Mine safety electricity

Electricity is an important energy source in the production and construction of mines. With the rapid development of mining in China, the degree of electrification is getting higher and higher, the relationship between mines and electricity is closer, and more and more people are in contact with electrical systems. Electricity is used to improve mine operations. The working conditions of employees and the improvement of mining productivity have played a huge role.

However, if the management of electricity is not good, improper inspection will bring many unsafe factors. Electricity has the characteristics of fast speed, invisibility, inability to touch, and inaudibility. Especially the working conditions of underground electrical equipment are special, the space is narrow, the environment is dark, the air is humid, and the electrical equipment and cables are vulnerable to pressure and pressure. The insulation is damaged, so the electric shock accident is extremely likely to occur in the underground. Therefore, in order to ensure the safe use of electricity in mines, the relevant regulations must be observed.

First, the power supply

(1) The design, installation, acceptance, operation, maintenance and safety inspection of various electrical equipment or power systems in underground mines shall comply with the current relevant safety regulations of the Ministry of Water and Electricity.

(2) The distribution voltage of all levels in the well shall comply with the following regulations:

1 The distribution voltage of the high-voltage network shall not exceed 7kV, and if it is conditional, it shall not exceed 10kV.

2 The distribution voltage of the low-voltage network shall not exceed 1200V.

3 lighting voltage, transportation roadway, no more than 220V; mining work surface, mining roadway, patio and patio to the working face, no more than 36V; line lights, no more than 36V.

4 The voltage of the portable power tool should be no more than 127V.

5 Motor vehicle power supply voltage, AC power supply does not exceed 400V, DC power supply does not exceed 600V.

(3) At least two lines shall be laid from the ground to the central power substation of the underground or the main pump house, and any one of the cables shall be faulty, and the original power transmission capacity shall be ensured. Small mines that are not in danger of flooding are not limited.

(4) Mine electrical equipment is prohibited from being connected to zero. The mine should use a mine transformer. If an ordinary transformer is used, the neutral point should not be directly grounded. A transformer or generator that is directly grounded at the ground neutral point is not allowed to supply power to the well.

(5) It is forbidden to install an automatic reclosing device for the circuit breakers that supply power to the underground and the circuit breakers of the underground central substation.

(6) Each mine must be provided with a map of the ground and underground power distribution system, a layout diagram of underground electrical equipment, and plans for power, telephone, signal, and electric vehicles.

Second, the electrical circuit

(1) Steel road belt armored cables shall be used for horizontal roadways or roadways with inclination angles less than 45°. Steel shaft armoured cables shall be used for shafts or roadways with an inclination of more than 45°. For mobile power lines, special rubber cables for underground use should be used. Armored cables should be used for downhole signals or control lines. For lighting cables laid down underground, if there is mechanical damage, steel cable armored cables should be used.

(2) The armored cable laid in the diverticulum or dry wood support roadway must be stripped of the jute skin and regularly coated with anti-rust and waterproof paint on the armored casing.

(3) The cable laid in the shaft must be adapted to the depth of the shaft, and no joint is allowed in the middle. If the shaft is too deep, the joint part should be placed in the middle section of the roadway.

(4) When laying the cable in the hole, the cable should be firmly fixed on the steel rope. When the hole is not stable, the protection tube should be laid.

(5) when laying the cables along the ground to be covered iron from non-combustible materials in the mass drifts individual lots. It is not allowed to cover the cable trench with wood or to lay cables in the ditch.

(6) Cables laid in mines must comply with the following regulations:

1 In horizontal wells or wells below 45, the cable suspension height and position should be such that it is not crushed by vehicle collisions. The distance between the cable suspension points should be no more than 3 m, and the factory factory clearance should not be less than 50 mm. It is not allowed to hang the cable on the air pipe.

No objects are allowed to hang on the cable. When the cable is laid in parallel with the wind pipe, it shall be placed above the pipe and shall not be less than 0.3 m from the pipe.

2 In shafts or wells above 45°, the distance from the cable suspension point shall not exceed 3m in the inclined shaft; in the shaft shall not exceed 6m, the clamps, clamps or other clamping devices for laying cables shall be able to withstand The weight of the cable must not damage the outer skin of the cable.

3 Rubber cable should have a core wire for grounding, and the grounding wire should not be used for other purposes.

4 The distance between the high and low cables must not be less than 0.3m.

(7) the cable through the firewall, waterproof wall portion or chamber, respectively, should be a metal tube or protective concrete pipe, should be strictly closed hole.

(8) For the cables in the roadway, signs with numbers, uses and voltages shall be hung at regular distances and at the branch points.

Third, electrical and protection

(1) The short-circuit capacity of the underground high-voltage network should not exceed 70 mV.A. When using an oil circuit breaker that is not specified for underground use, the maximum breaking capacity shall not exceed 1/2 of the rated capacity. The low-voltage feeder drawn from the underground central substation or the goaf substation shall be equipped with current. Protected automatic switch.

(2) When the overhead line is used for power transmission to the underground central substation, a lightning protection device shall be provided at the terminal line of the wellhead and the busbar side of the underground power distribution station.

(3) The high-voltage feeder of the underground substation should be equipped with a leak detection device, a low-voltage bus and a feeder that is sent to the working surface. A leak detection device or indicator for disconnecting the power supply should be provided.

(4) The leak detection device must be sensitive and reliable, and must not be arbitrarily cancelled. The on-duty personnel will check the operation of the operation on a daily basis.

Fourth, the electromechanical chamber

(1) Other permanent electromechanical chambers in the mine permanent central transformer substation or underground vehicle yard must be built. The chamber of the substation of the mining area shall be supported by non-combustible materials. The roof and walls of the chamber should be free of water.

(2) The ground of the central substation should be higher than the roadway of the population at the roadway o.5m; when adjacent to the pump house, it should be higher than the ground of the pump house by 0.3m. In the goaf substation and other electromechanical chambers, the ground should be 2.2m higher than the roadway surface of the population.

(3) For power distribution and drainage rooms with a length of more than 6 m, an outlet shall be provided at each end and an iron fence door shall be provided. Fire-resistant doors and waterproof doors shall be provided for the electromechanical chambers of mines that are in danger of flooding, explosion or fire.

(4) The control devices for various electrical equipment in the room must indicate the number and purpose, and have a power transmission stop sign. The diverticulum population must hang the safety sign “No staff is prohibited from entering”. High-voltage electrical equipment must be hung with a “high-voltage hazard” safety sign and should be illuminated.

5. Lighting, communication and signals

(1) All working sites, sidewalks and sidewalks leading to the site must be well lit.

(2) Mobile electric lighting can be used for the mining face. Portable mines and mining faces should be used for mines and mining faces that are at risk of explosion. The lighting of the explosives store shall be carried out in accordance with the provisions of GB 6722 "Blasting Safety Regulations".

(3) The 380V power supply line from the substation to the lighting transformer shall be a dedicated line and shall not be shared with the power line. The lighting power supply shall be taken out from the automatic switch on the low-voltage outlet side of the transformer in the substation.

(4) The bottom hole yard, the main electromechanical chamber, the dispatching room and the mining area shall be equipped with communication devices. Downhole substations, main pump rooms and main fan rooms must have direct access to the ground exchange or dispatch room. A direct telephone must be installed between the signal rooms of the main transport lanes.

(5) The electrical signal of the mine must be able to emit sound or illuminate at the same time. The lifting device shall have an independent signal system, the signal supply voltage shall not exceed 127V, and a dedicated transformer shall be provided for power supply.

Sixth, protective grounding

(1) The metal casing, cable accessories, metal sheath, etc. of all electrical equipment in the mine must be grounded. Metal structures close to the cable line in the roadway should be grounded.

(2) The provisions of the mine electrical equipment protection grounding system are:

1 All equipment that needs to be grounded and local grounding should be connected to the grounding trunk. The grounding trunk should be connected to the main grounding pole to form a grounding grid.

2 For mobile and portable electrical equipment, the grounding core of the rubber cable should be used and connected to the grounding trunk.

3 All grounded equipment in the mine must have a separate grounding cable. Do not connect the grounding cables of several electrical equipment in series.

4 The metal sheath of all cables in the mine must have a reliable electrical connection to form a grounding trunk.

(3) The grounding pole should meet the following requirements:

1 The main grounding pole of the equipment in the water tank or puddle shall be made of steel plate with an area of ​​not less than o.75m2 and a thickness of not less than 5mm.

2 The local grounding electrode installed in the drainage ditch shall be made of steel plate with an area of ​​not less than 0.6 m2 and a thickness of not less than 0.4 mm, or a steel pipe of the same area and thickness not less than 3.5 mm. And should be placed in the depths of the ditch.

3 Local grounding poles installed at other locations shall be made of steel pipes with a diameter of not less than 35 mm and a length of not less than 1.5 m, and shall be buried directly underground. There shall be at least 20 holes of not less than 5 mm in diameter on the steel pipe.

(4) The grounding trunk wire shall be made of flat steel with a sectional area of ​​not less than 100 mm2 and a thickness of not less than 4 mm, or round steel with a diameter of not less than 12 mm. The connecting line between the outer casing of the electrical equipment and the grounding trunk (except for the cable core), the cable metal connecting line at the two ends of the cable junction box shall be flat steel with an area of ​​not less than 48 mmz and a thickness of not less than 4 mm or a diameter of not less than 8 Round steel of mm.

All steels (5) grounding devices must zinc plating or tin plating. Corrosion protection measures shall be taken for the connection line of the grounding device.

(6) The grounding resistance of each main grounding pole shall not exceed 2 n from the main grounding pole to the farthest local grounding device. The grounding resistance of each mobile electrical device to the grounding conductor must not exceed 1Ω. When the single-phase grounding current of the high-voltage system is greater than 20A, the maximum contact voltage of the grounding device should not exceed 40V.

Seven, inspection and maintenance

(1) Inspection and maintenance of electrical equipment shall be carried out with reference to the following table.

Check item

check the time

Underground automatic protection device

Main electrical equipment insulation resistance

Determination of all grounding grids and total grounding grid resistance

High voltage cable withstand test, rubber cable

New installations and long-term non-operating electrical equipment must measure insulation and grounding resistance before closing

Once a season

Once a season

Once a season

Once a season

at any time

(2) Insulating oil used in electrical equipment and transformers, in general, physical and chemical properties and withstand voltage tests shall be carried out once a year; for insulating oils used in electrical equipment with frequent operation, pressure test shall be carried out once every six months; replace.

(3) Mine electrical operators must comply with the following regulations:

1 For power outages and power transmissions of important lines and important workplaces, and for overhauling electrical equipment above 700V, work permits must be issued by the competent electrical engineer or technician to issue work tickets.

2 For electrical equipment above 700V, protective equipment (insulated gloves, insulated shoes, insulating mats and insulating tables) must be used.

3 It is forbidden to electrify to repair or move any live equipment. When servicing or moving, the power must be turned off and the conductors completely discharged and grounded.

4 When the power is off and overhauled, all the cut switch handles should be locked, and the safety warning sign “Someone works, no power transmission” is hung.

5 must be done by one person, one person is guarded, and single operation is prohibited.

(4) Rubber cable for power supply to mobile machinery (rock loader, electric drill, etc.), close to the mechanical section, should be laid along the ground, but its length should not exceed 15m, there must be no joint in the middle. The cable should be placed in a position to avoid damage by the running machinery.

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