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>


Skip -

For your TC the right angle power triangle consists of three powers

   1. Active power (watts) - X axis
   2. Reactive power (RVA) or(VAR) - Y axis
   3. Total power (VA)- hypotenuse

The cosine of the angle between the Active power and the Total power is the
power factor as a decimal.

For this TC the 2000 represents the total power or VA. The 1080 probably
represents the active power or watts. The power factor angle would then be
arc cos (1080/2000) = 57.3 degrees. The power factor would then be cos
(57.3) = .54 or 54 percent. The reactive power would be VA sine(57.3) = 1674
RVA.

This NST would be considered a low power factor (LPF) transformer. If you
added a 159 uf capacitor it would bring the power factor to about 90
percent. It is not a good idea to make the cap any larger than 159 uf. You
could then use a smaller fuse. More information is on my website at
    http://www.miramar.sdccd.cc.ca.us/faculty/jcouture/tesla/index.asp?ID=5

John Couture


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-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, March 09, 2003 1:27 PM
To: tesla-at-pupman-dot-com
Subject: Re: Input power measurement


Original poster: "davep by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<davep-at-quik-dot-com>


 >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

          RMS?
          Roughly, yes...

 >input current regardless of waveform.

          Within its limits of frequency response.

 >Therefore my input power to the NST is nearly 2000 watts.

          _power_ is indeterminate with this arrangement.
          Input 'VA" (Voltamaps) us roughly 2000.
          input _power_ will be less.


 >I would appreciate comments from anyone who can help explain

 >the discrepancy between the 1080va rating of the "current

 >limited NST

          It's _current_ limited, rather than power limited.

 >and the measured input

          The measurement made is of VA rather than _power_.

          best
          dwp

...the net of a million lies...
          Vernor Vinge
There are Many Web Sites which Say Many Things.
          -me