Re: MOT pig limiters

To: tesla-at-pupman-dot-com
Subject: Re: MOT pig limiters
From: Bert Hickman <bert.hickman-at-aquila-dot-com> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Sat, 12 Sep 1998 14:29:48 -0600
Approved: terryf-at-verinet-dot-com
Tesla List wrote:
> 
> Original Poster: "Bill the arcstarter" <arcstarter-at-hotmail-dot-com>
> 
> It was written:
> >Bill,
> >
> >I haven't tried it, but I would guess that you would use a microwave
> oven
> >transfromer as a current limiting inductor just as you would a welder.
> Leave
> >it intact, short the outputs and run the current to be limited through
> the
> >primary - and the shunts should come into play.
> >
> >Ed Sonderman
> 
> Yes.  Thats also what we've been doing, but in light of my recent MOT
> saturation tests (haven't yet eval'd a MOT with a shorted-out secondary)
> it looks like we are getting more impedance due to the primary winding's
> resistance (0.5 ohms measured) , as opposed to inductive limiting.  I
> don't think that's really what we need, or is it?
> 
> I do know that my particular MOT would draw over 30 amps at 120V with
> the sec shorted out.  My 20 amp line fuses didn't like it much.
> 
> More experiments are needed! Where's my 0.1 ohm 100W resistor at... :)
> 
> I have a 10KVA 19900 (only 125 lb supposedly) pig coming to my doorstep
> late next week!  Woo Hoo!
> 
> Late friday Paul stumbled into a few (6 or 8?) 5KVA 14400 units, about
> the size of a 5-gallon bucket, at a scrapyard.  Is there any good way to
> ID these as to their PCB/no-PCB oil status, or is it a random risk?
> 
> If I can get them for the right price, is there an interest on the
> list??
> 
> -Bill the arcstarter
> Starting arcs in Cinci, OH
> http://www.geocities-dot-com/CapeCanaveral/Hangar/6160
> 
> ______________________________________________________
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Bill,

Usually, there will be a "No PCB's" sticker on the case somewhere. The
other option is to pop the lid on them, and take a look and a sniff. If
the fluid looks and smells like mineral oil, you should be OK. If these
have been in hard service, the oil may be a darker color, and may have a
bit of a "burnt" odor, but avoid purchasing any with any signs of carbon
in the oil.

Transformer PCB's have a definate yellower color, and the odor is
definately different NOT anything like mineral oil - it's more
"solvent-like". Also, transformer PCB's are almost twice as heavy as
mineral oil - mineral oil has a specific gravity of around 0.88, while
PCB's are around 1.55. Finally, there's the burn test - PCB's will not
burn. Period. Torture mineral oil enough and you can make it burn. 

Hope this helps,and happy hunting! I may be interested in one of these
if they look good and contin no PCB's...

-- Bert --