Explanation of the explosion-proof level of the motor
There are Exd IIB T4 and Exd IIC T4, which we are used to abbreviating as bt4 and ct4, both of which are suitable for all other explosive gas atmospheres except coal mines and underground
Exd IIB T4 stands for explosion-proof motor, which is an explosion-proof type factory motor, suitable for gas hazardous area 2, *high surface temperature not exceeding 135°C (see table below for hazardous areas)
Exd IIC T4 stands for explosion-proof motor, which is an explosion-proof type factory motor, suitable for gas hazardous areas Zone 1 and Zone 2, *High surface temperature does not exceed 135°C (see the table below for hazardous areas)
The gas hazard zone is divided into three areas: Zone 0, Zone 1 and Zone 2:
Zone 0, an area where explosive gases, vapours or mist occur continuously or for long periods of time during normal operation. Zone 0 rarely exists, except in enclosed spaces with hazardous substances (e.g., inside closed containers, inside fixed-top liquid storage tanks, etc.).
Zone 1: This is an area where explosive gases, vapours, or mists may occur occasionally during normal operation or are expected to occur at a low frequency
Zone 2: Refers to areas that do not appear during normal operation, and even if they do, they only occasionally appear for a short period of time.
After understanding the description of the explosion-proof level of the two equal motors, we intuitively understand that the explosion-proof level of CT4 is higher than that of BT4, and the main difference is that CT4 is suitable for a wider range of gas hazard areas. Gas and dust double explosion-proof composite explosion-proof motor, explosion-proof mark is Ex d IIC T4 Gb/Ex td B21 T135 °C in the application of flammable gas place standards and combustible dust places.
Detailed explanation of the parameters of dust-type explosion-proof motor
Combustible dust will explode after encountering the ignition source at a sufficient concentration, and the explosion gas wave will shake up the dust deposited on the surface of the article, and the air in the center of the explosion will form a negative pressure to supplement the fresh air to form a secondary explosion, which is very harmful, so the dust explosion-proof motor is widely used in the factory, first of all, we understand the classification of the dust use environment, which can be divided into 3 areas according to the new dust explosion hazard classification standard:
Zone 20: Locations and inside containers where combustible dust occurs continuously or frequently in quantities sufficient to form a mixture of combustible dust and air and/or may form an uncontrollable and extremely thick dust layer during normal operation.
Zone 21: During normal operation, there may be a place where the amount of dust is sufficient to form a combustible dust and air mixture, but is not classified as Zone 20. This area includes places directly adjacent to the point where dust is charged or discharged, where dust layers occur and where combustible dust and air mixtures that may be produced under normal operating conditions can be generated.
Zone 22: Under abnormal conditions, where combustible dust occurs occasionally and only for a short period of time, or where combustible dust accumulates occasionally or where a dust layer may be present and a combustible dust-air mixture is generated. If the exclusion of combustible dust accumulation or dust layers cannot be guaranteed, it should be divided into 21 zones.
After understanding the division of dust area, let's take a look at the model parameters of the explosion-proof motor: Ex tD B21 IP65 T135 °C (degree),
EX stands for Explosion-Proof Electrical Equipment;
tD stands for enclosure protection type, which is suitable for dust-proof electrical equipment;
B21 represents suitable for dust in zone 21, because zone 22 has lower requirements than zone 21, it is also suitable for zone 22; B indicates that the explosion-proof joint surface of the motor is a straight joint surface (A represents the plane bonding surface, the two can be used interchangeably, but in fact, the explosion-proof structure of straight mouth combination is safer than the explosion-proof structure of plane bonding)
IP65 represents the protection level, 6 means that the dust-tight motor has no dust ingress, and 5 means that the anti-water spray motor can withstand water spray in any direction;
T135°C (degrees) means that the temperature of the chassis is not more than 135 degrees.
Explosion-proof motor application place
1. 防爆型式:Ex dI Mb适于煤矿
2. Explosion-proof type: Ex d IIB T4 Gb. Suitable for places with natural gas (propane, ethylene) in the factory.
3. Explosion-proof type: Ex d IIC T4 Gb is suitable for places where the plant has a permissible gas (hydrogen, propane, ethylene).
4. Explosion-proof type: Ex tD B21 T135°C is suitable for places with combustible dust and flammable flying flotsam (such as feed, textile, flour, cement and other places that produce dust).
5. Explosion-proof type: Ex d IIC T4 Gb/Ex td B21 T135°C is suitable for places with flammable gases, as well as places with combustible dust and flammable fly flakes (such as feed, textile, flour, cement and other places that can produce dust).