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

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Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bigfoo39-at-telocity-dot-com>

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