Contactors/Mercury Wetted!

To: tesla-at-pupman-dot-com
Subject: Contactors/Mercury Wetted!
From: WILLIAM HENDERSON <hb-at-earthlink-dot-net>
Date: Thu, 12 Sep 1996 22:35:15 -0700
Tesla List wrote:
> 
> >From richard.quick-at-slug-dot-orgWed Sep 11 22:31:14 1996
> Date: Wed, 11 Sep 1996 03:14:00 GMT
> From: Richard Quick <richard.quick-at-slug-dot-org>
> To: tesla-at-poodle.pupman-dot-com
> Subject: 110/220V safety questions
> 
> Quoting Steve Roys <sroys-at-umabnet.ab.umd.edu>:
> 
> > I have a pair of 30A contactors that I want to use in my 220V
> > control cabinet.  The problem is that the power to the cabinet
> > is going to be from a 3-wire 220V outlet (2 hot and a ground),
> > and the relay coils are energized by 110V.  I have been told
> > that I should have a 4-wire circuit if I wanted to use a single
> > side of the 220V line to get 110V at any appreciable current,
> > but am I going to have problems if I just wire the relays up so
> > I use one hot side and the ground of the 220V to get the 110V
> > needed to energize the coils, or should I do something else.
> 
> Since we are talking about relay coils I would just go ahead and
> wire one side to your juice and the other to your third wire
> ground. I have done exactly that in my 240 volt power cabinets
> for years and never had a problem, I also run pilot lamps, the
> red panel illumination light, etc., in the same way. The fourth
> wire solution simply brings in another neutral wire, which is
> common to the third wire you already have. If you ran three wire
> in through EMT conduit your conduit should be bonded to the
> breaker box and meets code requirements for a dedicated ground in
> some wiring installations. I have done it both ways and never had
> a problem, but you will never find a poor connection in any of my
> 60 cycle work.
> 
> Richard Quick
> 
> ... If all else fails... Throw another megavolt across it!
> ___ Blue Wave/QWK v2.12Note
    I would suggest using mercury wetted rly's,I use 2 -100 amp puppies
on my system firing them with 28vdc.Before i used klunky contactors,that 
klunked/hummed and buzzed.I prefer to have quiet while listening to the bolts 
fly around.Each rly is a spst on each leg of the 230v transformer 
primary.These Relays can be picked up at surplus stores each of mine were 
$7.50 each,my other thought is to make your rotary spark gaps as quiet as 
possible-i have mine in sealed plexaglass boxes,one box inside of another
this way if you want to run the rotor in N2 its very easy,not to mention 
quiet and pretty!
bill  hb-at-earthlink-dot-net