That's very clever, syncing the motor speed to the power-line frequency!
My hunch is that you're seeing the variable-reluctance motor controller working to keep the motor torque relatively constant as the motor rotates through it's various pole positions. Variable Reluctance motors are basically stepper motors. Which means that they are simple, rugged, and inexpensive motors, but they require a very sophisticated motor controller in order to run both smoothly and efficiently. This Wikipedia article has a good overview.
VR motors inherently have high torque ripple, meaning that the torque you get from a given winding current varies greatly depending on the rotor position. A sophisticated controller, given rotor-position feedback, can largely compensate for the nonlinear torque curve by varying the winding-current magnitude as a function of the instantaneous motor-pole alignment. I can see that explaining the power-supply input current waveform you measured.
But I don't now why one of the eight current cycles (per motor revolution) would be different from the others.
PowerPro Input Power
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- BuckeyeDennis
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Re: PowerPro Input Power
Last edited by BuckeyeDennis on Fri Jul 23, 2021 6:38 pm, edited 2 times in total.
- JPG
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Re: PowerPro Input Power
What is the motor pulley to idler pulley ratio? 8 : 3 ???
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
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Goldie(Bought New SN 377425)/4" jointer/6" beltsander/12" planer/stripsander/bandsaw/powerstation /Scroll saw/Jig saw /Craftsman 10" ras/Craftsman 6" thicknessplaner/ Dayton10"tablesaw(restoredfromneighborstrashpile)/ Mark VII restoration in 'progress'/ 10E[/size](SN E3779) restoration in progress, a 510 on the back burner and a growing pile of items to be eventually returned to useful life. - aka Red Grange
Re: PowerPro Input Power
My measurements are a little crude as I didn't take anything out. But yes. I measured 3-1/8 and 1.176. I suspect they are metric, 80 and 30 mm. Far as I know the idler is same as conventional to maintain upper : lower shaft ratio.
- David