Technical code for safety of low voltage power sup

Safety technical specifications for low voltage power supply in coal mines

I. inspection and maintenance system

1. Establish a regular patrol inspection system. The mechanical and electrical department shall organize relevant personnel to conduct a comprehensive inspection on the low-voltage power consumption on the ground every quarter. Daily life, logistics and diversified businesses should regularly organize self inspection according to the actual situation of the unit. For unattended substations, maintenance personnel shall be arranged to patrol regularly. Patrol inspection should be organized immediately after storms and ice and snow

2. Establish a regular maintenance system. At least once a quarter, the substation of each place shall be powered off for maintenance, and the transmission and distribution lines shall be overhauled once a half year, and the maintenance records shall be carefully made

３. Effectively strengthen the safety management of unattended substations. Clarify the units in charge and assign them to each person. It is equipped with safety technical operation procedures, patrol inspection system, regular maintenance system, electrical preventive test system, power supply system diagram, insulation protection products, safety protection fence, safety signs, fire equipment for 4-ball friction and wear test, and door locks. In addition to strictly implementing the electrical operation procedures, special personnel must be assigned to take care of the maintenance and power transmission to prevent accidental operation from injuring people

II. Electrical construction safety

1. All personnel engaged in low-voltage electrical operations must be trained, pass the examination and work with certificates

2. Sporadic construction must implement the sporadic construction safety book system, and carry out electrical operation according to the safety technical measures within the scope specified in the construction assignment

3. The system of power failure, power inspection and discharge must be implemented. Live work and drunk work are strictly prohibited

4. Electrical operators shall dress as required and have complete tools when working. Special tools and safety belts must be used when climbing poles or heights

5. The power supply lines of high voltage, low voltage or low voltage erected on the same pole must be powered off before climbing the pole

III. power transformation and distribution facilities and distribution lines

1. The safety facilities of the power transformation and distribution substation are complete, and the power supply system diagram consistent with the actual situation is hung (the drawing includes the main wiring of the relevant upper and lower substations)

2. The allocated overhead line poles and towers must be marked with the line name and pole number. When high and low voltage are erected on the same pole, they shall be marked respectively according to the upper and lower positions

３. The signs of outgoing cables are clear

IV. new load and temporary electricity

1. Workshops, teams, dormitories and offices shall not increase the power load at will. When adjustment is required, an application must be submitted and the construction can be carried out only after the approval of the mechanical and electrical department

2. The temporary power and lighting power of capital construction projects shall be implemented after being approved by the mechanical and electrical department

v. overcurrent and leakage protection

the main switch and shunt switch of the secondary outgoing line of the transformer in the first substation (substation) have reliable overcurrent protection. The overcurrent setting value shall be set and tested once a year. The test shall be set at any time when the load changes, and the overcurrent setting test records shall be kept

the insulation resistance of the components of the falling experimental machine

the installation of two leakage protection

1. The mobile equipment and hand-held tools of the three-phase four wire power supply system, as well as the electrical equipment in wet and field workplaces all year round, must be installed with leakage protection. In places where the power supply is introduced by overhead friction contact, the power switch must be equipped with leakage protector

2. Leakage protectors should be installed indoors in dormitories

３、  The coordination of installing two-level leakage protection should be: the upper level switch should be installed with a leakage protector with 200mA medium sensitivity and action time of 0.2 seconds (or 0.1 seconds), and the next level switch should be installed with a leakage protector with action current of 30mA and high sensitivity and action time of 0.1 seconds

4. The protective zero line behind the leakage protector cannot be grounded repeatedly. Do not use two leakage protectors in parallel

VI. grounding and zero connection

1. For three-phase four wire low-voltage power supply system, the neutral line of power transformer must be grounded and set with zero bus. The section, connection mode and phase color meet the regulations. The outgoing cable grounding wire of distribution points at all levels must be connected to the grounding wire of power cable. The distribution point with 3 or more switches or feeding out 3 or more lines must be set with zero bus, and the power supply and load out. Therefore, this is the first time to prepare a two-dimensional metal carbide wire. The grounding wire must be connected to the zero bus, and the zero bus must be set with repeated grounding electrodes

2. In places with explosion hazards, the neutral point of low-voltage power supply system is strictly prohibited from grounding, and the underground grounding protection rules shall be implemented

3. In the system of neutral connection for electrical protection, the metal shell of all electrical equipment should be reliably connected with the grounding point of the power end through the protective ground wire or the working zero wire

4. The grounding resistance of the neutral lead out of the transformer shall not exceed 4, and each repeated grounding resistance shall not be greater than 10

5. Any equipment in the three-phase four wire low-voltage power supply system is forbidden to adopt local grounding protection without neutral connection

6. The grounding resistance of lightning arresters in ground step-down stations, well towers, derricks and other factory buildings shall not be greater than 10

7. Heating, gas supply and water supply pipelines shall not be used as grounding;  It is forbidden to bury grounding electrodes in the workshop;  It is strictly forbidden to use the direct lightning protection downlead and grounding electrode of tall buildings as the power or lighting zero line for repeated grounding or working grounding