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Re: Looking for motor



In a message dated 99-10-06 06:01:00 EDT, you write:

<< 
> 1 hp universal motor at 10,000 rpm, 
> 0 to 120v 25 amp variac,
> 14 inch G10 rotor with 12 25/32 brass inserts that
> hold 1/2" tugston electrodes
 
> The problem is I am having trouble attaining greater
> than 1800 rpms on the rotary.  I'm thinking this might
> be due to the tourque band of the motor. It probably
> is one hp at 10,000 rpms and is unable to overcome the
> weight of the rotor rpms. 

Rodney,

I'm surprised the motor can't spin any faster, but I guess the weight
takes its toll.  Have you tried applying a little extra voltage to the motor,
as long as you don't run the motor too long, and it doesn't get too hot, it
shouldn't be destroyed.  Another approach is to add a powerful squirrel 
cage blower and let the air blow against the electrodes in the corrrect
direction to help speed up the rotation of the disc.  A fellow coiler did 
this and gained a few thousand extra rpms, which is probably all you 
need, since you probably don't want TOO high of a break rate.

> What I'm looking to do, is
> construct a syncronous RSG, and I am looking for an
> 1800 rpm motor around 2 to 3 hp.  Does anyone know
> where I might be able to find such a creature?  

You could use a 1725rpm induction motor and modify it for sync operation
by grinding 4 flats on the armature (actually the squirrel cage rotor), to 
give
you 1800 rpm.  Or use a 3450rpm motor and grind 2 flats on the armature
for 3600 rpm operation.  This approach of grinding the flats will be much
cheaper than buying a sync motor most likely.  Both my sync rotary gaps
use this approach.

John Freau


> Thanks all,
> Rodney >>