Can a step-down transformer be ran in reverse?

Question

So that it may become a step up transformer

Answer 1

Yes.

The current-to-voltage ration will be the same in reverse.

For example if you have a 120Vin / 12 Vout STEP DOWN transformer rated at 100 milliamps for secondary current, then you coudl run it in reverse to provide 12 Vin / 120 Vout at 1 Amp.

In other words, this is a 10-to-1 ratio.  The voltage is stepped DOWN, but the current is stepped UP.

BUT, you have to be careful that you do not exceed the original rating!.  If you tried to reverse the transform an do 120Vin / 1200 Vout you would probably fry the transformer.

And remember, transformers only work on AC current, not DC.  You cannot hook a transformer to a battery and expect to get anything useful.

Answer 2

You would have to reverse the iron coiling. On a step down transformer, the side where the electricity enters has more iron coils, on the exiting side, it has less iron coils.Just reverse that around.

Answer 3

Yes, as long as you don't exceed the voltage rating of the winding.

For example, a 240 to 120 volt step down transformer can be connected as a 120 to 240 volt step up, but NOT as a 240 to 480 volt step up.

.

Answer 4

To a certain limit, yes transformers can be operated bi-directionally as you described.

But most transformers are specifically designed with a certain coil set as primary. This coil has a higher inductance than most secondary coils do, and an optimized resistance for it's inductance.

If you run a transformer "in reverse" you may expect higher drive requirements and perhaps higher losses, therefore lower power ratings. But it can be done.