Drill Press Motor Repair Help

[John Hasler]

I did some measuring on MOTOR 2, the 3 phase motor. These seemed more encouraging. All wires to the chassis were in the Mega ohm range resistance measurements for delta wiring. 3,5,9 to 1,6,7 - 5.1 ohms 3,5,9 to 2,4,8 - 5.3 ohms 1,6,7 to 2,4,8 - 5.3 ohms resistance measurements for Y wiring 3,9 to 2,8 - 10.8 ohms 3,9 to 1,7 - 10.5 ohms 2,8 to 1,7 - 10.5 ohms just for giggles I measures from 4,5,6 to the three legs and they all measured 7 ohms. i am "pretty sure" I ran it delta when it was pulling too much current. Should I try it Y?

Yes. Take a look at these drawings: http://www.electricmotorshop.net/home/?option=com_content&view=article&id=683&Itemid=340 Does the motor have a connection table on it anywhere? Sometimes it's on the inside of the junction box cover.

 

[videotrack]

I did some measuring on MOTOR 2, the 3 phase motor. These seemed more encouraging.

All wires to the chassis were in the Mega ohm range

resistance measurements for delta wiring.
3,5,9 to 1,6,7 - 5.1 ohms
3,5,9 to 2,4,8 - 5.3 ohms
1,6,7 to 2,4,8 - 5.3 ohms

resistance measurements for Y wiring
3,9 to 2,8 - 10.8 ohms
3,9 to 1,7 - 10.5 ohms
2,8 to 1,7 - 10.5 ohms
just for giggles I measures from 4,5,6 to the three legs and they all measured 7 ohms.


i am "pretty sure" I ran it delta when it was pulling too much current. Should I try it Y?

Usually the motor will show if it is supposed to run Delta or Star, with either a triangle or Y symbol on the faceplate. Some motors are required to have a Star-Delta starter for starting, but 3HP is a little light-on for that being a mandatory requirement. The motor will draw less current and produce less HP in Star, but I would definitely try that.

- - - Updated - - -

No burnt smell, but there is only 1.1 ohms between the power terminals. I measured that without the capacitor hooked up.

The motor should be able to be manually started (e.g. by spinning the shaft with power applied), even if the start winding or capacitor were faulty.

The fact that it won't do this, and that the run windings have continuity, is an indicator of shorted turns.

A good few people have provided a number of worthwhile ideas for testing, checking, and none of these have lead to a resolution. Unfortunately, I would look at replacing the motor...

 

[Tutt]

I wired up the motor with the Y scheme and it worked perfectly! I couldn't get it to pull the rated current no matter how hard I pushed the drill press. The motor barely got noticeably warm to the touch.

i remember looking for a delta or y on the name plate. I never could find anything. Now that I look again the frame is "56y". Is that the designation or just a coincidence? I figured that was just for the dimensions of the motor.

i agree that we have thoroughly trouble-shot the single phase motor and it's time to find a replacement.

Thanks again guys!!! I learned a lot!

 

[videotrack]

I wired up the motor with the Y scheme and it worked perfectly! I couldn't get it to pull the rated current no matter how hard I pushed the drill press. The motor barely got noticeably warm to the touch.

i remember looking for a delta or y on the name plate. I never could find anything. Now that I look again the frame is "56y". Is that the designation or just a coincidence? I figured that was just for the dimensions of the motor.

i agree that we have thoroughly trouble-shot the single phase motor and it's time to find a replacement.

Thanks again guys!!! I learned a lot!

The “Y” that is shown as a part of the frame size generally means that the motor has a special mounting configuration. It's not usually an indicator of Star connection. But if it works as Star then you've solved your problem (well one of them, anyway)

Incidentally, is the center-line of the motor shaft 3.5" from the base of the motor, and the shaft is 5/8" dia? They are often values that 56 frame size motors use.