Transform 3ph 480 vac to 1ph 230 vac

tbone1

Anybody heard of this? I found a transformer on line, wanted to see if anyone has done this. Thanks

joecaption

And why would you want to?
It's not likly any home will even have 3 ph 480 to convert.

tbone1

Well I actually work as an Industrial power plant technician and I have new bandsaw that came in and it is 230 1ph and the old one was 480 3 ph. So instead of finding a different panel to run wire from I want to just transform and be done.

jbfan

It is done all the time, but sounds like you may be in over your head.

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tbone1

@jbfan..how do you figure i'm in over my head?

jbfan

First thing you asked was if anyone had heard of transforming 3 phase 480v to single phase 230.

That tells me you don't have a lot of experience in electrical.

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tbone1

I've done step up and down transforming with A/C and D/C but I've never seen it done from 3ph to 1ph.
I've worked in aviation for 24 years working on ground power generators and electrical systems, 400Hz 220 and 120 volt systems.
Commercial power is basically the same but with some differences.

micromind

I think what JB was getting at is you cannot transform 480 3ø into 230 1ø. You can however, transform 480 1ø into 230 1ø.

Generally speaking, such a transformer will be 480 to 240, not 230.

And yes, this is done on a regular basis in industrial plants.

You'll need to protect the primary of the transformer from overcurrent, ground faults and short circuits. Since it is two-wire in and two-wire out, the secondary will be protected by the primary protection, and does not need it own.

Rob

mpoulton

In every reasonably large commercial building, ALL of the 120V power comes from a 480V 3ph service. Almost every large building has transformers that provide 120/208 3ph or 120/240 1ph from the 480V 3ph service. You really need to have an electrician do this. 480V systems are NOT safe to work on without substantial knowledge and experience - especially in industrial facilities where the fault current is very high and arc flash is a major hazard. I'm all in favor of people learning things and gaining experience, but working on 480V systems in industrial plants is not the way to do it.

Julius793

I don't do commercial but if I had to take a guess his single phase would be 277v not 480v. Now to the op, industrial questions should be posted on electriciantalk.com

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mpoulton

There are two ways to connect the transformer, but both use 480V on the primary. You either use a 1ph 480V:120/240V transformer, with two phases on the primary, or you use a 480V:240V high-leg delta 3ph transformer with a delta-connected 480V primary.

A 480V primary is always used because it spreads the load across two of the three phases instead of just one.

Julius793

If it is a 480v primary that is phase to ground or phase to phase? I'm assuming phase to phase which would be a 277/480 service?

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jbfan

Phase to phase on 480v is 480v, phase to gorunded conductor is 277v.

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Julius793

That makes sense so what he would need is a 277 to 230 transformer.

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AllanJ

Is there any such thing as a 240/480 volt 3 phase high leg system?

The answer would not be relevant if the OP uses a 480 to 240 volt single phase transformer or even a 480 to 240 volt 3 phase transformer if the latter was a super eBay bargain.

Since the old saw was 3 phase 480 volt they had to have had 3 phase 480 volt power at that location.

By the way, for a 3 phase system or 3 phase circuit with a single voltage stated, that is the phase to phase voltage.

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