EVonvaltie@aol.com writes...
>You make it sound so simple to just "sniff out" transformer windings. Tell
>me how you sniff out the current ratings. Especially on a multiple winding
>transformer for which you have no prior knowledge of the relative power
>ratings of each winding.
>
>As one who has designed his share of transformers, I am amazed that you
>can simply "sniff out" the results of that design process without knowing
>any of the basic design guidelines that were used. Let me and others in on
>your magic.
>
>Eric von Valtier K8LV
Magic? Hardly. VOM to locate the windings, a piece of paper to draw a
picture, and a variac to bring voltage on the suspected primary up slowly.
Removing the transformer from the chassis with some of the insulation on
the wires helps.
As far as current ratings? Guess, based on DC resistance, the weight of
the transformer, and testing into a resistive load bank. 240V halogen
light bulbs are handy for making a load bank.
Knowing what kind of gear the transformer came from helps. Having the
manufacturer's spec sheet or the equipment manual helps a lot more! Alas,
I have only a few HP manuals, so it's not always practical for me to "look
it up."
It takes maybe 10 minutes to set up my test jig, and then a few minutes per
transformer to test. It would take about 10 seconds with the right data
sheets.
Jim N6OTQ
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