13 Jun
2009
13 Jun
'09
7:59 a.m.
Tony Duell wrote:
I wouldn't dispute that, but neither does it detract from my point.
There are many parameters that go into the design of such a transformer.
I'd figure one can hold some of them constant and vary others. Those
taps may not be at simple 'proportionate' locations for the different
frequencies.
((other) was in parentheses so as not to exclude the resonance winding
in the discussion.)
The other thing that changes with f is the
inductive impedance of all the
(other) windings of the transformer. Ferro-resonance transformers do not rely
only on the resonance principle, magnetic/inductive issues are also very
involved. I'm not at all convinced that simply changing the C is adapting the
supply for the new frequency (50 Hz). That you are having to go so far off the
theoretical new C would tend to support this.
Possibly. However, I have a ferroresonant supply (for a pair of Diablo
Model 30 hard disks) which has tappings on the 'resonant' winding for 50
or 60 Hz operation. There's a table inside saying how to strap it for
different input voltages and t h2 frequencies. The capacitor, IIRC is not
changed, just the tappings.
This would seem to indicate it's possible to design a ferroresonant
transformer with the 'main' windings are OK for either frequency. Of
course this doesn't mean all such transformers are designed that way. And as others have pointed out, changing the value of
the capacitor is
not quite the same thing ans changing the tappiongs on the inductor.
Funny, I thought that was one of the points I was making.
Changing the C in accordance with the standard resonance equation was a
reasonable experiment but I'm not surprised it doesn't seem to have
worked out. The transformer works around core saturation, on the knee
(non-linear portion) of the flux/I curve, consequently L of the windings
is not constant over a cycle and it's not a simple resonance situation.