Dripproof Guarded Motor is a dripproof machine whose ventilating openings are guarded in accordance with the definition for dripproof motor.

• A. Dripproof Motor
• B. Explosion-Proof Motor
• C. Dripproof Guarded Motor
• D. Dust-Ignition-Proof Motor

Answer: (C)

The main idea is how motor protection classifications are combined to describe a specific type of motor. A motor labeled dripproof guarded is one that is designed to resist dripping water and, at the same time, has its ventilating openings guarded to prevent contact with the openings. The statement describes exactly that: a dripproof machine whose ventilating openings are guarded according to the dripproof motor definition. So this is the combined classification—dripproof guarded motor.

Why the others don’t fit: an explosion-proof motor is built to contain any internal ignition and is used in hazardous atmospheres, which isn’t indicated here. a dust-ignition-proof motor is designed to resist ignition from dust in the environment, also not indicated. a plain dripproof motor would protect against water drip but wouldn’t include guarded ventilating openings, which the description specifies.