Misunderstandings in choosing dust explosion-proof motors_How to choose dust explosion-proof motor models

Misunderstandings in choosing dust explosion-proof motors

1. Generally, when users purchase explosion-proof motors, they are often tempted by relatively low-priced products. This is because most explosion-proof users believe that explosion-proof motors are already very mature products on the market, have been around for a long time, and do not have high technical content, so they can be used. What they don’t know is that low-priced explosion-proof motor products can cause various faults during use, affecting the user’s normal production safety and directly causing unnecessary economic losses to the user.

2. In another case, when users purchase explosion-proof motors, if they are not very proficient in motor knowledge and think that they are just simply using explosion-proof motors, then many users will only pay attention to the power of the motor and use the power as the main technical parameter for purchase.

How to choose dust explosion-proof motor model

1. Risk of fire and explosion caused by combustible dust

Combustible dust refers to dust that may burn or smolder after mixing with air and can form an explosive mixture with air at normal temperature and pressure. A combustible dust environment refers to an environment in which a mixture of dust, fibers or flying combustible materials and air can continue to burn and spread on its own after being ignited under atmospheric conditions. Operating equipment should be equipped with dust explosion-proof motor equipment to prevent dust from causing explosions and other unexpected fire situations.

The presence of combustible dust can cause the following risks.

(1) Dust clouds generated by any release source, including dust layers or dust accumulations, will constitute an explosive atmosphere;

(2) Dust layers that are unlikely to form a dust cloud may ignite due to self-heating or hot surfaces and cause a fire hazard or overheating of equipment.

In addition, in explosive atmospheres, the ignited dust layer may also become an ignition source for the dust cloud.

2. The main path by which electrical equipment in a combustible dust environment may ignite combustible dust

(1) The surface temperature of the dust explosion-proof motor is higher than the dust ignition temperature. The dust ignition temperature is related to its performance, existence state (such as accumulation or formation of dust cloud), dust layer thickness and the geometry of the heat source;

(2) Dust explosion-proof motors (such as switches, contacts, rectifiers, brushes and similar parts);

(3) Accumulated static discharge;

(4) radiated electrical energy (such as electromagnetic radiation);

(5) Mechanical sparks, friction or heat related to electrical equipment.

3. Measures to prevent the risk of ignition of electrical equipment in combustible dust environments:

Because combustible dusts are dangerous: when they are dispersed in the air in any way, they will form a potentially explosive environment. In addition, the combustible dust layer can be ignited and become an ignition source for the explosive environment. Therefore, electrical equipment installed in the explosion-proof motor environment should avoid ignition of the explosion-proof motor, and its surface temperature limit should be lower than the ignition temperature of the dust cloud or dust layer. Specifically, it is necessary to do the following.

(1) The surface temperature of dust explosion-proof motors that may accumulate dust or may come into contact with dust clouds must be kept below the temperature limit specified in the standard;

(2) Any parts that generate (or may generate) electric sparks or arcs or parts whose temperature is higher than the ignition temperature of dust should be placed in an enclosure that is sufficient to prevent dust from entering, or the energy of the circuit should be restricted to prevent the occurrence of arcs, sparks or temperatures that can ignite combustible dust; the enclosure of dust explosion-proof motors must be able to meet the requirements of the operating environment before they can be put into use.

(3) Dust explosion-proof motors must be able to prevent any ignition source associated with electrical equipment.

In addition, electrical equipment in combustible dust environments must also comply with the regulations.