1. Pre-use inspection of explosion-proof electrical equipment: To ensure that the equipment meets the explosion-proof quality requirements before use, the "Regulation" stipulates: "Before using explosion-proof electrical equipment, it should be inspected for its 'Product Qualification Certificate', 'Explosion-proof Qualification Certificate', 'Safety Mark for Coal Mine Products', and safety performance. The coal safety mark must be verified on the website before use to confirm the coal safety certificate number and ensure it is within the validity period. Only after passing the inspection and obtaining the qualification certificate is the equipment allowed to be used."
The certification is affixed by explosion-proof inspectors inside the equipment. The issued certification is replaced every six months.
Main inspection items before use:
Are all the equipment components complete and intact?
② Are explosion-proof casings, junction boxes, bases, etc., deformed? Slight bulges or dents must not exceed the intact standard.
③ Is the explosion-proof shell 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 and observe the sensitivity and reliability of the opening, stopping, and clamping (or operation) actions, ensure the operation is normal, and check for any noises. The placement sequence should comply with the specified requirements. ⑥ The gap of the explosion-proof junction surface should meet the requirements, and each explosion-proof gap of every equipment and appliance should be measured individually.
7. Check for rust and mechanical damage on the flameproof joints, ensure the application of rust-preventive oil, and treatments such as phosphatizing should be conducted. The roughness must meet specifications, and mechanical damages like pinholes and scratches should not exceed the规定的 limits.
Upon inspection, electrical equipment meeting the explosion-proof quality requirements should be recorded in the Well Equipment Acceptance Record Form, and a "License" should be issued by the explosion-proof inspector. The "License" should indicate the equipment's name, specifications, model, serial number, recipient unit, inspector's name, and ID number.
2. Underground electrical equipment must comply with all technical requirements for explosion-proof performance. Electrical equipment with compromised explosion-proof performance must be handled or replaced immediately, and its continued use is strictly prohibited.
3. The setting value for underground overflow protection must match the calculated value. For those with inadequate sensitivity, use phase-sensitive protection. All types of overflow protection must undergo electrical tests as per regulations, and a flow test must be conducted before entering the well.
4. Strictly prohibit disconnection of various electrical protections in the wells. Non-specialists are strictly forbidden from operating leak detection relays. Operational leak detection relays must be adjusted for capacitive current compensation as per regulations, and the daily inspection and remote inspection systems must be strictly enforced.
5. Electrical equipment with the following issues is prohibited from being used in the well:
(1) Combustible surface rust and scratches exceed the specified limit.
(2) Insulation seat破裂resulting in loose terminal posts, deformed terminals, or stripped threads.
(3) Conductive bolts and nuts exhibiting rust beyond the specified limit;
(4) Hose nozzle malfunctions or breaks;
(5) The switch body does not match the housing, the cover does not fit the housing, the handle is missing, or the rotation is not smooth; the connection between the conductive bolt on the upper cavity of the switch and the terminal lug is loose.
(6) The mechanical interlock of the switch failed.
(7) Missing power isolation cover and hazard sign for power supply within the switch.
(8) The switch base bracket is broken or not securely fastened.
(9) Certificates of explosion-proof compliance issued without inspection by a designated electrical equipment explosion-proof inspector; certificates with inspection periods exceeding 6 months or without the inspector's serial number stamp.
(10) The protective cover at the motor's fan blade area is not securely fastened to the motor housing.
6. The grounding bolts for the metal enclosures of electrical equipment and armored cable junction boxes should be complete and qualified, free of rust.
7. Nuts on mechanical components or areas prone to loosening due to impact loads should be replaced with anti-loosening nuts (lock washers) or other anti-loosening devices. Bolts and nuts used for securing electrical parts should also be equipped with anti-loosening devices, and spring washers should be installed tightly against the nuts.
8. The specifications of fasteners (including flat washers and spring washers) for the same part should be consistent.
After the nut is tightened, the threads of the bolt should extend 1 to 3 pitches beyond the nut. Additional washers or nuts should not be added under the nut to reduce the protrusion length of the bolt.
10. Explosion-proof enclosures for electrical equipment should be clean, intact, and have clear explosion-proof markings. The following conditions constitute a failure of explosion-proofing:
(1) The casing exhibits cracks, weld separations, and deformities exceeding 50mm in length, with a concave-convex depth surpassing 5mm.
(2) Utilizing explosion-proof components (referring to critical pressure-activated transmission parts) from factories that have been produced with certifications from non-designated inspection units.
(3) Rusty scales have peeled off from the interior and exterior of the explosion-proof housing.
Locking devices are incomplete or deformed, thus failing to provide mechanical locking function.
Observation windows (holes) in explosion-proof compartments (cavities) are loose, cracked, or made of ordinary glass.
(B6) Explosion-proof motor junction box lacks internal explosion-proof insulating seat.
(7) Modification of the explosion-proof housing's original design and installation shape resulted in electrical clearances or creepage distances not meeting regulations.
11. The cable introduction device's wiring sockets should be complete, tight, and well-sealed. Unconnected cable introduction devices should be sequentially fitted with sealing rings and metal plates, followed by tight fastening; otherwise, it is considered to be unexploded.
12. The Three-Defined Issues System:防爆inspectors regularly inspect explosion-proof electrical equipment. Issues identified are addressed through the Three-Defined System, referred to as the "Three-Defined Table." After rectifying the issues, a follow-up review is mandatory, and based on the review results, responsible parties will be rewarded or penalized accordingly.
13. Anti-Explosion Equipment Package System: Implementing a package system is an effective measure to enhance the daily maintenance of anti-explosion equipment during production and operation, ensuring that its explosion-proof performance remains in good condition. The "package system" involves dividing the equipment into groups based on their distribution, types, and quantities, with each group consisting of operators, maintenance personnel, and forming a package team responsible for the operation, maintenance, management, inspection, and repair of the assigned equipment. The package team must divide responsibilities among its members, implement a system of designated personnel for designated machines, with names displayed for accountability, and have a practical reward and punishment system to encourage employees 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, it is essential to establish an inspection and maintenance system for explosion-proof equipment. According to the provisions of the "Regulations," regular checks 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. This will help identify and eliminate potential hazards in a timely manner.
Electric equipment should adhere to the five principles of "Three Noes, Four Haves, Three Wholes, Two Alignments, and Three Constants."
"No Three" – No chicken feet, no sheep tails, no exposed joints.
"The Four 'Haves': equipped with leakage and overcurrent protection devices, screw and spring washers, sealing rings and baffles, and grounding devices.
"Triple Full": Full protective equipment, full insulation tools, and complete technical drawings and documents.
"Two Standards of Perfection": Cables hung neatly and equipment kept clean and orderly.
"Three Commitments": Adherence to the use of residual current relays, lighting and signal comprehensive protection, and gas cutoff and wind turbine interlock systems.
16. Electrical equipment should not exceed its rated values during operation. Before explosion-proof electrical equipment is introduced into a 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 of compliance can the equipment be allowed into the mine.
17. The selection of underground cables shall comply with the following regulations:
The horizontal difference at the cable laying location should correspond to the allowable horizontal difference specified for the cable.
(2) The cable should be equipped with conductors of sufficient cross-section for protective grounding.
The cross-section of the cable's secondary core should meet the requirements of the power supply line's load.
