The correct answer is: C. Cumulative compound motor
A cumulative compound motor is a type of DC motor that has both series and shunt windings. The series winding is connected in series with the armature, while the shunt winding is connected in parallel with the armature. The combination of these two windings gives the cumulative compound motor a number of advantages over other types of DC motors.
One advantage of the cumulative compound motor is that it has a high starting torque. This makes it ideal for use in applications where a large amount of torque is required at startup, such as machine tools.
Another advantage of the cumulative compound motor is that it has a good speed regulation. This means that the speed of the motor remains relatively constant even under load changes. This is important in applications where a constant speed is required, such as in machine tools.
Finally, the cumulative compound motor is relatively efficient. This means that it uses less power than other types of DC motors, which can save money on energy costs.
The other options are incorrect because:
- A series motor has a high starting torque, but its speed is not constant under load. This makes it unsuitable for use in machine tools.
- A shunt motor has a good speed regulation, but its starting torque is low. This makes it unsuitable for use in machine tools.
- A differential compound motor has a high starting torque and a good speed regulation, but it is less efficient than a cumulative compound motor. This makes it a less desirable choice for use in machine tools.