Factory/dealer screwup

[Joethemechanic]

They often are not good enough to prevent motor damage if the motor is running when you lose a phase. This is especially true when the motor is operated at its service factor horsepower....a practice done by some air compressor manufacturers to permit them to use a small motor than they really should.

However some newer electronic overloads have phase loss built in. If they installed a separate phase loss relay, I can only assume that their overloads do not have that function.

With the old school heaters in the magnetic motor starters I never had a problem burning up a running motor losing a phase. Current would increase on the remaining two and trip out. I can't say that since adjustable overloads have become common. Too many people jacking up the overloads so it becomes the next shift's problem

 

[don_resqcapt19]

With the old school heaters in the magnetic motor starters I never had a problem burning up a running motor losing a phase. Current would increase on the remaining two and trip out. I can't say that since adjustable overloads have become common. Too many people jacking up the overloads so it becomes the next shift's problem

Have seen that exact thing happen many times with that type of equipment.

 

[Joethemechanic]

I did have a pump station one time that blew a primary on the poco side. I think the big pump was 250 HP 4160 volt. It was running and generating a false/weak 3rd phase. They lost some smaller 480v 3 phase motors. I can see it helping in that situation

 

[retirede]

Have seen that exact thing happen many times with that type of equipment.

If one of our larger plant compressors with eutectic alloy overloads lost a phase under any significant load, it would fry the motor every time.

 

[ptonsparky]

A

If one of our larger plant compressors with eutectic alloy overloads lost a phase under any significant load, it would fry the motor every time.

Pretty much what I found with irrigation well motors. Running into SFA with overloads sized to not trip. The area well guys sold 100 HP motors, not Motor Savers. Wonder why.

 

[Jraef]

These are powered off the line voltage, haven’t seen any like these before. Usually the electronic ones are powered by the current flowing through them. Apparently this is an issue with this manufacturer, they knew exactly what happened.

Yeah, if the control power for the SSOL was tapped off of the line, and the line voltage doubled, that would cause a RUDE (Rapid Uncontrolled Disassembly Event).