Electric Motors/motor wiring


Hi:  I have a vintage 1940's Delta triple duty ball bearing bench grinder. 110V, single phase, 3450RPM, 6.6AMP, 1/2HP, type SS, 60 cyl, Frame 165, Temp rise 55C.  It was running great when I decided to let a friend in the restoration field restore it. It came back looking like new, but will not run. It spins freely when disconnected from power, but when powered up, it just hums, but the shaft will not spin, even if spun by hand to give it a "kick start", it will not spin on its own. The restorer is not sure that he connected the wires the way they were originally (apparently he did not label them). There are 4 wires coming from the motor, 2 large white wires and 2 smaller tan wires. The 2 larger wires run through a "contact switch" inside the cover, and the 2 smaller wires come from the windings. I would like to know how the wires should be properly connected to the incoming hot and ground voltage wires. Any help would be greatly appreciated. Thank you.

use an ihm meter and check the circuits and the resistance. The circuit with higher resistance is the start winding. one end should go thru the starting contacts.
Then on the outside the run and starts are paralleled.
see generic dwg. IDisreard cap if yours doesnt have one.

Electric Motors

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Harcharan Singh Diocee


Electric motor winding redesign, AC and DC. Troubleshooting, motors controls generators. Vibration analysis, dynamic balancing, root cause analysis: electrical and mechanical.


thirty five years electro-mechanical and Senior Management


Journeyman Motor Rewinder, Millwright, Industrial Electrician, Vibration Analyst level II. Certified Electrical Technician ASTTBC, FSR Class B, in BC. Laser alignment specialist. Marine machinery repairs. Business Management Certificate. Last 19 yrs as Plant Manager

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