Re: [CAD_CAM_EDM_DRO] Re: Mariss' power supply circuit

You might want to check that whole line for voltage drop, crimp by crimp.
You may well have a bad crimp. You could do a quick check by connecting a
small wire to the power company's ground and running it back to your box and
measuring the voltage between the small wire and your neutral; it should be
quite low. It might also be interesting to measure the voltage between
ground (green) and neutral. I saw a case in a plant a few years ago where
the electricians had pulled hot from one (and ground?) transformer and
neutral from another. In that case I measured a very noisy 50 volts AC
between neutral and ground. The noise was driving a bunch of PCs and MACs in
that area absolutely batshit.

Many years ago a friend had a couple of "Trash-80" computers in his house
and they kept crashing. Upon investigation I found one set of receptacles in
the house went to about 180 volts, the other to 40 volts when a window air
conditioner started. I traced it back to a loose neutral in the main power
box. The problem was on the power company side of the circuit, so he called
them. The guy that came out to fix it ended up in the hospital with a
severely burned hand; the neutral wire was as just under red heat due to the
loose connection. Beware of hot crimps.

----- Original Message -----
From: "Les Watts" <leswatts@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, June 19, 2002 7:16 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Mariss' power supply circuit


> Good idea!
>
> I could even take power from the wild leg and another leg of my generated
3
> phase.
> But I should mention that the 240v here is not too bad... we just have an
> argument
> about the quality of the neutral line from the transformer to the box.
> 120v sometimes rises to nearly 240v on the side that has the heaviest
load.
> I am real unhappy about it since I measured the
> float on the power company neutral BEFORE my meter.
> It is a long run with several
> aluminum crimps.
>
> But I will save this for sci.engineering.electrical.
> Les
> Leslie Watts
> L M Watts Furniture
> Tiger, Georgia USA
> http://www.rabun.net/~leswatts/wattsfurniturewp.html
> engineering page:
> http://www.rabun.net/~leswatts/shop.html
> ----- Original Message -----
> From: "Keith Bowers" <kabowers@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Wednesday, June 19, 2002 5:46 PM
> Subject: Re: [CAD_CAM_EDM_DRO] Re: Mariss' power supply circuit
>
>
> > At the risk of being old fashioned you might consider isolating yourself
> > from the AC mains using a motor-generator (MG) setup. Moderately severe
> over
> > voltage would not be a problem to an MG set. They also tend to eat
spikes
> > and short dropouts. Add a big flywheel and you can ride out all sorts of
> > nastiness <G>. IIRC at one time MGs and LARGE flywheels were the core of
> the
> > emergency power for Cheyenne Mountain.
> >
> > ----- Original Message -----
> > From: "Les Watts" <leswatts@...>
> > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > Sent: Wednesday, June 19, 2002 4:46 PM
> > Subject: Re: [CAD_CAM_EDM_DRO] Re: Mariss' power supply circuit
> >
> >
> > > Yes that sounds about right. I figure peak current is determined
> > > by either armature saturation or magnet coercivity and has a safety
> > > factor. I don't think it's thermal because the time is so short.
> > >
> > > A high line voltage perhaps causing an amp failure and a motor over
rev
> > > would seem to be one condition where a braking resistor would be
> > > preferable to shorting the windings though... then the regeneration
> > > current could exceed max locked rotor. My floating neutral can
> > > (and quite possibly will) do that. I need a diesel generator or
> something.
> > > I may just end up running the computer and servo amps off of 240vac.
> > >
> > > Les
> > >
> > >
> > > Leslie Watts
> > > L M Watts Furniture
> > > Tiger, Georgia USA
> > > http://www.rabun.net/~leswatts/wattsfurniturewp.html
> > > engineering page:
> > > http://www.rabun.net/~leswatts/shop.html
> >
> >
> >
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> OFF Topic POSTS: General Machining
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you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this as a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
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