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Re: SSTC does 10 foot sparks

Original poster: "John Couture" <johncouture-at-bellsouth-dot-net> 

John -

I have made reccomendations in the past for testing Tesla coils when they
are rated in energy rather than power units. These tests leave a lot to be
desired and would be improved by coilers over time if they were used. Some
coilers in the past have already performed these types and found no major
problems in using them. The tests do end up with shorter spark lengths.

John Couture


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, June 21, 2004 9:03 AM
Subject: Re: SSTC does 10 foot sparks

 > Original poster: "john cooper" <tesla-at-tesla-coil-dot-com>
 > Very intersting stuff, how do we agree on a baseline or procedure for
 > energy in/energy out measurements?  Or am I asking too much?  I'd be most
 > interested in someone describing and identifying the equipment/measurement
 > techinques necessary, then we can either follow those procedures or 'wave
 > our dix in the air' claiming whatever.
 > John
 > ---------- Original Message ----------------------------------
 > From: "Tesla list" <tesla-at-pupman-dot-com>
 > Date:  Sun, 20 Jun 2004 17:03:02 -0600
 >  >Original poster: Sean Taylor <sstaylor-at-uiuc.edu>
 >  >
 >  >John,
 >  >
 >  >I'm sure there will be many people replying to this, so I'll keep it as
 >  >short as possible :-)
 >  >
 >  >>I agree you cannot "get more average power out than what is coming in".
 >  >>However, it is very possible to get much more pulse power out than
 >  >>power in.
 >  >
 >  >I completely agree, this is the whole thing with capacitor discharges,
 >  >can charge them at a low rate, and discharge much faster to create high
 >  >peak currents.  This concept is used all over the place in technology.
 >  >
 >  >  With Steve's TC it appears that the average power in is about
 >  >>4800
 >  >>watts and the pulse power out is about 300 KW giving a power gain of
62.5 .
 >  >
 >  >The concept of "power gain" is a VERY misleading one.  Power is DEFINED
 >  >energy transfer per unit time, so by definition when comparing two
 >  >unless otherwise stated, you are comparing a total power transfer.  The
 >  >difference is when you consider peak power, which is the instantaneous
 >  >of energy transfer.
 >  >
 >  >>With a potential power output of 300 KW it is obvious that a very
 >  >>long spark would be possible depending on the TC design. That is why
 >  >>power instead of energy units is not good for rating Tesla coils. It
 >  >>exagerate the output possibilities of a coil so you have to be very
 >  >>about the input conditions.. If you use energy units you will not have
 >  >>type of problem. The energy output units will always be less than the
 >  >>units.
 >  >
 >  >Not necesarily true.  Energy output at a chosen time (perhaps between
 >  >bangs) will be much less, about 0, than the input energy.  Also, saying
 >  >input or output energy entails energy transfer, implying a rate, not
just a
 >  >quantity of energy.  With any sort of energy storage device, energy in
 >  >out can be very different from each other.
 >  >
 >  >
 >  >>"Peak power out will be larger than peak power in" is another example
of the
 >  >>confusion caused by using power with Tesla coils.
 >  >
 >  >I wouldn't call this a confusion so much as a difference of measurement
 >  >techniques.
 >  >
 >  >  "Peak power out"
 >  >>cannot be
 >  >>larger than "peak power in" unless there is a time difference between
 >  >>two
 >  >>stated powers.
 >  >
 >  >Peak power out and peak power in can be very different, and either one
 >  >be greater than the other.  I think what you mean by "unless there is a
 >  >time difference . . . " is that the total time that the power is
 >  >over is different for the input and output.  You can have a single spike
 >  >power at say 10W, and measure for however long you want, and still only
 >  >have a 10W peak, the time doesn't matter.  I think you are confusing
 >  >integrating over the two times (yielding energy) rather than recording
 >  >peak power transfer.
 >  >
 >  >  This means bringing in time into the process which gets
 >  >>you
 >  >>into an energy process.
 >  >
 >  >Not really, depending on how you use the time.  Dividing by time will
 >  >an average power transferred per time, multiplying/integrating will give
 >  >you an amount of energy transferred.
 >  >
 >  >  It would be preferable to say that "Peak power
 >  >>out
 >  >>will be larger than average power in".  This still requires more
 >  >>explanation. The time period involved in the output vs the time period
 >  >>involved in the input. And we are back again into energy out vs energy
 >  >
 >  >A peak power is an instantaneous event, there is no measurement over
 >  >for the peak.  It happens, and it's over with, there is no amount of
 >  >that matters.  The time that energy is being transferred overall may be
 >  >(and will be) different between the input and output, but this is not a
 >  >concern for peak power measurements, and is the whole essence of power
 >  >storage devices/pulse discharges.  It's why a TC works!
 >  >
 >  >
 >  >>Note that when using average power that you are adding time to the
 >  >>units which brings you into the energy unit solution. This has caused
 >  >>confusion for coilers in the past. Average power is actually energy
 >  >>you have to use time to find the average power.
 >  >
 >  >Again, see above, just because you use time doesn't mean you get energy.
 >  >There is a big difference between average power and energy.  Average
 >  >is calcualted from W/sec, over a specified period of time yielding Watts
 >  >again.  Energy is just a specific quantity of energy, no time involved
 >  >whatsoever.
 >  >
 >  >  In other words when you
 >  >>connect a wattmeter to the input of a TC you are measuring many
 >  >>depending on how you want to use them. For example the wattmeter gives
 >  >>at the TC input
 >  >>
 >  >>    1.  wattage
 >  >>    2.  average wattage
 >  >>    3.  peak wattage
 >  >>    4.  instantaneous wattage
 >  >>    5.  volt amps
 >  >>    6.  RMS wattage ??
 >  >
 >  >Strictly speaking, wattmeter doesn't give you all these things, it gives
 >  >you one:  average "wattage", or power.  Some, with storage functions,
 >  >give you peak power, but this can be the peak over 1 cycle, or the peak
 >  >instantaneous power.  In an AC circuit, you have instantaneous power,
 >  >is defined as instantaneous current times instantaneous voltage, but is
 >  >very meaningful in terms of what is actually going on because both I and
 >  >are going positive and negative continuously.  This is where average
 >  >comes in - the average over one AC cycle.
 >  >
 >  >Because of non-resistive loads, the power transfer can be going in to or
 >  >out of the "load", meaning the instantaneous power is positive
 >  >negative other times, so an average "power" is used to represent what
 >  >is actually being done - also know as the real power, measured in Watts.
 >  >The RMS current and RMS voltage, considered without and phase difference
 >  >the "apparent power" - Volt-Amps, and often most devices are rated to a
 >  >certain VA because the wire has to handle a certain amount of current,
 >  >it doesn't care if it's in phase with voltage or not, there is still
 >  >amount of current to be passes.  The imaginary power, measured in VA
 >  >reactive, is just the part of the current that is purely reactive,
 >  >imaginary, or 90 degrees out of phase with the voltage that does
 >  >no work whatsoever, and can't because the average power is zero - half
 >  >time energy is flowing into the load, the other half out of the load,
 >  >effective energy transfer is zero, and power is zero.
 >  >
 >  >>Correctly using all of these parameters can be very confusing. You can
 >  >>all of the above confusion by properly using energy units to rate Tesla
 >  >>coils. If the wattmeter is used as an energy meter you have to do some
 >  >>and you end up with different numbers compared to using it as a power
 >  >>For example a 100 watt wattmeter will give you 50, 100, 200, etc, watt
 >  >>seconds when used as an energy meter if the times are 1/2, 1, 2, etc,
 >  >>seconds.
 >  >
 >  >So how is this less confusing than using power?  I can run my 1" TC for
 >  >days on end and claim that "consumed" more than 30 MJ.  Then I'll go run
 >  >15" 10 kVA pig coil for under an hour, and it'll "consume" the same
 >  >of energy.  So what's the point?  I can also tell you that one coil has
 >  >bang energy of 2 J, and another 10 J.  If the breakrate of the first is
 >  >bps, and the second is 120 bps, they "consume" the same amount of energy
 >  >per time, or use the same power.  I can also tell you that the National
 >  >Ignition Facility at LLNL consumes over 2 MJ in one shot, much less than
 >  >one second, while running my small TC will take over 5.5 hours to
 >  >the same amount of energy.  So, how do you propose we use energy to
 >  >TCs?  I'm not seeing how it would work.
 >  >
 >  >
 >  >>There is a much more to comparing power vs energy and I find that in
some of
 >  >>my past posts I have used the words incorrectly. Coilers are correct
 >  >>they say that power and energy can muddy the waters.
 >  >
 >  >I think trying to compare energy and power is utterly useless.  I think
 >  >can all agree that when we talk about power input, we are talking about
 >  >average power, or just a rate of energy transfer into our coils.
 >  >less than 4800 W input is the average power going into his coil, and
 >  >must leave at the same rate, whether it be in the form of heat, light,
 >  >electricity.  However, instead of entering at a (relatively) constant
 >  >as happens on the 60 Hz line (since 60 Hz is slow compared to RF), the
 >  >power is leaving in large pulses that happen as often as he dictates by
 >  >breakrate of the coil, and while these peak powers occur at a lower duty
 >  >cycle than the input power has, there are much larger peak powers
 >  >of instantaneous power) present on the output.
 >  >
 >  >Okay, so that wasn't as short as I expected, but I hope that clears up
 >  >nomenclature questions for everbody (and maybe for myself, as I'll
 >  >be corrected on some things I wrote).
 >  >
 >  >Sean Taylor
 >  >Urbana, IL
 >  >
 >  >
 >  >
 >  >