Detail of GB 50070-2020

Introduction of GB 50070-2020

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. According to the requirements of Document JIANBIAO [2015] No.274 issued by the Ministry of Housing and Urban-Rural Development of the People's Republic of China - Notice on printing and distributing the development and revision plan on engineering construction standards and codes in 2016, the drafting group of standard has revised this standard through extensive investigation and study, careful summarization of practical experience and reference to relevant international and foreign advanced standards and on the basis of widely soliciting for opinions. The main technical contents of this standard are: general provisions, terms, basic requirements, subterranean part of underground mine, open pit and dump of surface mine, electric traction, preparation plant and major fixed equipment. The main technical contents revised by this standard are as follows: the relevant contents of the resistance drive system for the rotor series of wound rotor asynchronous motor in Clause 8 of the original code are deleted, and important provisions about underground distribution voltage and protective earthing are increased and modified. The provisions printed in bold type in this standard are compulsory and must be enforced strictly. The Ministry of Housing and Urban-Rural Development of the People’s Republic of China is in charge of the administration of this standard; China National Coal Construction Association responsible for the routine management; Beijing Huayu Engineering Co., Ltd. responsible for the explanation of specific technical contents. During the process of implementing this standard, the relevant opinions and advices, whenever necessary, can be posted or passed on to Beijing Huayu Engineering Co., Ltd. (Address: No.67, Ande Road, Xicheng District, Beijing, 100120, China). Contents 1 General provisions 1 2 Terms 2 3 Basic requirements 4 4 Subterranean part of underground mine 9 4.1 Power supply and distribution system 9 4.2 Electric apparatus and protection 11 4.3 Cable lines 13 4.4 Electric apparatus chamber 15 4.5 Lighting 16 4.6 Protective earthing 18 5 Open pit and dump of surface mine 21 6 Electric traction 26 6.1 General requirements 26 6.2 DC traction substation 27 6.3 DC traction network 28 7 Preparation plant 35 7.1 Power supply and distribution system 35 7.2 Process flow control 36 8 Major fixed equipment 38 8.1 Hoist of underground mine 38 8.2 Main fan of underground mine 41 8.3 Main drainage pump of underground mine 41 8.4 Air compressor 42 8.5 Belt conveyor 42 8.6 Cargo ropeway 43 Explanation of wording in this standard 45 List of quoted standards 46 1 General provisions 1.0.1 This standard is formulated for the purpose of implementing national laws, regulations, principles and policies for design of electric power in mine, ensuring life safety and equipment safety, achieving reliable power supply and distribution, saving energy, being friendly to environment, using advanced technologies and being economical and reasonable. 1.0.2 This standard is applicable to electric power design for new construction, renovation and extension of various mines (except for petroleum mines). 1.0.3 The scheme and equipment level for design of electric power in mine shall be reasonably determined according to mine scale, process characteristics, load nature, electricity consumption capacity and regional power supply conditions. 1.0.4 In the design of electric power in mine, the relationship between short-term and long-term development of electric power in mine according to engineering scale, service life and development plan of the mine, with the short-term development to be given priority, and the long-term development to be reasonable considered. When conditions permit, the infrastructure shall be combined with production electricity facilities. 1.0.5 In addition to this standard, the design of electric power in mine shall also meet the requirements of the current relevant standards of the nation.   2 Terms 2.0.1 mining area substation substation that distribute power to the whole or part of mining area, which usually includes several mines, surface mines, ore dressing plant and administration and production management organizations, auxiliary and affiliated enterprises in the mining area 2.0.2 surface main substation power transformer and distribution center for enterprise located on the ground of mine or surface mine, which receives and converges the external power supply of the enterprise and has the function of distributing all or part of the load within the enterprise, also known as total step-down substation 2.0.3 underground main substation underground transformer and distribution center which is set in the shaft station or main transportation roadway at the main mining level, receives the power supply from the mine ground, and has the function of distributing all or part of the load at this mining level (or sometimes including the adjacent mining levels), also known as underground central substation 2.0.4 working section substation substation that distributes loads to one or more underground mining areas 2.0.5 plant of utilizing castoff or by-product in mine for generating electricity enterprise that uses low-heat-value waste generated in mine production and processing and mining by-products such as coalbed methane as fuels to produce electricity and heat 2.0.6 mining electric apparatus for non-explosive atmospheres electric apparatus meeting the specific safety requirements of mine and also applicable to underground normal operation area with no explosive hazards 2.0.7 underground main earthed electrode metal-plate-type earthed electrode arranged in underground main or auxiliary dibhole 2.0.8 underground local earthed electrode earthed electrode set in underground location equipped with centralized or separate electric apparatus, in addition to main earthed electrode 2.0.9 underground protective conductor conductor set for underground electrical safety   2.0.10 underground earth device assembly of underground earthed electrode, earth conductor and earth bus, among which the earthed device containing underground main earthed electrode is called the main earthed device, and the earthed device containing underground local earthed electrode is called local earthed device 2.0.11 underground general earth network all earth systems which are mutually connected and have good conductivity, formed by main earthed devices and local earthed devices scattered in several underground locations which are connected with earthed conductors, at one or more underground mining levels or in underground local areas 2.0.12 underground conventional prospective touch voltage limit maximum expected contact voltage allowed to persist for unlimited time in underground environment in order to ensure personal safety   3 Basic requirements 3.0.1 Mine power loads shall be divided into primary loads, secondary loads and tertiary loads, which shall meet the following requirements: 1 The following loads shall be classified as primary loads: 1) The main drainage pumps of mines with underground flooding hazards and the drainage pumps of the mining area for downhill mining; 2) The main fans of mines with the hazards of explosion or serious damage to human health; 3) The shaft hoist for frequently lifting and lowering personnel in mines; 4) The drainage pumps for open pits of surface mines with flooding hazards or drainage pumps working through roadways; 5) Other equipment that shall be regarded as primary loads according to the current relevant national standards. 2 The following shall be classified as secondary loads: 1) Single equipment or interrelated groups of equipment directly related to mineral mining, transportation, lifting, processing and outward transportation in a large mine except for the primary loads; 2) Underground fixed lighting equipment without portable lighting fixtures, or emergency lighting equipment used to ensure the continuation of normal activities in workplaces with primary loads on the ground and secondary loads in large mines; 3) Power supply equipment for mine communication and safety monitoring devices; 4) Unwatering/drainage pumps for large surface mines; 5) Signal power supply equipment for railway stations; 6) Other equipment that shall be regarded as secondary loads according to the current relevant national standards. 3 Power equipment that does not belong to the primary loads and the secondary loads shall be classified into the tertiary loads. 3.0.2 The power supply for mines should be taken from substations in the regional power system, mining area substations, power plants for coal and electricity production or power plants in mining areas (mines). When it is difficult to obtain power from the above substations or power plants, it is allowable to obtain power from substations of neighboring enterprises. 3.0.3 The power supplies and the power supply lines of mines shall meet the following requirements: 1 Mines with primary loads shall be powered by dual power supply; when one circuit of power supply is interrupted, the other circuit of power supply shall not be damaged at the same time, and the power supply capacity shall at least ensure that all the primary loads of the mines are supplied with power, and should meet the power demand of secondary loads of the mines. 2 Large and medium-sized mines should be powered by two-circuit power supply lines; when either way of the two-circuit power supply lines is interrupted, the other power supply line shall ensure that all the primary and secondary loads are supplied with power. 3 Small mines without primary loads may be powered by one-circuit power supply lines. 3.0.4 The setting of self-contained power supply in mining areas (mines) shall be determined by technical and economic comparison according to regional power development planning, overall planning of mining areas, comprehensive utilization planning, relevant national industrial policies, industry access policies, environmental and water resources protection policies, and it shall meet one of the following conditions: 1 The mine is far away from the power system, or it is difficult to obtain all the required power from the power system; 2 Sufficient low heat value waste or coal bed methane and other mining by-products for power generation are generated as fuel in the process of production and processing in the mine, where it is suitable for building a plant of utilizing castoff or by-product in mine for generating electricity; 3 The mine or its vicinity has reliable heat load and central heating conditions, which is suitable for the development of cogeneration projects; 4 There are conditions to develop other distributed generation.   3.0.5 The power supply voltage of mine power should be 10kV~110kV; after it is determined to be reasonable through technical and economic comparison, other levels of voltage may be used. When the economic and technical indexes of two voltages are not much different, the higher voltage should be used. 3.0.6 For a mine project where the mine power supply voltage is greater than or equal to 20kV, the primary distribution voltage of the mine should be 10kV; after it is determined to be reasonable through technical and economic comparison, the project may be supplied with power of 6kV or locally of 20kV and above voltage. 3.0.7 The number of main transformers in surface main substation of the mine shall be determined according to the following requirements: 1 For large and medium-sized mine projects, two or more sets should be used; 2 If the two power supplies of primary load of the mine need to be transformed by the main transformers, two or more sets may be used; 3 For small mine projects without primary loads, one set may be used. 3.0.8 If there are two or more main transformers in the surface main substation of the mine, when one of them stop running, the capacity of the other transformers shall be able to ensure the power supply for primary and secondary loads. 3.0.9 The neutral earthed mode for the 6kV or 10kV system in the mine shall be selected according to the requirements of uninterrupted power supply in the mine, the influence of single-phase earthed fault voltage on personal safety, the magnitude of the current of single-phase earthed capacitance, the overvoltage of single-phase earthing and the requirements for insulation level of electric apparatus, and shall meet the following requirements: 1 If a single-phase earthed fault occurs in the 6kV or 10kV system and the fault circuit needs to be kept running for a short period of time without immediate removal, the system shall be unearthed, high resistance earthed or arc suppression coil earthed, and the current flowing through the single-phase earthed fault point shall be limited within 10A; 2 If a single-phase earthed fault occurs in the 6kV or 10kV system and the fault circuit needs to be cut off quickly, the system may be low resistance earthed, and the current flowing through the single-phase earthed fault point shall be limited within 200A; 3 For the 6kV or 10kV system for supplying power to open pits and dumps of underground or surface mines, the neutral point shall not be directly earthed.   3.0.10 For the surface main substations in the underground mines and surface mines and other substations that distribute power to open pits and dumps in underground or surface mines, single-phase earth protection shall be set up on each 6kV or 10kV feeder wire according to the following requirements: 1 If the neutral point of the 6kV or 10kV system in a mine is unearthed, high resistance earthed or arc suppression coil earthed, selective single-phase earth protection shall be set up, and the protection shall act on signal or trip-out; 2 If the neutral point of the 6kV or 10kV system in the mine is low-resistance earthed, two-stage zero sequence current protection shall be provided; the first stage shall be zero sequence current quick break with a time limit of no more than 0.5s; the second stage shall be zero sequence overcurrent protection with a time limit that shall be the same as that of interphase overcurrent protection. 3.0.11 The electromagnetic compatibility levels of the internal coupling points of the mine power supply and distribution system should meet the requirements of the current national standard GB/T 18039.4 Electromagnetic compatibility - Environment - Compatibility levels in industrial plants for low-frequency conducted disturbances for the electromagnetic compatibility levels of Class 3 plants. When the internal coupling points of the distribution system are used to supply power to equipment and devices sensitive to power disturbance, measures should be taken to improve the local electromagnetic environment or connect the equipment and devices with the power supply that meets the requirements of the current national standard GB/T 18039.4 Electromagnetic compatibility - Environment - Compatibility levels in industrial plants for low-frequency conducted disturbances for the electromagnetic compatibility levels of Classes 1 and 2 plants. 3.0.12 The location of the surface main substation in a mine shall meet the following requirements: 1 It shall be close to the load centers, convenient for incoming and outgoing lines; 2 It shall be economical in land utilization; 3 It should not be set up above land resources; 4 It shall be far away from pollution, environment with fire and explosive hazards, and environment with noise and vibration; 5 It should avoid unfavorable geological zones such as faults, areas with landslide hazards, low-lying areas and subsidence areas; 6 It shall be at least 200m from the mining boundary of the open pit of surface mine; at least 40m from the standard-gauge railway. 3.0.13 In addition to the relevant requirements of the nation and the power industry, the paths of fixed high-voltage overhead power lines in a mine shall be selected according to the following requirements: 1 Such lines shall not be erected in blasting operation areas and unstable waste disposal areas, and shall be kept an appropriate safe distance from them. 2 Well (mine) field boundary, fault mine pillars or other mine pillars should be used; if no mine pillars are available, the lines should seldom pass through the surface road sections of the mine and avoid passing through the initial subsidence areas. 3 If it is necessary to pass through a subsidence area due to restrictions of conditions, such lines shall seldom pass through the road section of the subsidence area, and there shall be enough safe distance between the two-circuit power lines passing through the subsidence area and other necessary safety measures shall be taken; mine power lines erected on the same poles (towers) should not pass through areas where subsidence may occur or subsidence areas which are not stable yet.

Contents of GB 50070-2020

1 General provisions 2 Terms 3 Basic requirements 4 Subterranean part of underground mine 4.1 Power supply and distribution system 4.2 Electric apparatus and protection 4.3 Cable lines 4.4 Electric apparatus chamber 4.5 Lighting 4.6 Protective earthing 5 Open pit and dump of surface mine 6 Electric traction 6.1 General requirements 6.2 DC traction substation 6.3 DC traction network 7 Preparation plant 7.1 Power supply and distribution system 7.2 Process flow control 8 Major fixed equipment 8.1 Hoist of underground mine 8.2 Main fan of underground mine 8.3 Main drainage pump of underground mine 8.4 Air compressor 8.5 Belt conveyor 8.6 Cargo ropeway Explanation of wording in this standard List of quoted standards