Testing Transformers

[Zak]

Hello all i do apologize if this has been asked already but i am just having a hard time finding good information on the process taken to find the full current capabilities of an unknown A/C transformer. I have tons of transformers i have salvaged, i am sure everyone does, and i would like to start using them i can of course easily find the voltage but idk if i should just hook it up to a dummy load or some light bulbs to find the current not too sure any help would be appreciated.

 

[Brickbat]

Not possible. There are some 'rules of thumb' that might get you close (eg load it until the voltage drops 10% or something, measure the core area, etc.) but they're not that reliable.

 

[Hyperion]

Not possible. There are some 'rules of thumb' that might get you close (eg load it until the voltage drops 10% or something, measure the core area, etc.) but they're not that reliable.

Yep, agree - you could measure the output voltage, & thus deduce the turns ratio, measure the thickness and resistance of the wire used for the primary & secondary windings and so on, which with a considerable amount of mathematics might get you reasonably close. But in my opinion measuring by loading will be unlikely to give you accurate results either. I feel you would do better to Google the identification numbers on the transformers themselves and maybe find the spec's online.

However, if you took them to someone who designs and builds transformers, they may have the know-how to either measure directly or calculate more accurately the spec's you need. You might even find a 'transformer whisperer' at one of those places, who can tell you what they are just by looking at them.

Good Luck