At 09:29 AM 1/18/2001 -0800, you wrote:
>Another way to question this:
>
>How can you be certain the secondaries will be in phase
>with each other? They most certainly won't be if they
>aren't identically wound (hard to do even when you wind
>on the same core).
>
No. Testing for phase is easy Jim. It only takes a few minutes to
determine the correct phasing of multiple windings, whether they're on the
same core or not. But you're right. Ensuring that the windings are in
phase isn't something any of us have mentioned so far. I'll guess that
correct phasing was assumed by most of the readers here.
>And what will you do to prevent the fields from interacting
>to buck or boost in close proximity to each other? You
>will have to mount them broadside and isolate these
>transformers with rectifier stacks, or spend a great deal of
>time fiddling with the windings. You may still have to unwind
Not required in this application Jim. This isn't like audio where you
would be concerned about 60 cycle hum pick-up in an adjacent high impedance
audio output transformer.
>
>Also you will have to insure that the PIV of the stacks aren't
>exceeded. And here is the kicker: If the outputs are not nearly
>in phase, each winding will be carrying greater than half the
>load at some part of the cycle! Consider that if the windings
>are exactly 0 or 180 deg out of phase with full wave, then no
>problem. Ok if exactly in phase with a half wave stack. But
>each transformer will carry the full load when the other isn't!
>
I assume you are referring to the paralleled windings here, rather than the
combined DC output method ?? With the combined rectifier output method,
the phasing of the windings doesn't matter.
Phil
>At least with half wave the duty cycle will be lower. Of course
>the size of your capacitor bank and the inrush current will have
>to be looked at too.
>
>Jim, ac6tk
>
>
>
>
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