Danfoss Invertor question

We have just had a new control panel installed that has a danfoss invertor in it, the company that installed the mains power 380V 3 phase neutral and earth (Ireland) got a phase and neutral mixed up, in other words we had a phase to the neutral connection and the neutral to the phase connection. The panel was powered up although all breakers and fuses where disconnected. The vsd is not working and the company who supplied the panel are saying it is our fault because we had a phase and neutral crossed over (the invertor is 3 phase and no neutral connection)my knowledge of vsd's isn't good enough to argue with them, so we are sending the vsd to danfoss for a report and then we can start arguing over who pays for what. Does anyone here think that the vsd would go faulty because of supplying the vsd with only 2 phases and a neutral instead of 3 phases and no neutral.

any help appreciated.

sparky

It may have not been the mains connection to the drive; maybe a power supply has gone high output and done the drive through the control side?

Thinking about it I am sure our drive had 2 supplies; 3 phase for the mains for the power side; then another seperate single phase supply for the control side. Maybe that could be your problem?

Can you get Danfoss out on site. We had a large one fail at our site after a power cut (the surge just before the cut killed the drive)

The engineer who turned up had an entire drive in spare parts, very impressive. He got us up and running quickly.

If you can get them to site you can talk to the guy himself and that has got to be better

Please define "The vsd is not working". Is it doing absolutely nothing, or do you get an error displayed, or...

there is nothing at all displayed on the screen, it is completely dead, even though the 3 phase power is present.

Ok, this is weird. A missing phase wouldn't harm a VFD that's not running (hey, even if it was), so why would connecting neutral instead of the third phase have this effect? Timbo_uk does have a point: Something killed the controls, not the power output...

Did you get it fixed then?

we replaced the invertor, and are waiting for the report from Danfoss.

i'll let you know what the outcome is.....politics...who needs it!!

sparky64 said:

we replaced the invertor, and are waiting for the report from Danfoss. i'll let you know what the outcome is.....politics...who needs it!!

Click to expand...

I think you have the right idea. Have factory check out to ensure no factory problem and what happened.

I do not see how single phasing it ONLY could or should damage VFD assuming it is able to sense for 3 phases ie lost phase. If not and you tried to run under full load you may have blown a rectifier (??)

I do not see how the neutral / single phasing could have fouled up the control power even though its neutral and teh 3 phase neut would be common ie tied to ground system.

If you are lucky the lawyers will take the politics albatross off your neck and start the big dog fight comprised of factory contractor owner / operator.

Dan Bentler

This might not be as political as it seems. If I understand what happened correctly, the drive essentially saw three phase power with a corner ground (one phase grounded). The core of the drive can run off of power configured that way but, when the drive is CE rated, there is an RFI/EMI filter network inside that is needed to meet CE requirements. This network depends upon a balanced input voltage to ground and when it gets something else, tries to force the balance. Of course, the network isn't tough enough to do that and the factory smoke starts to leak out.

I wouldn't be surprised if that's what happened.

Some manufacturers with CE rated drives provide network disconnecting screws so, if you have a floating or unbalanced supply, you can disconnect the network and avoid the failure. Of course, you can't do that in a district where the CE rating is enforced. There, you would need a drive isolation transformer with a grounded wye (star) secondary and leave the network connected.