Re: Input power measurement

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

Original poster: "Chris Roberts by way of Terry Fritz <teslalist-at-qwest-dot-net>" <quezacotl_14000000000000-at-yahoo-dot-com>


I actually just had a problem that is similar to what you are talking 
about. I was running my 9/120 NST coil at the school yesterday and all of a 
sudden, the coil stopped running. Scared the crap out of me, thinking I 
killed my transformer. Instead, the 12 amp fuse on the variac gave out. 
Odd, seeing as the NST should only pull 9 amps. Does that mean I might be 
overstressing my 10 amp variac? I am using a LTR cap on my coil. I remember 
hearing (this may or may not be true) that an LTR cap "pulls" more energy 
out of the transformer. If this is true, then that's probably the reason 
for my coil. It might be the along same lines for your transformer. Either 
that, or the NST might have had some shunts removed. Is there any way you 
could measure the output of the NST?

  Tesla list <tesla-at-pupman-dot-com> wrote:
Original poster: "Skip Greiner by way of Terry Fritz "
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



-Chris