Question about ballasting and VA

To: tesla-at-pupman-dot-com
Subject: Question about ballasting and VA
From: "Adam" <adamsmith-at-Mediaone-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sat, 26 Feb 2000 01:22:11 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme


OK, I understand how my inductive ballasting limits current through my PT,
but what I don't understand is how to calculated VA through the PT for tesla
service.  I set up my PT w/ballast, and took some measurements.

My Setup:

4 shorted 9/60 NSTs in parallel are my ballast, in series with the PT
(14,440 volt, 1500 VA).  All measurements taken with 120 volt input to this
system.

Here's the data I recorded:

Condition 1 (PT HV side shorted):

    Voltage across PT:                5 volts
    Voltage across NSTs:            115 volts
    Current from wall:             18.7 A
    PT short-circuit current:     140.0 mA

Condition 2 (PT HV winding open-circuit):

    Voltage across PT:             115 volts
    Voltage across NSTs:             5 volts
    Voltage across PT HV side:       ? not measured, but presumably 13.8kV
    Current from wall:             690 mA

Does this mean that when I run a jacob's ladder with the PT (closer to
condition 1), I'm only putting about 100 VA through the transformer (5 volts
* 18.7 A = 93.5 VA)???  Or am I doing some math wrong here.

Question 2: Since I know my NST ballast allows only 18.7 amps max through
the PT, does this mean that the most VA this setup could possibly allow in
Tesla operation is 18.7 * 115 = 2150 VA ?

-Adam
adamsmith-at-mediaone-dot-net