Re: PFC on MOT Pair

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

Original poster: "Tom Stathes by way of Terry Fritz <twftesla-at-qwest-dot-net>" <newphreak_16-at-yahoo-dot-com>

Download WinTesla (i believe that is what its called) 
Feed your info into it and it will tell u the prober
PFC.
--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Matthew Smith by way of Terry
> Fritz <twftesla-at-qwest-dot-net>" <matt-at-kbc-dot-net.au>
> 
> Hi All
> 
> College was a long time ago and I can't remember how
> to work this out - 
> anyone help?
> 
> Two MOTs - primaries in parallel, secondaries in
> series; they are rated 
> for 240V input and both have approximate turns ratio
> of 1:7.95, each 
> giving approximately 1.9kV.
> 
> Mains frequency is 50Hz.
> 
> I have determined the primary restistances to be 2.7
> and 3.0 Ohms and 
> the secondary resistances 85 and 109 Ohms
> respectively.  These figures 
> were measured using a Wavetek 27XT and confirmed
> using decade resistance 
> + Wheatstone Bridge of a "traditional" Megger
> tester.  (The inductance 
> didn't half make the needle vibrate at low cranking
> speeds - like trying 
> to measure AC with a DC voltmeter.)  I attempted to
> measure inductance 
> using the Wavetek, but it was either two low or too
> high to register.  I 
> have yet to check primary current since I currently
> lack a CT and don't 
> like using DMMs directly for current measurement!
> (I've had one fry before.)
> 
> I guess that is not enough data to calculate the
> value of a PFC 
> capacitor but I would like to know
> 
> a) is there a rule of thumb value for capacitor
> sizes for an array like 
> this?
> b) what is the actual formula that I should be
> using, if I had the 
> inductance figures (which is what I guess that I'm
> missing)?
> 
> Cheers
> 
> Matthew Smith
> 
> 
>