25V/70V Transformer identification

[klem kedidelhopper]

I have a large number of small line to voice transformers that came
out of a very large municipal facility These are all from different
manufacturers. Some are tapped to watts and some are different. I
would like to re employ these on a current project which will require
70V units , but I do not know whether they are 25V or 70V
transformers. Can anyone suggest an easy way to determine this? I have
tried comparing them with known transformers, however resistance
readings are too variable to determine anything concrete. Thanks, Lenny

 

[Michael A. Terrell]

On 6/17/2012 4:15 PM, klem kedidelhopper wrote:

I have a large number of small line to voice transformers that came
out of a very large municipal facility These are all from different
manufacturers. Some are tapped to watts and some are different. I
would like to re employ these on a current project which will require
70V units , but I do not know whether they are 25V or 70V
transformers. Can anyone suggest an easy way to determine this? I have
tried comparing them with known transformers, however resistance
readings are too variable to determine anything concrete. Thanks, Lenny

The only way to know is to measure the turns ratio, if they are unmarked.

Turns ratio squared* low side impedance = the high side impedance. Then
use the formulas I posted earlier to determine the wattage at 70.7 V.

 

You got any kind of signal generator ? Feed ot woth that and measure voltage and it is a matter of simple math.

J