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South Bend Heavy 10 - Motor Problem / Question

Ilon

Plastic
Joined
Jun 1, 2022
I have a recently purchased SB Heavy 10 (1965 era) that I purchased from someone who got it from someone, etc. Its in great shape, and has apparently been restored recently. It runs really well with one exception, the motor, which appears to be new, is really running hot. All of the wires from the motor are the same color black, and everything in the switch is black. How do I begin to track down if my new motor is wired correctly? My electrical skills are almost nill. Ideas and advice is appreciated.
 

Roger Best

Plastic
Joined
Dec 31, 2020
Why would it be wiring? A local wiring defect should give a localised hot spot, or the motor shouldn't run. Happy to have someone explain starting capacitors to me on this point and other technicalities. I recall they can be a nightmare.
I suggest you check that the machine turns freely, its well engineered so apart from accelerating its considerable inertia it should go round with very little effort. If its stiff the motor is over-working.
If you get no-where despite the advice you will receive don't be afraid to get an expensive machine tool electrician in, he can check your insulation and earthing and make sure the machine is safe.
Good luck.
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
1) how hot is "really hot?" Get an IR thermometer and check it.
2) this is a TEFC motor - totally enclosed, fan cooled. Is there anthing obstructing the airflow over it?
3) unless it's been re-wired by a former owner, the black wires probably have numbers in the insulation. Look close.
4) the motor is "thermally protected" and will shut itself off it it gets too hot. Not sure what the overtemp point is for this.

Many motors are rated to run at 80 degrees C, which is WAY too hot to leave your hand on for even a moment.
 

Dobermann

Hot Rolled
Joined
Jan 2, 2014
Location
North Carolina
The real issue is how much current is it drawing during normal operation. Without that information you have no basis on which to decide if it's being overloaded. Besides, most modern motors are designed to operate at full load with a temperature so high you can't really put your hands on it. So....how much current does it draw (each phase) and what is the motor shell temperature. Without that information you can't really make any judgement.
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
It's a single phase motor. And if he uses an amp-clamp to measure the current it will give the wrong answer when he computes the power being disssipated in the motor for calculating heating issues.

A proper measurement of the motor temp is indeed called for.
 

Dobermann

Hot Rolled
Joined
Jan 2, 2014
Location
North Carolina
He doesn't need to calculate anything. All that's required is to determine if the line current is greater than, less than, or the same as the rated nameplate current for the motor. If it's less than the nameplate currents, either full load or full load plus 1.15 service factor, then the motor should not be overheating--and here we mean overheating relative to the design spec's of the motor. Then the next question is what's the actual shell temperature of the motor? Many can run happily at 120F to 140F or even higher if equipped with the right winding insulation. You can't put your hand on that temperature for very long.

If the line currents are too high then the motor is either overloaded or the line voltage is too low.

But we need the numbers!
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
You can't leave your hand on an 80 C motor housing for very long! My point was an amp clamp meter will read full nameplate current even when the motor is just idling.
 








 
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