Hey Garry...there are several methods of ballasting a piggie, the best I have seen so far is to use an EI frame with about 18 -20 sqr inches on the middle column for 30A worth of capacity. Wind about 200- 250 turns of THHN insulated solid copper wire on it ( ehhh # 8-10 should be good). Adjust the gap of the E and I portion of the frame untill you achieve 30ish amps draw. For my core it is 1/4" spacer between the E and I sections. See the picture at link below
http://members.cox.net/bunnikillr/Dscf0232.jpgIf you are looking for variable currnet control, a slide choke would be more effective.
As far as pushing the limits on a variac, it can be done for a minute or two with a cool down period of several minutes. I personally dont like going much more than 30% above rating of variac for more than 2 minutes at a time.... Ive already smoked a 1256D by pushing it to 45A for about 3 minutes straight. burned the brushes and melted 2 of the windings on it.... repairing it wasnt that fun either...
Scot D garry neeley wrote:
Hey guys, I'm in need of a little help. I've built several coils from9kv30ma to 2.2 kva. I recently aquired a 50kva pole pig and a 240v/280 out variac @ 30 amps. I want to use all the power I can but I dont want to smoke my variac either. I've been researching different ballasting methods but I'm still unclear. ideally I would like to have 7.2kva out of the pig. Which brings me to the question, how could I ballast the pig to only draw 30 amps @240v. (on a budget) And how much do you think I could overate the variac meaning safe levels over 30 amps for short runs if possible at all. Thanks in advance. Bamacoiler_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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