Re: Math help...

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

John,

I agree that in an air core transformer we avoid various ferromagnetic
"core" losses, and most of the other losses are electrical in nature. These
electrical losses continuously steal energy from the system even though the
magnetic transfer mechanism between windings is indeed lossless. While most
of these electrical losses stem from the main gap, other losses come from
resistance in the primary, secondary, and ground path, dielectric losses,
radiation losses, corona, etc. Various design techniques which reduce the
cumulative impact of these electrical losses (i.e., John's guidelines)
should result in higher efficiency systems.

Best regards,

-- Bert --

Tesla list wrote:
> 
> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>
> 
> Bert -
> > What are the parameters for the flux losses in magnetic circuits? I agree
> that creating the energy in the primary cap involves electric circuit
> resistive losses. But the energy transfer between the TC pri and sec coils
> is a magnetic flux energy transfer with no flux losses.
> 
> It is my undestanding that when Malcolm refers to 90-95% efficiency in the
> TC energy transfer between the pri and sec coils he is referring to the
> electric circuit losses involved in the wiring but no flux losses in the
> magnetic circuit. I agree with this concept and accept his tests results.
> 
> The number of energy transfers between the pri and sec coils affects the
> efficiency for the electric cicuits but has no effect on the magnetic flux
> transfers.
> 
> John Freau's guidelines for efficient coil design cannot be commented upon
> because he does not show any calculations.
> 
> John Couture
> 
> --------------------------------
> 
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Wednesday, July 11, 2001 6:31 AM
> To: tesla-at-pupman-dot-com
> Subject: Re: Math help...
> 
> Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <bert.hickman-at-aquila-dot-net>
> 
> John,
> 
> As Ed points out, energy transfer in magnetic circuits where ferromagnetics
> are involved are never lossless. However, John is correct for the typical
> air core transformer used in a 2 coil TC.
> 
> The example I was discussing compared the initial energy residing in the
> tank cap at the instant the main gap fired versus the maximum energy in the
> secondary at the end of the first energy transfer cycle. This was the
> condition that Malcolm described (if I recall, this was done quite some
> time back...). But if you don't directly measure the secondary voltage, how
> can this be accomplished??
> 
> The measurement was done by:
> 1. Using a "magic" value for coupling (so that both the voltage and current
> simultaneously hit zero upon completion of an energy transfer
> 2. Preventing breakout from the toroid even at peak secondary voltage
> 3. Permitting the peak secondary energy to transfer back into the primary
> circuit (easy, since it's virtually impossible to quench the gap under
> these conditions)
> 4. We then measure the primary capacitor voltage once the secondary's
> energy has completely transferred back into the primary capacitor.
> 
> We actually measure the primary tank cap voltage before and after TWO
> energy transfers. We can then back compute the energy that must have been
> transferred to the secondary during a single primary-to-secondary energy
> transfer. Under these conditions, it was determined that you could transfer
> over 90% of the original tank energy to the secondary. Once it was there,
> we can either dissipate part of it as streamers (desirable case) or return
> most of it back to the primary (the case we measured).
> 
> This does not take into effect losses in the charging circuit, and we have
> purposely avoided losses from leaders/streamers. It does not address
> scaling. However, anything that reduces main gap losses and secondary
> losses will improve the primary-secondary transfer efficiency. High Z
> primaries and lower operating frequencies (i.e., John Freau's guidelines
> for efficient coil design) should apply...
> 
> Hope this explains the situation...
> 
> -- Bert --
> --
> Bert Hickman
> Stoneridge Engineering
> Email:    bert.hickman-at-aquila-dot-net
> Web Site: http://www.teslamania-dot-com
> 
> Tesla list wrote:
> >
> > Original poster: "John H. Couture by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>
> >
> > Bert -
> >
> > I agree with your excellent comments below, however, I believe it should
> be
> > pointed out that the energy transfer in all magnetic circuits is 100%
> > because there are no losses in magnetic circuits. Electric losses are only
> > in electric circuits and the efficiency is the ratio of output/input. This
> > means that when reffering to electrical efficiency the input and output
> > calcs should be shown. This can be a difficult task when talking about
> Tesla
> > coils.
> >
> > I understand the voltage can be used to find the joules (energy) in the
> > primary capacitor but how do you determine the energy in the secondary
> > circuit when the secondary voltage of an operating TC is an unknown? I
> > avoided this problem by using a light bulb for the secondary load in my
> > test.
> >
> > When we say the TC efficiency can be about 90/95% what are the input and
> > output conditions? Coilers talk about TC efficiencies but I have never
> seen
> > any published input/output calcs. In my TC Construction Guide page 14-4 I
> > show a simple efficiency test I made with a small TC and the input/output
> > calcs were shown. Have any other coilers made these tests? The test showed
> > an overall efficiency of 56%. Larger coils have efficiencies much lower.
> > What are the input and output calcs for the 90 to 95% efficiencies? How do
> > they relate to the overall efficiency? How do these 90/95% efficiencies
> vary
> > with TC size?
> >
> > John Couture
> >
> > ----------------------------
> >
> > -----Original Message-----
> > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > Sent: Sunday, July 08, 2001 9:02 PM
> > To: tesla-at-pupman-dot-com
> > Subject: Re: Math help...
> >
> > Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <bert.hickman-at-aquila-dot-net>
> >
> > Josh and all,
> >
> > That's an excellent question, Josh - and it goes to show that very few
> > things are truly simple in coiling... :^)
> >
> > Malcolm is correct. Previous experiments have measured primary tank
> > capacitor voltage during a complete primary-secondary-primary energy
> > transfer cycle. These have shown that the efficiency of the first
> > primary-to-secondary transfer (from an initially charged tank capacitor to
> > a fully resonating secondary) can indeed exceed 90%. However, this makes
> no
> > statement regarding how efficiently we were able to charge the tank cap
> > from the mains supply in the first place. For that, we need to talk a bit
> > more about capacitor charging circuits...
> >
> > -------------------   snip

-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com