On Wed, 27 Aug 2003 06:23:40 -0400, "Mike, K8LH"
<k8lh@kramerairtool.com> wrote:
>How can you determine the power handling capability of a transformer???
_________________________________________________________
The power handling capability of a transformer in a steady-state
condition is determined mainly by it's internal temperature.
Excessive heat buildup reduces the breakdown voltage of insulation,
both of the wires and the insulation between windings.
If you know nothing at all about the transformer, I'd recommend
letting it get no hotter than about 140 degrees F - slightly hotter
than your hand can stand to touch it. Transformers with ordinary
insulation should handle that ok. If you want to be conservative, run
it even cooler and it will last even longer.
For test purposes, a string of 120 volt light bulbs of the appropriate
wattage can be used as a dummy load. They have the advantage of
increasing resistance with increasing current, so they have a sort of
built-in regulation. I'd recommend using a variac to bring the
transformer up to full power to avoid the initial surge when the lamps
are cold. I have done this with transformers in the few hundred watt
range, but never at the kilowatt level. Be careful!
--
73, Bill W7TI
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