U.S 120/208 3ph 4w to European 230vac single phase

[grasfulls]

Sorry if this is out there already, the few threads I found with keywords did not quite cover it. A client wishes to install some European single phase equipment for testing - EVC's requiring 230vac with a grounded conductor. What is the optimum way to provide a 230vac 20 SP circuit with the necessary neutral wire? I am thinking a buck boost transformer to bump up two legs of the 208 to around 230, then an isolation transformer to create the grounded conductor?

If this works, should the grounding of the secondary conductor be isolated from the primary grounding?

I am also guessing I would need to feed the setup with a two pole 30amp and then provide protection on the secondary side with a SP 20 amps? That is more of a question than a guess. Actual load is 230vac 50/60hz 16 amps. Would it be safer to use a 2pole breaker or fuses on the secondary?

In the event they want more circuits available, is there a good way to convert all 3 phases to 230 and provide a neutral.? Maybe a 100amp primary feed and a wye secondary at 230?

Thank you

 

[Little Bill]

I may be wrong but I don't think a buck/boost will work for separating the grounded conductor. I thought the grounded (neutral) in a buck/boost or auto transformer was connected. It's not isolated between primary and secondary.

 

[qcroanoke]

Sorry if this is out there already, the few threads I found with keywords did not quite cover it. A client wishes to install some European single phase equipment for testing - EVC's requiring 230vac with a grounded conductor. What is the optimum way to provide a 230vac 20 SP circuit with the necessary neutral wire? I am thinking a buck boost transformer to bump up two legs of the 208 to around 230, then an isolation transformer to create the grounded conductor?

If this works, should the grounding of the secondary conductor be isolated from the primary grounding?

I am also guessing I would need to feed the setup with a two pole 30amp and then provide protection on the secondary side with a SP 20 amps? That is more of a question than a guess. Actual load is 230vac 50/60hz 16 amps. Would it be safer to use a 2pole breaker or fuses on the secondary?

In the event they want more circuits available, is there a good way to convert all 3 phases to 230 and provide a neutral.? Maybe a 100amp primary feed and a wye secondary at 230?

Thank you

I would look at a 208 delta to 400/230 wye transformer. Not an off the shelf item but would work.
Is the equipment also 50 hz?

 

[templdl]

Sorry if this is out there already, the few threads I found with keywords did not quite cover it. A client wishes to install some European single phase equipment for testing - EVC's requiring 230vac with a grounded conductor. What is the optimum way to provide a 230vac 20 SP circuit with the necessary neutral wire? I am thinking a buck boost transformer to bump up two legs of the 208 to around 230, then an isolation transformer to create the grounded conductor?

If this works, should the grounding of the secondary conductor be isolated from the primary grounding?

I am also guessing I would need to feed the setup with a two pole 30amp and then provide protection on the secondary side with a SP 20 amps? That is more of a question than a guess. Actual load is 230vac 50/60hz 16 amps. Would it be safer to use a 2pole breaker or fuses on the secondary?

In the event they want more circuits available, is there a good way to convert all 3 phases to 230 and provide a neutral.? Maybe a 100amp primary feed and a wye secondary at 230?

Thank you

With the iplengthy post simply, you have 208y/120 and need 230v 1ph 2w is that correct? What you need is a 1ph transformer with a 208pri and a 240v secondary. Painless. You should be able to determine what KVA try that you need to serve your load.
But you did mention maybe a buck/boost transformer which is a good option if you don't need isolation. Refer to a manufactures catalog for a boost transformer that would provide you with a voltage close to 230v out. The reason that I say close to is that bucking or bostion can be done only is given voltage increments. There is one that will boost from 207 to 230v. Again, go to the manufactures catalog and select a B-B transformer that will provide you with the required KVA. But don't be fooled by the actual KVA of the transformer though as it only needs enough capacity to boost the voltage 23v. If you do go with a B-B you will safe money but it is extremely important that you follow the manufactures writing diagram, extremely important! Also, pay very close attention to how the NEC addresses providing over current protection of B-B transformers in art 450 and don't try to second guess it as you are dealing with a B-B transformer and not the common isolation transformer.
NEC art 450 does cover transformer over current protection which you should have a copy of.
You have mentioned European but I'm sure that you understand that you won't magically get 50hz from a 60hz sopply voltage.

 

[kwired]

I connected some European made equipment once that was shipped with a isolation transformer, we happened to be connecting it to 120/240 single phase source and all the transformer effectively did was to create a separately derived source which one output lead was grounded to match what is typical in a European installation. Can't recall for certain but seems the transformer had primary taps for adjustment for variance in primary voltage - so you likely are changing that tap for an application with 208 input volts.

Check to see what recommendations the equipment manufacturer maybe has? They have a transformer they sell or at least recommend for such applications.

 

[ActionDave]

Sorry if this is out there already, the few threads I found with keywords did not quite cover it. A client wishes to install some European single phase equipment for testing - EVC's requiring 230vac with a grounded conductor. What is the optimum way to provide a 230vac 20 SP circuit with the necessary neutral wire? I am thinking a buck boost transformer to bump up two legs of the 208 to around 230, then an isolation transformer to create the grounded conductor?

You may not need a transformer at all. The equipment may work on 208V just fine and there is no worry about one of the legs being grounded. Voltage is voltage to the equipment. A bigger deal might be the Htz.

 

[Tony S]

If this is for testing then you need to think long and hard on this.

50Hz will need a method of frequency change from 60Hz. It will need to be a “clean” supply, an inverter won’t do.

The voltage you should aim for is 415/240V, mid way between what it “officially” is and what it actually is.

 

[GoldDigger]

And if you think that you can find a 240 to 240 isolation transformer more easily than a 208 to 240 or 120 to 240 (if you have a 208Y120 service) then a buck boost will work fine.
I would try to get the one line at ground in case the equipment does not insulate that side of the equipment for 120 above ground.

 

[grasfulls]

400/230 50hz

400/230 50hz

I would look at a 208 delta to 400/230 wye transformer. Not an off the shelf item but would work.
Is the equipment also 50 hz?

It is listed 50/60hz, so we are ok there.

 

[petersonra]

Sorry if this is out there already, the few threads I found with keywords did not quite cover it. A client wishes to install some European single phase equipment for testing - EVC's requiring 230vac with a grounded conductor. What is the optimum way to provide a 230vac 20 SP circuit with the necessary neutral wire? I am thinking a buck boost transformer to bump up two legs of the 208 to around 230, then an isolation transformer to create the grounded conductor?

That is as good a way as any. However you can probably get a transformer that will change 208 to 230 directly without having to have an extra xfmr. We have one in our shop for testing 230 V stuff and we only have 208 coming in.

If this works, should the grounding of the secondary conductor be isolated from the primary grounding?

Except through the actual ground conductor(s).

I am also guessing I would need to feed the setup with a two pole 30amp and then provide protection on the secondary side with a SP 20 amps? That is more of a question than a guess. Actual load is 230vac 50/60hz 16 amps. Would it be safer to use a 2pole breaker or fuses on the secondary?

Safer? No. If one side is grounded there is no real safety issue involved that would make it safer to open both lines.

In the event they want more circuits available, is there a good way to convert all 3 phases to 230 and provide a neutral.? Maybe a 100amp primary feed and a wye secondary at 230?

You could probably get a 208 delta to 230 wye xfmr. It might be a special order.

It is not like this is some unique circumstance that no one else has ever run into. Call the Acme Transformer people and ask to talk to tech support. They will fix you up with a solution in about 60 seconds. Probably will email you a diagram and a PN while you are still on the phone with them. Might even be something they stock.

 

[grasfulls]

We have a transformer doing this - ACME

We have a transformer doing this - ACME

That is as good a way as any. However you can probably get a transformer that will change 208 to 230 directly without having to have an extra xfmr. We have one in our shop for testing 230 V stuff and we only have 208 coming in.

It is not like this is some unique circumstance that no one else has ever run into. Call the Acme Transformer people and ask to talk to tech support. They will fix you up with a solution in about 60 seconds. Probably will email you a diagram and a PN while you are still on the phone with them. Might even be something they stock.

What breand is your transofmrer? I will call ACME today, and thank you for the simple broken out answers, my simple mind appreciated them.

 

[grasfulls]

208 to 230 ACME

208 to 230 ACME

That is as good a way as any. However you can probably get a transformer that will change 208 to 230 directly without having to have an extra xfmr. We have one in our shop for testing 230 V stuff and we only have 208 coming in.


You could probably get a 208 delta to 230 wye xfmr. It might be a special order.

It is not like this is some unique circumstance that no one else has ever run into. Call the Acme Transformer people and ask to talk to tech support. They will fix you up with a solution in about 60 seconds. Probably will email you a diagram and a PN while you are still on the phone with them. Might even be something they stock.

Thank you for the suggestion -

ACME's solutions is:
ACME model T2535153S Transformer is a 240/480 primary with a primary tap for 216VAC. Attaching 208 to this will yield 231 vac on the secondary.

 

[kwired]

Thank you for the suggestion -

ACME's solutions is:
ACME model T2535153S Transformer is a 240/480 primary with a primary tap for 216VAC. Attaching 208 to this will yield 231 vac on the secondary.

Many places a 208 nominal system actually operates between 212 and 218 - connect that to your 216 tap and you probably have something in the 243 to 252 range for output.