380 volt 50KW induction heater that won't turn on

[Jraef]

Ahhh... the old "I got such a deal on this!" problem. Wasn't such a deal after all now, was it?

380V in other parts of the world is ALWAYS a Wye connection (they call it "Star") connection and it is VERY common to use Phase-to-Neutral as the control voltage, because it is "free". You now have three problems;

1. It will not work, and ...
2. You are EXCEDING the Ground Reference Voltage of the equipment. It is designed to never see more than 220V to ground. By connecting it to a Delta 380V system, the ground reference is now floating (as evidenced by your different readings, which are more likely capacitive). You can have serious problems with any controls, electronics and protective devices that might be part of this unit. You will need to get them a 380Y220V transformer, and...
3. It is almost CERTAINLY not UL listed, so make sure that you, as the EC, cover your butt from a liability standpoint in that you are connecting unlisted equipment, which may be a problem with their insurance carrier if anything should go wrong, and you will want it IN WRITING that you informed them that this is the case.

 

[petersonra]

It seems unlikely to me that a 480 to 380 V transformer would not come with a wye secondary. The only use for such a transformer is for European equipment and they are all wye connected.

It might be worth taking another look at the transformer nameplate to see what it is for sure.

 

[petersonra]

It is almost CERTAINLY not UL listed, so make sure that you, as the EC, cover your butt from a liability standpoint in that you are connecting unlisted equipment, which may be a problem with their insurance carrier if anything should go wrong, and you will want it IN WRITING that you informed them that this is the case.

If the equipment is of a type that is required to be listed, I don't see how a statement in writing that it is unlisted is anything other than admitting liability if something goes wrong, and probably increases the EC liability from unlikely to all but certain.

 

[synchro]

If the equipment is of a type that is required to be listed, I don't see how a statement in writing that it is unlisted is anything other than admitting liability if something goes wrong, and probably increases the EC liability from unlikely to all but certain.

I can certainly understand your point.
It's just my opinion, but perhaps the OP should do what's necessary to provide a 380/220V wye output but nothing else. He can then show the customer that the L-L and L-N voltages are correct vs. what he had before. But any wiring and connections to the customer's choice of equipment would be left up to them and their choice of another electrician. And if there's documentation it can say that the OP removed the wiring to the equipment and did not install any wiring to the output of a newly configured transformer. In this scenario the OP would not be involved in case there are any problems with the equipment itself, or its use at 60Hz (although that could be OK).
I agree that mentioning the status of the equipment as unlisted within a document might lead to issues down the road.

The inverter inside of the induction heater is likely to be similar to those in VFD's. And so the knowledge and experience on this forum regarding supplying power to VFD's should be applicable to this case.

By the way, some other options for the OP to consider would be using a grounded wye-delta as a grounding transformer, or replacing the Δ-Δ with an autotransformer like this one (if the 480V supply provides a neutral):
...

3-Phase Autotransformer 600-480v or 480-380v

For smaller kVA sizes of this design click here. Voltages: 600-480v or 480-380v This autotransformer is designed to convert either of the 2 voltage combinations listed above in order to run equipment such as solar panels, motors, CNC machines, welders, conveyor systems, pumps, printing...

store.maddoxtransformer.com

But as petersonra mentioned in post #22, first double check whether the existing transformer has a wye output.

 

[LarryFine]

the person that bought it was not an electrical. they were trying to save money and do it them selves.

 

[Besoeker3]

Ahhh... the old "I got such a deal on this!" problem. Wasn't such a deal after all now, was it?

380V in other parts of the world is ALWAYS a Wye connection (they call it "Star") connection and it is VERY common to use Phase-to-Neutral as the control voltage, because it is "free". You now have three problems;

Not for me and others. For us it is three phase three wire delta for industrial applications.

 

[GoldDigger]

Not for me and others. For us it is three phase three wire delta for industrial applications.

Is that three wire delta ungrounded? Corner grounded?
If it is actually derived from a three wire wye with the wye-point grounded or uses a grounding transformer to control line to ground voltage, the result seen by the equipment is no different from a four-wire wye supply except that you cannot use line to neutral as a power source.

 

[Besoeker3]

Is that three wire delta ungrounded? Corner grounded?
If it is actually derived from a three wire wye with the wye-point grounded or uses a grounding transformer to control line to ground voltage, the result seen by the equipment is no different from a four-wire wye supply except that you cannot use line to neutral as a power source.

Generally transformers have a live and neutral for residential/commercial applications. Industrial applications usually have three phase.

 

[zbang]

Industrial applications usually have three phase.

Are they earthed/bonded in any way? (What's the fault current path?)
It sounds like the OP's machine would not be considered "industrial".

 

[Besoeker3]

Are they earthed/bonded in any way? (What's the fault current path?)
It sounds like the OP's machine would not be considered "industrial".

Depends on the system.
Residential is usually 4.0mm^2

 

[GoldDigger]

Generally transformers have a live and neutral for residential/commercial applications. Industrial applications usually have three phase.

I am still interested in the way the three wire supply is referenced to earth.

 

[Besoeker3]

I am still interested in the way the three wire supply is referenced to earth.

It is the earth, generally local.

 

[Besoeker3]

Cancel

 

[zbang]

It is the earth, generally local.

But how is it earthed? Is one phase earthed? Has a zigzag-transformer? That's what we're trying to find out.

 

[Besoeker3]

But how is it earthed? Is one phase earthed? Has a zigzag-transformer? That's what we're trying to find out.

The single phase or three phase is just that. That isn't earthed. The earth does that.

 

[wwhitney]

For us it is three phase three wire delta for industrial applications.

The question is, do those 3 phases have an established voltage relative to local earth due to the upstream equipment? E.g. because the upstream transformer has a wye secondary, with the neutral point earthed, and then just the 3 phases are distributed to utilization equipment. Or are those 3 phases all floating relative to local earth? E.g. because the upstream transformer has a delta secondary, and the system downstream of the delta secondary has no connections to earth.

Cheers, Wayne

 

[Besoeker3]

The question is, do those 3 phases have an established voltage relative to local earth due to the upstream equipment? E.g. because the upstream transformer has a wye secondary, with the neutral point earthed, and then just the 3 phases are distributed to utilization equipment. Or are those 3 phases all floating relative to local earth? E.g. because the upstream transformer has a delta secondary, and the system downstream of the delta secondary has no connections to earth.

Cheers, Wayne

Usually, there is a local earth.

 

[wwhitney]

Usually, there is a local earth.

Connected to?

Cheers, Wayne

 

[jim dungar]

The Europeans use different terminology than the North Americans do when describing earthing.

They might say TT for transformer neutral and frame connected to earth.

 

[Besoeker3]

Connected to?

Cheers, Wayne

Yes, usually. There are some examples when it is not.