The main reason are mechanical causes and electrical causes
1. Mechanical Causes
1.1 Shaft Misalignment, incorrect motor-to-pump coupling
1.2 Dry running
1.3 Corrosive or abrasive fluids, too much sand or gravel in the water
2. Electrical Causes
2.1 Overvoltage
2.2 Phase loss
2.3 Excessive harmonic content
2.4 Overcurrent, such as motor idling, or stall condition
2.5 Prolonged low-speed operation of a non-inverter motor
2.6 Prolonged overspeed operation
2.7 Voltage-to-frequency ratio of the power supply does not match motor characteristics