question about step down transformers

[picmacmillan]

a freind of mine who collects scap metal has come across what i can gather is a stepup, or a stepdown transformer....is anything like this of any use to us?...i have no idea what it could be used for, if used at all..your comments would be sincerely appreciated...pickster

[finnsawyer]

Assuming you have no data on it you can test it.  Run some ac into one set of terminals and see what you get out the other(s).  You can determine continuity using an Ohmmeter.  This might also indicate which is the primary.  Its usefulness will be determined by the step-up ratio and by its size.  I recommend using a filament (6.3 or 12.6 volt) transformer to provide the test ac.  Have fun.

[Opera House]

Put a 100W lamp in series with the test coil.  If that coil is rated at line voltage or higher, the lamp won't light.  This will safely allow you to get ratio measurments of the coils.

[pyrocasto]

and yes they can be useful to us for stepping up or down voltage. Stepping up, if you have a long line to run to the batteries. Stepping down if you have higher voltage stuff, like 48volts in panels, to step down to a 24v or 12v battery.

It all depends on the specs of the transformer.

[wooferhound]

Never apply a DC Voltage to a Transformer. A transformer is a Dead Short to DC Voltages and will burn up letting out the Magic Smoke. Don't hook your Panels to a transformer directly.

 Transformers ,  Robots in Disguise !?

[picmacmillan]

thanks gents...looks like i am going garbage picking pickster

[pyrocasto]

Thanks, I didnt know that. So what would you use for dc?

[Chiron]

You can feed a transformer with DC if you use a "chopper" circuit.

Older tranformer type inverters would feed a transformer by switching the current on and off on the primary windings. Most used a center tapped primary like the one at http://www.aaroncake.net/circuits/inverter.htm

You could convert/step up your low voltage DC for transmission to the home then use another transformer and rectifier to convert back to low voltage DC for charging or whatever.

If you can get your hands on an old 7.2kV line tranformer you could get a 60:1 voltage ratio with an inverter/chopper feeding the 120/240 side of the transformer.

I'd only advise this approach if your array or mill was quite a distance from the house, like with a wind turbine on top of a ridge a mile or more away. Line losses would be very small and smaller gauge wire could be used but the insulation would need to be better because of the higher voltages.

THIS IS EXTREEMLY DANGEROUS!!! Don't try it unless you have experience with high voltage or can get someone who does to hook it up for you.

With a 24V array you would be generating 1,440VAC making line losses very small but one small slip with it could cause serious death or injury.

HTH

Chiron

.

[pyrocasto]

Thanks Chiron.

One part I found funny in your post though.

"serious death or injury"

hehe