PFC for Neons
Uncorrected neon transformers are usually 50% power factor. To correct them
for 90% power factor add a capacitor calculated as follows:
For 120 volts c uf = .079 V A
For 240 volts c uf = .020 V A
V = neon secondary volts A = neon secondary amps
The factors K1 = sin(arccos(LPF)-sin(arccos(HPF))
K1 = .43 for 50% to 90% power factor
For 120 volts K2 = (.43 x 10^6)/(6.283 F V) F = 60 Hz
K2 = (.43 x 10^6)/(377 x 120^2) = .079
For 240 volts K2 = .0198 or .02
Example: Neon 15000 volts 60 ma 120 volts 60 Hz
C = .079 x 15000 x .06 = 71.1 uf
Note that power factor correction is normally used to reduce your electric
This has little value with Tesla coils because they are not operated for
I do not believe that paying more for a HPF neon or adding a capacitor is
Also adding a capacitor in parallel with the primary neon winding can lead
to resonance problems as indicated by some of the Tesla List letters.
Power factor is not efficiency. The efficiency of typical neons is about 96%
for both low and high power factor. A higher power factor means less current
from the utility but the current saved is reactive current which does not
affect the meter. A wattmeter only registers watts.
Efficiency is based only on watts, not reactive VA. The money you save with
HPF is based on other factors. If you are confused, you are not alone.