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Re: Cap-driven x-former?

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

You didn't get that from Mouser... Probably C&H or H&R..
It's a "illumination transformer" -> think high power NST.  The third
winding runs at about 600V (assuming the primary is 120V) and is used to
connect a capacitor for power factor correction (to compensate for the
leakage inductance).  They obviously did a little trade analysis between
voltage and capacitance to determine the optimum voltage.

They're wide available surplus catalog items at about $40-50 each.  You can
wire up 4 to make a "super NST" with 18-20kV output at 200-300 mA, which
makes a very nice supply for jacobs ladders and pulling arcs.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, June 06, 2004 4:49 PM
Subject: Cap-driven x-former?

 > Original poster: FIFTYGUY-at-aol-dot-com
 > Folks-
 >      I bought a HV transformer many years ago (from Mouser, probably) that
 > a unique feature that I have never figured out.
 >      It's a 5KV, 300mA secondary, 110V primary. Single phase, no windings
 > connected to ground at all. From my recent TC research, I learned that
 > X-former also has magnetic shunts (which have since resisted all my
 > attempts to
 > remove them without destroying the unit). Makes a pretty impressive
 > Ladder
 > driver with the high, but self-limited current.
 >      What has puzzled me is why it has a third winding that requires the
 > of a cap to make the transformer run. The third winding is center tapped,
 > it's inside (wound closer to the core) of the secondary. The center tap is
 > used, but the seller's ad mentioned the cap requirement, and they included
 > cap and a connection drawing.
 >      With the cap, it's works great. Without, the HV leads barely put out
 > spark. How does this thing work, and can this "extra winding with cap"
 > principle be applied to other existing HV transformers as well?
 >      More specs: Seller advertised it as out of a copier power supply.
 > on the side of the unit is "General Electric part # 9T68Y5022G10". Made
 > Eastman Kodak (with an Eastman Kodak part #).
 >      Cap is a 10uF 1000VDC oil-filled type.
 > -Phil LaBudde