So if I want to have add resistance in series with the power line to match
the power supply
to the line? This will improve the efficiency of my power supply? Hmmmmm
You can't conjugate match most DC power supplies because the
current and voltage waveforms
into and out of the power transformers are not sinusoidal. They contain
many harmonics.
73
Bill wa4lav
At 06:06 AM 7/11/02 -0400, you wrote:
>Hi Alex,
>
> > I will remind you for the "n" th. time that these words have been used
> > as a comparative point for those that do not understand the process of
> > nullifying a reactance with one with an opposite sign.
> >
> > To be more concise and to clarify this issue once and for all:
> >
> > Any device, including a power transformer has a definite and
> > measurable reactance at it's operating frequency. In the case of an
> > 220VAC transformer this reactance has two components, one inductive -
> > from the winding it self - and one capacitative created form the
> > internal inter-thread and coil to core capacitance. All losses in a
> > transformer, including leakage, are related to these rectances. A good
> > engineer will always attempt to reduce them as it ultimately
> > translates in heat.
>
>
>That's where you are incorrect Alex. You are confusing power factor
>correction or resonance with conjugate matching. They are two very
>different things!!
>
>To achieve resonance or correct power factor, we simply add a
>reactance of the opposite sign either in series or in parallel with
>the system reactance. This brings voltage and current into phase, and
>corrects any VAR power problems outside the resonant system.
>
>The equation involves only -j and +j terms.
>That is what you incorrectly are calling "conjugate match".
>
>Conjugate matching by definition includes an R term. A conjugate
>match is when R+jx is complemented with an equal but opposite R-jx.
>
>If you conjugately matched a power supply to the power mains, as you
>claim, current would be phenomenal! That is because the source
>resistance of the power mains is VERY very low.
>
>We do conjugately match antenna systems, and can use matching stubs
>to insure a conjugate match, but that is only because we are dealing
>with power limited sources that have a lot of dissipative or non-
>dissipative source resistance. I'm afraid if someone conjugately
>matched a power transformer to the power lines, they would blow the
>breakers or start a large fire.
>
>If you look at any engineering text, you will see conjugately
>matching always involves R and X terms, while the effect you call
>conjugate matching is actually just resonance or power factor correct
>at best.
>
>73, Tom W8JI
>W8JI@contesting.com
>
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