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About Charles C. Jones
Expertise
Let Me help you with your problems with single phase and three phase electric motors. I can tell you how to troubleshoot your motor problems. From simple testing of capacitors, how to test your windings, replacing bearings, and general maintance. Before we go any further, remember these words of advice: Disconnect the power before you do anything! Please limit your questions to electric motors and there immediate components. I review each question, and if I can answer or help, then I will. If you receive a rejection, it means it is out of my expertise, and just do not have the answer. I'll be waiting for your question, and see if I can help you. Thanks for using AllExperts!

Experience
I have 30 years experience in the repair of electric motors and related equipment. I am a master machinist in the field of motor repair. I have been employed with my company for 27 years. When you ask your question, give me all the information you can about your problem. I have a lots more to add, but for the everyday do-it yourself kinda person, it might get to technical. So ask away, if I can't give you a good answer, I'll find someone who can

You are here: Experts > Industry > Electric Power/Utilities > Electric Power & Utilities > wiring a 220 volt Doerr motor

Electric Power & Utilities - wiring a 220 volt Doerr motor

Expert: Charles C. Jones - 11/3/2009

Question
QUESTION: I was given a Doerr motor to replace the 3-phase motor on an
old engine lathe (Sheldon) that I just bought. The problem is that there is no wiring diagram on the motor. The specs. on the plate are: 1/2 HP, single phase, 230 volt, 6.0 amp, 850 RPM.
Other numbers on the plate are 74481EL891 and 262-474C1. The wires are labeled T1, T3, T5, T8, T9. That's all the info I have!
Can you tell me how to hook up these wires?
The lathe has an Allen Bradley FWD-REV drum switch that has a diagram. I think I can figure this out if I know what the motor
leads are.
Thanks!

ANSWER: Les, all I can supply is this NEMA standard wiring diagram,

http://farm1.static.flickr.com/114/253735324_c7d4920bc5_o.jpg

I do not understand why they have a number T3 and T9 brought out from the winding. For a single voltage 230 volt motor, it should be T1-T5 L1, and T4-T8 L2. I would really need to see the motor so I could trace the leads.

Another thing that puzzles me is why you have such a low rpm motor. As I am a machinist, such a low rpm motor is usually seen on large boring machines an large mills. I have two large lathes and one small lathe in my shop, and all these are equipped with 1800 rpm motors.

---------- FOLLOW-UP ----------

QUESTION: The NEMA diagram doesn't explain the wires that I have. I took the motor apart and here is what I found:
T1 and T5 go to the windings at the same location. (They may be joined at that point.#
T8 goes to the capacitor. #There are two.)
T9 goes to one side of the reset button.
T3 goes to the other side of the reset button.
An internal wire, T12 goes from the capacitor to the contacts on what appears to be the thermal protection system.
An un-marked wire goes from the thermal protection to the windings.
An internal wire, T11 runs from the capacitor to the windings at the same point as the as the un-marked wire.
Internal T4 appears to be attached to T3 at the reset button and then runs to the same spot on the windings as the above two.
Can you translate this info what leads should be used to make L1 and L2?
Is there a neutral wire needed or just L1 and L2?

The original 3-phase motor was 1150 RPM. This motor is a "freebie" from a friend and he got it from a third party. It's origin was a commercial washing machine, big and heavy with a 7/8 in. shaft. It appears to be re-conditioned - new paint and clean as new on the inside. I will have to work with the pulleys to get the original lathe speeds.

Thanks a lot for your help!

Les

Answer
I have been away this weekend, but I haven't forgot you. I will try to have a answer for you this evening, if I can figure it out.

After making a drawing of the data you gave, here is my best and only guess. Make T1 and T5 L1. Make T9 and T8 L2. Insulate T3. Here is the reason for my answer. T1 and T4 are the ends of the main or run winding. T5 and T8 are the ends of the start windings. What you called a thermal protector is actually a stationary switch, which takes the start winding out of circuit after the motor reaches operating speed. If, as you say, T3 is connected to T4 on one side of the reset, then using it as a line would bypass the reset button. You do not need a neutral, just connect the lines from the lathe switch to the connections above. But do make sure the ground is connected to the frame of the motor.

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