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3-phase converter construction



Subj:	Re: 3-phase current
Date:	12/9/98
To:	tesla-at-pupman-dot-com


 In a message dated 12/5/98 8:56:45 PM EST, tesla-at-pupman-dot-com writes:
 
 << Subj:	 3-phase current
  Date:	12/5/98 8:56:45 PM EST
  From:	tesla-at-pupman-dot-com (Tesla List)
  To:	tesla-at-pupman-dot-com
  
  Original Poster: "Shady M's Hivh Voltage Supply" <hivolt-at-gil-dot-net> 
  
  
  Hi there,
  
  Yea, I'm new here.  
  
  My problem is that I just got ahold of a 10KV power supply, and actually
  managed to get all 700 pounds of it to my house-- But I've got no way to
  power it.  Does anyone know the ballpark cost for piping in 3-phase
  current, or what they usually charge for branching it in from a place
  where it's already installed?
  
      Hi SM,
 
 Build a 3-phase converter --- lots cheaper than Edison -- 
 The price here ( Altadena Ca. ) was 1100 $ between poles +	a bond to 
 guarantee minimal monthly usage + a removal fee when done!!
 
    I built a converter from a 25 H.P. 3-phase motor ---
 
 The start caps are two 4800 ufd. -at- 200 VDC (250 VDC Surge ) ,
connected back to back for A.C. application.

                     + o-----| |------| |-------o +

                              select any wire for the third phase ( in this
illustration,
use # 2 )
                        between wires 1& 2 ,connect the start cap. through a 
relay or knife switch . ---- connect the flux correction caps to the same 
wires ( 1 & 2 ) permanently in circuit ----

           For high starting currents ,a resistive line can be used to start
the motor . ---- In my case, the start current is in excess of 130 amps !
I have only a 50 amp service --- 

o------1

o------2

o------3


 The flux slippage correction capacity required was around 700 ufd.
 
    The no-load current without flux correction was 30+ amps,
 with correction ,around 3 amps --
 
     No problems running heavy equipment ,including 5 HP air compressor,
 hot tank ( 5 HP ) plus lathe,mill ,tig, mig etc.( not all at the same time
however ) :>)

      
 regards,

                Sandy