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Re: TC RMS Conditions - was Voltage/Length etc. (fwd)
---------- Forwarded message ----------
Date: Sat, 14 Feb 1998 23:52:58 +0000
From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: TC RMS Conditions - was Voltage/Length etc. (fwd)
Antonio, All -
From your remarks it is obvious I have not made myself clear regarding RMS
conditions. I agree that RMS can be confusing. It is a mathematical
calculation to determine electrical losses or energy consumed in all types
of waveforms. In computing the RMS values for voltage, and current the
equations contain an integral for the "mean" in the root, mean, square
(RMS). This integral uses time both as a finite value and a "dt" interval.
The Tesla coil transformer also uses time in two different ways.
In the TC primary the input wattage is a continuous RMS condition (pseudo
sinusoidal steady state). The TC secondary output is an instantaneous
condition (transient). This means that in the TC transformer the electrical
energy can be stored in the TC primary capacitor on a continuous basis but
the energy in the secondary is released in short pulses of sparks on a
RANDOM basis . A drawing showing this condition is in several publications
including my Tesla Coil Construction Guide.
This type of electrical operation means that power can be magnified by
changing the time intervals in the primary and secondary circuits . This
type of power magnification occurs in many kinds of electrical devices.
The basic equations in my opinion for Tesla coil operation are as follows:
The Tesla coil primary energy (Jp) equations per break are:
Joules = input watts (continuous)/breaks
Jp = .5 Cp Vp^2 x eff
The Tesla coil secondary energy (Js) equations are:
Js = Jp/dt = sec watts (instantaneous) x eff = Vs x Is = Is^2 x Rs
Js = ,5 Cs Vs^2 x eff
The Tesla coil secondary voltage and spark length equation is:
Spark inches = (KVs/65)^1.43
This equation is from empirical data and subject to change when more data
becomes available. The spark length is a controlled spark length. Note that
the current affects the appearence of the spark so this parameter should be
calculated as above.
It is obvious that beginning with the known input wattage for the TC it is
possible to determine the TC output provided the efficiency and the dt time
values can be found. This is the real world Tesla coil problem. Three
scientists, Tuve, Breit, and Dahl solved this problem for their 5 million
volt coil in 1930. The power magnification was 567 and the current was 340 ma.
Certainly there are many other ideas out there. Generally only isolated
equations are shown. The advantage to using a set of equations from input
watts to spark length is that both input watts and spark length can be
easily measured to verify the equations. The JHCTES TC computer program
starts with input wattage and outputs spark inches. The program has a total
of 46 parameters that are coordinated to produce a tuned coil. This program
has proven to be reasonably accurate over the several years it has been
used. There are no other programs similar to it for comparing results.
What is your explanation of how the energy and power is utilized in the
Tesla coil, input watts to spark length?
How about other coilers? Energy and power only, plus equations. Note that
TC resonance does not magnify power.
John Couture
-----------------------------------------------------------
At 09:29 PM 2/13/98 -0700, you wrote:
>
>
>---------- Forwarded message ----------
>Date: Thu, 12 Feb 1998 20:45:45 -0800
>From: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: TC RMS Conditions - was Voltage/Length etc. (fwd)
>
>John H. Couture wrote:
>
>> The RMS conditions for AC electrical circuits covers a lot of territory
>> and I can cover only part of the story. I will start with a comment on RMS
>> conditions of the 60 HZ currents that are normally used for the inputs of a
>> Tesla coil. This current is a continuous sine wave current that has a RMS
>> current value equal to .7071 of the peak current. The RMS current times the
>> RMS voltage gives an RMS power. The energy in joules is equal to the RMS
>> power in watts x seconds. These RMS conditions are also called stedy state
>> conditions.
>
>Plase do not use the term RMS in this context. RMS means simply "the square
>root of the mean square", and is a form of computing the equivalent DC voltage
>of current that would produce the same power dissipation over a resistor.
>It has no relation with waveform. If you want to talk about sinusoidal signals
>use the correct name "sinusoidal steady-state".
>Note also that the mean power (there is no "RMS power") transferred by
sinusoidal
>signals is:
>P=V*I*cos(angle between V and I), with V and I being RMS values (peak
value/sqrt(2)).
>The frequencies must be equal, otherwise the mean power is always zero.
>
>> The secondary voltage is equal to Vs = sqrt(2Js/Cs)
>
>What is Js?
>
>Antonio Carlos M. de Queiroz
>mailto:acmq-at-compuland-dot-com.br
>http://www.coe.ufrj.br/~acmq
>
>
>