
your statement is to vague.

james

 

[janner_10]

It shouldn't make any difference, the drive should be told to stop instantly when the light curtain breaks, the delayed signal is then used to remove the torque, be it contactor or STO terminals.

When you remove the STO terminals the drive just coasts to a stop, this is why you have an instant and delayed outputs on safety relays, if your drive cannot stop before the delayed signal de-energised, you will need to introduce a brake so it will do so.

The system isn't unsafe if the safety relay has a dial on the front for the off delay time, but the facility's' procedure for not limiting access to the electrical cabinet that houses it. When I worked for an OEM in the past, we used Pilz and they had a little flap on the front which could be cable-tied closed, we used our own branded cable ties on it so we knew if anyone had been tinketing.

 

[RoTaTech]

we knew if anyone had been tinketing.

. . . or tinkering.

 

[Jeev]

It sounds less like you have a safety system, and more like you have a controlled stop triggered by a light curtain. This is going to meet barely the lowest criteria for Performance Level, if you can meet a Safety Category and Stop Category at all.