Transformer help

[Allan Christer]

I have been given a small transformer which apparently came from a 110V UPS for a computer. I did not get a wiring diagram or colour coding for the input output and would be grateful for any help.

I think (dangerous) that the heavier red and black are the + and _ of the higher voltage input (line and neutral) although I have no idea what the blue wire is for - some kind of sense?. The output or lighter wires are red, yellow (lower DC voltages?) green (ground?) and black (ground or what??).

Can anyone advise? Pic is attached.

 

[shortbus=]

You can't always use color codes on transformers, manufactures some times use there own. here is a link to a way to figure out windings with a multimeter; https://www.radioremembered.org/xfmr.htm

 

[SABorn]

If you have limited knowledge of working with mains power i would say sell it for scrap and buy a transformer of known wiring.

For example it could be wound for 110 VAC and also for 240 VAC as many are, and in Australia Brown and Blue are standard colour coding for Brown 240v active and Blue neutral, but as Shortbus said it dont mean the makers followed this code.

Often the primary windings will be a lighter gauge wire than the secondrys but can you be sure 100% when you apply power to it you have it correct. i say you can not be, so for saftey reasons bin it.

Transformers are cheaper than funerals.

Pete.

 

[Allan Christer]

Thanks Shortbus and SABorn,

I appreciate the assistance and guidance, especially the warnings from SAB.

I'll keep you advised, and will be very careful, Shortbus' guidance is especially useful, and I won't be using mains voltage until I have sorted this little thing out.

Allan

 

[crutschow]

To be safe if you decide to connect the transformer to the mains, use an incandescent bulb (say 100W) in series with the transformer. The resistance of the bulb is low enough to pass the normal transformer magnetizing current and will allow you to measure the output voltages, but will prevent anything bad from happening if you have the wrong connection.

The light should glow dimly, if at all, if you are connected to the correct transformer wires. If the bulb lights fairly brightly when connected, then you have the wrong connection.