Transformer Problem explanation needed

[wf1318]

Transformer Problem

Hello, I have some question about transformer.
I have a transformer that is 220VAC input, 12VAC output, 12VA...

My questions are:
1. What is 12VA meaning?
2. How can I know the max. current of this transformer?
3. If I swap the input & output.......therefore it will become 12VAC input, 220VAC output......so, what is the max. current of this transformer now???


Thanks!

 

[banjo]

Transformer Problem

VA stands for Volt-Amp. It is the product of the AC voltage and current. Therefore, you transformer is capable of 12V at 1A output.

If you reverse the transformer, you step up the voltage, but step down the current. Therefore, I would expect about 55mA output at 220VAC.

P.S. The VA rating of some transformers is very generous. When run continuously at that load some transformers will run hot and the output voltage may sag.

 

[pauloynski]

Re: Transformer Problem

Furthermore, the VA rating is commonly specified at "the maximum current that heats the transformer to a certain temperature, usually 70°C, with resect to an ambient temperature of 25°C using a resistive load".