# 600 or 480



## Rap2 (Dec 17, 2010)

I have decided to solve my grounding issue with my local utility by installing a normal delta/wye transformer between my PV inverter and the service.

I can either use a 480v/480v transformer or the PV inverter can operate at 600 volts and I can use a 600v/480v transformer.

Distance and wire size are not much of a concern, are there any notable advantages to running at 600 volts (transformer cost is about the same).


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## Vintage Sounds (Oct 23, 2009)

600v is nice because you can use smaller wires and experience less voltage drop but you're saying neither of these two things are a big deal in your case. If so, I guess it just depends which transformer is easier for you to get. Being in the US I guess a 480 to 480 would be more common. Over here 600v services are the standard in commercial.


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## Rap2 (Dec 17, 2010)

the only reason I am putting in the transformer is to solve a grounding requirement by the utility, I guess I was wondering if somehow a higher voltage to lower voltage transformer would be in any way more efficient due to something like the length of the windings or whatever...

Thank you for the reply sorry to be grasping at straws


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## oliquir (Jan 13, 2011)

is it legal in the nec to use some 600 volt stuff?


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## dronai (Apr 11, 2011)

Rap2 said:


> the only reason I am putting in the transformer is to solve a grounding requirement by the utility, I guess I was wondering if somehow a higher voltage to lower voltage transformer would be in any way more efficient due to something like the length of the windings or whatever...
> 
> Thank you for the reply sorry to be grasping at straws


This is my guess. Someone correct me if i'm wrong.The windings are 1 to 1 ratio on turns for 480 to 480

600V - 480V more copper on what ever way your going. Up, or down. more copper equals more losses.


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## jmsmith (Sep 10, 2011)

If you can go 480 to 480, go for it! Transformer are a high-dollar item, especially if you go for voltages that are not commonly used in your area. Yes, you can get by with smaller primary wiring at 600v for the same KVA, but unless you are talking a VERY long distance, I don't see where the savings in cable would justify the expense of the transformer. If it was me, I would go the 480V delta-wye.

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## Rap2 (Dec 17, 2010)

jmsmith said:


> If you can go 480 to 480, go for it! Transformer are a high-dollar item, especially if you go for voltages that are not commonly used in your area. Yes, you can get by with smaller primary wiring at 600v for the same KVA, but unless you are talking a VERY long distance, I don't see where the savings in cable would justify the expense of the transformer. If it was me, I would go the 480V delta-wye.
> 
> Sent from my iPhone using ET Forum


Its about 4 grand for the 220KVA transformer, 480/480 is about the same price as 600/480. I tend to use the highest voltage i can on long runs, 600 volts is the threshold without having to get into special wire and is a popular enough voltage that the transformers are readily available. 

In fact if I use 2 transformers to boost up and back down for a long run I do not have to use standard voltages between them and I will tap the 480 side of a 480/208 transformer up to 504 volts or 600 if its built that way.


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## Rap2 (Dec 17, 2010)

oliquir said:


> is it legal in the nec to use some 600 volt stuff?


Any voltage you want as far as I know as long as you stay within the parameters of the wiring,insulation and equipment you are interconnecting (and whatever licensing you may have to mess with said voltage... ). 

you can build a device such as a transformer and have it go from a standard voltage like 208 to 588.5 volts to supply whatever 588.5 volt device you may have or knock it back down on the other side with another custom transformer to 208 ect..

In fact buck and boost transformers do all kinds of weird voltages to kick up or kick down a line.


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## jmsmith (Sep 10, 2011)

I was going under the assumption that your PV was somewhat CLOSE to the point of service, and just plain read-over the fact that it was capable of 600v output... My bad! You can go either way here, the question here is which way would be more efficient during operation. That all varies with the transformer (IR losses, core losses, efficiency, pf, etc). Best of luck...
- Jim

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