Model K starts, runs for 3 seconds, then motor stops - updated!

[johansen]

Run the motor from 120vac single phase with an amp clamp meter. The motor won't start and the amps will be in the 40 amp range for a 5hp motor. Rotate through all 3 phases (only 1 second needed to measure the amps) and see if the amps are significantly different. If so the motor has internal problems.

 

[dalmatiangirl61]

Thanks for the better pic! I think there are only 2 per contactor, on the left they are labeled 1 and 2, right above the wires labeled 1 & 2, the little pig tail looking things. On the right they are labeled 11 and 13, or is that T1 and T3, the round ceramic things.

Before you fiddle with those make sure L2 goes thru center tap on the contactors, if rotation is wrong swap the outside leads only. Test it, if still tripping then investigate heaters.

 

[rons]

I read elsewhere tonight that an exposed lead wire in the motor could cause this. When I pulled the motor wiring junction box cover off to check how lead wires were paired I saw one lead wire with some missing insulation. The wires are almost 60 years old so....there could be others. Maybe pulling the motor and replacing the numbered wires is in order? Is that a 'home shop' kind of job or best left to a motor rebuilder?

I replaced the lead-in wires for a 3 phase motor. That was a little more than a week ago.
Easy to do but make a diagram that marks each of the nine wires on the stator.

My motor ran fine but the wires were much worse than yours. I could see patches of green copper where insulation used to be.
At the lead-in connection your wires will probably be brazed to the stator wires. I decide not to bring a torch so close to the wiring
so I didn't braze. I used a hex barrel crimp between the stator and lead-in wires and then flowed solder. Cover with shrink tubing.
Of course you have to label the wires.

 

[tx656]

Run the motor from 120vac single phase with an amp clamp meter. The motor won't start and the amps will be in the 40 amp range for a 5hp motor. Rotate through all 3 phases (only 1 second needed to measure the amps) and see if the amps are significantly different. If so the motor has internal problems

I just tried this. First I just disconnected T2 and T3 from L2 and L1 and tried the Monarch 'FWD' switch. Nothing. No hum, no buz, no sound.

Next I flipped the L1 L2 L3 switch that feeds the machine 'off'. Then I bypassed the coils, the heaters, and whatever else is in that box by directly wiring T1 to L1. (T2 and T3 are still disconnected). With the clamp meter in place I flipped the the disconnect switch 'on'...and nothing. No pop, no hum, no buzz. I'm guessing I 'cooked' something pretty good in the motor yesterday when it ran for 6-8 seconds (resulting in the popped circuit breaker that feeds my RPC at the main).

Thanks for all the help and idea guys. I'm going to pull the motor etc this afternoon and get it into a shop.

 

[tx656]

Agree that the advice was to wire a leg of 120 directly to the motor. By bypassing the Furnas box and having an L1 that was ‘hot’…(and wired directly to the motor) as soon as I flipped on the disconnect…isn’t that what I effectively did?

 

[tx656]

Pulled motor out.





There was geological swarf behind the Furnas box. Given where the box was in relation to the chuck...not sure how it got there!



Ready for a trip to a motor shop.


I'll post with any updates.

 

[tx656]

A neighbor recommended a motor shop about a half hour south of me. Took them a week or so to get around to testing it. They said it was 'bad'. I considered a rewind. They said MINIMUM $900 (but expect more). I got the feeling it would be closer to $2,000. No charge for the checkout. They didn't seem excited about finding a replacement motor to sell me.

First I needed to figure out what to buy. Came across this very good explanation of the NEMA motor coding.

https://www.surpluscenter.com/images/techhelp/nema2.pdf

The old motor is a '215' but has a non-standard 1 1/8" shaft. The new standard for '215' is 1 3/8" shaft. After a brief search a used one turned up near Austin, TX (I'm going to call that Providence). After some 'offer/counter offer' on ebay I got it for $140 plus shipping. Shipping was $100+ but it saved me a 7 hour round trip. Arrived in 2 days in great condition. Very well packed. Random observation. Everything I have bought used online related to machining has been VERY WELL packed. The custom packaging for an 8" chuck I bought was a work of art!



I had to buy an 8" gear puller to swap the pulley over to the new motor. (Was surprised I didn't have an 8" in the drawer). I pulled the fan cover off so I could put the shaft directly on a metal plate when installing the pulley on the replacement motor.

After I had the pulley off I decided to pull the cover on the motor to see if I could spot burned wires, etc. No burned wires but I did find this.



I hate mice.



I hooked up the replacement motor to my test stand. Sounded good!



The base plate was nasty. So I pulled that out to clean up. Not the easiest job. The pins that hold it in had been in a while.



Then it was time to test fit the new motor.



Well that's a problem. Motor connection box is on opposite side of where it was on the old motor.

The replacement motor would need to mount 1"+ to the right of where the original motor was. After getting it square/where I wanted it I marked the position it with spray primer. That's my favorite way to mark hole like this.


I have no idea why there are other holes tapped in this base plate. The motor I pulled out sure seemed like it was the original motor. It matches the motor data plate located in the belt housing. Oh well, it won't keep me awake at night.



Some hole drilling on the Wells Index 745 followed by some tapping (with the set my father bought me over 30 years ago).



Then it was time to test fit with the innermost belt. Came out great.



The disconnect switch box and the motor contacts box were nasty. I spent too many hours working on cleaning those up with the purple stuff. So much better working with 'clean' parts. Today I reinstalled all of the electrics and tested the motor/forward/reverse. Belts were slapping so tightened those up. No oil in head stock so only ran a SHORT time. It works!!!!

Next step is to pull out the oil pump and test/clean it. I'm wondering how I'll verify the oil pump is supplying all of the lines/the lines are clear. If I can't figure that out it will be a separate post.

Thank you everyone for all of the advice.

 

[4GSR]

Kind of late to reply to the thread. I have a spare 5HP 1750RPM 3-phase motor here that could have saved you some time and money on shipping. Oh well, glad you got it running. I picked up a bunch of surplus motors from HGR's Ft Worth warehouse a while back. I bet they still have motors in stock too!