السلام عليكم ورحمة الله وبركاته
Dear Brother
You must differentiate between two types of faults
Overcurrent (over loading) faults and Short circuit faults
Let me explain:
For motors
when bearings get old, the motor is over loaded and its current increases but the situation is still not critical, so overloads which reacts according to the heating effect of the current will react but it takes some time to trip the circuit.
But what happens when the bearing is crashed and amage the motor winding insulation is a short circuit and the current value is so high that an immediate tripping of the circuit is a must, to avoid more series troubles such as fire. Thus fuses are used, the attached file shows how to protect a motor
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