Re: ballast

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bert.hickman-at-aquila-dot-net>

Max,

You almost got it right... but you needed to use the line frequency
instead of 500 Hz:

Under full load, your transformer is rated for:

  VA = 14400*0.5 = 7200 VA

In order to drive it off a 120 volt source, you'll need to be able to
limit the short circuit current to:   

  Ip = 7200/120  = 60 Amps

Which implies that you'll need a ballast reactance of:

  Z = 120/60 = 2 Ohms (inductive)  - so far so good in your
calculations...

Your line frequency is either 50 or 60 Hz (not 500...). So the estimated
ballast inductance should be:

  L = (1000*2)/(2*Pi*F)  in mH
So:
  L = 5.5 mH at 50 Hz
Or
  L = 4.5 mH at 60 Hz

Safe coilin' to you!

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com


Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Gbjsjg-at-aol-dot-com>
> 
> My Power Transformer is 14400kv and .5 amps. I figured out that that ist has
> 2 ohms of reactance. The equation calculate the inductance to limit the
> current is not coming out right.
> 
> R= 2ohms of reactance
> F= 500 cycles (right)
> pie= 3.14159
> L= x inductance
> 
> L= R*1000
>      2pie*F
> 
> So my equation would be-
> 
> L=      2*1000
>     2*3.14159*500
> 
> Its coming out to a wierd number like .4 something at 120 volts. Any help on
> the mh I will need to limit my current? Also does anyone know what I should
> use to limit the current?
>                                                             -Thanks Max
Joseph