【2026 Motor Temperature】The highest temperature experienced by the motor
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At what temperature can a regular motor operate normally? What is the maximum temperature that the motor can withstand? If the temperature of the motor cover measured is more than 25 ℃ above the ambient temperature, it indicates that the temperature rise of the motor has exceeded the normal range; generally, the temperature rise of a motor should be below 20 ℃. Typically, motor coils are wound using enameled wire, and at temperatures above around 150 °C, the enamel coating on this wire loses its integrity due to the high temperature, resulting in a short circuit in the coil. When the coil temperature is above 150 ℃, the temperature of the motor housing is around 100 ℃; therefore, if the temperature of the housing is used as a reference, the highest temperature experienced by the motor is 100 ℃.
For reference – below are the common reasons for high motor temperatures and the corresponding solutions: 1. If the motor’s actual voltage exceeds the rated voltage by more than 10%, or if it is below the rated voltage by more than 5%, this will cause the motor to heat up and its temperature to rise under normal load conditions; in such cases, the voltage should be checked and adjusted.
2. An imbalance in the three-phase supply voltage of the motor can also cause the motor to overheat, as an imbalance in the three-phase voltage of more than 5% leads to an imbalance in the three-phase currents. The solution is to check and adjust the voltage.
3. Contact problems with the motor’s power switch or a blown fuse in one phase can both cause operation with an incomplete phase supply, which in turn leads to an increase in the motor’s temperature. The solution is to repair or replace the damaged components.
4. The wiring of the motor’s windings is incorrect, which causes the motor to overheat when operating under its rated load; the solution is to correct the wiring errors in the windings.
5. A short circuit or ground fault between the turns or phases of the motor’s stator windings can cause the current in the motor to increase, leading to a rise in temperature. The solution is to apply insulation at the center or replace the windings directly.
6. Broken bars in the squirrel-cage rotor of the motor or loose connections in the windings of the wound-rotor type can cause an increase in current through the cooling system, leading to temperature rise. The solution is to weld and repair the rotor or replace it.
7. When the bearings of the motor are severely worn, significant friction occurs, generating heat. The solution is to check whether the bearings are loose and whether there is any misalignment between the stator and the rotor.
8. An excessive load on the motor is also a cause of overheating; reducing the load or replacing it with a motor of higher power can resolve the overheating issue.
9. Excessive frequent starting of the motor, high ambient temperature, poor ventilation, and other factors can also cause the motor’s temperature to rise too high. Reducing the number of starts, lowering the ambient temperature, ensuring unobstructed air passages, removing dust and oil deposits, and maintaining proper operation of the fan can all help address such overheating problems.
For a motor that is in operation, if the current does not exceed the motor’s rated current, it indicates that there are basically no problems with the circuit. If the original load remains unchanged, it is necessary to check whether the voltage is within the rated range; generally, 380V is considered normal within a range of plus or minus 5%. Check whether the ambient temperature is too high. Is the bearing lacking oil? Whether the cooling fan is damaged.