Which motor is described as totally enclosed and not equipped for cooling by external means?

• A. Totally Enclosed Nonventilated Motor
• B. Totally Enclosed Motor
• C. Open Motor
• D. Guarded Motor

Answer: (A)

The key idea is motor enclosure and cooling method. A motor that is totally enclosed and not designed to be cooled by external air is a Totally Enclosed Nonventilated motor. It is sealed to prevent any ventilation through openings and has no external cooling devices like fans. Heat is removed only through the motor housing by natural convection and conduction to the surrounding air, not by forced air or external cooling paths. This type is used when you need to protect the motor from dust, moisture, or hazardous environments and when external cooling isn't desired or feasible. The other options involve some form of external cooling or an open enclosure, which doesn’t match the description of being totally enclosed with no external cooling.