As shown in the illustration of an electrically operated watertight door controller, what type of motor is used to open and close the watertight door? EL-0115

Correct Answer: Option C — Series wound DC motor

Series-wound DC motors provide exceptionally high starting torque required to unseat and move heavy, gasketed watertight doors. Their torque-speed characteristic makes them ideal for marine hydraulic and mechanical door operators under emergency conditions.