According to the explosion-proof principle, explosion-proof motors can be divided into explosion-proof motors, increased safety motors, positive pressure motors, non-sparking motors and dust explosion-proof motors.
Working principle of explosion-proof motor:
It uses a flameproof enclosure to isolate the electrical parts that may produce sparks, arcs and dangerous temperatures from the surrounding explosive gas mixture. However, this kind of shell is not sealed, and the surrounding explosive gas mixture can enter the inside of the motor through the gaps between the joint surfaces of various parts of the shell. An explosion may occur when it comes into contact with ignition sources such as sparks, arcs, and dangerous high temperatures in the housing. At this time, the flameproof housing of the motor will not only not be damaged or deformed, but also when the explosion flame or hot gas spreads through the gap between the joint surfaces, Nor can it ignite the surrounding explosive gas mixture.
Working principle of increased safety motor:
It is a motor structure that will not produce arcs, sparks or dangerous high temperatures under normal operating conditions, and then takes some mechanical, electrical and thermal protection measures to further avoid arcs, sparks or dangerous high temperatures under normal or recognized overload conditions. The danger of high temperature, thereby ensuring its explosion-proof safety.
Working principle of positive pressure motor:
Equipped with a complete ventilation system, there are no structural dead spots inside the motor that may affect ventilation; the shell and pipes are made of non-combustible materials and have sufficient mechanical strength; the shell and main pipes maintain a sufficiently large positive pressure relative to the outside atmosphere; The motor must have safety protection devices (such as time relays and flow monitors) to ensure sufficient air exchange. It must also have automatic protection or alarm devices for under-pressure in the shell; the quick door or cover on the shell must be connected to the power supply. Interlocking device. There is currently no unified series of positive pressure motor products in our country.
Working principle of non-sparking motor:
This motor refers to a motor that will not ignite the surrounding explosive mixture under normal operating conditions, and generally does not cause ignition failure. Compared with the increased safety motor, in addition to the insulation dielectric strength test voltage, winding temperature rise, tE (the AC winding after reaching the rated operating final temperature at the highest ambient temperature, from the time when the starting current passes through the time until it rises to the limit Temperature time) and starting current ratio do not have special regulations like the increased safety type, other aspects are the same as the design requirements of the increased safety type motor.
Working principle of dust explosion-proof motor
This motor means that its casing is designed and manufactured according to specified conditions. It can prevent dust from entering the motor casing. Although it cannot completely prevent dust from entering, the amount of entry does not hinder the safe operation of the motor. The accumulation of internal dust will not easily cause an ignition hazard, and it will not be used during use. Motors that can cause explosions of surrounding explosive dust mixtures.
Post time: Jan-16-2024
