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Re: better sync motor mods? a formula...



Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Scot,

	Many thanks for this great information!  We could have months and $$$
experimenting with this!  However, you went and got the answer for us :-))

Cheers,

	Terry


At 04:30 AM 11/29/2000 -0600, you wrote:
>Hi All...
>
>
>Ive been following this thread and my curiosity got the best of me ...  so I 
>went to school (
>U.N.O. ) and asked one of the Mech. Eng. in Electrical motor design about 
>modifications.
>
>the results of the conversation ended up as follows.
>
>cutting flats are better in the long run for stability and startup ( cap 
>start types)
>Vcuts are good for low start torque motors but can loose sync easier
>
>the width of the cut can depend upon 2 items
>the design of the case windings ...   dead pole or non dead pole
>( if there is a point at which the windings are formed away from each other 
>this can be considered
>a dead pole area. , and then there is the true dead pole area , this is in 
>which there is a lack
>of windings in the core slot.)
>
>as far as cutting the rotors a formula was derived for simplicity
>
>a 38 degree arc ( for non dead pole windings) is suggested
>
>a 40 degree arc for true dead pole windings
>
>
>the 38 degree arc formula is...
>this will determine the WIDTH of the cut made upon the rotor
>
>2 X (sqrt(R^2 - (R X .9455)^2))
>(( the .9455 = the cosine of 1/2 of the arc angle))
>
>
>
>the 40 degree is ...
>
>2 X (sqrt(R^2 - (R X .9397)^2))
>
>
>for a 38 degree cut...
>example    we have a rotor of 3" diam.    therefore the R =1.5"
>
>R squared = 2.25        (R X .9455) squared  = 2.011
>
>2.25 - 2.011 =  .23385
>
>the square root of  .2385 = .4884
>
>this multiplied by 2 = .9768" width of the cut made to the rotor
>
>
>hope this helps ...
>
>
>Scot D
>
>