Re: Need a variable-speed 2hp or greater AC motor for serious gap drive

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jerry Chamkis by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jchamkis-at-bga-dot-com>

The Atmel 8 bit RISC u-processor family (Mouser or DigiKey) have a pair of 10
bit PWM and another pair of 8 bit PWM, very easy to program (flash and
EEPROM) and a $79 complete development system.  Ferinstance, the AT90S8535
has the 4 PWM channels, 8 channels of rock-solid 10 bit A-D, serial comm,
in-system programming, 4 K of code flash, 512 bytes of RAM, 512 bytes of
EEPROM, etc.- for about $7.  I use it for just about everything these days.
(I don't work for Atmel or anything like that).

Jerry

On Sunday 08 June 2003 08:50 am, Tesla list wrote:
 > Original poster: "Jeremy Scott by way of Terry Fritz <teslalist-at-qwest-dot-net>"
 > <supertux1-at-yahoo-dot-com>
 >
 > If you don't mind DC, www.sciplus-dot-com has a 2HP 120V
 > 4800 RPM DC motor (from a treadmill I think.) Tricky
 > part there is getting the thing to spin at the right
 > speed and phase adjustment. I bought one and am
 > currently designing a digital IGBT/MOSFET drive for
 > it. Speaking of which, I'm looking for something
 > (chip/circuit) that provides at least 10 (preferably
 > 16) bit PWM. The BS2p's PWM command is sorely lacking
 > the resolution for accurate speed control.
 >
 > --- Tesla list <tesla-at-pupman-dot-com> wrote:
 >  > Original poster: "Nick Andrews by way of Terry Fritz
 >  > <teslalist-at-qwest-dot-net>" <nicothefabulous-at-hotmail-dot-com>
 >  >
 >  > Well, the squirrel cage on a swamp cooler (evap) is
 >  > pretty good size and
 >  > spins fairly fast, and they are driven by 1/4 up to
 >  > 1-1/2hp motors just
 >  > fine.  And they (obviously) move a fair bit of
 >  > air...  Much larger and more
 >  > rotating mass than most rotor discs I've seen.
 >  >
 >  > Nick A
 >  >
 >  > >From: "Tesla list" <tesla-at-pupman-dot-com>
 >  > >To: tesla-at-pupman-dot-com
 >  > >Subject: Re: Need a variable-speed 2hp or greater
 >  >
 >  > AC motor for serious
 >  >
 >  > >gap drive
 >  > >Date: Mon, 02 Jun 2003 06:33:03 -0600
 >  > >
 >  > >Original poster: "W.R. Langston by way of Terry
 >  >
 >  > Fritz
 >  >
 >  > ><teslalist-at-qwest-dot-net>" <blangsto-at-iwvisp-dot-com>
 >  > >
 >  > >Dan,
 >  > >
 >  > >Funny you should ask. My son, the currently
 >  >
 >  > practicing physicist
 >  >
 >  > >(government paid research physicist -- a shade too
 >  >
 >  > accustomed to the
 >  >
 >  > >concept of over-engineering IMHO ;-), has machined
 >  >
 >  > as close to a
 >  >
 >  > >bulletproof rotary gap as my eyes have ever set on.
 >  >
 >  > Somehow he has managed
 >  >
 >  > >to get almost all the people in his section excited
 >  >
 >  > about this project and
 >  >
 >  > >directly in on the design and machining work -- if
 >  >
 >  > you've ever worked in a
 >  >
 >  > >government lab, that should explain everything
 >  >
 >  > about what is going on here.
 >  >
 >  > >It looks like it will require 1 1/2 hp to cause
 >  >
 >  > this thing to quiver, let
 >  >
 >  > >alone spin. However, once in motion, it should be
 >  >
 >  > able to reverse feed
 >  >
 >  > >Hover for a few seconds as it slows down.
 >  > >
 >  > >If there has ever been something that looked
 >  >
 >  > virtually indestructible,
 >  >
 >  > >this is it. Once it is all together, I'll post a
 >  >
 >  > photo. One picture is
 >  >
 >  > >worth a thousand poetic phrases. The base and
 >  >
 >  > standups are all 1" alloy,
 >  >
 >  > >the shaft is 1" SS round stock. It is electrically
 >  >
 >  > isolated (read that
 >  >
 >  > >"insulating belt driven"), and the disc is 1" x12"
 >  >
 >  > G11. Last time I looked
 >  >
 >  > >at the design, the electrodes were to present a
 >  >
 >  > hemispherical, 1/2" face
 >  >
 >  > >to each other -- set at an appropriately calculated
 >  >
 >  > angle to allow for the
 >  >
 >  > >burn-off of early arc and/or late quenching to wear
 >  >
 >  > uniformly (I'm betting
 >  >
 >  > >that part of the plan will just never work, what
 >  >
 >  > with windage and random
 >  >
 >  > >heat transfer and magnetic field effects on the arc
 >  >
 >  > and all).
 >  >
 >  > >At any rate, I cannot change his mind to down size
 >  >
 >  > the thing, so it fell
 >  >
 >  > >to me to come up with a variable speed control for
 >  >
 >  > the 1 phase, 240v, 2 hp
 >  >
 >  > >motor we have now, or a motor and control to suit
 >  >
 >  > whatever can get the job
 >  >
 >  > >done.
 >  > >
 >  > >So, thanks for your input, I'll pass it on to the
 >  >
 >  > "team." You see, I am
 >  >
 >  > >over 50 (one foot in the ground already and the
 >  >
 >  > other on uncertain
 >  >
 >  > >footing), no longer in an "official" lab... so what
 >  >
 >  > do I know -- about
 >  >
 >  > >anything -- in the face of the educated, under
 >  >
 >  > thirty crowd????
 >  >
 >  > >Oh well, he is my retirement plan, so I guess I'll
 >  >
 >  > humor him ;-)
 >  >
 >  > >Have a great day,
 >  > >Bill L.
 >  > >
 >  > >Tesla list wrote:
 >  > >>Original poster: "by way of Terry Fritz
 >  >
 >  > <teslalist-at-qwest-dot-net>"
 >  >
 >  > >><dhmccauley-at-spacecatlighting-dot-com>
 >  > >>
 >  > >>
 >  > >>If you need one in a hurry, you probably can't be
 >  >
 >  > too picky in what you pick
 >  >
 >  > >>up used.  Best bet is to check out Grainger-dot-com.
 >  > >>They have a very large number of universal motors
 >  >
 >  > / induction motors from
 >  >
 >  > >>the fractional range up to the hundreds of HP.
 >  > >>
 >  > >>Why do you need one between 2 and 5 hp for 15-25
 >  >
 >  > kW.  I've typically seen
 >  >
 >  > >>less than 1HP universal motors used on 15-25kW
 >  >
 >  > sized ARSG.
 >  >
 >  > >>Unless you are making a HUUGGGEEE rotor, than i
 >  >
 >  > think a 0.5-1.0HP motor
 >  >
 >  > >>would suffice.
 >  > >>
 >  > >>Dan
 >  > >>
 >  > >> > Hello folks,
 >  > >> >
 >  > >> > Do any of you have a source for either a
 >  >
 >  > universal type AC motor of
 >  >
 >  > >>between
 >  > >>
 >  > >> > 2 and 5 hp, or a variable speed (chopper-type?)
 >  >
 >  > controller usable for a 2+
 >  >
 >  > >> > hp induction motor? We need to have built and
 >  >
 >  > tested an ASRG for 15-25 kW
 >  >
 >  > >> > by July 1st.
 >  > >> >
 >  > >> > I suppose a suitable sized, and cool-running DC
 >  >
 >  > motor (speed controllable)
 >  >
 >  > >> > would work well enough too.
 >  > >> >
 >  > >> > We have the machining and structural aspects
 >  >
 >  > well enough in hand, but
 >  >
 >  > >> > finding a large enough, variable speed motor
 >  >
 >  > has proven very difficult.
 >  >
 >  > >> > We need to find one or the other asap.
 >  > >> >
 >  > >> > Thanks,
 >  > >> > Bill L.

-- 
Jerry Chamkis
jchamkis-at-bga-dot-com