trying to ID windings on a transformer

[Maxxarcade]

I have this big old transformer which appears to be new old stock. I'm trying to figure out what the ratings of the windings are.

I have checked the DC resistance on all terminals and this is what I found between the following pairs of terminals:

1-3 1.3 ohms (primary?)
2-4 1.3 ohms (primary?)
5-6 0.2 ohms (this is the big ~12 guage wire terminals sticking out)
7-8 0.5 ohms
9-10 0.5 ohms

Torwico seems to be gone, so I have no hope of finding a data sheet.

Not sure this transformer is for use on 120V input, since 1.3 ohms would draw 92 amps of input at 120V, would it not?

Any ideas on what this was used for?

[Harvey]

Re: trying to ID windings on a transformer

Measuring the DC resistance gets you almost nowhere, you really need to know the impedance - the resistance when an AC current is applied.

I found some details of Torwico electronics here - http://www.wand.com/core/CompanyProf...lectronics+L.P. , you might want to try and contact them.

[Maxxarcade]

Re: trying to ID windings on a transformer

I'll pull my impedance meter out tomorrow, but I'm not sure it will work since it's made for speakers.

That number for Torwico is disconnected, at least it was when I called earlier today. I think they went belly up a while back.

[kc8adu]

Re: trying to ID windings on a transformer

try the highest windings on 120 ac with a 100w lightbulb in series.
it should be dim.measure voltages on the others.
maybe 1-3 and 2-4 are both primary wih the pair paralell on 120 and series on 240?

[gg1978]

Re: trying to ID windings on a transformer

try the highest windings on 120 ac with a 100w lightbulb in series.
it should be dim.measure voltages on the others.
maybe 1-3 and 2-4 are both primary wih the pair paralell on 120 and series on 240?

This sounds like your best bet.. If you're going to use an impedance meter, i would think you'd want to measure it at 60Hz. It sure does look like a line transformer. I've worked with transformers that had both a splittable primary and secondary, so you could run it on 115/230VAC, and output either 44V at 1A or 22V at 2A.. As for the bare wire winding that is poking straight up instead of being brought out to a terminal board might be a custom winding that was added..


It appears that Torwico first filed for bankruptcy in late '89, and it was ongoing through at least '93 to '94, from the results of a google search. I don't think you'll find anything on the web..

[Maxxarcade]

Re: trying to ID windings on a transformer

try the highest windings on 120 ac with a 100w lightbulb in series.
it should be dim.measure voltages on the others.
maybe 1-3 and 2-4 are both primary wih the pair paralell on 120 and series on 240?

I was thinking the same about the primaries. Though it still seems like an awful low impedance winding to be 120V.

As for the bare wire winding that sticks out at the top and bottom, it looks factory and intentional. I think they left it that way because it was too big (and brittle) to bend around the small terminals.

My impedance meter only operates at 1Khz, so I may just have to make my own impedance jig, or use the light bulb test.

EDIT: Could it be that the transformer was used in tube based equipment? The large winding would be the filament output perhaps?

[Maxxarcade]

Re: trying to ID windings on a transformer

Figured it out with the light bulb test

1-3 and 2-4 are 120v/220v input as suspected.

5-6 is 45v (and probably a lot of amps judging by the wire size)
7-8 is 24v
9-10 is 24v

Thanks all for the help Now I can start checking other transformers I have in storage.