# 240, 4 wire to 120/208



## jgs8919 (Jan 23, 2014)

How can one change an incoming 240V, 4wire to 120/208V WYE?


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## Big John (May 23, 2010)

Buy a 240VΔ:208Y transformer...? There's no shortcut that I know of.


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## micromind (Aug 11, 2007)

Or get the POCO to change their transformers.


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## That_Dude (Feb 13, 2012)

jgs8919 said:


> How can one change an incoming 240V, 4wire to 120/208V WYE?


Is it 120/240 Single phase or high leg delta? More information will help you here.


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## Pharon (Jan 20, 2014)

If it's 240 volt, 4 wire, that sounds like 3 phase...


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## micromind (Aug 11, 2007)

Yep, my guess too. 

It's possible to lower the voltage and create a grounded wye using buck/boost transformers, but the ∆ system would need to be ungrounded.


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## jgs8919 (Jan 23, 2014)

micromind said:


> Or get the POCO to change their transformers.


How difficult is that? I am assuming also expensive..


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## jgs8919 (Jan 23, 2014)

That_Dude said:


> Is it 120/240 Single phase or high leg delta? More information will help you here.


A high leg delta. The way it is wired...one of the phases is unused and the other two are feeding a single phase subpanel. We want to install a PV system. So we want to know whether there is a cost effective way of changing the voltage configuration without having to install 3 single phase inverters.


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## That_Dude (Feb 13, 2012)

https://www.swgr.com/store/dry-type-low-transformer/product/11-4388.aspx Might help.


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## Pharon (Jan 20, 2014)

jgs8919 said:


> A high leg delta. The way it is wired...one of the phases is unused and the other two are feeding a single phase subpanel. We want to install a PV system. So we want to know whether there is a cost effective way of changing the voltage configuration without having to install 3 single phase inverters.


Check the listing of your 208 volt inverter. If it's good for 208 volts, it should be good for 240 volts -- since it's less overall current. And all the insulation ratings should be good for 250 volts anyway.

If not, then three 1-phase inverters will probably be cheaper than putting in a 208-240 volt, 3 phase transformer.

What's the kVA rating and manufacturer name of the inverter?


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## jgs8919 (Jan 23, 2014)

That_Dude said:


> Is it 120/240 Single phase or high leg delta? More information will help you here.





Pharon said:


> Check the listing of your 208 volt inverter. If it's good for 208 volts, it should be good for 240 volts -- since it's less overall current. And all the insulation ratings should be good for 250 volts anyway.
> 
> If not, then three 1-phase inverters will probably be cheaper than putting in a 208-240 volt, 3 phase transformer.
> 
> What's the kVA rating and manufacturer name of the inverter?


It is a small system. 13.08kW system and the inverter is:
http://www.svssolutions.com/wp-content/uploads/2012/08/SPR-10001f-1-UNI-SPR-11401f-1-UNI.pdf


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## jgs8919 (Jan 23, 2014)

jgs8919 said:


> It is a small system. 13.08kW system and the inverter is:
> http://www.svssolutions.com/wp-content/uploads/2012/08/SPR-10001f-1-UNI-SPR-11401f-1-UNI.pdf



Sorry wrong link.
Inverter is: http://www.svssolutions.com/wp-content/uploads/2012/08/SPR-11401f-3-208-240-DELTA.pdf


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## Pharon (Jan 20, 2014)

Both of those links are getting flagged for me as malware. But if you can open and view them, it should be self-explanatory. Or, just call the manufacturer and ask to speak with one of their technical support people. I'm sure they will be able to answer your question.


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## micromind (Aug 11, 2007)

jgs8919 said:


> How difficult is that? I am assuming also expensive..


Around here, the POCO will swap a delta bank for a wye at no cost. They're trying to get rid of deltas, especially pad-mount. 

If they're pole-mount and all 3 are the same size, they'll simply re-connect then internally and re-connect the service drop to a wye.


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## jgs8919 (Jan 23, 2014)

Thank you for all the advice everyone. The inverter manufacturer confirmed that I can just connect them to the three lines without pulling a neutral.


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