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

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

Original poster: "Crow Leader by way of Terry Fritz <teslalist-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

still sounds like too large of a motor, unless you are spinning a wheel 
under fluid. 12" disc is not much, even it was an aggressive pitch fan 
running at 10kPRM it would still be under 1HP. Take a look at model 
airplane engine ratings and propellers for comparison.
I can and (used to) spin a 1/2" thick 12" diameter steel plate at ~1700 RPM 
with a 1/8th or 1/4th (not sure which, but I know it's less than 1/3rd) HP 
induction motor all day long, with no overheated motor problems.
Something is wrong, orthe project is so overkill that it's silly, or it 
lacks bearings or something.
KEN


Tesla list writes:
>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.
>> >
>> >
>> >