Re: Ballasting Homemade Pig

[Pyrotrons-at-xxxxxxx (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

>I dont know whether anyone has tried this but some MOT's with >secondaries
>shorted might work, possibly several in paralel?  It's certainly worth a
>try.

Hi all!

Oh yeah - MOT's work excellent. Forgive me if I'm wrong, but I believe it's 
Alexander with the homeade pig (very cool). If you have MOT's, you could get 
the pig up-and-running pretty quickly, but you'll probably want to upgrade to 
better current limiting. (seeing that you've made a PIG yourself, it probably 
wouldn't be too hard for you to make a big current-limiting inductor for 
it.....)

As far as the neon transformer cores go: they would probably work excellent, 
but you'll have to be careful of them saturating and drawing a load of 
current. Assuming they're rated for 120V, it will probably work great if you 
put 3 in series, so the total voltage drops across each of them aren't too 
high. (perhaps someone more versed in this type of work could help)

Anyhow, just for the record, here's how Aron and I successfully limited 
current through our 5kVA pig to 20A. (-at- 240V = 4.8kVA)

Following the current, starting at the beginning:

current supplied by 240VAC wall plug.
goes into primary winding of MOT#1. 
leaves primary of MOT#1, and goes into primary of MOT#2
leaves primary of MOT#2, goes into pig
goes through pig, then flows back into 240V mains. 

Short the secondaries of both MOT's.

Use the BIG MOT's. The smaller ones draw a LOT of current and will burn up 
relatively quickly. (i'd say, they'd last 2-4 minutes shorted) The bigger 
ones will easily last 10 minutes at full short. Also, make sure the MOT's are 
the same, otherwise, one will see a higher voltage than the other one. The 
cores might saturate......but hey, realistically, what can hurt by trying?? A 
tripped breaker?? Wear eyeglasses and you'll be fine. It's okay to throw 
breakers.

If you have them on hand, this will get a new pig going. There are MUCH 
better forms of current limiting than this, though. (ex. arc welder, variac, 
homeade) I don't like purely resistive limiting, b/c it drops the voltage too 
much. A huge percentage of the power is lost as heat, instead of induced 
current like we want.
          
Take care everyone.