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Modular 10EE reversing under load.

9100

Diamond
Joined
Nov 1, 2004
Location
Webster Groves, MO
A modular 10EE with a 5 hp GE motor I look after needed a brush replaced, which we did with only minor trauma. Now as you bring the speed up running forward, it suddenly reverses, going to a similar speed in reverse. Naturally the tach doesn't work so that is an estimate. Turning the speed control down reduces that speed and around 500 RPM it switches back to forward. We had the motor pulled most of the way out of the base for other maintenance and I concluded that the mechanic who did it got the series field wires reversed, which is known to produce such behavior. Possibly the worn brush wouldn't pass enough current to cause reversal and it didn't show up before. I left the mechanic with instructions to switch S1 and S2. The customer called to say that it still malfunctioned.

I will go back in the morning but meanwhile, does anyone have a suggestion?

Bill
 
The guy got the brush on backwards. I didn't think to mention it since most motors have brushes that can only be put in one way. That seriously retimed the brush. Fortunately it was the top brush so switching it was easy. Works fine now.

The assembly mounts by the tab on the upper right. The jiggle in it aligns it but it can fit 180 degrees out.

Bill.

IMG_2870.JPG
 
LOL! Make anything Ijut resistant, Lybarger's Corollary swaps-in a bright guy, with his head in temporary rectal defilade, and yer screwed, anyway!

DAMHIKT, either... Oh, well. Didja know a large-frame Reliance 3HP will run on but 3 brushes if yah pulled one to go measure, lookup, and order new ones? Mind, that's really only on two, but it can cornfuse the eye..

:)

Sure, it will run on two if you pick the right two, but at reduced power. The armature is being energized four times per revolution, twice positive and twice negative. Note also that the brushes are not exactly 90 degrees apart, producing slightly smoother torque.

Bill
 








 
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