Need a 380Y/220 transformer

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wwhitney said:
The proposal is effectively a 240V:240V isolation transformer, followed by a 240V:216V autotransformer. It just puts it all together in one package on a single core, with the 240V isolation secondary coil the same physical coil as the 240V autotransformer "primary" coil.

Cheers, Wayne
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Not quite; there are 2 separate 240V coils (otherwise you couldn't have the necessary isolation to go from delta to wye!), but they are wound on the same core.
 
winnie said:
Not quite; there are 2 separate 240V coils (otherwise you couldn't have the necessary isolation to go from delta to wye!), but they are wound on the same core.
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I believe my description was accurate: a 240V:240V isolation transformer would have two 240V coils, and a 240V:216V buck transformer would have a 240V coil and a 24V coil. That's 3 total 240V coils. But you only need two as in your proposal, since the 240V isolation secondary coil can be the same as the autotransformer's 240V coil.

Cheers, Wayne
 
electrofelon said:
But none of those do 230->208.
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The Hammond C1FC25CE that was mentioned comes up as a 250VA 277V : 120/240V transformer. Used as 277V:240V 2-wire, that's a 1/sqrt(3) reduction. So with 240V on the primary you'd get 208V on the secondary. But if it has a -5% primary tap (assuming that's the naming convention, a tap for when the primary voltage is low), that would be 263V : 240V, which supplied with 240V would give you 219V.

If 250VA is insufficient, the next sizes up are 350VA, 500VA, etc.

Cheers, Wayne
 
wwhitney said:
The Hammond C1FC25CE that was mentioned comes up as a 250VA 277V : 120/240V transformer. Used as 277V:240V 2-wire, that's a 1/sqrt(3) reduction. So with 240V on the primary you'd get 208V on the secondary. But if it has a -5% primary tap (assuming that's the naming convention, a tap for when the primary voltage is low), that would be 263V : 240V, which supplied with 240V would give you 219V.

If 250VA is insufficient, the next sizes up are 350VA, 500VA, etc.

Cheers, Wayne
Click to expand...

I don't think this transformer has voltage adjustment taps.
 
electrofelon said:
But none of those do 230->208. That combination would be nearly perfect, if you can find me one I'll buy you a milkshake.
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OK, I was in a hurry and doing bad math and assumptions.

Try this one:
C1FC25XE

Actually does 220:240 natively.

Many other possibilities in this catalog, but I do not know how to interpret. Look at SCD23 and SCD26 pages.

 
electrofelon said:
I've got a small mixer I need to power. It needs 3 phases plus a neutral and my premise system is 240V, thus I need a 240 delta to 380y/220 transformer. The motor is only .75 KW. I can find such a transformer no problem however the smallest one immediately available is 3KVA and a couple grand. It won't be used much and isn't really a prize anyway so I'm just trying to come up with a cheaper option. It's an annoying voltage, he's trying to come up with another more common transformer that would have the same ratio and nothing works. I thought about making up my own Delta/Wye Bank out of single phase control transformers. I would need 240 to 220 volt transformers. Can't even find those. Anybody got any nice creative bastard solution I may have overlooked?
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wwhitney said:
The Hammond C1FC25CE that was mentioned comes up as a 250VA 277V : 120/240V transformer. Used as 277V:240V 2-wire, that's a 1/sqrt(3) reduction. So with 240V on the primary you'd get 208V on the secondary. But if it has a -5% primary tap (assuming that's the naming convention, a tap for when the primary voltage is low), that would be 263V : 240V, which supplied with 240V would give you 219V.

If 250VA is insufficient, the next sizes up are 350VA, 500VA, etc.

Cheers, Wayne
Click to expand...
winnie said:
I don't think this transformer has voltage adjustment taps.
Click to expand...
It's really frustrating I can't seem to find an actual wiring diagram or a label with enough resolution to make out. The best I could find was quite blurry but it did look like it had some taps. All the good resolution pictures I find are not of that actual unit and do not seem to have taps. Wayne where are you seeing specified that it has taps?
 
petersonra said:
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Shenzhen Factory Price 220v/230v/240v To 380v 3 Phase Voltage Transformer 30kva - Buy 240v To 380v Three Phase Transformer,3 Phase Voltage Transformer 380v To 220v,Transformer 30 Kva Product on Alibaba.com
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$360 plus $134 shipping.
Click to expand...
Wow that's cheap. So cheap it's scary
 
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