Re: what is "power factor rating?"

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Parpp807-at-aol-dot-com>

In a message dated 1/4/01 8:45:21 AM Central Standard Time, tesla-at-pupman-dot-com 
writes:

<< anyway what is the Power Factor Rating and why would I need a power 
 correction capacitor?(I didn't need one on my other coils)
 
 can anyone explain
 Joseph >>

Hi Joseph,

>>a 10kv .023 ma OBIT<<

I think you mean 23 mA.

Power factor considerations become important in circuits with large amounts 
of inductance and/or capacitance. Power equals volts x amps, EI. Only the 
power 
consumed in a pure resistance is converted to some form of energy. This is 
the power we
pay for. It is the power = I squared R. It is sometimes referred to as the 
TRUE POWER.  But there is also the reactive power produced by an inductive 
and/or a capacitive reactance. This may be referred to as the APPARENT POWER. 
I hope I'm not screwing up these terms. PF = APPARENT POWER / TRUE POWER. If 
there is no inductance or
capacitance in the circuit, the PF is unity, or 1. The problem arises because 
the voltage across an inductance produces a current that does not occur at 
the same time
as the current thru a resistance. The same is true for a capacitor, there is 
a time difference known as the phase angle. The phase angle between IR and IX 
sub L is + 90 degrees, and the phase angle between IR and IX sub C is - 90 
degrees.  So IX sub L and IX sub C will cancel. They are 180 degrees 
out-of-phase.  APPARENT POWER is = EI cos theta, and the formula becomes
PF = EI cos theta / EI. The PF is a dimensionless ratio always less than 1. I 
have fallen
into the time consuming habit of solving these problems with a vector 
diagram. I
learn better from pictures.  :-)).

I do not know of any instance in Tesla coil work where the PF is anything but 
inductive.
Therefore, to reduce a large inductive PF it may be desirable to add 
capacitance in
parallel with the inductance across the AC line. 
My NST bank right now consists of a parallel NST rig of 15/120. Without a PFC 
the metered AC current is around 5 Amps. Adding a PFC drops that current to 
slightly less than 3 Amps. This is with no load. I doubt that your 10/23 OBIT 
would require a PFC.

I hope this helps. You can get a much better explanation form any EE text or 
any text on 
AC theory. Also, probably from many others on the list.  :-)) Caveat emptor.

By the way, OBIT may qualify as an acronym in our Tesla context but its more 
common usage is simply as an abbreviation for OBITuary. That would not be an 
acronym.

Happy day,
Ralph Zekelman