Phases and rotor repair


Old 12-12-13, 05:27 AM
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Phases and rotor repair

Generator is Devilbiss GBV7000 with a B+S 14hp motor.
Problem: The insulator on the rotor broke and the winding came in contact and shorted to rotor shaft. Generator only puts out 120Vac. The shorted winding read 0 ohms to shaft. I unwound the wire repaired insulation and then rewound the rotor winding coil. With the rear cover removed I read 120vac between the green and red wire and also beteween the black and orange wire I have 120vac. So far so good two seperate 120VAC sources. The 2 phases only measure 18-20vac to each other. The 2 diodes on the rotor are good.

Question Is it possible that I wrapped the rotor winding in the wrong direction CW vs CCW?
I did try reversing the diode on repaired winding and voltage dropped to 60vac.
Correction from above with the diode reversed the stator windings read frem green to red 10vac and orange to black 10vac. I have since soldered diode back in with original polarity and now am back to 120vac on both stator windings.
It appears as if the two legs of 120vac are in phase with each other thus when one is high the other is also rather then at the low and thus the low reading from phase to phase. Would winding it in opposite direction cause the phase to invert and make the peak to peak voltage read 240? Im really at a loss and just guessing at this point.

Last edited by scandle; 12-12-13 at 06:29 AM.
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Old 12-12-13, 09:06 AM
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Ok, during my repair I wrapped the wire in a clockwise direction. The other winding on the rotor is CCW so I have unwrapped the wire and rewound the coil in a CCW direction. I applied some epoxy cement to the wire for security and when it dries I'll post back any positive results otherwise im throwing in the towel.
steve out
Old 12-12-13, 08:20 PM
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The direction it is wound would definitely cause a change in the output. I'm not an expert in that department, but I think you're on the right track. I have done some winding repairs on motors that are very expensive or very difficult to replace, and it can get tricky.

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