1. Winding overheating
Phenomenon: When overloaded, the current of the motor increases significantly, causing the winding to heat up and the temperature to rise.
Consequences:
Insulation damage: If the winding temperature exceeds the tolerance limit of the insulation material, the insulation layer may be damaged, resulting in a short circuit or ground fault.
Winding burnout: Continuous overheating may cause the winding to burn out, requiring the winding or the entire motor to be replaced, increasing repair costs and downtime.
2. Brush and commutator damage
Phenomenon: The brushes and commutator of a DC motor will withstand greater current when overloaded, resulting in increased brush wear and increased commutator surface temperature.
Consequences:
Brush wear: Increased brush wear may require frequent brush replacement, increasing maintenance costs.
Commutator damage: The increased commutator surface temperature may cause sparks, further damaging the commutator, resulting in poor commutation and affecting the motor's operating performance.
3. Speed drop
Phenomenon: When overloaded, the motor's output torque increases, resulting in a speed drop.
Consequences:
Degradation of rolling quality: During the steel rolling process, the decrease in motor speed will affect the speed of the rolls, which in turn affects the rolling speed and rolling quality. For example, it may cause uneven strip thickness and affect product quality.
System instability: The decrease in speed may cause the coordination of the entire steel rolling production line to be destroyed, affecting the normal operation of subsequent processes.
4. Overheating protection device action
Phenomenon: In order to protect the motor, the overheating protection device (such as thermal relay, overload relay, etc.) will act when overloaded.
Consequences:
Automatic shutdown: After the protection device is activated, the motor will automatically shut down to prevent further damage. This will cause production interruptions and affect production efficiency.
Equipment damage: If the protection device fails to act in time, the motor may be damaged due to overheating, increasing maintenance costs and downtime.
5. Mechanical component damage
Phenomenon: When overloaded, the output torque of the motor increases, which may cause excessive stress on the mechanical components.
Consequences:
Bearing damage: Excessive torque may cause the bearing to bear excessive load, accelerate bearing wear, and even cause bearing damage.
Gear damage: If the motor is connected to the gearbox, overload may cause excessive stress on the gear, causing gear damage.
6. Abnormal control system
Phenomenon: When overloaded, the current and voltage changes of the motor may exceed the normal operating range of the control system.
Consequences:
Decrease in control accuracy: The control system may not be able to accurately control the speed and torque of the motor, resulting in a decrease in the control accuracy of the rolling process.
Protective device malfunction: Overload may cause the protective device in the control system to malfunction, further affecting the normal operation of the equipment.
7. Energy waste
Phenomenon: When overloaded, the efficiency of the motor decreases and consumes more electricity.
Consequences:
Increase in energy consumption: Overload operation will increase the energy consumption of the motor and increase production costs.
Reduced efficiency: The efficiency of the motor decreases, affecting the production efficiency of the entire steel rolling production line.
8. Safety hazards
Phenomenon: When overloaded, the operating state of the motor is abnormal, which may cause sparks or overheating.
Consequences:
Fire risk: Overheating or sparks may cause fires, posing a serious threat to the safety of personnel and equipment.
Personal injury: Overload may cause equipment failure and increase the risk of operator injury.
