An explosion-proof motor refers to a motor that takes some explosion-proof measures to ensure that it can be used safely in explosion-hazardous places.
Explosion-proof motors can be divided into the following three types and their composite types according to their basic principles of meeting explosion-proof requirements:
1. Flameproof type (B type)
A motor that does not cause the explosion of an external explosive mixture when an explosion occurs inside the motor. The motor casing has sufficient mechanical strength (high-grade cast iron steel plate is the casing) so that it can withstand explosion pressure and external force impact without damage; all the gaps forming the entire explosion-proof casing; junction boxes, wire entry devices, etc. are required; control the temperature of the surface of the case so that it cannot reach dangerous temperatures.
2. Increased safety type (A type)
The motor has better sealing performance and adopts IP55 protection grade requirements; electromagnetic design should consider reducing the temperature rise; control the time when the rotor reaches the dangerous temperature when the rotor is locked and is equipped with automatic control electrical devices; improve the inter-turn, ground and phase-to-phase tests of winding insulation voltage; improve the inter-turn, to-ground and inter-phase test voltage of winding insulation; improve the reliability of conductor connection; control the minimum unilateral gap of stator and rotor. In short, the construction and electrical aspects prevent accidental sparks, arcs or dangerous temperatures, thereby increasing the safety level of operation.
3. Positive pressure type (P type)
Explosion-proof motors with positive pressure fresh air or inert gas (such as nitrogen) into the housing to prevent external explosive mixtures from entering the motor.