GBJ 65-1983 Grounding design specification for industrial and civil power installations
Some standard content:
Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Grounding of Industrial and Civilian Power Installations
Design Specification
GBJ65—83
1984 Beijing
Engineering Construction Standard Full-text Information System
W Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Grounding of Industrial and Civilian Power Installations
Design Specification
GBJ65—83
Editor Department: Ministry of Water Resources and Electric Power of the People's Republic of China Approval Department: State Planning Commission of the People's Republic of China Date of trial implementation: 1
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Notice on the issuance of "Industrial and Civil Power Supply System Design Specification", "Industrial and Civil 35kV Substation Design Specification" and other 14 design specifications by the State Construction Commission (71) Construction Reform Letter No. 150 requirements, the "Industrial and Civil Power Supply System Design Specification", "Industrial and Civil 35kV Substation Design Specification" and other 14 design specifications jointly compiled by the Ministry of Water Resources and Electric Power, the Ministry of Machinery Industry and relevant units have been reviewed by relevant departments. These 14 design specifications are now approved as national standards and will be implemented on a trial basis from June 1, 1984. The names, numbers and management units of the 14 specifications are as follows: "Industrial and Civil Power Supply System Design Specification" GBJ52-83, managed by the Ministry of Machinery Industry, and its specific interpretation and other work are the responsibility of the Second Design Institute of the Ministry of Machinery Industry.
2. "Design Specifications for Industrial and Civil 10kV and Below Substations" GBJ53-83 is managed by the Ministry of Machinery Industry, and its specific interpretation and other work is the responsibility of the Eighth Design Institute of the Ministry of Machinery Industry.
3. "Design Specifications for Low Voltage Distribution Devices and Lines" GBJ54-83 is managed by the Ministry of Machinery Industry, and its specific interpretation and other work is the responsibility of the Eighth Design Institute of the Ministry of Machinery Industry.
4. "Design Specifications for Power Installations for Industrial and Civil General Equipment" GBJ55-83 is managed by the Ministry of Machinery Industry, and its specific interpretation and other work is the responsibility of the Seventh Design Institute of the Ministry of Machinery Industry.
5. "Design Specifications for Power Installations for Electric Heating Equipment" GBJ56-83 is managed by the Ministry of Machinery Industry, and its specific interpretation and other work is the responsibility of the Design and Research Institute of the Ministry of Machinery Industry. 6. "Design Specifications for Lightning Protection of Buildings" GBJ57-83 is managed by the Ministry of Machinery Industry, and its specific interpretation and other work is the responsibility of the Design and Research Institute of the Ministry of Machinery Industry. Engineering Construction Standard Full Text Information System
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7. "Design Specifications for Power Installations in Explosion and Fire Hazardous Locations" GBJ58-83 is managed by the Ministry of Chemical Industry, and its specific interpretation and other work is the responsibility of the Chemical Engineering Design Company of the Ministry of Chemical Industry. 8. "Design Specifications for Industrial and Civil 35kV Substations" GBJ59-83 is managed by the Ministry of Water Resources and Electric Power, and its specific interpretation and other work is the responsibility of the East China Electric Power Design Institute of the Ministry of Water Resources and Electric Power.
9. "Design Specifications for Industrial and Civil 35kV High-voltage Distribution Devices" GBJ60-83 is managed by the Ministry of Water Resources and Electric Power, and its specific interpretation and other work is the responsibility of the Northwest Electric Power Design Institute of the Ministry of Water Resources and Electric Power.
10. "Design Specifications for Industrial and Civil 35kV and Below Overhead Power Lines" GBJ61-83 is managed by the Ministry of Water Resources and Electric Power, and its specific interpretation and other work is the responsibility of the Beijing Power Supply Bureau of the Ministry of Water Resources and Electric Power.
11. "Design Specifications for Relay Protection and Automatic Devices for Industrial and Civil Power Installations" GBJ62-83 is managed by the Ministry of Water Resources and Electric Power, and its specific interpretation and other work is the responsibility of the Northeast Electric Power Design Institute of the Ministry of Water Resources and Electric Power. 12. "Design Specifications for Electrical Measuring Instruments for Industrial and Civil Power Installations" GBJ63-83 is managed by the Ministry of Water Resources and Electric Power, and its specific interpretation and other work is the responsibility of the Southwest Electric Power Design Institute of the Ministry of Water Resources and Electric Power.
13. "Design Specifications for Overvoltage Protection of Industrial and Civil Power Installations" GBJ64-83 is managed by the Ministry of Water Resources and Electric Power, and its specific interpretation and other work is the responsibility of the High Voltage Research Institute of the Electric Power Research Institute of the Ministry of Water Resources and Electric Power. 14. "Grounding Design Specifications for Industrial and Civil Power Installations" GBJ65-83 is managed by the Ministry of Water Resources and Electric Power, and its specific interpretation and other work is the responsibility of the High Voltage Research Institute of the Electric Power Research Institute of the Ministry of Water Resources and Electric Power.
National Planning Commission
November 7, 1983
Engineering Construction Standards Full Text Information System
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Preparation Instructions
This specification is prepared by the Planning and Design Administration of the former Ministry of Water Resources and Electric Power in conjunction with relevant units in accordance with the Notice No. 150 of the former National Capital Construction Commission (71) Jian Ge Han Zi. During the preparation process, extensive investigations and studies were conducted, and the experience of power equipment grounding engineering design and production and operation since the founding of the People's Republic of China was summarized. The opinions of relevant units across the country were widely solicited, and the draft was finalized after review and revision in conjunction with relevant departments. The main contents of this specification include: general principles, general provisions, scope of protective grounding, grounding resistance, grounding device, grounding of fixed power equipment, grounding of portable and mobile power equipment, and grounding of DC power equipment. Since this specification is prepared for the first time, some contents need to be supplemented and improved in future work practice. During the trial implementation of this specification, if it is found that there is a need for modification or supplement, please send your opinions and materials directly to the High Voltage Institute of the Electric Power Research Institute of the Ministry of Water Resources and Electric Power and copy them to the Electric Power Planning and Design Institute of our ministry for reference in future revisions. Ministry of Water Resources and Electric Power
November 1983
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Chapter 1 General
Chapter 2
Chapter 3
General Provisions
Scope of Protective Grounding
Chapter 4
Grounding Resistance:
Section 1 High Voltage Power Equipment
Section 2
Low Voltage Power Equipment
Section 3
Section 4
Section Section 5
Chapter 5
Electrical Equipment in Areas with High Soil Resistivity
Overhead Lines and Cable Lines
Other Electrical Equipment
Grounding Devices
Section 1
Section 2
Section 3
Section 4
Chapter 6
Chapter 7
Chapter 8
Appendix 1
Appendix 2
Appendix 3
Central Power
Natural Grounding Electrodes and Artificial Grounding Electrodes·||tt ||Grounding device of substation
Grounding device of overhead line tower
Grounding device of power equipment in areas with high soil resistivity and permafrost areas 10 Grounding of fixed power equipment
Grounding of portable and mobile power equipment, grounding of DC power equipment
Calculation formula of power frequency grounding resistance
Explanation of terms
Explanation of terms used in this specification:
Engineering Construction Standard Full-text Information System
Engineering Construction Standard Full-text Information System
Main symbols||t t||E; when a ground short circuit occurs, the maximum permissible contact potential of the grounding device; together, the maximum permissible step potential,
-the total length of the horizontal and vertical grounding bodies of the grounding grid; L
the number of horizontal radial grounding bodies;
-the power frequency grounding resistance;
the radius of the circle with the same value as the area of the grounding grid, that is, the equivalent radius of the grounding grid,
-the total area of the grounding grid;
-the ground fault current used for calculation,
-the soil resistivity
-the soil resistivity of the ground surface.
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Chapter I General Provisions
Article 1.0.1 The grounding design of power installations must conscientiously implement the national technical and economic policies, and should ensure: personal and equipment safety, reliable power supply, advanced technology and economic rationality.
Article 1.0.2 The design of grounding of power equipment shall be reasonably determined according to the characteristics, scale, development plan and geological characteristics of the project. Article 1.0.3 The design of grounding of power equipment shall save non-ferrous metals and copper. Article 1.0.4 This specification is applicable to the grounding design of AC and DC power equipment in various industries such as industry, transportation, power, post and telecommunications, finance and trade, culture and education. Article 1.0.5 The design of grounding of power equipment shall also comply with the provisions of the current relevant national standards and specifications.
Chapter II General Provisions
Article 2.0.Article 1 To ensure the safety of personnel and equipment, power installations should be grounded or zeroed.
AC power equipment should make full use of natural grounding bodies for grounding, but the thermal stability of natural grounding bodies should be verified.
In DC power circuits that can form a current closed loop to the ground, natural grounding bodies shall not be used as the neutral line, grounding line, or grounding body of the current circuit. The neutral line, grounding body, and grounding wire dedicated to the DC power circuit shall not have a metal connection with the natural grounding body; if there is no insulating isolation device, the distance between them should not be less than 1 meter. The neutral line of the three-wire DC circuit should be directly grounded. Article 2.0.2 In the substation, electrical equipment of different purposes and different voltages should use a total grounding body unless otherwise specified, and the grounding resistance should meet the minimum value requirements.
Note: The grounding resistance in this specification refers to the power frequency grounding resistance. Article 2.0.3 If it is difficult to ground according to the requirements of this specification due to conditions, it is allowed to set up an insulating platform for operating and maintaining power equipment. The surroundings of the insulating platform should be kept as far as possible to prevent operators from accidentally touching foreign objects. Article 2.0.4 Power grids with directly grounded neutral points should be equipped with protection devices that can quickly and automatically cut off grounding short-circuit faults. Power grids with indirect neutral points should be equipped with signal devices that can quickly respond to grounding faults. If necessary, devices that delay automatic fault cutting can also be installed. Article 2.0.5 The neutral point of the low-voltage power grid can be directly grounded or ungrounded. When the safety conditions are high and there is a device that can quickly and reliably automatically cut off the grounding fault, the power grid should adopt the method of ungrounding the neutral point. Article 2.0.6 In low-voltage power grids with directly grounded neutral points, the shell of power equipment should adopt low-voltage zero protection, that is, zero connection. If there are few and scattered electrical equipment, it is difficult to use zero protection, and the soil resistivity is low, low-voltage grounding protection can be used. However, if the electrical equipment leaks electricity, the equipment casing and the metal parts electrically connected to it may be energized. Safety measures such as installing relay protection devices that automatically cut off the grounding fault, using insulating pads, installing fences or equalizing voltage should be taken. Low-voltage lines powered by the same generator, the same transformer or the same section of busbar should not use both zero connection and grounding protection methods. In low-voltage power grids, when it is really difficult to use zero connection protection for all, two protection methods can be used at the same time, but power equipment or line segments that are not zero-connected should be equipped with relay protection devices that can automatically cut off the grounding fault. The casing of power supply equipment in damp or particularly harsh places such as city defense and civil defense should be protected by zero connection.
Article 2.0.7 In low-voltage power grids where the neutral point is not directly grounded, the danger caused by insulation breakdown between the high and low voltage windings of the transformer should be prevented. A breakdown fuse must be installed on the neutral line or one phase line on the low-voltage side of the transformer. The terminals of low-voltage overhead power lines and the terminals of their branches should also be equipped with breakdown fuses on each phase line. In the safety voltage network, the neutral line or one phase line of the safety voltage power supply network should be grounded to prevent the danger caused by high voltage intrusion. If grounding is difficult, it can also be connected to the neutral line of the primary side of the transformer. Article 2.0.8 When determining the type and layout of the substation grounding device, the contact potential and step potential should be reduced as much as possible.
When a single-phase grounding occurs in a system with a small grounding short-circuit current, the fault is generally not quickly removed. At this time, the contact potential and step potential of the grounding device of the substation and power equipment should meet the requirements of the following formulas:
E;=50+0.05ps
E=50+0.2p
E,——contact potential (volts);
E—step potential (volts);
——soil resistivity on the ground surface (ohm·meter). (2.0.8—1)
(2.0.8-2)
In places with particularly harsh conditions, such as mines, underground and paddy fields, the allowable values of contact potential and step potential should be appropriately reduced. Article 2.0.9 When designing a grounding device, the effects of seasonal changes such as soil drying or freezing should be considered. The grounding resistance shall meet the requirements of this specification in all four seasons, but the grounding resistance of the lightning protection device can only consider the influence of the dry state of the soil in the thunder season. Chapter 3 Scope of protective grounding
Article 3.0.1 The following metal parts of the power installation shall be grounded or zeroed unless otherwise specified:
1. The base and casing of motors, transformers, electrical appliances, portable and mobile electrical appliances, etc.;
2. Power equipment transmission device;
3. The secondary winding of the mutual inductor;
4. The frame of the distribution panel and the control panel;
5. The metal structure and reinforced concrete structure of the distribution equipment inside and outside the room and the metal near the live parts Fences and metal gates; Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
6. The outer shell of AC and DC power cable junction boxes, terminal boxes and the outer sheath of cables, steel pipes for threading wires, etc.
7. Power line towers equipped with lightning conductors; 8. Metal towers and reinforced concrete towers for overhead power lines with small grounding short-circuit current without lightning conductors in residential areas on non-asphalt ground; 9. Power equipment such as switchgear and capacitors installed on distribution line towers; 10. The outer sheath of control cables.
Article 3.0.2 The following metal parts of power installations may not be grounded or zeroed, unless otherwise specified:
, 1. The casing of power equipment with an AC rated voltage of 380 volts or less and a DC rated voltage of 440 volts or less in a dry room with a poorly conductive floor such as wood or asphalt, except when maintenance personnel may touch the casing of the power equipment and a grounded object at the same time; 2. The casing of power equipment with an AC rated voltage of 127 volts or less and a DC rated voltage of 110 volts or less in a dry place; 3. The casing of electrical measuring instruments, relays and other low-voltage electrical appliances installed on distribution panels, control panels and distribution devices, as well as the metal base of insulators that will not cause dangerous voltage on the support when insulation damage occurs; 4. Equipment installed on a grounded metal structure, such as bushings, etc. (good electrical contact should be ensured);
5. Brackets in battery rooms with a rated voltage of 220 volts or less; 6. The casing of motors and electrical appliances that have reliable electrical contact with the grounded machine tool base.
Chapter 4
Grounding resistance
High-voltage power equipment
Section 1
Article 4.1.1 For power equipment with non-directly grounded neutral point, the grounding resistance of the grounding device shall meet the requirements of the following formula: 1. Grounding device shared by high-voltage and low-voltage power equipment
Engineering Construction Standard Full Text Information System
R≤10
(4.1.1-1)
R--the maximum grounding resistance (ohm) considering seasonal changes; I--the grounding fault current (ampere) used for calculation. When the total capacity of power equipment such as transformers running in parallel does not exceed 100 kVA, the grounding resistance should not exceed 10 ohms.
2. Grounding device used only for high-voltage power equipment R20
(4.1.1-2)
The grounding resistance should not exceed 10 ohms.
Article 4.1.2 In a power grid with an arc suppression coil grounded at the neutral point, when the grounding resistance of the grounding device is calculated according to formulas (4.1.1-1) and (4.1.1-2), the grounding fault current shall be taken as follows:
1. For the grounding device of a substation or power equipment equipped with an arc suppression coil, the calculated current is equal to 1.25 times the sum of the rated currents of the arc suppression coils connected to the same power grid in the same grounding device.
, For the grounding device of a substation or power equipment not equipped with an arc suppression coil, the calculated current is equal to the maximum possible residual current value when the largest arc suppression coil in the power grid is disconnected, but shall not be less than 30A.
Article 4.1.3 When determining the grounding fault current, the 5-10 year development plan of the power system and the plan of this project shall be considered. Article 4.1.4 In a small ground short-circuit current system, in order to ensure the rapid removal of the ground fault, the ground short-circuit operating current of the two-phase different points of the relay protection device, or the melting current of the fuse, shall be verified based on the grounding resistance of the substation grounding device. The ground short-circuit current should not be less than 1.5 times the operating current of the relay protection device converted to the primary side, or 4 times the rated current of the fuse. When the requirements cannot be met, the grounding resistance can be reduced or other measures can be taken. Section 2 Low-voltage power equipment
Article 4.2.1 The grounding resistance of the grounding device of low-voltage power equipment should not exceed 4 ohms.
Engineering Construction Standard Full Text Information SystemThe grounding resistance of a low-voltage power equipment grounding device should not exceed 4 ohms.
Engineering Construction Standard Full Text Information SystemThe grounding resistance of a low-voltage power equipment grounding device should not exceed 4 ohms.
Engineering Construction Standard Full Text Information SystemThe grounding resistance of a low-voltage power equipment grounding device should not exceed 4 ohms.
Engineering Construction Standard Full Text Information SystemThe grounding resistance of a low-voltage power equipment grounding device should not exceed 4 ohms.
Engineering Construction Standard Full Text Information SystemArticle 3 If it is difficult to ground according to the requirements of this specification due to conditions, it is allowed to set up an insulating platform for operating and maintaining power equipment. The surroundings of the insulating platform should be kept as far as possible to prevent operators from accidentally touching foreign objects. Article 2.0.4 Power grids with directly grounded neutral points should be equipped with protection devices that can quickly and automatically cut off grounding short-circuit faults. Power grids with indirect neutral points should be equipped with signal devices that can quickly respond to grounding faults. If necessary, devices that delay automatic fault cutting can also be installed. Article 2.0.5 The neutral point of the low-voltage power grid can be directly grounded or ungrounded. When the safety conditions are high and there is a device that can quickly and reliably automatically cut off the grounding fault, the power grid should adopt the method of ungrounding the neutral point. Article 2.0.6 In low-voltage power grids with directly grounded neutral points, the shell of power equipment should adopt low-voltage zero protection, that is, zero connection. If there are few and scattered electrical equipment, it is difficult to use zero protection, and the soil resistivity is low, low-voltage grounding protection can be used. However, if the electrical equipment leaks electricity, the equipment casing and the metal parts electrically connected to it may be energized. Safety measures such as installing relay protection devices that automatically cut off the grounding fault, using insulating pads, installing fences or equalizing voltage should be taken. Low-voltage lines powered by the same generator, the same transformer or the same section of busbar should not use both zero connection and grounding protection methods. In low-voltage power grids, when it is really difficult to use zero connection protection for all, two protection methods can be used at the same time, but power equipment or line segments that are not zero-connected should be equipped with relay protection devices that can automatically cut off the grounding fault. The casing of power supply equipment in damp or particularly harsh places such as city defense and civil defense should be protected by zero connection.
Article 2.0.7 In low-voltage power grids where the neutral point is not directly grounded, the danger caused by insulation breakdown between the high and low voltage windings of the transformer should be prevented. A breakdown fuse must be installed on the neutral line or one phase line on the low-voltage side of the transformer. The terminals of low-voltage overhead power lines and the terminals of their branches should also be equipped with breakdown fuses on each phase line. In the safety voltage network, the neutral line or one phase line of the safety voltage power supply network should be grounded to prevent the danger caused by high voltage intrusion. If grounding is difficult, it can also be connected to the neutral line of the primary side of the transformer. Article 2.0.8 When determining the type and layout of the substation grounding device, the contact potential and step potential should be reduced as much as possible.
When a single-phase grounding occurs in a system with a small grounding short-circuit current, the fault is generally not quickly removed. At this time, the contact potential and step potential of the grounding device of the substation and power equipment should meet the requirements of the following formulas:
E;=50+0.05ps
E=50+0.2p
E,——contact potential (volts);
E—step potential (volts);
——soil resistivity on the ground surface (ohm·meter). (2.0.8—1)
(2.0.8-2)
In places with particularly harsh conditions, such as mines, underground and paddy fields, the allowable values of contact potential and step potential should be appropriately reduced. Article 2.0.9 When designing a grounding device, the effects of seasonal changes such as soil drying or freezing should be considered. The grounding resistance shall meet the requirements of this specification in all four seasons, but the grounding resistance of the lightning protection device can only consider the influence of the dry state of the soil in the thunder season. Chapter 3 Scope of protective grounding
Article 3.0.1 The following metal parts of the power installation shall be grounded or zeroed unless otherwise specified:
1. The base and casing of motors, transformers, electrical appliances, portable and mobile electrical appliances, etc.;
2. Power equipment transmission device;
3. The secondary winding of the mutual inductor;
4. The frame of the distribution panel and the control panel;
5. The metal structure and reinforced concrete structure of the distribution equipment inside and outside the room and the metal near the live parts Fences and metal gates; Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
6. The outer shell of AC and DC power cable junction boxes, terminal boxes and the outer sheath of cables, steel pipes for threading wires, etc.
7. Power line towers equipped with lightning conductors; 8. Metal towers and reinforced concrete towers for overhead power lines with small grounding short-circuit current without lightning conductors in residential areas on non-asphalt ground; 9. Power equipment such as switchgear and capacitors installed on distribution line towers; 10. The outer sheath of control cables.
Article 3.0.2 The following metal parts of power installations may not be grounded or zeroed, unless otherwise specified:
, 1. The casing of power equipment with an AC rated voltage of 380 volts or less and a DC rated voltage of 440 volts or less in a dry room with a poorly conductive floor such as wood or asphalt, except when maintenance personnel may touch the casing of the power equipment and a grounded object at the same time; 2. The casing of power equipment with an AC rated voltage of 127 volts or less and a DC rated voltage of 110 volts or less in a dry place; 3. The casing of electrical measuring instruments, relays and other low-voltage electrical appliances installed on distribution panels, control panels and distribution devices, as well as the metal base of insulators that will not cause dangerous voltage on the support when insulation damage occurs; 4. Equipment installed on a grounded metal structure, such as bushings, etc. (good electrical contact should be ensured);
5. Brackets in battery rooms with a rated voltage of 220 volts or less; 6. The casing of motors and electrical appliances that have reliable electrical contact with the grounded machine tool base.
Chapter 4
Grounding resistance
High-voltage power equipment
Section 1
Article 4.1.1 For power equipment with non-directly grounded neutral point, the grounding resistance of the grounding device shall meet the requirements of the following formula: 1. Grounding device shared by high-voltage and low-voltage power equipment
Engineering Construction Standard Full Text Information System
R≤10
(4.1.1-1)
R--the maximum grounding resistance (ohm) considering seasonal changes; I--the grounding fault current (ampere) used for calculation. When the total capacity of power equipment such as transformers running in parallel does not exceed 100 kVA, the grounding resistance should not exceed 10 ohms.
2. Grounding device used only for high-voltage power equipment R20
(4.1.1-2)
The grounding resistance should not exceed 10 ohms.
Article 4.1.2 In a power grid with an arc suppression coil grounded at the neutral point, when the grounding resistance of the grounding device is calculated according to formulas (4.1.1-1) and (4.1.1-2), the grounding fault current shall be taken as follows:
1. For the grounding device of a substation or power equipment equipped with an arc suppression coil, the calculated current is equal to 1.25 times the sum of the rated currents of the arc suppression coils connected to the same power grid in the same grounding device.
, For the grounding device of a substation or power equipment not equipped with an arc suppression coil, the calculated current is equal to the maximum possible residual current value when the largest arc suppression coil in the power grid is disconnected, but shall not be less than 30A.
Article 4.1.3 When determining the grounding fault current, the 5-10 year development plan of the power system and the plan of this project shall be considered. Article 4.1.4 In a small ground short-circuit current system, in order to ensure the rapid removal of the ground fault, the ground short-circuit operating current of the two-phase different points of the relay protection device, or the melting current of the fuse, shall be verified based on the grounding resistance of the substation grounding device. The ground short-circuit current should not be less than 1.5 times the operating current of the relay protection device converted to the primary side, or 4 times the rated current of the fuse. When the requirements cannot be met, the grounding resistance can be reduced or other measures can be taken. Section 2 Low-voltage power equipment
Article 4.2.1 The grounding resistance of the grounding device of low-voltage power equipment should not exceed 4 ohms.
Engineering Construction Standard Full Text Information SystemArticle 3 If it is difficult to ground according to the requirements of this specification due to conditions, it is allowed to set up an insulating platform for operating and maintaining power equipment. The surroundings of the insulating platform should be kept as far as possible to prevent operators from accidentally touching foreign objects. Article 2.0.4 Power grids with directly grounded neutral points should be equipped with protection devices that can quickly and automatically cut off grounding short-circuit faults. Power grids with indirect neutral points should be equipped with signal devices that can quickly respond to grounding faults. If necessary, devices that delay automatic fault cutting can also be installed. Article 2.0.5 The neutral point of the low-voltage power grid can be directly grounded or ungrounded. When the safety conditions are high and there is a device that can quickly and reliably automatically cut off the grounding fault, the power grid should adopt the method of ungrounding the neutral point. Article 2.0.6 In low-voltage power grids with directly grounded neutral points, the shell of power equipment should adopt low-voltage zero protection, that is, zero connection. If there are few and scattered electrical equipment, it is difficult to use zero protection, and the soil resistivity is low, low-voltage grounding protection can be used. However, if the electrical equipment leaks electricity, the equipment casing and the metal parts electrically connected to it may be energized. Safety measures such as installing relay protection devices that automatically cut off the grounding fault, using insulating pads, installing fences or equalizing voltage should be taken. Low-voltage lines powered by the same generator, the same transformer or the same section of busbar should not use both zero connection and grounding protection methods. In low-voltage power grids, when it is really difficult to use zero connection protection for all, two protection methods can be used at the same time, but power equipment or line segments that are not zero-connected should be equipped with relay protection devices that can automatically cut off the grounding fault. The casing of power supply equipment in damp or particularly harsh places such as city defense and civil defense should be protected by zero connection.
Article 2.0.7 In low-voltage power grids where the neutral point is not directly grounded, the danger caused by insulation breakdown between the high and low voltage windings of the transformer should be prevented. A breakdown fuse must be installed on the neutral line or one phase line on the low-voltage side of the transformer. The terminals of low-voltage overhead power lines and the terminals of their branches should also be equipped with breakdown fuses on each phase line. In the safety voltage network, the neutral line or one phase line of the safety voltage power supply network should be grounded to prevent the danger caused by high voltage intrusion. If grounding is difficult, it can also be connected to the neutral line of the primary side of the transformer. Article 2.0.8 When determining the type and layout of the substation grounding device, the contact potential and step potential should be reduced as much as possible.
When a single-phase grounding occurs in a system with a small grounding short-circuit current, the fault is generally not quickly removed. At this time, the contact potential and step potential of the grounding device of the substation and power equipment should meet the requirements of the following formulas:
E;=50+0.05ps
E=50+0.2p
E,——contact potential (volts);
E—step potential (volts);
——soil resistivity on the ground surface (ohm·meter). (2.0.8—1)
(2.0.8-2)
In places with particularly harsh conditions, such as mines, underground and paddy fields, the allowable values of contact potential and step potential should be appropriately reduced. Article 2.0.9 When designing a grounding device, the effects of seasonal changes such as soil drying or freezing should be considered. The grounding resistance shall meet the requirements of this specification in all four seasons, but the grounding resistance of the lightning protection device can only consider the influence of the dry state of the soil in the thunder season. Chapter 3 Scope of protective grounding
Article 3.0.1 The following metal parts of the power installation shall be grounded or zeroed unless otherwise specified:
1. The base and casing of motors, transformers, electrical appliances, portable and mobile electrical appliances, etc.;
2. Power equipment transmission device;
3. The secondary winding of the mutual inductor;
4. The frame of the distribution panel and the control panel;
5. The metal structure and reinforced concrete structure of the distribution equipment inside and outside the room and the metal near the live parts Fences and metal gates; Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
6. The outer shell of AC and DC power cable junction boxes, terminal boxes and the outer sheath of cables, steel pipes for threading wires, etc.
7. Power line towers equipped with lightning conductors; 8. Metal towers and reinforced concrete towers for overhead power lines with small grounding short-circuit current without lightning conductors in residential areas on non-asphalt ground; 9. Power equipment such as switchgear and capacitors installed on distribution line towers; 10. The outer sheath of control cables.
Article 3.0.2 The following metal parts of power installations may not be grounded or zeroed, unless otherwise specified:
, 1. The casing of power equipment with an AC rated voltage of 380 volts or less and a DC rated voltage of 440 volts or less in a dry room with a poorly conductive floor such as wood or asphalt, except when maintenance personnel may touch the casing of the power equipment and a grounded object at the same time; 2. The casing of power equipment with an AC rated voltage of 127 volts or less and a DC rated voltage of 110 volts or less in a dry place; 3. The casing of electrical measuring instruments, relays and other low-voltage electrical appliances installed on distribution panels, control panels and distribution devices, as well as the metal base of insulators that will not cause dangerous voltage on the support when insulation damage occurs; 4. Equipment installed on a grounded metal structure, such as bushings, etc. (good electrical contact should be ensured);
5. Brackets in battery rooms with a rated voltage of 220 volts or less; 6. The casing of motors and electrical appliances that have reliable electrical contact with the grounded machine tool base. bzxz.net
Chapter 4
Grounding resistance
High-voltage power equipment
Section 1
Article 4.1.1 For power equipment with non-directly grounded neutral point, the grounding resistance of the grounding device shall meet the requirements of the following formula: 1. Grounding device shared by high-voltage and low-voltage power equipment
Engineering Construction Standard Full Text Information System
R≤10
(4.1.1-1)
R--the maximum grounding resistance (ohm) considering seasonal changes; I--the grounding fault current (ampere) used for calculation. When the total capacity of power equipment such as transformers running in parallel does not exceed 100 kVA, the grounding resistance should not exceed 10 ohms.
2. Grounding device used only for high-voltage power equipment R20
(4.1.1-2)
The grounding resistance should not exceed 10 ohms.
Article 4.1.2 In a power grid with an arc suppression coil grounded at the neutral point, when the grounding resistance of the grounding device is calculated according to formulas (4.1.1-1) and (4.1.1-2), the grounding fault current shall be taken as follows:
1. For the grounding device of a substation or power equipment equipped with an arc suppression coil, the calculated current is equal to 1.25 times the sum of the rated currents of the arc suppression coils connected to the same power grid in the same grounding device.
, For the grounding device of a substation or power equipment not equipped with an arc suppression coil, the calculated current is equal to the maximum possible residual current value when the largest arc suppression coil in the power grid is disconnected, but shall not be less than 30A.
Article 4.1.3 When determining the grounding fault current, the 5-10 year development plan of the power system and the plan of this project shall be considered. Article 4.1.4 In a small ground short-circuit current system, in order to ensure the rapid removal of the ground fault, the ground short-circuit operating current of the two-phase different points of the relay protection device, or the melting current of the fuse, shall be verified based on the grounding resistance of the substation grounding device. The ground short-circuit current should not be less than 1.5 times the operating current of the relay protection device converted to the primary side, or 4 times the rated current of the fuse. When the requirements cannot be met, the grounding resistance can be reduced or other measures can be taken. Section 2 Low-voltage power equipment
Article 4.2.1 The grounding resistance of the grounding device of low-voltage power equipment should not exceed 4 ohms.
Engineering Construction Standard Full Text Information System6. In low-voltage power grids with direct grounding at the neutral point, the outer shell of power equipment should be protected by low-voltage zero connection, i.e. zero connection. If there are few and scattered power equipment, it is difficult to use zero connection protection, and the soil resistivity is low, low-voltage grounding protection can be used. However, if the power equipment leaks electricity, the outer shell of the equipment and the metal parts electrically connected to it may be energized. Safety measures such as installing relay protection devices that automatically cut off the grounding fault, using insulating pads, installing fences or equalizing voltage should be taken. Low-voltage lines powered by the same generator, the same transformer or the same section of busbar should not use the two protection methods of zero connection and grounding. In low-voltage power grids, when it is difficult to use zero connection protection for all, both protection methods can be used at the same time, but power equipment or line segments that are not zero-connected should be equipped with relay protection devices that can automatically cut off the grounding fault. The outer shell of power supply equipment in damp or particularly harsh places such as city defense and civil defense should be protected by zero connection.
Article 2.0.7 In low-voltage power grids where the neutral point is not directly grounded, the danger caused by insulation breakdown between the high-voltage and low-voltage windings of the transformer should be prevented. A breakdown fuse must be installed on the neutral line or one phase line on the low-voltage side of the transformer. The terminals of the low-voltage overhead power line and its branch lines should also be equipped with a breakdown fuse on each phase line. In a safe voltage network, the neutral line or one phase line of the safe voltage power supply network should be grounded to prevent danger caused by high voltage intrusion. If grounding is indeed difficult, it can also be connected to the neutral line on the primary side of the transformer.
Article 2.0.8 When determining the type and layout of the substation grounding device, the contact potential and step potential should be reduced as much as possible.
When a single-phase grounding occurs in a system with a small grounding short-circuit current, the fault is generally not quickly removed. At this time, the contact potential and step potential of the grounding device of the substation and power equipment should meet the requirements of the following formulas:
E;=50+0.05ps
E=50+0.2p
E,——contact potential (volts);
E—step potential (volts);
——soil resistivity on the ground surface (ohm·meter). (2.0.8—1)
(2.0.8-2)
In places with particularly harsh conditions, such as mines, underground and paddy fields, the allowable values of contact potential and step potential should be appropriately reduced. Article 2.0.9 When designing a grounding device, the effects of seasonal changes such as soil drying or freezing should be considered. The grounding resistance shall meet the requirements of this specification in all four seasons, but the grounding resistance of the lightning protection device can only consider the influence of the dry state of the soil in the thunder season. Chapter 3 Scope of protective grounding
Article 3.0.1 The following metal parts of the power installation shall be grounded or zeroed unless otherwise specified:
1. The base and casing of motors, transformers, electrical appliances, portable and mobile electrical appliances, etc.;
2. Power equipment transmission device;
3. The secondary winding of the mutual inductor;
4. The frame of the distribution panel and the control panel;
5. The metal structure and reinforced concrete structure of the distribution equipment inside and outside the room and the metal near the live parts Fences and metal gates; Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
6. The outer shell of AC and DC power cable junction boxes, terminal boxes and the outer sheath of cables, steel pipes for threading wires, etc.
7. Power line towers equipped with lightning conductors; 8. Metal towers and reinforced concrete towers for overhead power lines with small grounding short-circuit current without lightning conductors in residential areas on non-asphalt ground; 9. Power equipment such as switchgear and capacitors installed on distribution line towers; 10. The outer sheath of control cables.
Article 3.0.2 The following metal parts of power installations may not be grounded or zeroed, unless otherwise specified:
, 1. The casing of power equipment with an AC rated voltage of 380 volts or less and a DC rated voltage of 440 volts or less in a dry room with a poorly conductive floor such as wood or asphalt, except when maintenance personnel may touch the casing of the power equipment and a grounded object at the same time; 2. The casing of power equipment with an AC rated voltage of 127 volts or less and a DC rated voltage of 110 volts or less in a dry place; 3. The casing of electrical measuring instruments, relays and other low-voltage electrical appliances installed on distribution panels, control panels and distribution devices, as well as the metal base of insulators that will not cause dangerous voltage on the support when insulation damage occurs; 4. Equipment installed on a grounded metal structure, such as bushings, etc. (good electrical contact should be ensured);
5. Brackets in battery rooms with a rated voltage of 220 volts or less; 6. The casing of motors and electrical appliances that have reliable electrical contact with the grounded machine tool base.
Chapter 4
Grounding resistance
High-voltage power equipment
Section 1
Article 4.1.1 For power equipment with non-directly grounded neutral point, the grounding resistance of the grounding device shall meet the requirements of the following formula: 1. Grounding device shared by high-voltage and low-voltage power equipment
Engineering Construction Standard Full Text Information System
R≤10
(4.1.1-1)
R--the maximum grounding resistance (ohm) considering seasonal changes; I--the grounding fault current (ampere) used for calculation. When the total capacity of power equipment such as transformers running in parallel does not exceed 100 kVA, the grounding resistance should not exceed 10 ohms.
2. Grounding device used only for high-voltage power equipment R20
(4.1.1-2)
The grounding resistance should not exceed 10 ohms.
Article 4.1.2 In a power grid with an arc suppression coil grounded at the neutral point, when the grounding resistance of the grounding device is calculated according to formulas (4.1.1-1) and (4.1.1-2), the grounding fault current shall be taken as follows:
1. For the grounding device of a substation or power equipment equipped with an arc suppression coil, the calculated current is equal to 1.25 times the sum of the rated currents of the arc suppression coils connected to the same power grid in the same grounding device.
, For the grounding device of a substation or power equipment not equipped with an arc suppression coil, the calculated current is equal to the maximum possible residual current value when the largest arc suppression coil in the power grid is disconnected, but shall not be less than 30A.
Article 4.1.3 When determining the grounding fault current, the 5-10 year development plan of the power system and the plan of this project shall be considered. Article 4.1.4 In a small ground short-circuit current system, in order to ensure the rapid removal of the ground fault, the ground short-circuit operating current of the two-phase different points of the relay protection device, or the melting current of the fuse, shall be verified based on the grounding resistance of the substation grounding device. The ground short-circuit current should not be less than 1.5 times the operating current of the relay protection device converted to the primary side, or 4 times the rated current of the fuse. When the requirements cannot be met, the grounding resistance can be reduced or other measures can be taken. Section 2 Low-voltage power equipment
Article 4.2.1 The grounding resistance of the grounding device of low-voltage power equipment should not exceed 4 ohms.
Engineering Construction Standard Full Text Information System6. In low-voltage power grids with direct grounding at the neutral point, the outer shell of power equipment should be protected by low-voltage zero connection, i.e. zero connection. If there are few and scattered power equipment, it is difficult to use zero connection protection, and the soil resistivity is low, low-voltage grounding protection can be used. However, if the power equipment leaks electricity, the outer shell of the equipment and the metal parts electrically connected to it may be energized. Safety measures such as installing relay protection devices that automatically cut off the grounding fault, using insulating pads, installing fences or equalizing voltage should be taken. Low-voltage lines powered by the same generator, the same transformer or the same section of busbar should not use the two protection methods of zero connection and grounding. In low-voltage power grids, when it is difficult to use zero connection protection for all, both protection methods can be used at the same time, but power equipment or line segments that are not zero-connected should be equipped with relay protection devices that can automatically cut off the grounding fault. The outer shell of power supply equipment in damp or particularly harsh places such as city defense and civil defense should be protected by zero connection.
Article 2.0.7 In low-voltage power grids where the neutral point is not directly grounded, the danger caused by insulation breakdown between the high-voltage and low-voltage windings of the transformer should be prevented. A breakdown fuse must be installed on the neutral line or one phase line on the low-voltage side of the transformer. The terminals of the low-voltage overhead power line and its branch lines should also be equipped with a breakdown fuse on each phase line. In a safe voltage network, the neutral line or one phase line of the safe voltage power supply network should be grounded to prevent danger caused by high voltage intrusion. If grounding is indeed difficult, it can also be connected to the neutral line on the primary side of the transformer.
Article 2.0.8 When determining the type and layout of the substation grounding device, the contact potential and step potential should be reduced as much as possible.
When a single-phase grounding occurs in a system with a small grounding short-circuit current, the fault is generally not quickly removed. At this time, the contact potential and step potential of the grounding device of the substation and power equipment should meet the requirements of the following formulas:
E;=50+0.05ps
E=50+0.2p
E,——contact potential (volts);
E—step potential (volts);
——soil resistivity on the ground surface (ohm·meter). (2.0.8—1)
(2.0.8-2)
In places with particularly harsh conditions, such as mines, underground and paddy fields, the allowable values of contact potential and step potential should be appropriately reduced. Article 2.0.9 When designing a grounding device, the effects of seasonal changes such as soil drying or freezing should be considered. The grounding resistance shall meet the requirements of this specification in all four seasons, but the grounding resistance of the lightning protection device can only consider the influence of the dry state of the soil in the thunder season. Chapter 3 Scope of protective grounding
Article 3.0.1 The following metal parts of the power installation shall be grounded or zeroed unless otherwise specified:
1. The base and casing of motors, transformers, electrical appliances, portable and mobile electrical appliances, etc.;
2. Power equipment transmission device;
3. The secondary winding of the mutual inductor;
4. The frame of the distribution panel and the control panel;
5. The metal structure and reinforced concrete structure of the distribution equipment inside and outside the room and the metal near the live parts Fences and metal gates; Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
6. The outer shell of AC and DC power cable junction boxes, terminal boxes and the outer sheath of cables, steel pipes for threading wires, etc.
7. Power line towers equipped with lightning conductors; 8. Metal towers and reinforced concrete towers for overhead power lines with small grounding short-circuit current without lightning conductors in residential areas on non-asphalt ground; 9. Power equipment such as switchgear and capacitors installed on distribution line towers; 10. The outer sheath of control cables.
Article 3.0.2 The following metal parts of power installations may not be grounded or zeroed, unless otherwise specified:
, 1. The casing of power equipment with an AC rated voltage of 380 volts or less and a DC rated voltage of 440 volts or less in a dry room with a poorly conductive floor such as wood or asphalt, except when maintenance personnel may touch the casing of the power equipment and a grounded object at the same time; 2. The casing of power equipment with an AC rated voltage of 127 volts or less and a DC rated voltage of 110 volts or less in a dry place; 3. The casing of electrical measuring instruments, relays and other low-voltage electrical appliances installed on distribution panels, control panels and distribution devices, as well as the metal base of insulators that will not cause dangerous voltage on the support when insulation damage occurs; 4. Equipment installed on a grounded metal structure, such as bushings, etc. (good electrical contact should be ensured);
5. Brackets in battery rooms with a rated voltage of 220 volts or less; 6. The casing of motors and electrical appliances that have reliable electrical contact with the grounded machine tool base.
Chapter 4
Grounding resistance
High-voltage power equipment
Section 1
Article 4.1.1 For power equipment with non-directly grounded neutral point, the grounding resistance of the grounding device shall meet the requirements of the following formula: 1. Grounding device shared by high-voltage and low-voltage power equipment
Engineering Construction Standard Full Text Information System
R≤10
(4.1.1-1)
R--the maximum grounding resistance (ohm) considering seasonal changes; I--the grounding fault current (ampere) used for calculation. When the total capacity of power equipment such as transformers running in parallel does not exceed 100 kVA, the grounding resistance should not exceed 10 ohms.
2. Grounding device used only for high-voltage power equipment R20
(4.1.1-2)
The grounding resistance should not exceed 10 ohms.
Article 4.1.2 In a power grid with an arc suppression coil grounded at the neutral point, when the grounding resistance of the grounding device is calculated according to formulas (4.1.1-1) and (4.1.1-2), the grounding fault current shall be taken as follows:
1. For the grounding device of a substation or power equipment equipped with an arc suppression coil, the calculated current is equal to 1.25 times the sum of the rated currents of the arc suppression coils connected to the same power grid in the same grounding device.
, For the grounding device of a substation or power equipment not equipped with an arc suppression coil, the calculated current is equal to the maximum possible residual current value when the largest arc suppression coil in the power grid is disconnected, but shall not be less than 30A.
Article 4.1.3 When determining the grounding fault current, the 5-10 year development plan of the power system and the plan of this project shall be considered. Article 4.1.4 In a small ground short-circuit current system, in order to ensure the rapid removal of the ground fault, the ground short-circuit operating current of the two-phase different points of the relay protection device, or the melting current of the fuse, shall be verified based on the grounding resistance of the substation grounding device. The ground short-circuit current should not be less than 1.5 times the operating current of the relay protection device converted to the primary side, or 4 times the rated current of the fuse. When the requirements cannot be met, the grounding resistance can be reduced or other measures can be taken. Section 2 Low-voltage power equipment
Article 4.2.1 The grounding resistance of the grounding device of low-voltage power equipment should not exceed 4 ohms.
Engineering Construction Standard Full Text Information System8-2)
In places with particularly harsh conditions, such as mines, underground and paddy fields, the allowable values of contact potential and step potential should be appropriately reduced. Article 2.0.9 When designing the grounding device, the influence of seasonal changes such as soil drying or freezing should be considered. The grounding resistance should meet the requirements of this specification in all four seasons, but the grounding resistance of the lightning protection device can only consider the influence of the dry state of the soil in the thunder season. Chapter 3 Scope of protective grounding
Article 3.0.1 The following metal parts of the power installation should be grounded or zeroed unless otherwise specified:
1. The base and casing of motors, transformers, electrical appliances, portable and mobile electrical appliances, etc.;
2. Transmission devices of power equipment;
3. Secondary windings of mutual inductors;
4. Frames of distribution panels and control panels;
5. Metal structures and reinforced concrete structures of distribution devices inside and outside the room, as well as metal close to live parts Fences and metal gates; Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
6. The outer shell of AC and DC power cable junction boxes, terminal boxes and the outer sheath of cables, steel pipes for threading wires, etc.
7. Power line towers equipped with lightning conductors; 8. Metal towers and reinforced concrete towers for overhead power lines with small grounding short-circuit current without lightning conductors in residential areas on non-asphalt ground; 9. Power equipment such as switchgear and capacitors installed on distribution line towers; 10. The outer sheath of control cables.
Article 3.0.2 The following metal parts of power installations may not be grounded or zeroed, unless otherwise specified:
, 1. The casing of power equipment with an AC rated voltage of 380 volts or less and a DC rated voltage of 440 volts or less in a dry room with a poorly conductive floor such as wood or asphalt, except when maintenance personnel may touch the casing of the power equipment and a grounded object at the same time; 2. The casing of power equipment with an AC rated voltage of 127 volts or less and a DC rated voltage of 110 volts or less in a dry place; 3. The casing of electrical measuring instruments, relays and other low-voltage electrical appliances installed on distribution panels, control panels and distribution devices, as well as the metal base of insulators that will not cause dangerous voltage on the support when insulation damage occurs; 4. Equipment installed on a grounded metal structure, such as bushings, etc. (good electrical contact should be ensured);
5. Brackets in battery rooms with a rated voltage of 220 volts or less; 6. The casing of motors and electrical appliances that have reliable electrical contact with the grounded machine tool base.
Chapter 4
Grounding resistance
High-voltage power equipment
Section 1
Article 4.1.1 For power equipment with non-directly grounded neutral point, the grounding resistance of the grounding device shall meet the requirements of the following formula: 1. Grounding device shared by high-voltage and low-voltage power equipment
Engineering Construction Standard Full Text Information System
R≤10
(4.1.1-1)
R--the maximum grounding resistance (ohm) considering seasonal changes; I--the grounding fault current (ampere) used for calculation. When the total capacity of power equipment such as transformers running in parallel does not exceed 100 kVA, the grounding resistance should not exceed 10 ohms.
2. Grounding device used only for high-voltage power equipment R20
(4.1.1-2)
The grounding resistance should not exceed 10 ohms.
Article 4.1.2 In a power grid with an arc suppression coil grounded at the neutral point, when the grounding resistance of the grounding device is calculated according to formulas (4.1.1-1) and (4.1.1-2), the grounding fault current shall be taken as follows:
1. For the grounding device of a substation or power equipment equipped with an arc suppression coil, the calculated current is equal to 1.25 times the sum of the rated currents of the arc suppression coils connected to the same power grid in the same grounding device.
, For the grounding device of a substation or power equipment not equipped with an arc suppression coil, the calculated current is equal to the maximum possible residual current value when the largest arc suppression coil in the power grid is disconnected, but shall not be less than 30A.
Article 4.1.3 When determining the grounding fault current, the 5-10 year development plan of the power system and the plan of this project shall be considered. Article 4.1.4 In a small ground short-circuit current system, in order to ensure the rapid removal of the ground fault, the ground short-circuit operating current of the two-phase different points of the relay protection device, or the melting current of the fuse, shall be verified based on the grounding resistance of the substation grounding device. The ground short-circuit current should not be less than 1.5 times the operating current of the relay protection device converted to the primary side, or 4 times the rated current of the fuse. When the requirements cannot be met, the grounding resistance can be reduced or other measures can be taken. Section 2 Low-voltage power equipment
Article 4.2.1 The grounding resistance of the grounding device of low-voltage power equipment should not exceed 4 ohms.
Engineering Construction Standard Full Text Information System
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