Re: How should we measure coil efficiency, was neon vs. potential transformer
From: Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: bert.hickman-at-aquila-dot-com
Sent: Monday, July 21, 1997 9:15 AM
To: Tesla List
Subject: Re: How should we measure coil efficiency, was neon vs. potential transformer
Tesla List wrote:
> From: FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
> Sent: Saturday, July 19, 1997 8:43 AM
> To: tesla-at-pupman-dot-com
> Subject: Re: How should we measure coil efficiency, was neon vs. potential transformer
> > >Hi John C,
> >> Again, I'm not concerned with my output power, only
> > >my spark length. We have a different viewpoint on this part of the matter
> >>since I'm more concerned with true input power vs. spark length,
> > >of the "true" efficiency. Suppose it turns out that the best way to build
> > >TC for longest sparks vs. input power is NOT the same way as to obtain
> > >best efficiency of output vs. input. This would be quite acceptable to
> > >I still don't see the importance of the energy in vs. energy out of a TC.
> >>This type of efficiency may or may not translate into long sparks and I
> > >suspect it may not.
> > John F.
> > Using the "longest sparks vs input power" would only make sense if a time
> > period is involved which would mean you are talking about energy. The TC
> > spark represents energy not power. Power is the RATE that energy is
> > in the TC. When watts per foot of spark is used, a period of one second is
> > implied. This means many sparks are involved in the one second period and
> > should be averaged (controlled spark).
> > The importance of "energy in" vs "energy out" is that it is the correct
> > way to represent the spark producing abilities of a Tesla coil. The energy
> > in comes from the power transformer. The energy out is the total number of
> > secondary sparks in a period of time such as one second. The total number
> > sparks are represented by the number of breaks per second. If only one
> > particular spark is used it would be very difficult to determine the energy
> > involved for that one spark.
> > The energy for the spark comes from the TC primary capacitor. The rate of
> > charging this capacitor is determined by the power (wattage) available from
> > the power transformer. The primary capacitor can be charged to a certain
> > energy level giving a certain spark length by a low wattage over a long
> > period of time or a high wattage over a short period of time. This means
> > that for a certain spark length the wattage can be anything unless a time
> > peroid is considered in the test. Wattage x time equals energy.
> > One of the main problems with rating TC's today is the lack of a standard
> > method to do the tests to get the rating. Because a standard test has not
> > been agreed upon by coilers, comparing various Tesla coils and magnifiers
> > has only a non-scientific value.
> > John Couture
> John C, All,
> I agree that a standard method for measuring coil efficiency is needed.
> I've said all along that the method I'm advocating ignores "true" (energy
> in vs. energy out) efficiency, and that it is more of a practical method
> for measurement. I've also suggested that sometimes a practical method
> has more value than a "scientific" method...it all depends on what we are
> trying to accomplish.
> Maybe some more of the list members will join the discussion.
> John Freau
John F., John C. and all,
Sometimes the quest for engineering precision may unnecessarily
complicate the development of a straightforward way of gauging coil
performance. Unfortunately, there are many parameters involved in Tesla
coils that are NOT easily/directly measureable - output power, output
voltage, and objective measures of streamer "character" (like color,
diameter, hotness). If we can't measure something, it's very difficult
to talk about it quantitatively(!) and comparatively - we're left with
hand-waving and Conservation of Energy arguments.
John Freau's approach at least provides us with a couple of measurable
parameters. Even if we COULD accurately measure input power and output
power, would the most efficient coil also product the "best" performance
as gauged by output spark length per watts in? Probably... but maybe
However, comparing performance (Length/watt) between optimally sized
coils may have significant merit. For every power level, there will be
at least one coil in the population of all coils that has the greatest
streamer length/watt. These would represent the most efficient coils in
their power class by our sparklength/watt measurement criteria - the
"state of the art" in coildom. However, for this to work, a consistent
way of measuring input power and output sparklength is needed. The
electronic opto-electronic wattmeter or simple 60 Hz analog wattmeters
may suffice as long as we were consistent. Streamer length may require a
more rigorous definition, like "attached streamer" not just one single
"strike". The proposed square-law relating length to power level is not
unreasonable... more coil data should provide more data points...
Safe coilin' to you!
-- Bert --