DC Motor Characteristics

DC motors are widely used in various applications due to their simplicity, reliability, and controllability. They are classified into different types based on their construction and connection, such as series, shunt, differentially compounded, and cumulatively compounded motors. Each type of motor has its own unique characteristics and applications.

3-Phase Induction Motor Characteristics

A 3-phase induction motor is a type of AC motor that is widely used in industrial applications. It operates on the principle of electromagnetic induction to convert electrical energy into mechanical energy. Some of the key characteristics of a 3-phase induction motor include:

1. High Starting Torque: Induction motors have a high starting torque, which enables them to start heavy loads without any additional starting devices.

2. Self-Starting: Unlike DC motors, induction motors are self-starting and do not require external means to initiate rotation.

3. Speed Control: The speed of an induction motor is primarily determined by the frequency of the applied voltage. By changing the frequency, the speed of the motor can be controlled.

4. Robust and Reliable: Induction motors are known for their robust construction and high reliability. They can withstand harsh operating conditions and provide long service life.

5. Efficiency: Induction motors are highly efficient, especially at full load. They have a relatively low power loss, which contributes to their energy-saving capabilities.

Similarity to a DC Shunt Motor

The characteristic of a 3-phase induction motor that is similar to that of a DC shunt motor is the speed control. In both types of motors, the speed can be controlled by adjusting the applied voltage.

- In a DC shunt motor, the speed is controlled by varying the field current, which in turn affects the back EMF and the armature current.

- Similarly, in a 3-phase induction motor, the speed is controlled by adjusting the frequency of the applied voltage. By changing the frequency, the synchronous speed of the motor is altered, which in turn affects the rotor speed.

Both the DC shunt motor and the 3-phase induction motor provide a wide range of speed control, allowing them to be used in applications where variable speed operation is required. However, it is important to note that the speed control methods and the underlying principles are different for these two types of motors.

Therefore, the correct answer to the given question is option 'B' - DC shunt motor.

B