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Re: Guide 60HzMatch
Tesla List wrote:
>
> > Subject: Re: Guide 60HzMatch
> > Subject: Re: Guide 60HzMatch
>
> Subscriber: tom_mcgahee-at-sigmais-dot-com Thu Jan 30 23:04:43 1997
> Date: Thu, 30 Jan 1997 22:43:20 -0500
> From: Thomas McGahee <tom_mcgahee-at-sigmais-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Guide 60HzMatch
>
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> ----------
> > From: Tesla List <tesla-at-poodle.pupman-dot-com>
> > To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> > Subject: Re: Guide 60HzMatch
> > Date: Wednesday, January 29, 1997 11:10 PM
> >
> > Subscriber: Esondrmn-at-aol-dot-com Wed Jan 29 21:02:07 1997
> > Date: Wed, 29 Jan 1997 15:25:54 -0500 (EST)
> > From: Esondrmn-at-aol-dot-com
> > To: tesla-at-pupman-dot-com
<BIG Snippola>
> >
> > Fr. McGahee,
> >
> > I have two thoughts on the subject. One is maybe we should mention the
> use
> > of Power Factor Correction caps to be used with neon sign transformers to
> > reduce the input current requirements and thus the size of the variac
> needed.
> > I would imagine most Tesla coils do use neon transformer power due to
> their
> > cost and availability.
> >
>
> Ed,
> (I got your coil revision and have updated the original file)
> Yes, Power Correction Caps are important, and should be included. I found a
> little on this by Richard Quick. What I'll need to know from the list
> members is what values to use for the most popular neons (9K 12K 15K at 30
> 60 90 ma). I don't have any data on the values yet. I hope someone reads
> this and lends a hand! I don't know whether there is a formula people are
> following, or just word of mouth.
Ask and ye shall receive! :^)
A rule of thumb that can be used for neons is that they will require
power factor correction for about half of their faceplate Volt-Ampere
(VA) rating. For example, a 15 KV 60 MA neon will be rated at
15000*0.060 = 900 VA. About half of this (450 VA) "looks" purely
inductive to the incoming line, and it's this reacitve component that we
want to "counteract" by using power factor correction (PFC) capacitance.
BTW, PFC capacitors must be AC-rated and non-electrolytic - oil-filled
mylar "can" type are ideal, and they should be connected directly across
the line input to the neon(s). PFC's will reduce the amount of current
drawn from the mains by getting the incoming voltage and current more in
phase with each other. While this won't save you on the electric bill,
or make longer sparks, it MAY let you run at higher power levels before
tripping the branch circuit-breaker in your garage or basement.
The capacitive reactance at a given frequency is 1/(2*Pi*F*C). Knowing
this, we can solve for the amount of capacitance required to counteract
the inductive reactance we've got:
Cpfc = (0.5*Vout*Iout*1e6)/(2*Pi*F*Vin^2) in uF
where Vout = faceplate HV output voltage of the neons
Iout = combined faceplate current of all neons
Pi = 3.14159
F = Line Frequency (50 or 60 Hz)
Vin = Mains voltage (typically 120 or 240V)
Typical values for 120 Volt input neons at 60 Hz are:
30 60 90 120
9000 25 50 75 100 uF
12000 33 67 100 133 uF
15000 41 83 124 166 uF
BTW, these do NOT need to be exact values to be effective.
<SNIP>
> Fr. Tom McGahee
Safe coilin' to you!
-- Bert --