Re: Power factor correction capacitors for MOTs

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

Original poster: "Virtualgod" <mike.marcum-at-zoomtown-dot-com> 

Here's a starting formula:  uF =        10^9             where F if line
freq, V is line voltage, and C is the corrected kVA
                                                 ------------- (C)
                                                   2(pi)FV^2
rating of the transfornmer (50% of VA rating for unmodded nst's). Since you
don't know and have no way to measure the uncorrected mots output VA under
load, probably be best to assume 50% efficiency for a ballpark figure, use
the previous formula, and then adjust the pfc by adding/removing microwave
oven caps in parallel, measuring the current drawn with a DMM. Whatever uF
draws the least current under load is what you need. I did this with a
modded  7.5/32 (originally 7.5/20) nst and found about 40uF works best, tho
TC's are hardly sinusoidal loads, so the pfc will only help so much.

Mike

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, November 10, 2004 10:47 AM
Subject: Power factor correction capacitors for MOTs


 > Original poster: "Borislav Trifonov" <bdt-at-shaw.ca>
 >
 > How do I determine the proper PFC cap, or if I even need one, for a
 > MOT?  Mine has been modified by removing the magnetic shunts and
 > reassembling the laminations so that they are interleaved, so I don't know
 > how that affects the usual numbers used.  I don't know how to measure PFC
 > and I don't have a scope.
 >
 >