1. ## Toroidal transformer question

I purchased a y236905 from avel lindberg.

http://www.avellindberg.com/transfor...ange_specs.htm

i am wondering about how to wire the primary's from my 115v source.
I see for 115v ac that it seems the input should be wired as parralel,
for 230v ac it should be wired in series.

http://www.avellindberg.com/transfor...onnections.htm

If my total applied ac voltage is 115v in series why would it show 230 v in
the wiring dia. is it just the way the 2 seperate coils are wound that would
make the applied 115v add up to 230v if wired in series?
I obviously am missing something , if it has 2 primarys and a potential of
115v is wired across the 2 coils in series the potential of 115v should not
change ?
what am i missing , besides my brains

2. ## Specs?

You are not missing anything. Just a bit of theory has gone, or never been.

The link you gave only gave output specs for the transformer.

The next part assumes the output of the transformer is loaded to 800 watts.

For 230v and 800w (Ignoring efficiency and resistive loss fudges by transformer designer)
230 volts x 3.48 amps = 800 watts.

for 115v applied
115 volts x 6.96 amps = 800 watts.

If you have 2 115v windings in series with 3.48 amps x (115 + 115) = 800w.
now if you put the 115v windings in parallel and apply 115v
The windings will be rated at about 3.5 amps.
When you have 2 in parallel, the total current at 115v will be 3.48 + 3.48 = 6.96 amps.

Now for some LIVE TESTING. No fingers connected at any time!
Now lets assume there is no load on the transformer secondary.

It is very important that the windings are phased correctly.

For 230vAC
When in series, then end of the one winding MUST go to the start of the other winding.

For 115vAC
When in parallel the starts are connected together, and the finishes are connected together.

If you have a spec sheet which clearly says which wires to parallel for 115v or which wires to connect in series then follow the instructions.

If the spec sheet shows a 230v connection, and shows the centre series connection, then one of those wires is a start of a winding, and the second is the end of the other winding.

If you don't know which are the starts, and finishes, then you need carry out some tests.
In the following S1 and F1 are winding 1 start and finish. S2 And F2 are winding 2.

On 115v it is easy to test if the phasing is correct.
1). If we don't know the start lets take one wire of each of the windings, and assume they are starts.
2). Connect them together. S1/S2
3). Connect 115v to S1/S2 and F1.
4). Measure between F1 and F2 with a meter on ACv (> 200v).
You should get very close to zero volts. If so go to step 6)
5). If you get 230 volts then the assumption at 1) was WRONG. It was actually S1/F2.
TURN OFF POWER
If you get to here a second time CALL IN AN EXPERT. You will kill yourself.
Make new assuption for S2, and go back to step 1)

6). TURN OFF POWER.
Connect F1 to F2, and apply power. Measure outputs. You should get 60V on each of the output windings.

3. Hi neilw20,
so if i am understanding this right , because it is rated at 800watts,
that is what is to determine the primary wiring configuration ,
at 115v / parralel / it will be able to handle over 6 amps, and at
230v /series / it can handle half that,,,
but what if , the primary's are wired in series and we connected 115v
across them and the ratio of the transformer is 1:1 ,, would the output be
115v but only able to handle half the transformers rated current ? The output
couldn't be 230v in this instance ?

4. ## Take care.

If you can't follow the steps I outline, you should get an electrician or elctronics person to explain what I have outlined.

If you apply 115v in the 230v configuration, then your output windings will be only 50% of the design value. This will do no harm, but it might not do what you intended.

If you email me your circuit diagram for what you are about to embark on I may be able to help further.
As previously mentioned, the www link for the 800w transformer does not give it's full spec.
Only output. It doesn't say what the input is/can be.

Take care.

5. Thanks neilw20, I have the instructions for the exact wiring , and do not intend to wire it any differently than what is called for .
I was only trying to see if I was missing something about the way transformers/coils work .
thank you