Basic requirements for designing explosion-proof distribution boxes

a. Design explosion-proof distribution box (control box) to meet equipment category and group requirements;

b. Design the explosion-proof distribution box (control box) to meet the requirements of the environment and occasions used;

c. Design explosion-proof distribution box (control box) equipment should withstand impact test, over-pressure test (static pressure) test;

d. Designing the explosion-proof distribution box (control box) The equipment casing is made of plastic. When the material is used under the highest ambient temperature conditions, the temperature index TI or RTI (mechanical impact) of the plastic material corresponding to 20000h should be better than that of the plastic casing or casing. The hottest temperature of plastic parts is at least 20K.

e. Design explosion-proof distribution box (control box) The equipment shell is made of plastic material, and the surface insulation resistance is not more than 109 Ω.

f. Design the explosion-proof distribution box (control box) The equipment casing is made of plastic material, and the surface area is not greater than the provisions of Table 5;

Table 5 Surface Area Limits

Maximum surface area / mm2

Class I equipment

Class II equipment

Device protection level

Class IIA

Class IIB

Class IIC

10000

EPL Ga

5000

2500

400

EPL Gb

10000

10000

2000

EPL Gc

10000

10000

2000

g. Design explosion-proof distribution box (control box) Class II electrical equipment shell material does not exceed the following requirements:

EPL Ga: 10% aluminum, magnesium, titanium and zirconium, 7.5% magnesium, titanium and zirconium;

EPL Gb: 7.5% magnesium and titanium;

EPL Gc: Except for fans, fan guards, and venting baffles that meet the requirements of the EPL Gb, there are no other requirements.

h. Design explosion-proof distribution box (control box) shell (explosion-proof type) explosion-proof joint surface width, joint surface hole distance, clearance, (three elements) to meet the requirements, flameproof thread engagement thread ≥ 5.

i. Design the width of the bonded joint surface of the explosion-proof distribution box (control box):

When V≤10cm3, not less than 3mm;

When 10cm3, <V≤100cm3, not less than 6mm;

j. Designing the explosion-proof distribution box (control box), the introduction device of the flameproof enclosure, the tolerance level of the metric threaded hole is specified to be 6H or more;

2.2 Design requirements for electrical components in explosion-proof distribution boxes (control boxes)

a. The electrical components in the flameproof enclosure must have “3C” certification, product certification, product specification

b. The electrical components that generate sparks and arcs in the increased safety enclosure must be explosion-proof components, and have a product explosion-proof certificate and a production license for the product.

2.3 Design of explosion-proof distribution box (control box) for electrical components - circuit breaker requirements

a Explosion-proof distribution box (control box) circuit breaker has a main circuit breaker and a branch circuit breaker;

Circuit breaker current distribution:

b Main circuit breaker rated current ≥ sum of rated current values of each circuit breaker;