Dear Motorland...
I'm running into an issue with a AC induction 300h/600rpm motor for a hoist. I'm getting a HIGH 2X line frequency with pole pass frequency side bands. Is there any info out there on airgap tolerences? The rotor currently has .0045 at the top and .0025 at the bottom. I'm hearing there is no line drawn in the sand on this.
Cary Weaver IR Analyzer Thermology L3 DoUseeGeen
Cary, air gap tolerance is manufacturer and motor specific. Static air gap and dynamic air gap will differ because of the magnetic torques on the rotor keeping it, or trying to move it into magnetic center. I recommend that you contact the manufacturer for the static tolerance or perform a current signature test analyzing for eccentricity. You would be looking for 4 peaks 120hz apart centered on the rotor bar pass frequency, (rpm x number of rotor bars.) If no peaks are present then your air gap should be ok.