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Three phase transformer

I have acquired a big(4kva) three phase transformer. the primary is a star configuration and the secondary a single voltage delta. it is wound on three limbs of an iron core. I can separate each of the primary and secondary windings to give three pairs each wound on a limb of the core. I suspect this is perfectly normal - but I've never looked at one before. Playing (on paper) with the turns ratios, my application of voltage step up from 240 to 415 would be satisified by putting each primary in series across the mains and putting each secondary in series. each winding would get less voltage than originally designed thus not exceeding the original turns per volt.

Provided I connect each winding start to finish in the right order, is there anything to stop me using it in this way?

I've done a bit of a search on three phase transformers but not surprisingly, I've not found anything about using them for single phase applications.

I'd be grateful for any info.

regards

Bob

"why is is that I always want to use things for purposes that they were not designed for??"

Reply to
Bob Minchin
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Because you like nice explosions/fire/smoke??? A 3phase transformer has partly shared magnetic core, and when you dont use 3phase source voltage, very interesting things can happen, like cancellation or adding magnetic flux. Cancelation can cause huge blind current, and adding may cause saturation of some core piece, also providing a nice short to the input voltage. I suggest using it only as a 3phase transformer, unless you like some fireworks. Of course you can experiment, by applying low voltage to it, and see what comes out. Have fun :)

Sjouke.

Reply to
Sjouke Burry

How can it have a 'single voltage'? if it is delta?

Not going to happen.

Reply to
Homer J Simpson

I used 'Single voltage delta' as distinct from multi voltage tapped windings

Solution is to put the windings on the outer limbs in parallel with each other and in series with the centre limb winding. On test there are no circulating currents or over heating problems.

This is done for both Primary and Secondary. Works a treat! None of the smoke escapes.

Bob

Reply to
Bob Minchin

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