Watts, VA, etc...
To: mail11:;-at-cimcad.enet.dec-dot-com (-at-teslatech)
Subject: Watts, VA, etc...
From: I am the NRA <pierson-at-cimcad.enet.dec-dot-com>
Date: Mon, 5 Dec 94 15:06:12 EST
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Rich provides very good info, however...
>A second way to correctly apply PFC capacitors to neon sign xfmrs
>is to set up an ammeter in series with the neon primary. Add PFC
>capacitors across the primary until the current drawn by the
>transformer is in line with the power required to achieve the
Yup. Which is also where the current minimizes...
>Another way to look at this: A 360 watt neon used as a Tesla
>power supply will typically draw 720 or more watts out of the
>wall if you check the draw with RMS volt and ammeters.
It is impossible to measure the watts with a votmeter and ammeter in
What is measured with these is called VA. (VOLTAMPERES). In AC work
VOLTS times AMPS is not WATTS, except at "unity" powerfactor. Which
is what this discussion is about, getting the transformer plus the
rest of the system to unity powerfactor, by adding caps.
(Rich and I are saying the same thing. I am being a stickler for
>Add PFC capacitance until the RMS draw shown by the meters is close to the
>rated output of the neon.
Yup. With the coil running. (sparkgap on, etc.) I believe a rough
check can be done with the unloaded transformer....
>This correction is not required on non-shunted, or externally limited
No sure. They will still have an inductive component to the load.
>... If all else fails... Throw another megavolt across it!