The housing of the explosion-proof motor junction box is usually made of stainless steel or special alloy material, which has the characteristics of corrosion resistance. Ordinary junction boxes are usually made of ordinary steel materials, which are easily corroded by chemicals in the environment and cause damage to the equipment. Explosion-proof motors are motors specially designed for use in flammable and explosive locations, and their electrical and mechanical properties need to meet specific standards and specifications.
Compared with ordinary motors, explosion-proof motors have more stringent requirements in terms of wiring, mainly in the following aspects:
The explosion-proof motor junction box has a special explosion-proof structure, which can protect the safety of equipment and personnel even in dangerous environments such as explosion and fire. In contrast, ordinary junction boxes lack corresponding explosion-proof measures, and are very easy to generate sparks in dangerous environments, causing explosions and other hazards.
Explosion-proof motor junction boxes are usually designed with the equipment in mind for safe operation in wet or watery environments, so they have good waterproof performance. Ordinary junction boxes usually lack this design and cannot guarantee the safe operation of the equipment in the event of water immersion.
1. Protection level: The junction box of the explosion-proof motor should meet the specific protection level requirements to ensure that it will not cause sparks and explosions in hazardous environments.
2. Wiring method: The wiring of the explosion-proof motor needs to meet specific standards and specifications, and usually adopts the "E" type wiring, that is, the upper end wiring, so that the sparks generated inside the motor will not cause explosion.
3. Material and grade of the terminal: The terminal of the explosion-proof motor is usually made of materials that are not easy to conduct electricity, such as copper and aluminum alloys, so as to achieve the effect of not generating arcs. The explosion-proof junction box is very different from the ordinary, with high strength, the finish of the assembly mating surface is relatively high, and the width of the butt surface has strict size requirements, and the separation of all leads inside and outside has strict sealing size requirements.
The electric spark in the junction box will not affect the combustion and explosion of flammable and explosive materials outside.
1. The position of the binding post must be convenient for the installation of cable cores or wires. It is convenient for regular inspection and repair during the use of the motor;
2. The junction box should be able to change the direction to facilitate the cable and wire inflow;
3. The junction box should be able to introduce paper insulation, rubber and plastic insulated armored cables, rubber flexible cables and steel casing wires. At the same time, it should be guaranteed to be able to fill the paper insulated cable (dry sealing or glue injection).
4. The internal dimensions of the junction box should allow the cable cores or wires to be easily arranged, so that they will not intersect with each other and contact with the grounding part of the junction box.
The junction box cavity and the motor cavity must be separated by an explosion-proof partition, and the cable core or wire connection to the stator winding must be an explosion-proof binding post that runs through this board. Cables or wires sealed with rubber rings are not as reliable as the joint surface clearances of metal housings. In addition, the explosion-proof performance of the cable entry section may be damaged during use due to rubber aging or poor installation quality. Therefore, if the inner cavity of the junction box is not separated from the inner cavity of the motor with normal sparks or components that are heated to very high temperatures, then once the cable or wire seal is broken and the explosive mixture penetrates into the housing, it may explode in the cavity and spread to the surrounding environment with a risk of explosion.
The strength of the material of the junction box parts of the explosion-proof motor should not be lower than the strength of the material of the motor housing. The enclosure of the junction box of the electric motor used in the underground must be made of steel or high-strength cast iron. Enclosures with a net volume of up to 2.5 litres can be made of C915-32 grey cast iron. The junction box housing material of the motor fixing the equipment is independent of its volume, and CU15~32 gray cast iron is allowed.
The wall thickness of the housing is determined according to the material used: steel - not less than 4 mm, cast iron - not less than 6 mm.
To sum up, the explosion-proof motor junction box has good corrosion resistance, explosion-proof, waterproof, protection and other properties, and can be applied to the wiring of electrical equipment in hazardous environments to ensure the safe and reliable operation of the equipment. In contrast, ordinary junction boxes are susceptible to environmental influences that can cause damage to the equipment, so special care is required when using them.