Re: Input power measurement

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

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
>
>
>
>