Timeismoney08
Member
Can someone explain the differences? Do I still need to protect behind a contactor/overload combo?
Thank you!
Thank you!
So why/when do I need to add motor overloads? Some applications just have breakers or fusing on some motors. What scenarios would make me want to use them also?
So an Overload is NEVER used in place of a CB, correct?
Thank you guys for the help!
It may depend on the type of motor, but most likely depends on the designer not allowing for or not caring about an overheating motor. If the motor is small and in a place where it doesn't matter if it burns out, then you might decide not to protect it. If the motor is very small the overloads become less accurate and useful, the motor may burn out before the overload reacts.Some applications just have breakers or fusing on some motors
I believe that most modern motor circuit breakers have differential tripping. If one phase is missing, it still trips at the proper (approximated) winding termperature. It is done with clever mechanical linkage in the trigger mechanism in the circuit breaker. For example Siemens 3RV motor circuit breakers all have this functionality.A miniature circuit breaker doesn't have the thermal component of a motor breaker, it can see sudden large over currents, but not small long lasting over currents. It also doesn't see the missing phase that the others will detect.