1957 115v motor draws massive current 1

[No Poke]

OK, I've found an old motor to put in a carpentry jointer. Really old. The previous one wasn't suitable so I picked this one up. Likely a GE but who knows? Anyway I honestly don't remember if I test ran the thing when I got it but I THINK I did. I found it needed bearings so I bought and installed them. It rolls over beautifully. It absolutely jumps to life though, gets really hot and pops the 15a breaker in about 30 seconds. It's drawing 54 amps! When I first took the wires off the terminals I identified them with silver ink rings around the ends and numbered the posts. I can't think I got that wrong. You guys that are good with these old things may know where in the field the wires come from by their colour. This motor has no brushes and a large capacitor on the top.

What I'm expecting to hear is that I've got a short in the field and all is lost but one never knows. You see from the tack that it's turning an appropriate 3,200 - 3,300 RPM.

Thanks for any help.

 

[waross]

Shorted capacitor?
Possibly leading to a start winding burnout.

 

[edison123]

You need the right capacitor and the right input volts of 110 V, 60 Hz. I don't see a capacitor.

Great ammeter. We don't get such 330 deg meters anymore.

 

[No Poke]

The original capacitor is on the top of the motor, out of the shot. It's there. That's actually my old Smith's tachometer you see, not an ammeter. I'm using a Fluke meter. Yes Waross, that's certainly a possiblity.

 

[jraef]

Most likely degraded insulation and shorted turns. A bad cap generally means it doesn’t start turning, it will just sit there and vibrate back and forth until something trips. Shorted windings, especially turn-to-turn, means less impedance and thereby higher current. If you have a Megger, you can do a few tests, or take it to a motor shop. But it’s likely going to cost you more to fix it than to just replace it.

Craftsman motors were made by Emerson Electric.

 

[waross]

Shorted windings, especially turn-to-turn, means less impedance and thereby higher current.

This is not a linear effect.
That is, 10% of the windings does not mean 10% less impedance and approximately 10% higher current.
The shorted windings act as a short circuited transformer winding.
The current is much more than an additional 10%.
The current through the shorted windings is excessive and the heat generated is excessive.
Complete failure may be expected in minutes or less.

 

[No Poke]

Thanks Gents. I try to carefully choose what I spend my time on and monkeying around with a motor that was born before I was is a bit over the top. Especially when I have another jointer in the shop that just needs a spit and polish. Perhaps I could make a lamp base out of it. My wife would absolutely love that.

This is a great forum, I must say.

 

[No Poke]

So, I changed my mind and decided to fix the motor. I'm tracking down the short in the field and after watching a bunch of YouTube videos on electric motor repair I must say I feel very optimistic.

 

[LittleInch]

after watching a bunch of YouTube videos on electric motor repair I must say I feel very optimistic.

Really?

 

[waross]

I feel very optimistic.

I think that the word that you intended is spelled "Pessimistic".

 

[stevenal]

Star, like, and upvote for No Poke. Thanks for the laugh.