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Re: Input/Output Power



---------- Forwarded message ----------
Date: Wed, 8 Oct 1997 08:23:41 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: tesla-at-pupman-dot-com
Subject: Re: Input/Output Power

Re the Fluke and interesting readings:

> From: Gary Johnson <gjohnson-at-kansas-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Input/Output Power 
> 
> At 08:30 PM 10/3/97 -0600, you wrote:
> >
> >
> >---------- Forwarded message ----------
> >Date: Fri, 3 Oct 1997 20:43:51 -0400 (EDT)
> >From: Rscopper-at-aol-dot-com
> >To: tesla-at-pupman-dot-com
> >Subject: Input/Output Power
> >
> >To the measurement experts:
> >
> >I put a current shunt in-line at the line to see if I could measure input
> >power.  First I measured 250VAC on my fluke for input voltage.  The current
> >shunt is 50mv=20A.  I used the fluke on the mV range and fired up the coil.
> > The shunt is inside the garage and the coil is in the driveway about 15feet
> >away.
> >
> >The fluke measured 165mv!  This equates to over 60 amps at 250VAC.  I only
> >have 30 amp breakers on this line.  Is the reading wrong, or is the breaker
> >too slow, or not good for this application????
> >
> I tend not to take Fluke readings at face value in this environment.  These
> are excellent instruments, but will give bad readings when used outside
> their design range.  I once taught a service lab for mechanical engineering
> juniors where we put a unipolar square wave into two analog meters, one dc
> and the other ac, and a Fluke.  The dc meter gave the average value
> correctly, the ac meter gave the rms correctly, and the Fluke gave nonsense.
> (Actually it gave the rms of the ac portion of the square wave, after the dc
> component had been filtered away.)
> 
> I suspect that in this environment that the Fluke is picking up rf from the
> operating Tesla coil.  To see if the Fluke leads are acting as an antenna,
> try measuring the voltage with both leads connected to the *same* end of the
> shunt. Theoretically, you will get zero.  I bet the Fluke will read
> something greater than zero, and the amount can be changed by rearranging
> the leads to change the area of the loop antenna.
> 
> Gary Johnson

Check your transformer primary current waveforms on the scope. I 
think you'll find the answer is there. I've seen some abominable 
waveforms from various transformer/choke setups used for Tesla 
supplies.

?
Malcolm