1. Before using explosion-proof electrical equipment, to ensure that the equipment meets the quality requirements for explosion-proof use, the "Regulation" stipulates: "Explosion-proof electrical equipment should be inspected for its 'Product Qualification Certificate', 'Explosion-proof Qualification Certificate', 'Coal Mine Product Safety Mark', and safety performance. The coal safety mark must be verified by checking the coal safety certificate number on the website before use and confirming it is within the validity period. Only after the inspection is approved and a qualification certificate is issued may the equipment be used.
The certificate of compliance is affixed by explosion-proof inspectors inside the equipment. The issued certificates are replaced every six months.
Key inspection items prior to use include:
Are all the equipment components complete and intact?
② Are explosion-proof casings, junction boxes, bases, etc., deformed? Slight convexities or concavities cannot exceed the standard for intactness.
③ Is the explosion-proof housing coated with anti-corrosion paint? It must be recoated with anti-corrosion paint after major or medium repairs.
④ Are all in and out line devices sealed? Use qualified rubber sealing rings, galvanized metal clamps, and galvanized挡板.
⑤ Power on for trial operation, observe the sensitivity and reliability of the opening, stopping, and closing (or running) actions, check for normal operation, and listen for any noise. The placement sequence should comply with the specified requirements. ⑥ The gap of the explosion-proof joint surface should meet the requirements, and each explosion-proof gap of every equipment and appliance should be measured individually.
7. The explosion-proof joint surfaces should be checked for rust and mechanical damage, coated with anti-rust grease if necessary, and undergo phosphatizing treatment as required. The roughness must meet specifications, with no mechanical marks such as pinholes or scratches exceeding the allowable limits.
Upon inspection, electrical equipment meeting the explosion-proof quality requirements should be recorded in the well equipment acceptance record form, and a "permit" should be issued by the explosion-proof inspector. The "permit" should specify the equipment's name, specifications, model, serial number, the unit receiving the equipment, the inspector's name, and serial number.
2. Electrical equipment underground must meet all technical requirements for explosion-proof performance. Electrical equipment with compromised explosion-proof performance must be handled or replaced immediately, and it is strictly prohibited to continue using it.
3. The set value for the well flow protection must match the calculated value. Use phase-sensitive protection for those with insufficient sensitivity. All types of overcurrent protection must undergo electrical testing as per regulations, and a flow test must be conducted before entering the well.
4. Absolutely prohibit the removal of various electrical protections from inactive underground wells. Non-specialists are strictly prohibited from operating leak detection relays. Operational leak detection relays must undergo capacitive current compensation adjustments as per regulations, and the daily inspection and remote inspection systems must be strictly enforced.
5. Electrical equipment with the following issues must not be used underground:
(1) Combustible surface rust and scratches exceed the specified limit.
(2) Insulation seat破裂 resulted in loose terminal posts, deformed terminal posts, or stripped threads.
(3) Conductive bolts and nuts exhibit rust beyond the specified limits.
(4) Horn mouth fitting or breakage, damage;
(5) The switch body does not match the housing; the turning cover does not fit the housing, lacks a handle, or is not smooth to turn; the electrical bolt on the top of the switch's interior is loosely connected to the terminal nose.
(Mechanical interlock of the switch failed.)
(7) Lacking power isolation cover and hazard sign within the switch;
(8) The switch base is broken or not securely fastened.
(9) No certificate of explosion-proof compliance issued by a designated electrical equipment explosion-proof inspector; although a certificate is present, it has expired beyond 6 months or lacks the inspector's serial number stamp.
(10) The protective cover at the motor fan area is not securely fastened to the motor housing.
6. The grounding bolts for the metal housing of electrical equipment and armored cable junction boxes should be complete and in good condition, free of rust.
7. Nuts on mechanical components or parts prone to loosening under impact loads should be replaced with anti-loosening nuts (lock washers) or other anti-loosening devices. Bolts and nuts used for electrical part fastening should also be equipped with anti-loosening devices, and spring washers should be securely seated against the nuts.
8. The specifications of fasteners for the same part (including flat washers and spring washers) should be consistent.
9. After tightening the nut, the bolt threads should extend 1 to 3 threads beyond the nut. No additional washers or nuts should be added underneath to reduce the protrusion length of the bolt.
10. Explosion-proof外壳 for electrical equipment should be clean, intact, and free from damage, with clear explosion-proof markings. The following conditions are considered as a failure of explosion-proofing:
(1) The shell has cracks, welds open, and deformation exceeding 50mm in length, with a concave-convex depth over 5mm.
(2) Utilizing explosion-proof components (referring to critical pressure transmission parts) from factories that have not been certified by an authorized inspection unit of the ministry.
(3) Rust flaking off both inside and outside the explosion-proof housing.
(4) Incomplete locking devices or deformation and damage render them ineffective for mechanical locking.
Observation windows (holes) in explosion-proof compartments (cavities) are loose, cracked, or made of ordinary glass.
(6) Explosion-proof motor junction box lacks internal explosion-proof insulating base.
(7) Modification of the explosion-proof housing's original design and installation shape resulted in electrical clearances or creepage distances that did not meet regulations.
11. Cable introduction devices should have complete and tight connections with good sealing. Unconnected cables should be sequentially fitted with sealing rings and metal shims, then securely fastened; otherwise, it is considered an explosion hazard.
12. The "Three-Defined" Issue System: Explosion-proof inspectors regularly inspect explosion-proof electrical equipment. Issues identified undergo the "Three-Defined" treatment system, known as the "Three-Defined Table." After the defined improvements are made, a re-inspection is mandatory. Based on the re-inspection results, responsible parties will be rewarded or penalized accordingly.
13.防爆设备包机制 Implementation of the package system is an effective measure to enhance the daily maintenance of explosion-proof equipment during production operations, ensuring that its explosion-proof performance remains in good condition. The "package system" involves dividing the equipment based on its distribution, type, and quantity, forming teams responsible for specific areas. These teams consist of operators, users, and maintenance personnel. They are responsible for the operation, maintenance, management, inspection, and repair of the assigned equipment. Each team member is assigned to a specific machine, with names displayed for accountability. Responsibility is assigned to individuals, and a practical reward and punishment system is in place to encourage staff to take care of the equipment and strengthen their sense of responsibility.
14. Explosion-Proof Equipment Inspection and Maintenance System To ensure the safe operation of explosion-proof electrical equipment underground and to prevent accidents before they happen, a system for inspecting and maintaining explosion-proof equipment should be established. According to the regulations, regular inspections and tests should be conducted on the explosion-proof performance of underground electrical equipment, the insulation levels of major electrical equipment, and the reliability of various protective devices, to promptly identify and eliminate potential hazards.
Electrical equipment should adhere to the five principles of "three no's, four yes's, three all's, two alignments, and three continuances."
"No Three": No chicken feet, no goat tails, no visible joints.
"The Four Haves": Flow and leakage protection devices, screw and spring washers, seals and shims, and grounding equipment.
"Three-in-One Protection": Full protective devices, full insulation equipment, and complete technical drawings and documents.
"Two Standards of Perfection": Cables hung neatly, equipment kept clean and tidy.
"Three Commitments": Commit to using residual current relays, adhere to the use of lighting and signaling comprehensive protection, and insist on using gas cutoff meters and wind power interlocks.
16. Electrical equipment should not exceed its rated values during operation. Before explosion-proof electrical equipment is brought into the mine, it must be inspected for its "Product Qualification Certificate," "Explosion-Proof Qualification Certificate," "Safety Mark for Coal Mine Products," and safety performance. Only after passing the inspection and receiving a certification can the equipment be allowed into the mine.
17. The selection of underground cables should comply with the following regulations:
The horizontal difference at the cable laying location should correspond to the allowed horizontal difference specified for the cable.
Cables should be equipped with conductors of sufficient cross-sectional area for protective grounding.
The cross-section of the cable's secondary core should meet the load requirements of the power supply line.
