QROKING@aol.com wrote:
> where near this figure, where is my design error? As I mentioned
before, my
> line voltage at the transformer input under a 45 amp "key down" load
only
> goes from 238 volts to 229 volts. This is well within electrical
specs. Now
> most of what I have been hearing is theroy, but what happens in REAL
world?
> ESR of the plate transformer? Dont know..but I dont think I can
wind a
> transformer any better than Mr. Dahl.
Maybe I haven't mentioned this in a way that makes sense, and that's why
it gets ignored. But the fact remains.....
YOU CAN NOT measure the line voltage with a RMS meter and expect to
learn anything about the quality of the line when it is used with a
capacitor input supply.
You need to measure the voltage drop with a PEAK reading meter having
the same time constant as the capacitor input power supply's filter
bank.
You have no idea if the power line is OK or not.
>errors in the the ARRL manual and Bill Orrs book. I must admit, I
>use these books to learn from, I am tend to believe what they say, >since I
>don't know of my own knowledge.
It is always a good idea to compare the area you are trying to
understand in amateur textbooks and articles with what professional
engineer textbooks describe.
The ARRL Handbook was always an excellent reference book, but they
completely reworked it in 1995. Like any new "product", there might be
some small errors that have crept in.
> school learnig AC theroy,(maybe I am getting bad info here too) and
I was
> taught the following.....Residential AC line voltage is 120 V RMS.
> The peak voltage is 1.414 of this or about 170v. The term RMS is
synonimis
> with the term effective voltage. Effective voltage is the vltage
that will
> "heat a resistor".
Power is E times I, at any given instant of time. RMS power ONLY applies
to a perfect sine wave, and the power is for one cycle only (remember
the PEP thing?). Effective POWER is E*I integrated over the period of
time you are specifying as a measurement period.
A capacitor input supply does not draw current in a sine wave shape. It
consumes current (and hence power)only at the peaks of each half cycle.
The ".707 thing" does NOT apply to either a choke supply or a capacitor
input supply, because neither supply charges to the RMS value.
The AVERAGE dc output voltage of a single pahse full wave rectified sine
wave is .637 times the peak voltage, not .707 times the peak. So with a
choke input supply the output voltage is .707 times 1.414 times the RMS
voltage, or .9 times the RMS.
Back to a capacitor supply. With low ESR, the output voltage stays very
near the peak voltage. If it does not, the power supply components or
power line MUST have very high ESR. In practical HV supply cases, you
can get nearly the same regulation with a capacitor supply as a choke
supply.
The only case where a choke is good is if you have a poor ESR power
line, and can't do anything about it, or if power factor is important.
You've been trying to apply .707 to all kinds of places where it does
not belong! That's a bad sine.
I was amazed to see the 95 ARRL Handbook didn't discuss ESR, even
though the graph on page 11.8 uses ESR as R1 and R2!!! Why have it in
the graph, if you don't describe what it is? Without understanding ESR,
the entire graph is useless!
Now a question, does Orr discuss ESR?
73 Tom
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