Nigel Goodwin said:
Styx said:
and as I stated it is acting MORE like a voltage divider rather than a "true" autotrasfomer
NO! - it acts solely as a potential divider, not at all like an autotransformer, as such the inductors will dissipate just as much heat as a resistive divider.
can we get back on topic or drop this
We're still waiting for a response about the source of the 339V DC, which I agree would probably be useful to know!.
Electric Machines 2nd Edition; Steady-State Theory and Dynamic Performance; Mulukutla S.Sarma; PWS Publishing Comany; ISBN 0-534-93843-4; p137
Topic: 4.6 Autotransformers
An extract
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1 + N1/N2 = 1 + a
N1 and N2 are inductor windings
Thus, the autotransformer with a transformer ratio of (1+a) can be treated as an equivalent two-winding trasformer with a turn ratio of a. The ratio of the autotrasformer configuation is much higher than the two-winding trasformer ration as shown below
Autotrasformer ratio/Two-winding trasformer ratio = 1 + 1/a
This ratio becomes much higher than unity, since for many autotrasformers applications
a is rather small and the ratio of teh terminal voltages (1+a) is very nearly unity. This is because most of the power in an autotrasformer is delivered to the secondary through
direct conduction and only a
small portion is delivered through
transformation or induction as it is in a two-winding trasformer
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Dont believe me? get out the book I have quoted above and check it out. The creation of a single phase coreless autotrasformer is a crude hack that is aeospace approved.
Also your comparrison of this "inductive divider" just like a resistive divider is completly wrong. If you were to connect a resistor straight across the AC no matter what frequecy is chosen current will flow based on V = I*R.
However, connect an inductor across an AC supply and increase its frequency then the current (and thus power trasfer) will decrease - standard inductor theory. No extra power is lossed, the inductor will just "oppose" the flow of current. It is this effect that this crude autotrasformer works on.
If resistors were used you would have conduction loss based on the current flowing, the only loss in this autotransformer arrangement is due to the equivent-series-resistance of the inductors.