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Re: why such a large motor???

Subject: 
           Skip Greiner wrote:
> 
> Tesla List wrote:
> >
> > Subject:
> >         RE: RSG -- rotary spark gap - why such a large motor???
> >   Date:
> >         Tue, 1 Apr 97 04:31:51 UT
> >   From:
> >         "William Noble" <William_B_Noble-at-msn-dot-com>
> >     To:
> >         "Tesla List" <tesla-at-pupman-dot-com>
> >
> > why do you use a 3/4 HP motor on the rotary gap you describe - it
> > doesn't seem
> > like there would be much wind resistance at 1750 RPM (which as you know
> > is
> > really 1800 RPM with some slippage to allow for load) - it would seem
> > that a
> > tenth or even a hundreth horsepower motor would be more than adequate -
> > there
> > is no other drag beyond the wind resistance/fan effect is there???
> >
> 
> Hi William and All
> 
> I drive a 9/16" , 7" diameter rotor with a 1/15hp motor at 1800rpm. It
> will just hold synchronism. A 1/10hp or more would be better. There is a
> lot of inertia and the windage is really quite high. Don't discount it.
> Larger diameters will require larger hp, and I suspect the hp
> requirement goes up at least by the square of rpm or diameter.
> 
> Skip
> 
> > -----Original Message-----
> > From:   Tesla List
> > Sent:   Friday, March 28, 1997 5:14 AM
> > To:     tesla-at-poodle.pupman-dot-com
> > Subject:        RSG -- rotary spark gap
> >
> > Subject:
> >         RSG -- rotary spark gap
> >   Date:
> >         Fri, 28 Mar 1997 10:06:08 -0700
> >   From:
> >         "DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
> >     To:
> >         "Tesla List" <tesla-at-pupman-dot-com>
> >
> > A 5/8 inch thick G-10 glass laminate makes a good rotor disc.  For 5-15
> > KVA
> > systems use a 1725 RPM 3/4 HP motor equipped with 10 electrodes on a 12
> > in.
> > dia. disk.  3450 RPM seems to overquench.  We use 1/2 dia. brass thru
> > holes
> > [Bill]  SNIP------------------

       Date: 
            Thu, 03 Apr 1997 08:28:49 -0800
       From: 
            Skip Greiner <sgreiner-at-wwnet-dot-com>
Organization: 
            Greiner, Ltd.
         To: 
            Tesla List <tesla-at-pupman-dot-com>
 
>   From:
>         "William Noble" <William_B_Noble-at-msn-dot-com>
>     To:
>         "Tesla List" <tesla-at-pupman-dot-com>
> 
> why do you use a 3/4 HP motor on the rotary gap you describe - it
> doesn't seem
> like there would be much wind resistance at 1750 RPM (which as you know
> is
> really 1800 RPM with some slippage to allow for load) - it would seem
> that a
> tenth or even a hundreth horsepower motor would be more than adequate -
> there
> is no other drag beyond the wind resistance/fan effect is there???
>

Hi William and All

I drive a 9/16" , 7" diameter rotor with a 1/15hp motor at 1800rpm. It
will just hold synchronism. A 1/10hp or more would be better. There is a
lot of inertia and the windage is really quite high. Don't discount it.
Larger diameters will require larger hp, and I suspect the hp
requirement goes up at least by the square of rpm or diameter.

Skip