First, explosion-proof electrical equipment is divided into two categories: I class coal mine electrical equipment; electrical equipment used by the II place outside the mine. Class II electrical equipment is divided into three categories: IIA.IIB.IIC.

    Second, to understand the division of the explosion-proof grade, first look at the explosive gas mixture at the ignition temperature of the grouping: group with T1.T2.T3.T4.T5.T6 that the ignition temperature t (° C), the ignition temperature of the T1 group:; 450 ° C <t; T2 as follows: 300 ° C <t ≤ 450 ° C; T3 as follows: 200 ° C <t ≤ 300 ° C; T4 to: 135 ° C <t ≤ 200 ° C; T5 : 100 ° C <t ≤ 135 ° C; the T6 for: 85 ° C <t ≤ 100 ° C.

    Third, we must understand the type of explosion-proof electrical explosion-proof type is divided into: flameproof, mark d; increased safety, signs for: e; positive pressure, signs for P; intrinsically safe, marked as i;: oil-filled sand filled encapsulation.

    Understanding of these points, a good understanding of the division of the explosion-proof grade, explosion-proof electrical equipment is used by the device category; explosive gas mixture temperature group; divided by the type of protection of explosion-proof electrical equipment, such as: proof mark dIIBT4, on behalf of, the type of explosion-proof electrical products for explosion-proof place in the class II category IIB (class) do not, the ignition temperature of the explosive gas T4 group.