Handling Power Loss - PowerFlex 700 & 20-ComE

[drawson]

We have a plant with a few dozen PowerFlex 700 drives in various frame sizes throughout driving mostly conveyors. They are networked via Ethernet/IP using a 20-Comm E card and controlled from ControlLogix processors. They have worked very well for us however this morning we had a snow storm that took all utility power in the plant down and we spent an hour walking around the plant resetting drive faults. DPI port communication faults.

I wasn't here when the power when the power went out so I don't know how long it was out, but it seems like long enough to knock down the PLC but not long enough to power down the whole drive.

Is there a good way to do reset the drives automatically in the event of a power outage?

I'm thinking something along the lines of on program first scan waiting 30 seconds for everything to get booted back up then setting the clear faults bit on each drive.

 

[curlyandshemp]

We have a plant with a few dozen PowerFlex 700 drives in various frame sizes throughout driving mostly conveyors. They are networked via Ethernet/IP using a 20-Comm E card and controlled from ControlLogix processors. They have worked very well for us however this morning we had a snow storm that took all utility power in the plant down and we spent an hour walking around the plant resetting drive faults. DPI port communication faults.

I wasn't here when the power when the power went out so I don't know how long it was out, but it seems like long enough to knock down the PLC but not long enough to power down the whole drive.

Is there a good way to do reset the drives automatically in the event of a power outage?

I'm thinking something along the lines of on program first scan waiting 30 seconds for everything to get booted back up then setting the clear faults bit on each drive.

Its a parameter in the drive on what to do with loss of comms.

Parameter 18 in the 20-Comm-E section. Comms Flt Action, by default it is set to fault. Change to it to stop. Also set parameter 19 to stop as well

 

[Derek McFarland]

The VFD should fault on loss of comms or it will not be controlled. You could monitor the faulted bit in the staus file and issue a reset via the command word if faulted with an operator control like a stop button.

 

[drawson]

Its a parameter in the drive on what to do with loss of comms.

Parameter 18 in the 20-Comm-E section. Comms Flt Action, by default it is set to fault. Change to it to stop. Also set parameter 19 to stop as well

So in the event of a comm loss the drive will just stop and then it can be started again when comm is re-established?

 

[curlyandshemp]

So in the event of a comm loss the drive will just stop and then it can be started again when comm is re-established?

Yes, I do this all the time after finding out on my first C-Net job years ago, that the PowerFlex were always faulting when I put the PLC in program mode. Parameter 19, Idle Flt Action

 

[Ken Roach]

C&S is right on. You're looking for Parameter 21 (Communications Fault Action) and Parameter 22 (Communications Idle Action).

The Comms Fault Action takes place when the 20-COMM-E loses its I/O connection either through link failure or cessation of traffic to the controller. Reasons include controller fault, switch powerdown, or cable unplug.

The Comms Idle Action takes place when the Controller is placed in Program Mode.

The characteristic fault code on PowerFlex 70/700 drives is "Error 75" for the onboard module, and "Error 72" for an externally mounted communication module.

Both Comms Fault and Comms Idle actions are set by default to the safest action, which is to fault the drive. I prefer to set mine to Stop the drive.

I like to add an HMI function to set the Reset Fault bits in the Command Word globally, just for events like this. But the long-term thing is to go around and set Parameters 21 and 22 in the 20-COMM-E to the proper setting.

 

[curlyandshemp]

C&S is right on. You're looking for Parameter 21 (Communications Fault Action) and Parameter 22 (Communiations Idle Action).

The Comms Fault Action takes place when the 20-COMM-E loses its I/O connection either through link failure or cessation of traffic to the controller. Reasons include controller fault, switch powerdown, or cable unplug.

The Comms Idle Action takes place when the Controller is placed in Program Mode.

Both are set by default to the safest action, which is to fault the drive. I prefer to set mine to Stop the drive.

I like to add an HMI function to set the Reset Fault bits in the Command Word globally, just for events like this. But the long-term thing is to go around and set Parameters 21 and 22 in the 20-COMM-E to the proper setting.

Ken,
sorry you are correct, I was looking at the 22-Comm-E parameter list

 

[allscott]

I would assume but haven't tried that a low to high transition of the start bit would have to be done in order for the drive to start again correct? You wouldn't want the drive to start by itself after a power flicker, hopefully the Estop circuit is wired as such this wouldn't happen anyway.

 

[drawson]

Thanks Guys.

 

[drawson]

I would assume but haven't tried that a low to high transition of the start bit would have to be done in order for the drive to start again correct? You wouldn't want the drive to start by itself after a power flicker, hopefully the Estop circuit is wired as such this wouldn't happen anyway.

That's correct. The drive needs to see a low to high transition after coms are established before it will start.

 

[drawson]

I would assume but haven't tried that a low to high transition of the start bit would have to be done in order for the drive to start again correct? You wouldn't want the drive to start by itself after a power flicker, hopefully the Estop circuit is wired as such this wouldn't happen anyway.

That's correct. The drive needs to see a low to high transition after coms are established before it will start.