ROTOR WINDING CLEARANCE
ROTOR WINDING CLEARANCE
(OP)
Clearance between rotor and windings is a mystery to me.
It appears to me that the clearances are too small for just the bearings and motor end plates to maintain properly. This is just a casual observation based on nothing specific.
I therefore suspect that magnetic field contributes to the stability of the rotor by holding it centered when rotating.
Is this correct?
It appears to me that the clearances are too small for just the bearings and motor end plates to maintain properly. This is just a casual observation based on nothing specific.
I therefore suspect that magnetic field contributes to the stability of the rotor by holding it centered when rotating.
Is this correct?
Richard Neff
Irrigation Craft





RE: ROTOR WINDING CLEARANCE
stator laminations
motor housing bore and endframe spigots
endframe bearing housings
rotor shaft
rotor laminations
- all the tolerances on these components are carefully defined so that even in the worst case tolerance build-up, the airgap is acceptable.
RE: ROTOR WINDING CLEARANCE
Here's one commonly used formula used in the motor repair industry.
Gap,inch=0.005+0.0003D+0.001L+0.003V
In which D is the stator bore diameter in inches; V is the rotor peripheral speed in thousands of feet per minute; and L is the core stack length in inches. For example, assume an 1800 rpm motor with a 10 inch bore and 8 inch stack length. The minimum gap equals 0.005+0.003+0.008+0.014, or 0.03 inch on a side.
Manufactures try to hold air gap variation to -+10% of the average or nominal value. For an integral horsepower ball bearing motor, with (for example) a 0.05" gap, that means an approximate range of 0.45" to 0.055" which is very common air gap.
For sleeve bearing motors the gap will be larger.
Hope this helps,
Kind Regards
motorhead
RE: ROTOR WINDING CLEARANCE
RE: ROTOR WINDING CLEARANCE
Rg = g / (muo x Ap)
where Ap is the surface area of the pole face and muo is the permeability of the air (free space).
If the air-gap is very small, the Ap is reduced to the effective air-gap area, Ag = Ap(t/(t+d)), where t is the rotor tooth width and d is the rotor slot width.
RE: ROTOR WINDING CLEARANCE
I will start another thread with my real question.
I had to ask that question first.
Richard Neff
Irrigation Craft