Three blown Powerflex 525s - don't know why

cardosocea said:

Do you have a link for it? I have to have these things in stock and it would be nice not to blow them up on startup.

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This is from Eaton. I believe most other manufacturers have similar instructions. There may be slight variations in what each recommends.

https://www.eaton.com/content/dam/e...ives/vfd-storage-and-reforming-capacitors.pdf

Update

Thanks for the replies. I'm no further ahead this morning. Couldn't find an more 525s, so I was forced to get a suitable 523. Installation is complete, but I just realized the 25-COMM-D Devicenet module won't work, despite clipping in perfectly. The motherboard on the 523 control module is closer than the 525. The 525 comes with an extender, which is too long for the 523.

To answer some of your questions:

1. The replacement drives were on the shelf for an unknown amount of time. I would say they were powered up <5 minutes before being tested.

2. Line voltage to ground was found to be 576V, 581V and 590V

The capacitors need to be reformed based upon this:

Table 3 - Drive Storage Duration and Reforming Recommendations
Duration Reforming Guideline
Under 2 years No reforming required.
2 …3 years Apply rated voltage, per the normal method, for 30 minutes under no load.
Over 3 years Using a DC power supply connected directly to the DC terminals of the product, ramp-up the voltage from 0…100% of DC bus voltage (as per Table 4) in
increments of 50%, 75%, and 100% rated voltage, under no load, for 30 minutes at each increment. See Figure 5 on page 4 for an illustration of this method.


https://literature.rockwellautomation.com/idc/groups/literature/documents/td/drives-td001_-en-p.pdf.

Reforming equipment.
https://www.bonitron.com/maintenance/m3628pcf/.

rguimond said:

1. The replacement drives were on the shelf for an unknown amount of time. I would say they were powered up <5 minutes before being tested.

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That does sound as if they should have been reformed, and the time they were powered up but not started were far from enough for the reforming.

rguimond said:

Monday, we had a VFD that controls the spped of a conveyor belt fail on us. Took the replacement out of the box, installed it and bam, it failed, too.

While waiting for a replacement, we meggered the motor and it was fine. To double-check, we brought it to a local moitor shop for testing. Changed the whip from disconnect to motor. Meggered everything from VFD output all all tested OK. There's a load reactor after the VFD

Today, we installed a replacement and it fried when power was applied. Even blew the fuse

Legs are roughly equal - 576, 580 & 588 volts

Any suggestions? The only thing I can think of is a bad local disconnect, but that seems unlikely

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Hi, I don't mean to be difficult or dense, however I was wondering about these voltages. You're in Canada, so it's 600 VAC incoming line. I would say that 3-phase voltage behaves the same everywhere. So....the inverse of 1.73 is .57 or 57%. 57% of 600 is ~ 342. You're stating that you have full line voltage on one leg to ground? (Post #17). Or am I misunderstanding something?

saultgeorge said:

I would say that 3-phase voltage behaves the same everywhere.

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I've heard in the southern hemisphere everything is upside down, so all three phases are 180° off what we're used to up here...

rguimond said:

…
2. Line voltage to ground was found to be 576V, 581V and 590V

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That indicates that you have an ungrounded delta power system. Ungrounded delta is bad for all VFDs. There are internal protection devices (MOVs and common mode capacitors) that are internally referenced to ground. When you connect to a delta power source, you are instructed to remove a jumper that connects the ground reference, otherwise those components will be damaged the first time there is a ground fault ANYWHERE on your system upstream of the drives. Those MOVs can then explode and cause collateral damage. All of this is in the manual. Did you pull those jumpers?

You mention testing the motor, but have you tested the cables/disconnect/anything else installed between the drive an the motor?

jraef said:

Did you pull those jumpers?

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+1. That's probably going to be a "NO". I also thought perhaps it was an open or loose neutral on a 4-wire system.

jraef said:

That indicates that you have an ungrounded delta power system. Ungrounded delta is bad for all VFDs. There are internal protection devices (MOVs and common mode capacitors) that are internally referenced to ground. When you connect to a delta power source, you are instructed to remove a jumper that connects the ground reference, otherwise those components will be damaged the first time there is a ground fault ANYWHERE on your system upstream of the drives. Those MOVs can then explode and cause collateral damage. All of this is in the manual. Did you pull those jumpers?

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jraef is correct and why I had asked for Line-Gnd measurement. Some VFDs even explicitly state not to be used on a delta power system. You need to remove the grounding jumpers at the least, and preferably install a Delta-Why isolation transformer wit grounded neutral to feed the VFD.

OV Jumper is removed, as was removed before install on the replacement drives.

Here's an update:

No 600V 15Hp 525 drives in Canada, so I picked up a 523 which is basically the same, but doesn't have on-board safety.

Installed the drive on Saturday, powewred it up and programmed it to run locally. I was able to run the motor in forward and reverse and vary the speed with the on-board pot. I then relaized that the 25-COMM-D status lights weren't on and quickly learned that the multi-pin jumper used with the 525 is about 12mm longer than the one required with the 523 and I didn't have a short jumper, so I was dead in the water. Went home for the day.

On Monday, I began making some calls to see if I could find a short jumper. I wasn't successful and learned from local Rockwell dealer that the onl;y way to get a jumper is to order a new 25-COMM-D! Of course, I did and it should arrive soon.

Frustratingly, however, I just opened the cabinet with the drive and saw F122, which indicates "I/O Board Failure"!!! WTF? I'm so beyond frustrated with this problem. I tried several power-cycles and re-seat attempts - no luck, so far

Rob... said:

You mention testing the motor, but have you tested the cables/disconnect/anything else installed between the drive an the motor?

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jraef said:

That indicates that you have an ungrounded delta power system. Ungrounded delta is bad for all VFDs. There are internal protection devices (MOVs and common mode capacitors) that are internally referenced to ground. When you connect to a delta power source, you are instructed to remove a jumper that connects the ground reference, otherwise those components will be damaged the first time there is a ground fault ANYWHERE on your system upstream of the drives. Those MOVs can then explode and cause collateral damage. All of this is in the manual. Did you pull those jumpers?

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Yes, jumpers were removed

Rob... said:

You mention testing the motor, but have you tested the cables/disconnect/anything else installed between the drive an the motor?

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Everything was tested - leads from drive to load reactor, cables from load reactor to local disconnect, local disconnect and the whip from disconnect to motor. All meggered to ground and to each other (with the drive disconnected)

So this one seemed to have been killed at night? What are the chances that supply voltage went high? Since you seem to be connected to an ungrounded delta power system, that power system can float high with respect to ground. Even though you have removed the ground jumpers, I wonder if it is still hurting them?

Can you get a transformer ahead of this thing? Delta primary to Wye secondary 1:1. You need to be sure and ground the center tap of the wye side. This way the Line-Ground will not be able to float high.