Re: [CAD_CAM_EDM_DRO] TIG Welders

Copper

Sorry I didn't say so. I have a Biomed Engineering mindset that considers
only copper. Twenty plus years as a service engineer installing, startups
and service of high power medical X-Ray systems. Now safely retired to
computer network maintance. Would never use Al wire.

If aluminum wires are used to feed an X-Ray system it will not be "stiff"
enough to meet Food & Drug calibrations standards. Aluminum wires are good
for transmission lines etc at many thousand volts. Never would use it in
commercial buildings or houses.

High power X-Ray systems typically would require doubling the wire size (in
circular mills) to feed these things and separate set of transformers from
the rest of the hospital. Typical setup was two systems synchronized
together being pulsed up to 12 times a second for 4 - 6 seconds bursts at
150 kW each level. 1 to 100 mS exposure time .

Systems used double secondary transformers one side going negative to - 75
kV DC and the other side going positive to 75 kV DC to get 150 kV across
X-Ray tube. Delta & Y wound secondary solid state diodes for 12 pulse
rectified DC out.

The switching mech. was forced commutation using six 1000V 1000 amp diodes,
a 1000 UF cap bank and two 1000V 1500 AMP SCR switches. One fires to short
the bridge and the second dumps the cap bank across the first SCR to force
it off.. You can hear the SCR click when they fire. The wafer physically
distorts when carrying that much current.

The limiting factor is the weight of the X-Ray tube anode which is a 5 -6
inch tungsten-molibium disk spinning at 10 K RPM. At the end of a 6 second
run at high frame rate the disk will be orange colored due to the heat
produced by the electrons hitting it which produce 99.999 percent heat &
.001 usable X-Ray.

Another impressive device is the film changers that move a 14 inch square
sheet of X-Ray film out of one lead box into an exposure area, stop it,
clamp it tell the X-Ray control to make an exposure unclamp when exposure is
over and move it to a second lead box for storage. The second sheet is being
moved in place right behind the first 12 times a second with nothing but
servo motors, mag clutches,rubber rollers and steel fingers.

Impressive stuff when it works, great fireworks when it fails.

Hugh

----- Original Message -----
From: Smoke <Smoke@...>
To: <CAD_CAM_EDM_DRO@egroups.com>
Sent: Friday, January 12, 2001 1:54 PM
Subject: Re: [CAD_CAM_EDM_DRO] TIG Welders


> Are you basing those amperage ratings on using copper or aluminum wires?
I
> do believe I saw a mention of using something like #4 aluminum wires.
>
> Smoke
>
> -----Original Message-----
> From: Hugh Prescott <hugh@...>
> To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
> Date: Friday, January 12, 2001 11:42 AM
> Subject: Re: [CAD_CAM_EDM_DRO] TIG Welders
>
>
> >14 gauge 3 conductor wire ???
> >
> >Been there, started that fire. NCG 180 amp AC stick welder. Good thick
> >plate to plate weld....crank up the amps....... weld ...... get fire
> >extengiusher........ get parts & make big extension cable.... finish
weld.
> >
> >14 gauge wire is normally rated 15 amps. Not a good idea if the device
can
> >trip a 30 amp breaker.
> >
> >14 gauge 15 amps
> >12 gauge 20 amps
> >10 gauge 30 amps
> > 8 gauge 45 amps
> >
> >Not sure about these, no book handy but probably close.
> > 6 gauge 55 amps
> > 4 gauge 75 amps
> > 2 gauge 100 amps
> >
> >And just going up a wire size over the minimum never hurt anything.
> >
> >Hugh
> >
> >----- Original Message -----
> >From: Joe Vicars <jvicars@...>
> >To: <CAD_CAM_EDM_DRO@egroups.com>
> >Sent: Friday, January 12, 2001 10:06 AM
> >Subject: Re: [CAD_CAM_EDM_DRO] TIG Welders
> >
> >
> >> Woody,
> >> I've had mine for 3 years now and always running from the dryer
> >outlet. I've never had any problems ecept my wife yelling at me
> >> cause she want's to use the dryer. I've used my 175 all the way up to
> 150
> >amps with stick welding. I rarely get above 75 with the
> >> TIG though.
> >> Now I also have a ProCut55 plasma and it WILL trip a 30amp breaker
if
> >you're cranked all the way up and using a heavy duty
> >> cycle.
> >> I made an extension cord with the welder plug on one end and a
dryer
> >plug on the other. It's about 16 feet, 14 ga. 3
> >> conductor. Never had any problems.
> >>
> >>
> >> Woody wrote:
> >>
> >> > OK, I know this isn't quit the correct forum for this question
> >> > but I've seen similar topics bandied about here before so
> >> > I'll go ahead & ask.
> >> >
> >> > At some point in my future I'm going to buy a welder. My
> >> > main concern is Aluminum welding so AC is a must.
> >> > >From the list, it seems the welder to have is the Lincoln
> >> > Squarewave 175. Seems reasonable.
> >> >
> >> > The problem I'm having is the spec'ed input and out put
> >> > ratings. The manual says the service feed must be 65A
> >> > breakered at 125A on a 230V line.
> >> >
> >> > This seems like allot for a 150A welder. The output of
> >> > 14.8V at the rated 150A is about 2.2KW. The input
> >> > requirements of 230V @ 65A is almost 15KW.
> >> >
> >> > That means almost 13KW dissipation in the welder.
> >> > Now, I'll admit I've probably got VA, Watts, RMS and
> >> > the like all screwed up, but 13 KILOWATTS?
> >> >
> >> > The manual ALSO says this thing can be run on
> >> > 8AWG Cu wire and a 50A plug.
> >> >
> >> > Come on!!! Somebody help me out here.
> >> > What am I doing wrong...
> >> >
> >> > Has somebody actually got one of these things and
> >> > if so what service are they using, what's it breakered
> >> > at and is working with out setting anything on fire?
> >> >
> >> > -G
> >> >
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> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the
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>
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