VSD (VFD) Not powering up when power is applied - Help

[jraef]

Thanks for the replies guys.

Before leaving site last night, both drives where taken to the customers other factory and powered direct from a 3 phase suuply there, but neither showed any signs of life. So drives must be dead.

The motor was checked for shorts all OK, i connect motor to a DOL contactor to test it and motor ran no problems.

Here in Australia i think most incoming supplies are TN-C-S earthing system, but is called MEN (multiple earthed neutral) instead of PEN.

I checked the earth back to the sub-board and couldn't find any issues, check between earth and each phase showed 240 volts meaning there is a earth connection back to the neutral link at the main board.

The motor is only .55kw with the VSDs being 0.75kw rated, and both can accept up to 480 volts input.

I've sent someone out to get me a single phase input instead of a 3 phase input to see if that works. Other than that i'm completely stumped.

You are left with line noise issues. Is there a reactor ahead of these drives?

 

[Gil47]

Check the wiring from the drive to the motor and make sure there
is no power factor capacitor connected to that wiring
I don't expect there will be but you never know till you check

Your motor of that size 0.55 kw, I would expect will be wired in star ( wye )
on the drive and also on DOL
that also would be worth checking

 

[jraef]

Have you given these drives a sniff test? Because not even having the displays come on indicates that the power supply board/circuit that runs the internals of the VFD must not be working at all, which is usually accompanied by that tell-tale acrid smell of over cooked insulating material or PC board material. Typically problems on the load side will cause load side component failures, but it's fairly unlikely that the displays would be dead from that, unless it was a very catastrophic failure. Those are usually obvious because the magic smoke escapes, and does so "with extreme prejudice". But a line side problem, one that causes a high current spike on the DC bus for example, can pop a PC board trace feeding a DC-DC converter used for control power, and it can be a silent-but-deadly end to the drive.

 

[holyhobgoblin]

Hi Guys

Gil47

I checked the motor and wiring, no problems found, as said in an earlier post, i ran the motor on DOL not problems.

Jraef

First thing i always do when i suspect something is blown, nothing even pulled them apart and no burns marks. Both units have LED's to show they are powered up. When i installed the new ABB it didn't light up ever.

Anyways i installed a single phase input drive, and bang its all working fine, so i'm completely baffled too why 2 drives failed.

The company i bought the ABB drive are going to inspect it and give me a report on their findings.

And just to top off a really bad, stressful two days we miss our flight home :angr:

One question though, how would one go about measuring line noise? if that was the issue

cheers guys

 

[jraef]

With a scope or scope meter, something with a fast response time too.

The single phase drive working is really curious. I can't imagine the mechanism by which that would make a difference.

 

[Lancie1]

The single phase drive working is really curious. I can't imagine the mechanism by which that would make a difference.

A possibility: two legs of the 3-phase motor feed partially shorted to each other. Sometimes (on a dry day) it works, but most times it causes a direct short of that phase.

For the single-phase load, maybe he luckily picked the one good leg and one of the bad legs, which would always work.

I checked the earth back to the sub-board and couldn't find any issues, check between earth and each phase showed 240 volts meaning there is a earth connection back to the neutral link at the main board.

But did you check each leg of the drive-to-motor cable with a megohmeter? That will show if you have a high-resistance short phase-to-phase or phase-to-ground. I am betting on a phase-to-phase partial short-circuit.

 

[DwSoFt]

I'm thinking the drive is single phase input. 3 phase output still. If the line power is delta corner grounded it may be causing the 3 phase input drive to not rectify properly and therefore no power to even light up. But if u use a drive that is single phase input 3 phase output and hookup just the ungrounded power wires it may just work. I am honestly just guessing but nothing else has come close to explaining it. It's not the motor since it runs on an across the line starter no overloads. It's the line power...

 

[Lancie1]

It's not the motor since it runs on an across the line starter no overloads.

That still does not mean that the power feeder can't have a partial line-to-line short, good sometimes, bad sometimes. I have seen it too many times. The only fix is to pull in new wire.

 

[DwSoFt]

I will not argue that that can happen. However the OP said the 2nd drive didn't power up even before he tried to run it. So that *should* narrow it down to the drive or power feed to it.

 

[Lancie1]

If the second drive did not "power up", it could also mean that its output transistors were burned up the moment power was applied. In the case that I mentioned previously, 3 drives were installed in sequence, power was turned on each, then there was instant destruction (also black-out of the drive HMIs) due to the phase-to-phase short at the motor.

Not thoroughly checking the wiring from drive-to-motor can lead to sequential, expensive, destruction of multiple drives. Reading 240 volts to ground with a voltmeter does not exclude a partial short-circuit. That only shows up when some amount of current is applied to break down the damaged insulation on the cables.

Anyways, I installed a single phase input drive, and bang, its all working fine,. . .

The problem is solved - for now! But probably there is at least one damaged leg in use for the new 1-phase drive. That means trouble is coming down the road in a year or so.

Some parameters that would have helped:
1. Does the power feed from drive to motor run underground in a conduit?
2. If in a conduit, during construction, were steps taken to seal the ends to prevent water from getting into the conduit.
3. Who was present when the cable or wire was pulled in? Was there a problem or incident that could have damaged the insulation?

 

[jraef]

If the second drive did not "power up", it could also mean that its output transistors were burned up the moment power was applied. In the case that I mentioned previously, 3 drives were installed in sequence, power was turned on each, then there was instant destruction (also black-out of the drive HMIs) due to the phase-to-phase short at the motor.

Not thoroughly checking the wiring from drive-to-motor can lead to sequential, expensive, destruction of multiple drives. Reading 240 volts to ground with a voltmeter does not exclude a partial short-circuit. That only shows up when some amount of current is applied to break down the damaged insulation on the cables.

The problem is solved - for now! But probably there is at least one damaged leg in use for the new 1-phase drive. That means trouble is coming down the road in a year or so.

Some parameters that would have helped:
1. Does the power feed from drive to motor run underground in a conduit?
2. If in a conduit, during construction, were steps taken to seal the ends to prevent water from getting into the conduit.
3. Who was present when the cable or wire was pulled in? Was there a problem or incident that could have damaged the insulation?

I like it, this is about the only scenario I see that can fit and I agree that further failure is in the wind. It might even be further exacerbated by the harmonics on the line side causing a capacitive interaction with something else, which increases the peak voltage and facilitates that phase-to-phase leakage, which goes away when the x-line starter is used. In that case too, further failure is imminent.

Disconnect and megger the feeder cables, but do the whole procedure, not just shorting all 3 together to check for leakage to ground, because that will not pick up a phase-to-phase short. Connect each phase conductor to ground one at a time, then energize the other two with the megger.