Internal overload single phase euro motor

[BHolcombe]

I have an SCM bandsaw with a 5hp single phase motor on it. Recently it’s simply dead when attempting to run it.

I opened the peckerhead and checked the motor leads with the switch ‘on’. I have 120v at both leads.

The motor does not make a buzzing or humming, I get nothing at all.

The capacitors are good and for posterity I swapped them to other new capacitors and the same result.

Any thoughts on what could be the issue?

 

[Peter from Holland]

Does it smell burned??

 

[BHolcombe]

Hi Peter, it does not smelled burned and last I ran it, it ran fine and did not quit unexpectedly.

I checked resistance across the terminals and got 0.7 ohms

I checked to ground and it shows OL which was good news.

 

[rons]

Time to take the end covers on the motor. Inspect your start mechanism.
Or take a picture.

 

[JST]

Is there a "reset" button anywhere on it? Typically on an end bell, but maybe elsewhere.

 

[BHolcombe]

Couldn’t find one, I may take it apart and check the start mechanism out. I’m planning to move to 3ph but it is handy to have some sort of backup.

 

[JST]

There are three types of internal overload protection that are reasonably common.

1) a thermal breaker with a visible reset button. Those are easy.

2) a self-resetting thermal breaker buried in the windings. These trip at a set temperature, and reclose after the temperature goes down to perhaps 20C below the trip temperature. You will think it is dead, but later it is OK again when it has cooled. They typically are good for only a few full-load trips before they fail open, so you do need to figure out the problem soon. These are usually a small rectangular thing perhaps 10 x 25 mm x 4mm thick, or smaller, with wires attached at one end.

3) A non-resetting thermal breaker buried in the windings. As it sounds, the breaker is permanently open after it trips. These are typically only in small "disposable" consumer motors and transformers, but may be found elsewhere. They are usually a small cylindrical device perhaps 5 or 6 mm diameter, flat at one end and pointy at the other, with a wire from the middle of each end.

When I say "buried" in the windings, they may be simply wrapped in insulation and poked in between windings, so that they are accessible, or in some cases may be actually invisible under layers of winding.

 

[BHolcombe]

Thank you!