Question- Derate transformer if use 230VAC tap?

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I want to use a 800 VA transformer to provide two 25V AC signals as an output for my 115VAC mains, but all I can buy is a 800 VA transformer that provides two 50 VAC taps.

However, the available Xformer can be wired for 230VAC. I can wire the primary in series for 230 V and use it with my 115 V mains (here in the US) and get the correct voltage on the secondary right?

So my question is whether or not the transformer needs to be derated down from 800VA to a lower value, since all the current is going through the primary in series rather than being split in parallel like it would be in a normal use.

- thanks.
 
Hi,
would it be too much to rewind the secondary down to 25Vac?
If you bought 2 *50Vac and could identify the mid-point of each winding then you could cut and extend the tails. Giving 4 * 25Vac. Now // two of each to give 2*25Vac @ the full 800VA. or by removing some from two windings get lower yet, say 2*25Vac & 2*18Vac?.
 
Hi,

a saw that Hammond http://www.hammondmfg.com has big toroids with at least 2x24V secondaries and 117V primaries.
But i never tested them nor do i know where to get them in the USA.

In Germany there is i.e. http://www.trafoshop24.de with a 630VA 2x 18VAC and also 800VA / 1000VA with 2x25VAC, but shipping would not be economical i assume.

I bought a few smaller ones from them and they work fine.

Jochen
 
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