During daily inspections and equipment commissioning in workshops and automated production lines, operators often encounter the same malfunction when dealing with motors whether high-power industrial AC motors, small DC motors or DC planetary gear motors. After operating for a period, the motor housing gets extremely hot, the thermal or overcurrent protection triggers an immediate shutdown automatically, and in severe cases, a pungent burnt odor from damaged windings can be smelled. There are three core triggers in total.
- Overloaded Load
Every motor has a rated load and rated torque,however Micro DC planetary geared motors are fitted with gear reduction structures which will amplify the damage caused by overload.
1.1 Excessive load: If the actual drag exceeds the motor’s rated torque, the windings will continuously carry high current resulting in sharp rising of copper loss and rapid temperature increase of the motor housing. Long-term overload will also wear and jam planetary gears, further increasing motor load and creating a vicious cycle.
1.2 Frequent start-stop: The inrush current during motor startup is much higher than steady-state operating current. Repeated startup and shutdown continuously impacts the coils and accumulates heat. Due to their thinner winding wire and lower thermal tolerance, small DC motors are more prone to rapid overheating and coil burnout from frequent cycling compared to high-power motors.
2.Poor Heat Dissipation & High Ambient Temperature
High-power AC motors feature built-in cooling fans and ventilation ducts for active cooling, whereas most small DC motors and DC planetary gear motors rely solely on their metal housings for natural heat dissipation without auxiliary cooling fans.Long-term operation leads to dust covering of the motor surface, in addition,compact and enclosed installation space, and high workshop temperature, all of which block heat dissipation. Heat which trapped inside the housing will cause extreme surface temperature. Large AC motors will trigger thermal protection, while small DC motors without protective devices will burn windings and produce burnt smell directly.
- Abnormal Supply Voltage
Both excessively high and low supply voltage will disrupt the motor’s normal operating conditions. When the voltage is too low, the motor must increase its current to maintain output torque, leading to significant heat generation; conversely, excessively high voltage increases magnetic core losses causing abnormal overheating in both AC and DC motors.Both AC and DC motors will suffer abnormal overheating. DC motors heat up far faster than industrial AC motors when the supply voltage deviates from the rated value.
Motor overheating issues typically develop progressively, you can spot abnormalities early by regularly checking housing temperature, unusual odors and protection switch status during inspections. If you notice a hot motor casing, burnt smell or thermal protection tripping, the motor must be shut down and disconnected from the power supply immediately for troubleshooting. Operating a motor with existing faults in the hope that it will hold up is risky; timely resolution of issues is essential to extend the motor’s service life and prevent equipment damage or safety accidents. If you need durable DC planetary gear motors with low heat generation, you are welcome to contact us to consult.