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Motor gets overheated due to
Shorted winding
Overload
Bearing fault
All of above
All of above
An electric motor generates excessive heat when the rate of internal electrical power loss exceeds its heat dissipation capacity. Severe thermal stress can be caused by electrical short circuits, mechanical overloads, or increased physical friction from bearing failures.
An electric motor generates excessive heat when the rate of internal electrical power loss exceeds its heat dissipation capacity. Severe thermal stress can be caused by electrical short circuits, mechanical overloads, or increased physical friction from bearing failures.
PlossтАЛ=I2R тАФ Stator/Rotor copper loss contributing directly to heating
TтИЭI тАФ Motor torque proportional to armature/stator current
╬ФTтИЭPlossтАЛ тАФ Temperature rise proportional to total losses
Excessive heating in motors is primarily caused by increased copper losses (I2R) and mechanical friction. A shorted winding reduces overall resistance and increases current drawn. An overload forces the motor to draw higher current to supply the required load torque (TтИЭI). Bearing faults create mechanical drag and alignment issues, increasing friction and current demand.
Shorted turn-to-turn insulation lowers impedance, leading to massive localized heavy current and heat.
Overloading demands torque beyond rated capacity, forcing elevated stator current draw.
Bearing breakdown increases mechanical friction, load drag, and can cause rotor-stator rub.
Overheating rapidly degrades motor insulation class limits (e.g., Class B, F, H). A 10┬░C increase above maximum temperature rating cuts insulation life by 50%.
Thermal overload relays (TOR) and thermal switches are integrated into motor protection circuits to prevent damage from these conditions.
D is correct тАФ Shorted windings, electrical overloads, and bearing friction all independently and cumulatively lead to excessive motor heating.
Always identify whether a cause of motor failure is electrical (short circuit, overvoltage), mechanical (bearing fault, misalignment), or operational (overload, restricted cooling).