Rich says:
>The total equivalent series R [ESR] is a determinant in such calculations.
???????????
What I'm suggesting is that a transformer can be checked for temperature rise at
a given current by doing the short circuit test. This heats the windings because
of the copper loss (i.e. heat generated by the current in the winding resistance
of primary and secondary). If the transformer is also saturating and producing
core heat becasue of this, it will add to the heating. The values of hot and
cold resistance of any one winding will give a measure of the temperature of the
windings at that current drain, from which a decision can be made as to whether
or not this is acceptable.
So you need to know Rcold and Rhot for any one winding. Not the total ESR or
anything else.
What you may wish to do, having got a winding temperature under your rated load
current and duty cycle, is to recalculate the regulation when the transformer is
at working temperature. That may or may not tell you something, or frighten you,
but to do that calculation you need to know the primary resistance and primary
current. Easy with one secondary winding: slightly more complex with several
windings, since you need to load up the transformer to the total (k)VA.
Was ham radio more fun when you scrounged the parts and cobbled together the rig
to go with them? Some of the signals (mainly from Europe) on 10m SSB in the
contest this weekend sounded like very cobbled together equipment.........
73
Peter G3RZP
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