Question 401Electricity & Electronics - Assistant Engineer

The correct answer is C) Series wound DC motor. The series wound DC motor is commonly used to operate electrically controlled watertight doors on ships because it provides the necessary torque and speed characteristics required for this application. The series wound configuration allows the motor to develop high starting torque, which is important for opening and closing the heavy watertight doors against water pressure. The other options are incorrect because: A) Permanent magnet DC motors do not have the same high starting torque capabilities, B) Compound wound DC motors are less suitable for this application, and D) Shunt wound DC motors generally have lower starting torque compared to series wound motors.