Variable Speed Motor: Series Motor

A variable speed motor is a type of motor that can operate at different speeds based on the application requirements. Among the different types of DC motors, the series motor is a variable speed motor.

Explanation:

• Series Motor: A series motor is a type of DC motor where the armature and field windings are connected in series with each other. As the name suggests, the windings are connected in a series circuit.

• Characteristics of Series Motor: The series motor has a high starting torque, which makes it suitable for applications where high torque is required at low speeds. The speed of the series motor is directly proportional to the applied voltage. Therefore, by varying the voltage applied to the motor, the speed can be controlled.

• Advantages of Series Motor: The series motor provides high starting torque, which makes it suitable for applications such as cranes, hoists, and elevators. The speed can be varied by controlling the applied voltage, making it suitable for variable speed applications.

• Disadvantages of Series Motor: The series motor has poor speed regulation, which means that the speed varies widely with changes in the load. The motor also has a tendency to overspeed in light-load conditions, which can be dangerous.

Conclusion:

Hence, the series motor is a type of variable speed motor that is suitable for applications where high starting torque and variable speed operation are required.

From speed-current characteristic curve it is obvious that the series motor is a variable speed motor i.e., speed varies with the variation in line current. With the decrease in load on a dc series motor, the speed increases and may become dan­gerously high at very light loads.