Sorry if I'm in the wrong site entirely, but motors do have circuits, just not electronic ones.
A clothes washer motor spins the tub normally with a very small load but full size loads cause thermal overload which trips cutoff. The room lights dim continually (not just at motor start) and the motor starts to smell before cutoff. The motor is about 40 yrs old.
I find nothing abnormal in mechanical parts (bearings, belts, etc.)
What do you think is happening here, an intermittent short in a winding perhaps? Or could it be that the line supply voltage is dropping excessively?
Help very much appreciated!
Thank you!
Frank

 

Have you examined the motor itself, motor bearings etc?
It certainly sound as though it could be wear, especially at that age of machine.
Could even be in the gear-box.
Max.

 

Have you examined the motor itself, motor bearings etc?
It certainly sound as though it could be wear, especially at that age of machine.
Could even be in the gear-box.
Max.

I have looked for sources of abnormal friction. The motor bearings and the main bearing that supports the shaft that goes to the tub, as well as the bearing on the discharge pump all seem fine. You can spin the tub easily by hand. What do you think of the intermittent winding short theory where the short occurs only during heavy load? Thank you for your time.

 

If the motor noticeably dims the lights then there is a problem with your power supply.

 

the motor starts to smell before cutoff.

Have you checked the wiring and its terminations for signs of overheating?
Is the belt tension correct?

 

If the motor noticeably dims the lights then there is a problem with your power supply.

In my house it has not been uncommon for some motors (e.g. capacitor start) to dim lights slightly on start when working properly. I will today be checking line voltage and current with Kill-a-Watt when motor runs.

 

Have you checked the wiring and its terminations for signs of overheating?
Is the belt tension correct?

Motor windings? Which terminations? As you may know, old washers have the motor mounted on a spring-loaded carriage that governs belt tension. The belt is intended to slip when the motor starts with a full tub. Drain occurs simultaneously and tub turns faster (as belt grabs more) as tub empties. Belt has not been changed and the carriage is sliding correctly.

 

This is one of those cases where to properly troubleshoot the problem, you do require a clamp current meter.

I repaired clothes washers during my college days, to have some extra spending money. That was in the mid to late 1970s, so your washer design would be contemporary.
I can tell you that bushings start to seize as they warm up and/or under load. First intermittently, then fully.

Your motor current will be normal during the first couple of minutes, then you would see spikes.

Or you could have an internal winding short.

Either way, the current would spike.
The only way to see this issue is with a clamp probe, specially one that has in addition to normal digital readout, an instantaneous reading bargraph.

Beg, borrow or purchase a clamp probe.

 

Motor windings? Which terminations?

The wiring and terminations of the cable leading to the motor.

 

This is one of those cases where to properly troubleshoot the problem, you do require a clamp current meter.

I repaired clothes washers during my college days, to have some extra spending money. That was in the mid to late 1970s, so your washer design would be contemporary.
I can tell you that bushings start to seize as they warm up and/or under load. First intermittently, then fully.

Your motor current will be normal during the first couple of minutes, then you would see spikes.

Or you could have an internal winding short.

Either way, the current would spike.
The only way to see this issue is with a clamp probe, specially one that has in addition to normal digital readout, an instantaneous reading bargraph.

Beg, borrow or purchase a clamp probe.

I'm very sorry to have troubled you guys. I should have checked the line voltage first. An old hair dryer (1675 watts) pulls the voltage in all outlets down to between 95-105. At line input to the house, without load I have 115v. With dryer load, it drops to 95-105 at the source as well. One good thing: I know the problem is not in a branch circuit!
So it apparently had nothing to do with the washer. Does everything I've told you make sense?
Again thank you all so much for your time and great ideas! I would think this might be traced to a bad neutral outside the house. Frank

 

I'm very sorry to have troubled you guys. I should have checked the line voltage first. An old hair dryer (1675 watts) pulls the voltage in all outlets down to between 95-105. At line input to the house, without load I have 115v. With dryer load, it drops to 95-105 at the source as well. One good thing: I know the problem is not in a branch circuit!
So it apparently had nothing to do with the washer. Does everything I've told you make sense?
Again thank you all so much for your time and great ideas! I would think this might be traced to a bad neutral outside the house. Frank

BTW, special thanks to Albert Hall who had it right!

 

If the motor noticeably dims the lights then there is a problem with your power supply.

True indeed! Use a voltage meter and monitor the supply line voltage at the outlet because you may have a problem in the external power wiring.
To check the motor, first disconnect the power by unplugging the dryer, and then measure the resistance from the motor connections to the motor frame. They should all be either an open circuit or a very high value, at least one megohm. If not, and the value is just a few ohms, the motor has failed.

 

True indeed! Use a voltage meter and monitor the supply line voltage at the outlet because you may have a problem in the external power wiring.
To check the motor, first disconnect the power by unplugging the dryer, and then measure the resistance from the motor connections to the motor frame. They should all be either an open circuit or a very high value, at least one megohm. If not, and the value is just a few ohms, the motor has failed.

I will use your motor test the next time I have an issue. National Grid found a bad neutral at the meter. Ironically, I had the same problem at my summer house, attributed to the salt. I didn't put the two together right away because I figured lightening couldn't strike twice. I'm 76. Is it possible I could see another bad neutral in my lifetime???
I haven't run the washer yet- will report back tomorrow.
Thanks again Al!
Frank

 

Sometimes very useful is to make the oscillogram for motor current. If there is minor shorted turn in stator, there will be sudden jump in the current at certain Voltage. If it is collector motor, You will clearly see if the single bobbin is damaged. If the async have somewhere "eternal" You shall see even that by asymmetry. If there will be some mechanical problem, current will syncing with rpm.

 

I will use your motor test the next time I have an issue. National Grid found a bad neutral at the meter. Ironically, I had the same problem at my summer house, attributed to the salt. I didn't put the two together right away because I figured lightening couldn't strike twice. I'm 76. Is it possible I could see another bad neutral in my lifetime???
I haven't run the washer yet- will report back tomorrow.
Thanks again Al!
Frank

"Bad Neutral", and failing mains supply connections are not respectors of history at all. I have come across both more than a few times. And salt-laden air is always a bad actor for electrical systems. The voltage check is simple and easy enough that it can be done by almost anybody competent to use a voltmeter. And it is safe enough that I do not hesitate to suggest it.

 

Sometimes very useful is to make the oscillogram for motor current. If there is minor shorted turn in stator, there will be sudden jump in the current at certain Voltage. If it is collector motor, You will clearly see if the single bobbin is damaged. If the async have somewhere "eternal" You shall see even that by asymmetry. If there will be some mechanical problem, current will syncing with rpm.

Sorry not to have replied sooner. The washer does run perfectly now. And thanks again to everyone! Frank

 

Indeed! Conditions that attack connections often lead to repeated faults being created. There are commercially available anti-corrosion compounds available and they do help if they are correctly applied.