How do I measure the ratio of a transformer?

Question

I have a number of unknown transformers, how can I measure the ration of the loops in the transformer?

Answer 1

like between the primary and secondary windings? I would say... well, what kind of transformers do you got?

Answer 2

You can apply an AC voltage to one side and measure the output a the other, however, you need to use some caution in doing this as you may wind up stepping up to dangerous voltages. You might try a 6V or so step down transformer as a supply, maybe with a series resistor to limit current.  Of course this means you have to have at least one known transformer to start with.

Answer 3

You should be able to divide the secondary winding by the primary winding to find the voltage ratio. If the secondary winding is twice the primary, your voltage should increase two times.

Vs/Vp=Ns/Np

note that this is ideal, but a transformer is highly efficient regardless. It's a tad more complex really, but I think thats what your looking for...maybe

Answer 4

Well tinkertailorcandlestickmaker is correct, but the process would not necessarily be dangerous.  All currents are dangerous, but all you would be measuring would is the open circuit voltage of the secondary, so no secondary current.  So the only current on the primary side would be the magnetizing current for the transformer, which would be a small percentage of the rated current.

Apply a known low voltage on one side and measure voltage produced on other side.  Start voltmeter on high scale and decrease to get accuracy.  Divide voltage applied/voltage measured to get turns ratio.

If voltage is too large to be measured, reverse transformer.