Allen Bradley Powerflex VFD throwing Input Phase Loss alarm

Hi all,

Client with a pretty much brand new AB Powerflex VFD starting throwing Fault 17: Input Phase Loss this afternoon. Started doing some searching and reading, so I understand the principle of what this fault means but I'm having a hard time believing it's actually a phase loss, because several other VFDs are all running off the same three phases and this is the only drive that's faulting. Thus I'm asking for a sanity check, if the drive really was seeing a phase loss (and we're assuming the loss is coming from the utility) wouldn't the other VFDs that are identical also fault for the same reason (assuming they're identically programmed, but they should be)? I suppose if one of the power connector terminals was loose something like this could be happening, maybe this drive is seeing the phase loss because of a loose connection? I've also read that the "input phase loss" is *actually* an indication of excessive DC ripple, so it could be the bus capacitors but is that likely in a drive that was integrated just months ago? Is AB known for poor quality drives?

Thanks for any help!

Each drive is fused separately, did you check fuses could be blown. If you have and they are good, just check all connections.


But you are right if there was a phase loss you would think all drives would see it.


As for the drive the circuit that senses phase loss could be defective. I would do all the checks like fuses and lose terminals and if that is not it replace the drive.

I'm going to guess that this is a PowerFlex 753 drive. If I'm correct you can disable this fault in the parameters. Here is a Tech Connect on the subject. As for the quality of AB drives in general. Eh, they don't seem to be any better or any worse that what you get for other manufactures.

defcon.klaxon said:

Hi all,

Client with a pretty much brand new AB Powerflex VFD starting throwing Fault 17: Input Phase Loss this afternoon.

Click to expand...

Presuming it's a 753-755 series willxfmr indicated you can program around it. Any chance the client has a floating delta or high resistance ground? If he does when you have a ground fault they will sometimes report falsely about phase loss.

Thanks for the replies all, electrician is on site I'll report back what is found.

Powerflex drives don’t actually sense the incoming lines, phase loss is detected by looking at the DC bus ripple. Other things such as a bad DC bus cap can cause that too. But I would first check the simpler things like loose connections, blown fuses etc.

Hi,

Was the load hooked up to a hi-pot tester without being disconnected from the VFD?
I have seen this cause all kinds of issues with VFD's.