Hi all,

Not sure if this is the correct forum but it's power related so the closest I could find.

If you look at the attached image of a transformer it states 120V to 240V, can somebody explain how you would get 240V out if the output taps are directly across one winding?

I can only assume that if the other winding was connected this would give 480V out (assuming the windings are matched). Is that correct or am i getting my knickers in a twist?

Cheers

Mitch

 

Hi Mitch,
The transformer image shows the two Secondary windings in Parallel, this is done to increase the capable current output of the transformer.

Are you measuring 240V output when the transformer is connected as your image.?
E
Connecting the two secondary winding in series would give 480V, at approx half the possible current of the 240v version.
Note: when connecting secondary windings in series, the correct phasing of the two windings is important.

 

Hi @ericgibbs

I've not actually got the transformer, it's just for knowledge and understanding
You're right, they are in parallel. Didn't spot that. Why would it be done like that?

 

Each secondary winding will be 240V, so connecting them in parallel will sum the current capability, as stated above in #2.

Connecting the secondaries in series will add the voltages, rather than the currents, so giving 480V as you surmise.

 

Didn't spot that. Why would it be done like that?

Hi M,
this is done to increase the capable current output of the transformer.

Also, it enables the manufacturer to use winding wire of approx half the gauge.

E
OT. Give my regards to the Spire

 

Apologies @ericgibbs and @boostbuck , didn't see the additional information before I replied initially.

Ok, makes sense now you've pointed it out.

Many thanks, much appreciated

 

I get the impression from the drawing that this is a controls transformer. Then by definition it is intended to provide both isolation and voltage changing.