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Re: [TCML] sync. motor

 Bob,

I think it should sync-lock the way you did it.  I usually make
the flats about 1/4 the diameter of the armature or so but in any case
it shouldn't be that critical.  

Some folks use the "dead pole" concept but I've never bothered with that.   

I assume you tried using a 140 volt step-up type variac to see if that
helps.  If you have a super-heavy rotary gap rotor with electrodes,
attached to the motor shaft, that might be creating too much wind
friction and preventing sync?  I assume you tried it without a rotor
however.  

You could try feeding it with maybe 150 volts just as a quick test
to see if it syncs?

A capacitor-start induction motor should be fine for this application.  

Could it be a 208V or 240V motor, but you're using 120V?  I assume
that's unlikely but I figured I'd mention it because I can't think of any 
reason the modification would not work.  It's a mystery to me.  

Cheers,
John   

 


 

 

-----Original Message-----
From: robert massa <massahbob@xxxxxxxxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Mon, Sep 19, 2011 4:52 pm
Subject: [TCML] sync. motor




  I have a G.E. 1/3hp motor,  Cat.No.C367, Mod.-5KC35MN73H, capacitor start.  

The diameter of the armature is 3.115.  I machined 4 flats .910 or 7/8"wide, 

indext 90dg. on center.  Put it back together and it still runs 1725 rpm max. 

Have variace and good mechanical tacometer, will slow down at lower volts but 

will not run higher, so -

   1- Do I need to enlarge the flats ?

   2- Is there a formula to figure the flats ? 

   3- Did I use the wrong type motor ?    The set up was brutal on my antique 

horizontal mill, but now have that part figured out. I looked through the old 

postings and couldn't get to the right info. Some one even said " It's almost 

impossible to screw up" or something like that.  Have a couple more motors, to 

test thier theory ; ).  Realy apreciate the knowledge you guys share.   Bob

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