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Re: Input Power Measurement



Subject:     Re: Input Power Measurement
       Date:  Wed, 28 May 1997 17:31:16 +1200
       From:  "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization: Wellington Polytechnic, NZ
         To:  tesla-at-pupman-dot-com


Hi Skip, all,
              I don't know whether the answer is going to please or 
not......

>        From: Skip Greiner <sgreiner-at-wwnet-dot-com>
> Organization: Greiner, Ltd.
>          To:  tesla list <tesla-at-pupman-dot-com>
> 
> 
> Hi All
> 
> It is obvious to all that any given transformer can be run in excess of
> its rating. Thus, a 1kva transformer may be run with 2kva input and
> live. This does not mean that the TC is being run at 1kva since the
> transformer is rated at 1kva.
> 
> How can the actual input power to the TC be measured????????

Technically, it is Ecp x BPS = Power. To get an accurate measurement
requires measuring cap voltage/energy at gap fire time over a number 
of cycles and measuring the number of breaks during this period. That 
is pretty hard to do in a non-sync system because energy per gap 
fire can vary enormously. I think most people will be stunned to see 
the actual figure pop out. In most cases it is just a fraction of 
power as measured at the wall although a careful choice of "current 
limiting" inductance can help improve this figure greatly. Actually, 
I think Greg summed it up well in a post earlier where he mentioned 
dwell time shunting the power source. For pure inductive charging 
(minimal resistive losses), the shorting of the power source is not a 
big issue resistive loss-wise, but it does subtract from the time 
available for cap charging.

My two cents. I stand to be corrected.
Malcolm
<snip>