Explosion proof mark Exd I, Exd II at4, Exd II BT4, class I, the maximum surface temperature not exceeding 150 DEG C (when motor surface may accumulate dust), not more than 450 DEG C (when the surface of the motor will not accumulate or measures can be taken to prevent the accumulation of coal dust); class II of the maximum surface temperature shall not exceed: (450 DEG C) T1, T2 (300 DEG C), T3 (200 DEG C), T4 (135 DEG C); junction box can be respectively made into three or six terminals for rubber sheathed cable (or plastic cable and steel pipe wiring structure. .