Overload relay does not trip and burns the motor ABB AX09

[lemonginger]

A friend of mine has a factory in Southeast Asia and was complaining that one of the motors at his factory keeps burning and had to fix the motor because the overload relay/breaker does not trip. His factory is 5 hours away from the main city and so getting a qualified electrician takes sometimes. And I also wanted to make sure I understand what the situation is before someone gives us wrong quote. I took some pictures to show you all what type of breakers/relays and motors are being used. I see that there is a setting dial set at 1.3. It looks like the size of the motor is small, 0.55kw. Is the breaker/relay too big for the motor? Is that why the relay does not trip? Any suggestions would be appreciated because I hate to see him keep fixing and replacing the motor. Where and how should the relay be set at? Thank you all!

ABB AX09
ABB CA5X

 

[GoldDigger]

If the motor is burning out, the underlying problem is that it is regularly being overloaded. Using a correctly set overload may protect the motor from damage, but I suspect that it will trip often enough to be a production problem.
Either the motor was undersized to start with or the settings of the equipment it is powering are being miss set in an attempt to get more production from the machine.
He needs to take a close look at what the machine is doing, and whether there are unusual conditions that happen infrequently that cause damage or just a constant low level overload reducing motor life.

It appears to be a CE design motor, which unlike typical NEMA motors we are used to has no mechanical overload tolerance at all.

If they have the correct overload relay installed but someone tweaked the setting based on what they thought were nuisance trips it will not be able to do its job. The 1.3 setting sounds suspicious to me.

 

[broadgage]

Ideally, this should be properly investigated, including.

Measure the motor current and compare with nameplate.
Check that the overload setting is no more than the nameplate amps.
Check driven machinery to see if it is overloading the motor.
Log line volts to ascertain if regular low line volts is causing over current.
Check ambient temperature and ventilation.

Meanwhile, back in the real world, It looks to be a small and relatively cheap motor. It might therefore be tempting to forgo any time consuming and therefore costly investigation, and instead simply to replace the motor with the next standard size up.

 

[ptonsparky]

Picture 3 shows a lot of dust or dirt of some kind on the motor. Does it accumulate enough to prevent cooling?

 

[topgone]

That OL looks like a TA25DU class 20 (trips in 20 seconds when subjected to a current 6X its setting) from ABB. The range for that relay is from 1.3 to 1.8 A. Relay should have tripped many times and protected motor could be burned if OLR is set to automatically reset.
Like what others have said, please verify loading of motor if not overloaded and ask about cleanliness of the motor (dirt reduces the motor's ability to dissipate motor frame heat).

 

[kwired]

many possibilities here. Simplest being motor not big enough for the load being demanded, along with overload protection set above motor rating. Poor cooling also been mentioned. Then you may have improper voltage or unbalanced voltage, too many starts in short time, driven machinery issues causing overloading (though proper overload setting should protect from this), automatic reset, or even manual resets before motor has had time to cool.

If motor is undersized for the demand, make sure you are not exceeding the machine design before just increasing motor size. Bigger motor may not trip overloads or burn out motors, but other components will likely start failing as well if constantly being pushed beyond their design capacity.

 

[Jraef]

Looks as though the motor nameplate Amps is 1.53 @400V, so a setting of 1.3A would nuisance trip. That then may lead to operators constantly resetting it, or worst case someone figured out how to jump out the trip contact so that the motor runs to destruction. In addition if that part number description is correct, an IEC motor should never have a Class 20 Overload curve, IEC motors are designed as Class 10. Class 20 is for NEMA designed motors.

I agree though, a proper investigation needs to be done because if the motor is never even CLOSE to the FLA, thus never tripping the OL relay, it may be overheating for some other reason, ie dust accumulation so no cooling capability.