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microwave transf.

Subject: 
        microwave transf.
  Date: 
        Fri, 28 Mar 97 13:48:13 EST
  From: 
        tweagan-at-maind.dnet.dupont-dot-com
    To: 
        tesla-at-pupman-dot-com


Hi Malcolm

You wrote:

      < Date: 
            Thu, 27 Mar 1997 09:02:20 +1200
      < From: 
            "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>


<Hi all,
<        Having measured primary currents and motitored waveforms on 
<these things, I offer the following:
<    Calculating power dissipation in the house supply when 
<paralleling these things up is completely unrealistic if you base it 
<on RMS values. A single transformer has a terrible form-factor and 
<generated current waveforms like this:
      **
     *  *
    *    *    
   *      *
*            *           *
                *     *
                 *   *
                  * *
                   *
<with current peaks hitting around 18A  (230V supply). Two paralleled 
<gave the variac a real workout. A TC cap across the secondary made no 
<sybstabtial difference to the primary current either. These peaks 
<will be causing I^2R heating in any poor connections in the household 
<wiring while the transformer is drawing little real power due to the 
<phase difference between current and voltage.

<Malcolm


I have four 120v units connected in a series/parallel arrangement for
a 10kv supply.It's true that these things do some strange things to a
meter's readings when in a circuit where  the outputs are
shorted.I am using a homemade inductive ballast on the primary side that
limits the current to 25 amps max at 240v.I made it so that I can select
the amount of inductance so I can take the current down as low as 7A
with
an intermediate step for medium power too.I realize that the inductor
has
a voltage drop so the primary isn't really seeing the full 240v but a
jacob's ladder sure has a lot of umpf.There isn't much run time on the 
array (minutes) but as the weather warms up in Canada I'll see what it
can take.

Tom