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Re: An Interesting Problem
---------- Forwarded message ----------
Date: Fri, 17 Oct 1997 08:47:50 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: An Interesting Problem
Hello John,
> From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: An Interesting Problem
>
> At 03:31 AM 10/15/97 +0000, you wrote:
> <SNIP>
> >Around 300 - 350kV based on an estimated transfer efficiency of 70 -
> >80%. It won't be far off and I now have a means of measuring this
> >efficiency pretty accurately.
> ------------------------------------------------------
> How do you measure the efficiency?
Answer: by comparing secondary energy at the end of second ringup to
energy at the end of the first ringup. This is not completely accurate
and should be done on the primary waveform as the two ringups
mentioned don't measure the first ringup loss. In observing the
secondary waveform with a scope aerial you can't measure absolutes
but you can measure relatives. Since Energy is proportional to V^2
you can see how the method works. For example, if V second ringup =
1/2V first ringup you can safely say that between the two peaks, 3/4
of the energy has gone. Since you are interested in the loss over _1_
transfer, you halve that loss figure to get an approximation
(probably more like 2/3). BTW, a coil that loses to this degree is
scrapheap material.
> --------------------------------------
- - - - - - - - - - - - - - - >
> >I am doing far better than that. I note that in many writings Tesla
> >was somewhat loose in his terminology. Richard Hull can correct me if
> >I'm wrong but Tesla often used Watts when he was really talking
> >Joules. The system in question has thrown sparks around 5 feet with a
> >primary energy of no more than 3J pumped 100BPS. Well worth noting
> >that I have yet to obtain that efficiency in smaller coils but all
> >that leads me to strongly suspect that the impact of low frequency
> >operation on streamer formation speed has more to do with it than
> >coil size as such. I have obtained sparks around 2 feet long on one
> >system on a single shot basis with 10J. But I think this is all
> >getting off the track anyway.
> ------------------------------------------------------------------
> Tesla was an electrical engineer. I doubt that he would confuse watts and
> Joules.
I still think that he does. I don't recall ever seeing him use Joules
either in the Notes or in his earlier works.
> Note that " 3J pumped 100 BPS" is a 300 watt coil producing 5 foot
> sparks! This is certainly a record. Am I interpreting this correctly?
You are. However, I am unwilling to claim a record until I have got
the power supply losses (wallplug figure) to as near zero as I can.
The supply is not mains-resonant and current limiting is primarily
resistive in the transformer windings which are losing an awful lot
of power. They get very hot with a short run.
> John Couture
Malcolm