I have a customer that has a piece of equipment that was shipped with a 15kva 3-phase Delta to Wye transformer. The only power at the facility is Wye configuration. I have been told by some that I can still use the transformer and to just not run the neutral to the transformer. If this is true, then why do Wye to Wye transformers even exist?
Feeding a Delta to Wye transformer with a Wye primary?
- Thread starter Don Dula
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electrofelon
Senior Member
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- Cherry Valley NY, Seattle, WA
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- Electrician
A Delta primary transformer means just that the primary windings are connected in a delta. Whether the feeding electrical system is Delta or wye does not matter, as long as the voltage is correct. The transformer still gets fed by three legs. There is no place to land a neutral on a Delta primary transformer so you don't run it or use it.
kwired
Electron manager
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Agree with EF. All the primary winding cares about is seeing three 120 degree offset inputs within it's voltage rating. It won't even care which or if any those incoming lines are grounded. Give it that and you will get designed output on the secondary.
LarryFine
Master Electrician Electric Contractor Richmond VA
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- Henrico County, VA
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Welcome to the forum.
Yes, you can supply a delta load from a wye source. Think of a 3ph 208v motor as an example.
Yes, you can supply a delta load from a wye source. Think of a 3ph 208v motor as an example.
electrofelon
Senior Member
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- Cherry Valley NY, Seattle, WA
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- Electrician
A few other things that are an expansion of the topic and just for completeness:
Particularly in medium voltage transformers there very well may be sound engineering reasons to go with a YY transformer and to match the transformer configuration to the source. Ferroresonance for example might be one.
Also for single phase MV transformers, the transformer is typically described by the type of system that will be feeding it and this implies how many medium voltage bushings the transformer has. For example a 12470GRDY/7200 has a 7200V primary and is fed line to neutral and intended to be fed from a multi-grounded neutral system. It will have one primary bushing with the primary neutral connected to the tank. You could not feed this transformer with two ungrounded legs. On the other hand a two bushing transformer could be fed line line or line neutral.
Particularly in medium voltage transformers there very well may be sound engineering reasons to go with a YY transformer and to match the transformer configuration to the source. Ferroresonance for example might be one.
Also for single phase MV transformers, the transformer is typically described by the type of system that will be feeding it and this implies how many medium voltage bushings the transformer has. For example a 12470GRDY/7200 has a 7200V primary and is fed line to neutral and intended to be fed from a multi-grounded neutral system. It will have one primary bushing with the primary neutral connected to the tank. You could not feed this transformer with two ungrounded legs. On the other hand a two bushing transformer could be fed line line or line neutral.
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- Licensed Electrician
Ya know there are a lot of people on this forum that are smarter than me. I never felt like you were one of them until now.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
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- Electrician
Aww shucks.... Yeah MV transformers are described a little bit differently. It's weird the first time you look at a single phase transformer and see a three-phase designation on it
. I had to learn the basics when I did a step up step down at my house. Since then I've done a few step up step Downs to medium voltage for customers,. But I wouldn't call myself an "MV guy".- Status