RE: Input power measurement

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

Original poster: "John H. Couture by way of Terry Fritz <teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>


All -

It should be noted that on Richie's web site below the example for the
loading at resonance charging is Watts = V x I = 200,000 x 2 = 400,000 watts
or
400 KW. This amount of load on a house service would not be possible because
of the limitations of the utility electric service. Therefore, when
calculating the loading at the NST (or any TC power transformer) the
limitations of the electric service have to taken into account. If the
service voltage is 240 volts the service current would be W/V = 400000/240 =
1666 amps, not possible with the typical house service.

The question is what exactly would the true voltages and currents be at the
TC power transformer of any size or load when these high wattages are
involved? It is very possible that with a weak electric service the resonant
charging voltage at the NST would not be high enough to overstress the NST.
This can only be determined by doing the necessary calculations. To my
knowledge no one has ever done these calculations for any Tesla coil system.

Note that this is not a crank posting. I agree with Richie's calcs as far as
they go.

John Couture

------------------------------

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, March 09, 2003 1:32 PM
To: tesla-at-pupman-dot-com
Subject: Re: Input power measurement


Original poster: "Barton B. Anderson by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <classictesla-at-netzero-dot-com>

Hi Skip,

Resonant mode running is causing the high charging current. The cap value
is designed to be resonant with the transformer at mains frequency
(charging frequency). At resonance, LC reactances are ideally removed and
leave only the winding resistance in the circuit. Thus, a maximum current
characteristic is achieved (which is the purpose of running in a resonant
mode). Richie Burnett has a good write up of this (sometimes ok, sometimes
not).

http://www.richieburnett.co.uk/resonant.html#resonant

Take care,
Bart

Tesla list wrote:

 >Original poster: "Skip Greiner by way of Terry Fritz
 ><teslalist-at-qwest-dot-net>" <sgreiner-at-wwnet-dot-com>
 >
 >Hi all
 >I am using a 9kv at 120ma NST. In operation I use an iron vane ammeter
 >(known to be within 5% accuracy) to monitor current. My mains voltage is
 >nominally 117V. Interestingly the current into the NST is about 17A when
 >running in resonant mode. It is my understanding that an iron vane meter
 >reads true input current regardless of waveform. Therefore my input power
to
 >the NST is nearly 2000 watts.
 >
 >I would appreciate comments from anyone who can help explain the
discrepancy
 >between the 1080va rating of the "current limited NST and the measured
input
 >in resonant mode operation.
 >Skip
 >
 >
 >
 >