Re: [Fwd: High power Variacs]

From: 	Kristian Ukkonen[SMTP:kukkonen-at-cc.hut.fi]
Sent: 	Saturday, January 03, 1998 9:46 PM
To: 	Tesla List
Subject: 	Re: [Fwd: High power Variacs]

On Fri, 2 Jan 1998, Tesla List wrote:

>    I've got a 16Kw pole pig, and I'm looking for a variac to control it at full
>power (64A, 240V) anyone got any ideas where I could get one? (In the UK).
>                                        Thanks
>                                            Steve Rodway

Most not-so-modern industrial and medical x-ray systems have a LARGE
variac to adjust voltage to tube. The units have the variac directly
connected to hv xformer and diodes after the xformer connected to x-ray
tube. At least here in Finland hospitals are dumping those old systems.
Medical systems have large xformers as the systems are designed to produce
lots of instantaneous x-ray output while industrial radiography equipment
can have longer exposure times and are usually portable. 

So, contact companies that sell new x-ray equipment and ask where the
CONTROL CABINETS of old units go. They DO NOT require a permit as you
don't want the tube which is the radiation emitting part.  You may ask
from hospitals as well - try to get some engineer to talk with.. Get the
variac WITH the cabinet as that way you get a nice power cabinet after
removing the extra x-ray related stuff and replacing it with
coiling-related stuff.. They are usually 2meter height rack-cabinets with
variac at the bottom. 

You can easily transport the units with car trailer as with the cabinet
you can tilt that cabinet on the trailer - the mass is at the lower part
of cabinet.

I've been able to get some BIG 3-phase variacs this way with REALLY
reasonable price (scrap copper). These are motorized. Some of them
have a small dc motor and gearbox so you can install a joystick
and have adjustable speed for moving the carbons.. Really handy!!

If you happen to come to Finland I can sell you one.. The small ones
weight 60kg with 1mm*5mm rectangular wire. You can operate one of these
with single phase as well and as a bonus you get a variac with isolation
xformer action. Using two windings should double current rating (if core
can take it) but requires sawing off one leg (and no isolation). The
physical size of the small ones is about 30cm*20cm*50cm. 

| Kristian Ukkonen       |  Do as thou wilt shall be the whole of the law |
| kukkonen-at-alpha.hut.fi  |_____  Chance favours the prepared mind  |-------
| http://www.hut.fi/~kukkonen |  Fear is the mind-killer  |---------
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