Transformer Question

[linguist]

Can a step down transformer be used as a step up transformer?

If a transformer has a 120v primary & a 30v secondary winding can 30v be applied to the secondary to get 120v at the primary.

I can't see why not but maybe there is something I am missing.
Does this change the VA rating?

Cheers.

 

[colin55]

Yes. It will work in reverse by putting 30v on the secondary. If you want a 120v supply that has a limited wattage, so you can use it to test pieces of equipment without damaging or blowing things up, simply connect a 120v: 30v transformer to the supply then connect the same type of transformer so that the two 30v windings are connected to each other and the output will be 120v but the wattage will be 15 or 30 watts (according to the wattage of the lowest-wattage transformer).

 

[linguist]

Thank for the reply colin55,

Yes I thought it would work ok.

Cheers