Answer / varun

The main difference between normal motor and flameproof motor is the construction of the frame of the motor. Electrically the 2 motors are identical (depending on the manufacturer and money)

The flameproof motor's frame is more robust with larger spigots and end caps on the bearing housing. This more robust frame is needed if a gas explosion (not electrical explosion) occurs inside the frame of the motor, the explosion needs to be contained inside the frame and the flame need to be cooled down by the time it reaches the outside.The larger spigots on the frame is acting same as a cooler for the flames (this is called the flame path).

The sizes of the spigots are determined by the volumetric capacity of the frame, in other words the larger the frame size the larger the spigots. This effectively is needed because the more gas that will be able to gather in the frame of the motor, the bigger the explosion will be, the bigger the spigots needs to be to create a longer flame-path to cool the flame down.

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