Have a bench grinder that was given to me and runs fine if you spin it up by hand - the capacitor is missing. Is there a way to determine what size/part no. capacitor will work with a 115V 60Hz Single Phase motor?
Thanks in advance.
HP?
3/4 HP, 3600 RPM
Likely a motor start capacitor.
CDE motor start capacitor catalog page (download this - right mouse click - Adobe Acrobat)
I am looking at a NOS Mallory motor start capacitor on my bench -- it is rated at: 108-130 mfd at 250 VAC
Application Guide
gb
If it's used only for starting.
Easiest test would be to spin it up by hand and then use a multimeter to check for voltage across the wires where the cap would go. If you see full line voltage, it's a run cap.
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Sam Goldwasser wrote in news: snipped-for-privacy@plus.seas.upenn.edu:
Most bench grinders I've seen use a motor run capacitor.
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But if he has to spin it to start it, that would imply it's just a starting capacitor. Can you hear an audible click as it picks up speed and again just as it slows to a stop?
Do you have a mfg. or model number for this bench grinder?
gb
No, a split phase induction motor with an open or missing cap will not start regardless of whether it is a start or run cap. Spinning by hand will get it going (assuming minimal load).
An induction motor designed to have a run cap will still run without one if started manually but won't have rated torque.
An induction motor designed to have a start cap will still run without one if started manually and will have rated torque.
The main functional difference is that the start cap is not rated for continuous operation and is removed from the circuit once the motor reaches about 75 percent of operating speed.
--- sam | Sci.Electronics.Repair FAQ:
Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.
"w9gb" wrote in news:xdqdnezDzPPH0gXYnZ2dnUVZ snipped-for-privacy@comcast.com:
Central Machinery Industrial #36127
Central Machinery Industrial #36127 is what it says on the label.
Hope this doesn't end up getting posted 3 times - having trouble sending....
Central Machinery Industrial #36127
Central Machinery is sold by Harbor Freight Tools, Inc. They may still have the manual on file.
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