saturable reactor ideas


I asked a couple weeks ago of possible ballasting uses for a transformer 
I have. Unfortunately I recieved no responses :(  But it now appears 
that I may be able to use it in a saturable reactor. I had been toying 
with the SR idea for a while but know very little of them. Now that the 
SR posts are going around I figure I'd ask. I have a transformer out of 
a 3-phase power moniter. It is quite large, designed to pass at least 
90A, the windings are actually bars instead of wire. It is a square 8, 
or two 'windows'. I guess it probably would be an absolute pain to get 
the windings off. And I dont know what the different cores are, b-h, or 
v-i or whatever they were. Could someone mention what these are - I am 
sure there are others wondering also. Now let me get this strait. The 
outer two legs are the coils in series  with the two 120V windings of 
the pig, and they are wound so that there feilds cancel. The middle 
winding is many turns of small wire for the DC input. Let me see if I 
can draw some ascii.

   |             | 
   |             | 
   |             |

  L1     L2     L3
   --------------     }
   |      |      |    }sat
   o      o      o    }react
   o      o      o    }
   o      o      o    }
   |      |      |    }
   --------------     }

   |             |
   |             |
   |             |
 120V(+)         120V(-)

L2 is the DC control coil. The 120 + and - are the two opposite phase 
hot lines. In this setup, would L1 and L2 be wound both the same way, or 
would one be CW and the other CCW? When wound properly, does that mean 
that there will be none, or very little induced AC in the control 
winding (L2)? I have read very different descriptions of the control 
winding. I have an extra 7.5A 0-140V variac, bridge, and several DC 
filter caps, 6,000uF 200V. I also have lots of magnet wire, especially 
#24 - which was mentioned to use- but how many turns? Perhaps I should 
just wind a single layer or so, all the way up the center leg, and if it 
appears to be too many turns then I could just strip some off. But what 
would happen if there were too many turns? Would is saturate too 
quickly? Could you place a heavy duty rheostat in series with the 
control winding for fine adjustment - that may reduce the problem of 
sharp non-linearities in the control.

Just a few questions - as I would like to think that this could be done.

Tristan Stewart, KC2EBM

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