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Re: TC RMS Conditions - was Voltage/Length etc. (fwd)
---------- Forwarded message ----------
Date: Fri, 13 Feb 1998 07:57:23 +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.
Jim, Gomez, All -
What are RMS conditions? This question has been asked under several subject
titles so I have put this reply under a new more appropiate title. It should
be noted that this is a hurried attempt to answer the question and there
could be some undetected problems. RMS refers to the heating effect of
currents (I^2R) in AC circuits which can involve either sine and non sine
waves. I will refer only to sine waves.
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.
If the energy obtained from the above RMS conditions is consumed in less
that one second intervals the power in watts released can be much more than
the number of joules of energy per interval. The equation is watts =
joules/dt where dt is the fraction of seconds taken to consume the energy.
These are non-RMS conditions or transient conditions. Note that we are
talking only about sine waves with the same peak amplitudes or dampened sine
waves. However, the frequencies could be different.
In the Tesla coil the 60 HZ currents that are charging the primary
capacitor are under RMS conditions. The equation is joules = watts x
seconds giving the energy in the pri capacitor. The discharge currents
from the capacitor are non-RMS conditions flowing into the primary coil as
dampened sine waves at RF frequencies. These currents create a magnetic
field around the pri coil that cause currents to flow in the secondary coil.
The power in the secondary coil is then
watts = joules/dt where joules are equal to the joules in the
primary capacitor minus losses and dt is a value of less than one second. It
is obvious the problem is to find the value of "dt". Because dt is less than
one the watts in the secondary can be greater than the joules in the secondary.
The secondary voltage is equal to Vs = sqrt(2Js/Cs) The problem is
that "Js" cannot be found without knowing "dt". In the Tuve et al coil of
1930 the dt was estimated. This gave a power output of 1700 KW with an input
of 3 KW or a power gain of 567. This was at one bang per second and 25%
efficiency. This also gave a secondary voltage of 5 million volts. Some of
the calculations are shown in my Tesla Coil Construction Guide.
Note that the secondary voltage cannot be found by resonance because the
resonance equation does not contain a variable for voltage
Fr = 1/(6.283 sqrt(LC)).
It is obvious by this equation that resonance does not give a power or
voltage gain. Other equations must be used.
Comments welcomed.
John Couture
----------------------------------------------------------------
At 09:12 PM 2/11/98 -0600, you wrote:
>
>----------
>From: Jim Monte [SMTP:JDM95003-at-UCONNVM.UCONN.EDU]
>Sent: Wednesday, February 11, 1998 12:44 PM
>To: tesla-at-pupman-dot-com
>Subject: Re: Voltage/Length (fwd)(the Kevlar thread)
>
>>From: John H. Couture [SMTP:couturejh-at-worldnet.att-dot-net]
>>Sent: Tuesday, February 10, 1998 12:50 AM
>>To: Tesla List
>>Subject: Re: Voltage/Length (fwd) (the Kevlar thread)
>>
>>
>> Greg, Jim, All -
>>
>> There are two problems with what is shown below.
>> The 985 KV (Vs) cannot be measured with any instruments to verify this
>>voltage.
>
> I thought the point of this was that the 985kV secondary voltage was
> a reasonably accurate voltage estimate that needed to be explained/
> correlated with other system parameters.
>
>> The 24.2 J assumes RMS conditions which do not exist in the Tesla coil
>>secondary circuit.
>
> What are "RMS conditions"?? I've heard of steady-state conditions,
> transient conditions, and boundary conditions, but never "RMS
> conditions". I have only heard RMS (Root Mean Square) being used to
> quantify the average value of a voltage or current. For a periodic
> voltage v(t) with period T, the RMS voltage = sqrt(IT(v(t)*v(t))/T),
> where IT(x) is the integral of x over 1 period.
>
---------------------------------- Big snip
> Jim Monte