JB/T 10181.1-2000 Calculation of cable current carrying capacity Part 1: Current carrying capacity formula (100% load factor) and loss calculation Section 1: General provisions
Some standard content:
ICS29.060.20
Mechanical Industry Standard of the People's Republic of China
JB/T10181.1~10181.6--2000
idt IEC 60287
Calculation of the current rating of electric cables2000-04-24 release
National Machinery Industry Bureau
2000-10-01 implementation
IEC Foreword ·
IEC Introduction ·
JB/T10181.1-2000 Calculation of cable current carrying capacity Part 1: Current carrying capacity formula (100% load factor) and loss calculation Section 2: General provisions
JB/T10181.2-2000 Calculation of cable current carrying capacity Part 1: Current carrying capacity formula (100% load factor) and loss calculation Section 2: Eddy current loss factor of metal sheath of double-circuit planar arrangement cable JB/T10181.3-2000 Calculation of cable current carrying capacity Part 2: Thermal resistance Section 1: Calculation of thermal resistance
JB/T10181.4-2000 Calculation of cable current carrying capacity Part 2: Thermal resistance Section 2: Free air Calculation method for the reduction factor of the current carrying capacity of cable groups not exposed to direct sunlight in the atmosphere JB/T10181.5-2000 Calculation of cable current carrying capacity Part 3: Sections related to operating conditions Section 1: Benchmark operating conditions and cable selection JB/T10181.6-2000 Calculation of cable current carrying capacity Part 3: Sections related to operating conditions Section 2: Economic optimization selection of power cable cross-section Building 321Www.bzxZ.net
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JB/T10181.1~10181.6-2000
This standard is equivalent to the International Electrotechnical Commission (IEC) standard IEC60287 "Cable current carrying capacity calculation" (including IEC60287-11 Amendment No. 1 (1995), IEC60287-31 Amendment No. 1 (1999) and I EC60287--3-2 Amendment No. 1 (1996). This standard is the first mechanical industry standard formulated in China. This standard is the basic calculation method standard for wires and cables, and is widely used by cable design, laying and installation departments, and is therefore equivalent to the IEC60287 standard.
JB/T10181 consists of the following parts under the general title "Cable Current Carrying Capacity Calculation": JB/T10181.1 Part 1: Current Carrying Capacity Formula (100% Load Factor) and Loss Calculation Section 1: General Provisions
JB/T10181.2 Part 1: Current Carrying Capacity Formula (100% Load Factor) and Loss Calculation Section 2: Eddy Current Loss Factor of Metal Sheath of Double-Circuit Planar Arranged Cable JB/T10181.3 Part 2: Thermal Resistance
Section 1: Calculation of Thermal Resistance
JB/T10181.4 Part 2: Thermal resistance
Section 2: Calculation method for the reduction factor of the current carrying capacity of cable groups in free air without direct sunlight JB/T10181.5 Part 3: Sections related to operating conditions Section 1: Benchmark operating conditions and cable selection JB/T10181.6 Part 3: Sections related to operating conditions Section 2: Economic optimization of power cable cross-section Comparison of this standard with IEC60287 standard structure As shown in the following table: Appendix A and Appendix B of this standard
JB/T10181.1
JB/T10181.2
JB/T10181.3
JB/T10181.4
JB/T10181.5
JB/T10181.6
JB/T10181.6-2000 are both indicative appendices. This standard is proposed and managed by the National Wire and Cable Standardization Technical Committee. The main drafting unit of this standard: Shanghai Cable Research Institute. The main drafter of this standard: Ma Guodong.
IEC60287
IEC60287—1-1
IEC60287-1-2
IEC60287-2--1
IEC60287-22
IEC60287—31
IEC 60287—32
JB/T10181.1~10181.6--2000
IEC Foreword
1IEC (International Electrotechnical Commission) is an international standardization organization composed of national electrotechnical committees (IEC National Committees). The purpose of IEC is to promote international cooperation on all issues of standardization in the electrical and electronic fields. To achieve this purpose, in addition to organizing various activities, IEC also publishes international standards. And entrusts technical committees to formulate these standards. Any national committee that is interested in a standard can participate in the formulation of the standard. .International organizations, governmental or non-governmental organizations that have business dealings with IEC may also participate in the formulation of standards. IEC and the International Organization for Standardization (ISO) work closely together on mutually agreed terms. 2 IEC formal resolutions or agreements drawn up by technical committees on behalf of national committees on technical issues of particular concern to them express international consensus on these issues as far as possible. 3 These documents are published in the form of standards, technical reports or guidelines, used internationally in the form of recommended documents, and in this sense are recognized by national committees. 4 In order to promote international unification, IEC national committees are frank in adopting IEC international standards in their countries and regions to the greatest extent possible. Any differences between IEC standards and corresponding national or regional standards should be clearly pointed out in the national or regional standards. 5 International standards IEC60287-11, IEC60287-1-2, IEC60287-2-1, IEC60287--2-2, IEC60287-3-1 and IEC60287--3-2 were developed by IEC Technical Committee 20, Subcommittee 20A: "High Voltage Cables". 5.1 The first edition of IEC 60287-1-1 replaces Sections 1 and 2 of the second edition of IEC 60287 published in 1982 and the corresponding parts of Amendment No. 3, without technical changes. The text of IEC 60287-1-1 and its Amendment No. 1 (1995) are based on the following documents: June Law/DIS Documents
20A(CO)75
20A/262/DIS
Voting Report
20A(CO)81
20A/280/RVD
All information on the voting for the approval of this standard can be found in the "Voting Report" listed in the table above. 5.2 The text of IEC60287-1-2 is based on the following documents: DIS
20A(CO)151
Voting Report
20A(CO)161
All the information on the voting and approval of this standard can be found in the "Voting Report" listed in the table above. 5.3 IEC60287--2-1 replaces Section 3, Appendix C and Appendix D of the second edition of IEC60287 (1982) without technical changes.
The text of IEC60287--2-1 is based on the following documents: June Legal Document
20A(CO)75
Voting Report
20A(CO)81
All the information on the voting and approval of this standard can be found in the "Voting Report" listed in the table above. 5.4 IEC60287-2-2 standard text is based on the following documents: June Law Document
20A (CO) 125
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Voting Report
20 A (CO) 135
Voting All information on the approval of this standard can be found in the "Voting Report" listed in the table above. This section was originally published as IEC1042.
5.5IEC60287-3-1 replaces Annex A and Annex B of the second edition of IEC60287 (1982) without technical changes. The text of IEC60287-3-1 and its first amendment (1999) are based on the following documents: June Law Document/FDIS
20A(CO75
20A/403/FDIS
Voting Report
20 A(CO)81
20A/408/RVD
All information on the voting to approve this standard can be found in the "Voting Report" listed in the table above. 5.6 IEC60287-3-2 replaces the first edition of IEC1059 (1991) without technical changes. The text of IEC60287-3-2 and its first amendment (1996) are based on the following documents: DIS/FDI S
20A(CO)131
20A/308/FDIS
Voting Report
20A(CO)139
20A/322/RVD
All the information on voting to approve this standard can be found in the "Voting Report" listed in the table above. Appendix A and Appendix B are prompt appendices.
JB/T10181.1~10181.6-2000
IEC Introduction 1
To facilitate revision and adoption, IEC 60287 divides the standard into three parts and several sections. Each part is divided into several sections and published as separate standards. Part 1: Current-carrying formulas (100% load factor) and power losses Part 2: Thermal resistance formulas
Part 3: Sections on operating conditions
IEC 60287-11
This section contains formulas for R, W, A, and A. This section includes a method for calculating the allowable current-carrying capacity of cables based on detailed values of allowable temperature rise, conductor resistance, losses and thermal resistivity. The calculation formula for losses is also given in this section. The parameters included in the formulas in the standard vary with the cable design and the materials used. The values given in the tables are either internationally recognized, such as resistivity and temperature coefficient of resistance, or are generally acceptable in practice, such as material thermal resistivity and dielectric constant. In the latter case, some of the values given are not characteristics of new cables, but rather characteristics applicable to cables after long service. In order to obtain uniform and comparable results, the values given in this standard should be used for current carrying capacity calculations. However, other values may be more suitable for the material and design and may be used and the corresponding current carrying capacity may be given in addition, provided that the different values are cited. The various parameters of the operating conditions of the cable may vary greatly from country to country. For example, with regard to ambient temperature and soil thermal resistivity, different countries specify values based on different considerations. If they are not based on a common basis, the values adopted by different countries may lead to erroneous conclusions when compared superficially. For example, different expectations may be drawn about the cable life, as some countries design based on maximum values for soil thermal resistivity, while others use average values. In particular, soil thermal resistivity is very sensitive to the moisture content of the soil and may vary significantly over time, depending on soil type, topography and meteorological conditions and cable loading. Therefore, the following selection method for the various parameters should be adopted. The numerical values are preferably based on measured results. These results are often included in national standards as recommended values so that the values commonly used in the country are used in the calculation. These measured values are given in Part 3, Section 1. Part 3, Section 1 gives the required information. IEC 60287--2-1
This section contains methods for calculating the internal thermal resistance and external thermal resistance of cables when they are laid in free air, in conduits and directly buried. The parameters included in the formulas in the standard vary with the cable design and the materials used. The values given in the table are either internationally recognized, such as resistivity and temperature coefficient of resistance, or are generally accepted in practice; such as material thermal resistivity and dielectric constant. In the following, use notes:
11 This IEC introduction includes the introduction content of IEC60287--1-1, IEC60287-2-1, IEC60287-2-2, IEC60287-3-1 and IEC60287--3IV
一2 parts and sections for the convenience of editing and cross-reference. Building 321---Standard Query Download Network
|tt||In one case, some of the values given are not characteristics of new cables, but characteristics applicable to cables after long-term operation. In order to obtain uniform and comparable results, the values given in this standard should be used for current carrying capacity calculations. However, other values that are more suitable for this material and design can also be used and the corresponding current carrying capacity is also proposed, as long as the different values are cited. The various parameters of cable operating conditions can vary greatly from country to country. For example, with regard to ambient temperature and soil thermal resistivity, different countries specify corresponding values based on different considerations. If they are not based on a common benchmark, the values adopted by different countries can lead to erroneous conclusions when compared superficially. For example, there may be different expectations for cable life. Some countries design based on the maximum value of soil thermal resistivity, while other countries use average values. In particular, soil thermal resistivity is very sensitive to the moisture content of the soil and may change significantly over time, depending on the soil type, topography and meteorological conditions and cable load. Therefore, the following selection method for various parameters should be adopted. The numerical values are preferably based on measurement results. These results are often included in national standards as recommended values so that the values commonly used in the country are used in the calculation. These measured values are given in Part 3, Section 1. Part 3, Section 1 gives the required information. IEC 60287—22
This section provides the calculation method and data for the reduction factor of the current carrying capacity of cable groups laid horizontally in free air, neglecting dielectric losses. It should be used in conjunction with Part 2, Section 1.
IEC60287--31
This section includes reference values for soil thermal resistivity and ambient temperature for various countries. This section also contains summary information that the user needs to select the appropriate cable type.
The various parameters of cable operating conditions can vary greatly from country to country. For example, with regard to ambient temperature and soil thermal resistivity, different countries specify values based on different considerations. If they are not based on a common reference, a superficial comparison of the values adopted by different countries can lead to erroneous conclusions. For example, there may be different expectations for cable life, with some countries designing based on maximum values for soil thermal resistivity and others using average values. The soil thermal resistivity, in particular, is very sensitive to the moisture content of the soil and may vary significantly over time, depending on the soil type, topography and meteorological conditions, and cable loading. Numerical values are preferably based on measured results. These results are often included in national specifications as recommended values so that the values commonly used in the country are used in the calculations. This section collects these values. IEC602873-2
This section was formerly IEC1059.
1 Overview
The method of selecting cable cross-section is usually to find the minimum allowable cross-section, which is also to minimize the cable investment cost. This method does not take into account the loss costs incurred during the life of the cable. The increase in energy costs and the high energy consumption caused by the use of new insulation materials and possible operating temperatures (such as XLPE and EPR operating temperature of 90°C) require the selection of cable cross-sections from a wider economic perspective, not only to minimize the initial cost, but also to minimize the sum of the initial cost and the loss costs during the economic life of the cable. In the latter case, a larger conductor cross-section is selected instead of the conductor cross-section based on the minimum initial cost. As a result, the energy consumption is lower when the same current is transmitted, and when the entire economic life is considered, the cost savings are much greater.
Using appropriate estimates of load growth and energy costs, the future energy consumption costs of the cable during the economic life can be calculated. The most economical conductor cross-section is obtained when the sum of future energy consumption costs and initial purchase and installation costs is minimized. V
The overall cost savings of conductor cross-sections larger than those selected for thermal properties are due to the much lower Joule losses compared to the increased acquisition costs. The values of the financial and electrical parameters used in this standard are not special, and the combined savings in acquisition and operating costs are about 50% (see Appendix A6). Similar results are obtained for shorter financial periods. The more important feature pointed out by example is that within the economic value range shown in Figure A3, the possible cost savings do not depend decisively on the conductor cross-section. This has two implications: a) The error in financial data, especially the data that determines future costs, has little effect. Although it is beneficial to collect the most realistic and correct data; but using data obtained by reasonable estimates can still achieve considerable savings. b) Other factors related to the selection of conductor cross-sections that determine the overall economics of the cable line, such as fault current, voltage drop and size rationality, should be given due attention, without losing too much benefit due to the choice of economic cross-sections. 2 Economic aspects
In order to combine the cost of cable acquisition and installation with the cost of energy consumption during the economic life of the cable, it is necessary to express it in comparable economic values, which are related to the same point in time. It is convenient to use the date of purchase of the cable line installation as the time point and call it the "present tense". The future energy consumption costs are then converted to an equivalent "present value". The method of discounting is used, and the discount rate is related to the loan cost.
The method adopted in this standard is to ignore inflation. This is because inflation affects both loan costs and energy costs. If these items are considered in the same period of time and the impact of inflation on both is close to the same. The economic section can be well selected without introducing the complex factor of inflation increase. To calculate the present value of energy consumption costs, appropriate values of future load growth during the economic life of the cable (25 years or more), annual kWh price increase and annual discount rate must be selected. This standard cannot provide guidance in these aspects, because these values depend on the conditions of each cable line installation and financial control. Only suitable formulas are proposed, and it is the responsibility of the designer and the user to negotiate and determine the values of the economic factors to be used.
The formulas recommended in this standard are clear and easy to understand, but in specific applications, it is assumed that the financial parameters remain unchanged during the economic life of the cable. In any case, the above evaluation of the correctness of these parameters is also relative. There are two methods for calculating the economic cross-section based on the same financial concept. The first method considers a series of conductor cross-sections to calculate the economic current range of each conductor cross-section intended for a particular installation condition, and then selects the conductor cross-section whose economic current range includes the required load. This method is suitable for cases where two similar cable installations are considered. The second method is more suitable for cases where only one cable installation is considered, calculating the optimal cross-section for the required load, and then selecting the closest standard conductor cross-section. 3 Other criteria
Other criteria, such as short-circuit current and its duration, voltage drop and cable cross-section rationalization, must also be considered. However, the selection of cables with economic conductor cross-sections must also be able to meet the above points well. Therefore, it is best to select cables in the following order: a) Calculate the economic cross-section:
b) Check whether the calculated cross-section can transmit the maximum load expected at the end of the economic life of the cable without exceeding the maximum allowable conductor temperature according to the methods given in JB/T10181.1, JB/T10181.2 and JB/T10181.3 standards: c) Check whether the selected cable cross-section can safely pass the expected short-circuit current and the corresponding duration and the ground fault current: d) Check whether the voltage drop at the end of the cable exceeds the allowable range: e) Check according to other criteria applicable to the specific cable installation. In order to complete the economic selection work, appropriate attention should be paid to the consequences of power interruption. It may be necessary to use a larger conductor cross-section than required for normal load conditions, and (or) the economic selection also needs to make corresponding recommendations to the power grid or adapt to the power grid. VI
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Another part of the cost may be the financial consequences of making wrong decisions due to probabilistic reasons. However, this is a problem in the field of decision theory and is beyond the scope of this standard. Therefore, the selection of cable economic cross-section is only part of the overall economic problem of the system, and other important economic issues need to be considered separately.
Machinery Industry Standard of the People's Republic of China
Calculation of the current rating of electric cables Part 1: Current rating equations (100% load factor) and calculation of losses Section 1: General
1 Overview
1.1 Scope
JB/T10181.1-2000
idtIEC60287-1-1:1994
This standard applies to the steady-state operation of all AC voltage levels and DC voltage cables of 5kV and below laid in air or soil. The soil includes cables laid directly in the ground, pipelines, cable trenches or steel pipes with or without local soil drying. The term "steady state" means that the continuous constant current (100% load factor) is just sufficient to asymptotically reach the maximum temperature of the conductor under the condition that the surrounding environment is assumed to be unchanged.
This section provides the calculation formulas for the rated current carrying capacity and various losses. These formulas are basically rigorous, and the values of some important parameters are intentionally unspecified. They can be divided into three groups: one is related to the cable structure (such as the thermal resistance of the insulation material), which is selected from representative values in public publications; one is related to environmental conditions, whose values may vary widely, depending on the conditions of the laying site where the cable is used or is to be used;
one is derived from the negotiation between the manufacturer and the user, including the safety margin of operation (such as the maximum conductor temperature). 1.2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard by reference in this standard. At the time of publication of the standard, the versions shown are valid. All standards are subject to revision, and parties using this standard should investigate the possibility of using the latest version of the following standards. GB/T 39561997
GB/T17048 — 1997 |1997
1.3 Symbols
Conductors of cables
Hard aluminum wire for overhead stranded wires
Guidelines for the selection of high-voltage cables
Calculation of cable current carrying capacity Part 2: Thermal resistance Section 1: Calculation of thermal resistance International standard for copper resistors
Testing of oil-filled cables and compressed air cables and their accessories Rated voltage 1kV (U,=1.2kV) to 30kV (U,=36kV) extruded insulated power cables and accessories
The symbols used in this standard and the parameters they represent are given below: Approved by the State Bureau of Machinery Industry on April 24, 2000 Building 321-
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Armor cross section
Factor (see 2.4.2)
Factor (see 2.4.2)
Capacitance of each core
Outer diameter of cable
Outer diameter of insulation
Outer diameter of metal sheath
JB/T10181.1—2000
Diameter of an imaginary concentric cylinder tangent to the crest of the corrugated metal sheath Diameter of an imaginary concentric cylinder tangent to the inner surface of the trough of the corrugated metal sheath Coefficient (2.3.5)
Sunlight radiation
Magnetic field strength (2.4. 2)
Inductance of metal sheath
Inductance component caused by steel wire
Current in one conductor (effective value)
Coefficient defined in 2.3.5
Coefficient defined in 2.3.5
AC resistance of conductor at its highest operating temperatureAC resistance of armor
Equivalent AC resistance when metal sheath and armor are connected in parallelAC resistance of metal sheath
DC resistance of conductor at highest operating temperatureDC resistance of conductor at 20℃
Thermal resistance of each wire core between conductor and metal sheathThermal resistance between metal sheath and armor
Thermal resistance of outer sheath
Thermal resistance of surrounding medium (higher than surrounding medium) (ratio of cable surface temperature rise at ambient temperature to loss per unit length) Corrected external thermal resistance of cable in free air under sunlight Voltage between conductor and shield or armor
Armor loss per unit length
Conductor loss per unit length
Dielectric loss per unit length of each phase
Metal sheath loss per unit length
Total loss of metal sheath and armor per unit length
Metal sheath reactance (two-core cable and three single-core cables arranged in a triangle) mm2
Ampere-turns/m
K·m/W
K·m/W
K·m/W
K·m/W
K·m/W
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