Power flex 4 powerup problems

Hi Guys
We have a conveyor cabinet (4years old) that has 14 powerflex 4's for 14 1hp motors. Today after powering up, 2 drives would not powerup. Incoming voltage ok (460v). We ordered in 2 drives and replaced. When we powered up cabinet after changing, NOW 3 more (different) drives will not powerup. After about 10 minutes with power on, 2 of the drives then powered up. Changed out last drive. Powered up all ok but 1 drive took about 5 minutes to power up. Any toughts on what is happening here? Somebody must of ran into this problem before. Today I removed all MOV jumper links. Not getting much help from AB tech. I would perfer input from the guys on the frontlines.
Thanks

clank said:

Hi Guys
We have a conveyor cabinet (4years old) that has 14 powerflex 4's for 14 1hp motors. Today after powering up, 2 drives would not powerup. Incoming voltage ok (460v). We ordered in 2 drives and replaced. When we powered up cabinet after changing, NOW 3 more (different) drives will not powerup. After about 10 minutes with power on, 2 of the drives then powered up. Changed out last drive. Powered up all ok but 1 drive took about 5 minutes to power up. Any toughts on what is happening here? Somebody must of ran into this problem before. Today I removed all MOV jumper links. Not getting much help from AB tech. I would perfer input from the guys on the frontlines.
Thanks

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I had a similar experience with the PF40 big bother of the PF4. They were fine as long as they were powered up, if you had a power outage, or powered down the cabinet for service. Some would not come back on when power was restored. Repeated application of power would eventually get them going again in most cases, with replacement the only option for those that didn't.

I found a Tech Note on the Allen Bradley Forums stating there was a problem with a component on the VFDs. I did get some replaced by Allen Bradley, and had the others repaired. Have a look on the Forums, and see if you can find anything for the PF4.

http://forums.rockwellautomation.com/t5/community/communitypage

You might have to create an account, but as far as I know they are public.

Stu.....

We had one PF4 that acted the same way. It was "spared out" by a previous modification, but we wanted it there and ready to go so we could use it in an emergency (just move 2 control wires and motor leads to it).

After leaving the power on for an hour or more this "Lazarus drive" would come back to life. This seems to be repeatable as long as the power is off for a couple of hours. Power down for 5 minutes and back up, and it seems to do fine.

This panel would kill off drives in groups of 2 or three just like the case described by the O.P. The 2nd time we lost a group of them, I dug into the wiring a little deeper and found the OEM had tied all the power supplies (+24vdc AND DC Common) together, and fed that power to a 1746-OB16 card which supplied stop/run fwd commands to the drives.

I removed the +24 connections to the drives so they could no longer leech off each other, and rewired it like it is supposed to be (all the DC commons tied together and used the panels 10amp power supply for the run/stop signals).

Since then we have still lost a drive or two, one at a time, but they aren't dying in droves anymore. That Lazarus drive is still in there though, but hopefully we'll never need it.

So, you might check to see how the control power is wired to those drives, and also let us know if there are comms adapters installed. Mine have ethernet adapters on most of them, but not sure if that's relevant, or if that is what pushes the little on-board power supply up to its limit.

I would also look into common nuetral bondings, This is a system thats been online for 4 years. Having worked for 14 years in a high washdown enviroment I've seen similar behaviors with AB and other name brand drives. Tighten down all connections. (good PM routine as well). Look for whats changed.

clank said:

Hi Guys
We have a conveyor cabinet (4years old)

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So, how old are the drives themselves?
See this old thread, as this issue has been discussed here before.


At one of our customer's plants, RA replaced a number of Powerflex drives (under warranty?) if they were manufactured within a certain date period.