GB/T 3048.2-1994 Test methods for electrical properties of wires and cables - Test method for resistivity of metallic conductor materials
Some standard content:
National Standard of the People's Republic of China
Test methods for electrical properties of electric cables and cables
Test of resistivity of metallic conductor materials
GB/T 3048.2—94
Replaces GB 3048.2 83
Test methods for delermining electrical properties of electric cables and wires Measurement of resistivity of metallic conductive materials This standard is equivalent to 1FC)468 (1974) Test methods for resistivity of metallic materials. 1 Subject content and scope of application
This standard specifies the terminology, test equipment, sample preparation, test procedures, test results and calculations for resistivity tests of metallic conductor materials. This standard is applicable to the determination of volume resistivity and mass resistivity of solid (non-twisted) copper, aluminum and their alloy metal conductor materials, as well as the determination of the unit length resistance of solid metal conductor materials (uniform cross-sectional area). This standard is also applicable to the determination of volume resistivity, mass resistivity and unit length resistance of metallic resistance materials. The method provided in this standard is an arbitration test method for determining the resistivity of solid conductors with a resistivity range of 0.01~2.0n·mm2/m under standard conditions. The permissible conditions for routine tests are specified in the relevant clauses. The general requirements, definitions and periodic calibration requirements for electrical performance tests of wires and cables are specified in GB/T3048.1. 2 Reference standards
GB/T3048.1 General principles for electrical performance tests of wires and cables GB1214 Vernier caliper
GB1216 Outside micrometer
3 Terminology
3.1 Volume resistivity vrlume tesistivity Volume resistivity is the resistance of a conductor per unit length and per unit cross-sectional area at standard temperature. Its value is calculated by formula (1):
Wherein: A(ta)
?R(ta)
Z,(t。)
R(t。)--resistance of the sample with gauge length at standard temperature t: A(te)--cross-sectional area of the sample at standard temperature: (t。) gauge length of the sample at standard temperature t. 3.2 Mass resistivity mass resistivity 1)
Mass resistivity is the resistance of a conductor per unit length and per unit mass. At standard temperature t, its value is calculated by formula (2):
Approved by the State Bureau of Technical Supervision on May 19, 1994 and implemented on January 1, 1995
GB/T3048.2—94
I,(tu)
Wherein: (t,) is the mass resistivity at standard temperature t,; R(t) is the resistance of the gauge length specimen at standard temperature t, i.e., the mass of the specimen;
ttto) is the gauge length of the specimen at standard temperature t; 12(tn) is the standard temperature t. 3.3 Resistance per unit length The resistance per unit length at standard temperature is calculated by formula (3): R()
Z,(tu)
Where: R,(to)—resistance per unit length at standard temperature; R(ta)—resistance of the gauge length specimen at standard temperature, (za)—gauge length of the specimen at standard temperature. -2)
（3）
3.4 IACS conductivity percentage
The IACS conductivity percentage is the IACS volume conductivity percentage or the IACS mass conductivity percentage, which is the ratio of the resistivity specified in the international annealed copper standard (whether volume or mass) to the resistivity of the same unit specimen multiplied by 100. For example, the volume resistivity is expressed by formula (4):
0. 017 241 × 100
The volume resistivity of the specimen at 20,0·mm/m. In the formula;
IEC: Publication 28 (1925) provides standard values of volume resistivity and mass resistivity equivalent to the international annealed copper standard, as shown in Table 1.
Conductivity at 20℃
Volume resistivity
Equivalent resistivity
Mass resistivity
4 Test equipment
Table 1 and 1.ACS equivalent resistivity standard value% iACS
- mm/ta(μ-m)
a·g/m?
0.017 241
1. 724 1×10-8
0. 153 28
1.5328×10**
4.1 The total error of the resistance measurement system should be ±0.15%. The total error includes: calibration error of standard resistor, comparison error between sample and standard resistor, error caused by contact potential and thermoelectric potential, and heating error of sample caused by measuring current. The total error allowed for routine test is ±0.30%.
4.2 Vernier caliper: 1000±0.1mm, in accordance with GB1214. Lever micrometer: the indication error of the gauge head is 1μm, in accordance with GB1216. 4.3 Precision balance.
4.4 Thermometer: accuracy 0.1℃.
GB/T 3048.2—94
4.5 Precision constant temperature liquid bath (if necessary): 20±0.1℃. 5 Sample preparation
5.1 Shape
5.1.1 The sample is a rod, wire, strip, row or pipe of any shape with a roughly uniform cross section, and its surface should be smooth. Where possible, the sample should have a complete cross section. 5.1.2 The relative standard deviation of the cross section measured 5 or more times at equal intervals for the specimen gauge length shall not exceed 1%. It is allowed not to exceed 2% for routine tests.
5.1.3 When measuring the mass per unit length, the two ends of the specimen shall be flat and perpendicular to the longitudinal axis. There shall be no burrs, flash and edges (serrated edges) on the surface of the specimen.
5.1.4 When preparing specimens taken from block materials, care should be taken to prevent significant changes in material properties. Plastic deformation will cause the material to become harder and increase the resistivity; heating will cause the material to anneal and reduce the resistivity. 5.2 Characteristics
5.2.1 The resistance on the gauge length between the potential joints shall not be less than 0.000 01 2.5.2.2 The gauge length shall not be less than 0.3m. Other dimensions shall be compatible with the test equipment.5.2.3 The surface of the specimen shall be free of cracks and defects. The specimens with a transverse dimension of 1mm and above shall be inspected with the naked eye, and the specimens with a transverse dimension of less than 1mm shall be inspected with a 20x magnifying glass.
The surface of the specimen shall be basically free of spots, dust and oil, especially on the surface of the current and potential joints. If necessary, the specimen shall be cleaned before measuring the dimensions.
5.2.4 There are no joints.
6 Test steps
6.1 General provisions
6.1.1 The four-point method shall be used for specimens with a resistance of 10α and below, and the two-point method may be used for specimens with a resistance greater than 10M. During routine tests, if the resistance of the sample is greater than 1, the two-point method is allowed. 6.1.2 The measurement errors of each item shall comply with the provisions of Table 2. Table 2 Allowable measurement errors
Item name
Cross-sectional area
Use known sample density;
Mass in narrow air
Sample length
Sample density
Weighing with fluid:
Mass in air
Arbitration test
± 0. 05%
±0, 05%
± 0. 05%
±0. 04%%
Routine test
Project name
Mass in liquid
Liquid density
Total error caused by temperature
Temperature control
Temperature calibration
Total error
Volume resistivity
Mass resistivity
Electricity per unit length
6.2 Temperature measurement and control
GB/T3048.2-94
Continued Table 2
Arbitration test
± 0. 04%(0. 1 C)
6.2.1 Both the standard resistor and the test sample should be at a temperature of 15-25°C 6.2.2 During the entire test process, the temperature measurement and control should meet the following requirements: a.
The total error caused by temperature should not be greater than +0.06%! Sideways test
-0, 25%
±0. 15%(0. 4r)
±0,45%
Temperature measurement and control accuracy: The product of temperature error and resistance temperature coefficient should not be greater than ±4% (0.1°C); the test temperature should meet the following requirements: The product of temperature difference (t-) and the error of resistance temperature coefficient of the sample should not be greater than 0.4%. For detailed analysis, see Appendix C of this standard.
In order to ensure the above requirements, a liquid bath should be used when necessary. 6.3 Length measurement
At the test temperature: , measure the gauge length 1 between the two potential points of the sample, () accurate to ±0.05%. 6.4 Selection of test current
Under the condition of meeting the sensitivity requirements of the test system, the minimum test current should be selected as much as possible to avoid excessive temperature rise. When the average resistance value measured by a current 40% larger than the test current exceeds 0.06% of the average value measured by the test current, the temperature rise test is considered to be too large and invalid. A smaller test current should be selected. 6.5 Resistance measurement
6.5.1 When measuring by the four-point method, the potential contact points should be formed by fairly sharp blades and be parallel to each other and perpendicular to the longitudinal axis of the sample. The contact points can also be sharp needle-shaped contacts.
6.5.2 The distance between each potential contact point and the corresponding current contact point should be no less than 1.5 of the circumference of the sample cross section. 6.5.3 Pay attention to eliminating the measurement errors caused by contact potential and thermal potential. The current reversal method can be used. Read a positive connection reading and a reverse connection reading, and take the arithmetic mean. The balance point method (compensation method) can also be used. When the closed current is reached, the galvanometer basically does not observe the impact.
6.5.4 When using the Kelvin (Thomson) double-hip bridge, the cross-line resistance between the standard resistor and the sample should be significantly smaller than both the standard resistance and the sample resistance. Otherwise, appropriate methods should be adopted to compensate, such as lead compensation, so that the ratio of coil and lead resistance is sufficiently balanced, and the influence of cross-line resistance is reduced to ensure that the accuracy of the bridge meets the specified requirements. 6.6 Cross-sectional area measurement
6.6.1 The measurement error should not exceed ±0.15%. 6.6.2 For simple cross-sectional specimens, the cross-sectional area can be reasonably calculated from the linear cross-sectional dimensions. When measuring the scale, at least five measurements should be made at approximately equal intervals along the maximum length of the specimen, and the arithmetic mean should be calculated. GB/T 3048.294
The ratio of the standard deviation of the mean to the mean itself should not be greater than ±0.15 megahertz. 6.6.3 For specimens with relatively complex cross-sections, when the error of the average cross-sectional area directly measured and calculated exceeds 0.15%, the cross-sectional area shall be determined according to formula (5):
A(2) =
Wherein: 4(t) - cross-sectional area at test temperature t; specimen mass, accurate to ±0.05%;
(ridee)
- total length of specimen at test temperature, accurate to ±0.05%; g(t)
d(t) - density of specimen at test leakiness:, accurate to ±0.12%. 6.7 Mass measurement
(5)
Attention shall be paid to reducing the error of weighing in air to meet the requirements of formula (5). If necessary, the buoyancy should be corrected according to formula (6): mads (dwda)
dw (ds-d)
where: mA ... apparent mass measured by weighing; -- sample density,
tw base density;
dA -- air density, 1.2 kg/mt.
6.8 Density measurement
When the error of sample density is less than ± 0.12% or its density is unknown, the sample density should be measured by weighing in air and in a liquid of known density:
The sample can be measured directly or with a test piece of the same density as the sample. 6.8.1 The test temperature of air and liquid should be selected to minimize the error caused by convection. 6.8.2 When weighing in liquid, the uniformity of liquid temperature should ensure that the error of liquid density is not more than ± 0.08%. The hanging wire used to suspend the sample in the liquid should be as thin as possible. When weighing in the air, the extended part of the hanging wire should be immersed in the same liquid to eliminate the influence of surface tension. When the diameter of the hanging wire exceeds 0.051m1, a hanging wire with a diameter twice its diameter should be used for the second weighing. The weight difference between the two weighings should not exceed ±1[dt/(ds--d)Tingzhao of the apparent mass of the sample in the liquid. When water is used as the liquid, an appropriate wetting agent should be added, which should not exceed 0.03% by weight, and care should be taken to basically remove all bubbles on the surface of the sample before weighing.
6.8.3 The mass measurement error should not be greater than ±0.04d/d)% in the air and should not be greater than +0.08Ldt/(ds~di)]% in the liquid.
6.8.4 The sample density is determined by formula (7): ds madht) -ny(cds
ma mr.()
Wu Zhong: mA-
the apparent mass of the sample measured in air: - the apparent mass of the sample measured in liquid: - the air density at the test temperature t, 1. 2 kg/m; da
d(t)——the liquid density at the test temperature. (7)
GB/T 3048.2-94
Note: When this method is used to determine density, the thermal error of the cross-sectional area depends on the errors of ma (ais/di.) and m. (dsdi)/di., so the allowable error is specified as a percentage of the reciprocal of these values. See Appendix C for details. 6.9 Routine test regulations
During routine tests, except for the following provisions of this article, the rest shall comply with the provisions of this standard. 6.9.1 The standard resistor and the sample shall be kept at a temperature of 10~~35℃. 6.9.2 Before testing, the sample and the standard resistor shall be stored in a non-ventilated cabinet in the laboratory for at least 1 hour, or placed in a wave bath, and the air temperature and liquid bath temperature in the cabinet shall be measured. The temperature measurement and control shall meet the following requirements. The total error caused by temperature shall not exceed ±0.25%; a.
The product of the temperature error and the resistance overflow coefficient shall not exceed ±0.15% (0.4℃); b.
c. Temperature difference (t-t,) The product of the error of the temperature coefficient of resistance of the specimen should not be less than ±0.15%. Under routine test conditions, the temperature difference (t-t.) can be increased to the value reserved in the formula in Chapter 7. 6.9.3 The measurement error of the specimen gauge length is allowed to be no more than ±.10%. 6.9.4 The cross-sectional area error is allowed to be no more than ±0.50%. When the difference between the two cross-sectional areas determined by linear dimensions is greater than 0.70%, or the cross-section is complex, it should be measured in accordance with the provisions of Article 6.6 of this standard, and the error provisions are as follows:
The mass measurement error is allowed to be no more than ±0.10%; the length measurement error is allowed to be no more than ±0.20% 1 The sample density error is allowed to be no more than ±0.45%. 6.9.5 When measuring density, the liquid density error is allowed to be no more than +0.20%. The measurement error of weighing in air is allowed to be no more than ±0.30 (di/ds)%: The measurement error of weighing in liquid is allowed to be no more than ±0.30Ld/(ds-)%. When the diameter of the hanging wire is greater than 0.15mm, a hanging wire with a diameter twice the point diameter should be used for the second weighing. The error between the two weighings is allowed to be no more than 0.10[d,/(ds-d,]%.
7 Test results and calculations
7.1 Considering that both resistance and linear dimensions change with temperature, the values measured at the test temperature: should be converted to the standard temperature during calculation. This standard stipulates that 1. is 20°C. The calculation according to the formula specified in this standard has sufficient accuracy. 7.2 Resistance calculation
Assume that the resistance of the sample changes linearly with temperature, and the resistance is calculated according to formula (8): R(t)
R2o =1+ a2o( 20)
Where: R—resistance of the sample gauge length at -20°C; R()
actually measured resistance of the sample gauge length at the test temperature; resistance temperature coefficient of the sample at 20°C.
7.3 Calculation of resistance per unit length
The resistance per unit length at standard temperature 20℃ is calculated according to formula (9): R,(t)
Rt 20 = I+ (a2 -%(- 20)
Where: R,(t)-
Resistance per unit length of the specimen at test temperature t: t8)
GB/T 3048. 2--94
---The linear expansion coefficient of the specimen, for most materials, is much smaller than the temperature coefficient of resistance αa. When (t--20) is small, > can be ignored. This applies to various calculation situations in this standard. 7.4 Calculation of volume resistivity
The volume resistivity at standard temperature 20℃ is calculated according to formula (10): (t)
P20 -1+ (a2o +)(= 20)
formula, () is the volume resistivity of the sample at the test temperature t. 7.5 Calculation of mass resistivity
The mass resistivity at standard temperature 20°C is calculated using formula (11): (t)
61+(a20-2)(-20)
Where: (t) is the mass resistivity of the sample at test temperature t. 7.6 Calculation of linear dimensions and cross-sectional area
(10)
(11)
When the temperature at which the total length and cross-sectional area of the sample are measured is different from the temperature at which the resistance and gauge length are measured, the conversion should be performed according to formulas (12) and (13).
t2() =(t)[1 +(t -t)
A(r) = A(t)[1 + 2(t = t))
Wu Zhong: t(t):
The total length of the sample at the temperature!
A(r)-cross-sectional area of the specimen converted to temperature t:.(t) total length of the specimen at the test temperature; A(r)-
-cross-sectional area of the specimen at the test temperature t.
8 Test records and test reports
8.1 The test records shall record the following in detail: a.
Specimen number;
Material type;
Average cross-sectional area of the specimen, number of measurements and standard deviation of the average cross-sectional area at the test temperature: Measurement method: arbitration test method or routine test method; Test temperature;
Average resistance of the specimen, number of measurements and standard deviation of the average resistance at the test temperature! Calculated resistivity or resistance per unit length of the sample at 20°C, calibration temperature coefficient of resistance per unit length, sample length and cross-sectional area; mechanical treatment and heat treatment before the test (resistivity may change with these treatments, and should be explained according to the data) When there are special requirements, the following items should also be included in the test record. Each measurement of the transverse linear dimension, together with the calculated cross-sectional area for each group of measurements, is summarized in a table; b.
When weighing to determine the cross-sectional area, there should be sample length, mass in air, mass in liquid (if used), code density, liquid density, sample density, cross-sectional area calculated accordingly, and temperature during measurement. When using other test pieces to determine density, it should be explained: a summary table of each resistance measurement.
8.2 The test report shall include the following contents:
Commissioning unit, date:
Testing method and standard:
Source and specification of sample:
Measurement statement
Measurement result:
GB/T 3048.2-94
When there is a special requirement, the relevant contents in the test record may be included in the report. Characteristics
Volume electrical conductivity t), 10a·m
Temperature coefficient of resistance cm(), 10 3/℃
Temperature coefficient of linear expansion 7, 10/℃
Temperature coefficient of volume resistivity, 10110-m/CDensity ds(to), 10°g ma
GB/T 3048.2—94
Appendix A
Characteristic values of copper and aluminum at 20℃
(reference)
Note: ① is standard annealed copper. The values of e, and ds are also applicable to the given values of commercial annealing 1FC28. ②Aluminum busbar is commercial pure aluminum busbar material. α(to) is the maximum value, given value of IEC 105. ③Duraluminum wire is commercial hard drawn aluminum wire. (t.) is both the standard value and the maximum value, given value of IFC,111. (a) Annealed aluminum wire is commercial aluminum wire. p(t) is the maximum value given by IEC121. The @e value is calculated based on the values of p and ? given in IEC publication 1. See Appendix B for details. Appendix B
Temperature calibration
(reference)
Durable aluminum wire
Annealed aluminum wire
The use of the temperature coefficient of resistance to calculate the volume resistivity at standard temperature, as described in Chapter 7, is generally used. However, there are other advantages when using other methods. If the temperature coefficient of volume resistivity e is defined by formula (1), the value of e for copper is almost the same as that of all commonly used copper alloys, and the value of ε for aluminum is the same as that of aluminum alloys. o(t) = p(t,) + e(tz — t)
（B1)
Thus, when measuring resistance and size at temperature:, the calculated volume resistivity (t) can be used to accurately calibrate the temperature to the standard temperature to using formula (B1) based on the value of e in Appendix A. At the same time, the relationship between the temperature coefficient of resistance (t,) and e at the standard temperature can also be expressed by formula (B2). α(ta)
Rongzhong: -
Linear expansion coefficient.
++++++++.( B2 )
GB/T 3048. 2—94
Appendix C
Error analysis
(reference)
C1 Resistance, resistivity and unit length resistance error analysis The resistance R(t.) of the specimen can be calculated from the standard resistance by comparing the equation (C1) provided by the measurement technique and its measurement ratio N: R
Wu Zhong R
Unknown resistance:
-standard resistance:
Z, Z-the impedance of the balanced arm of the bridge.
Assuming that the resistance and length in the considered range vary linearly with temperature, during measurement, the sample [its resistance R, -R(t)] has a temperature t, and the standard resistor [resistance Rs(t')] has a slightly different temperature t. If the standard resistor is calibrated at the standard temperature t?·but this temperature is different from the standard temperature of resistivity, then: Rs(t) = Rs(tz)[1 + ag(th ta)] where:
resistance temperature coefficient of the standard resistor.
R(t) =NaRs(t)
=NR()[1+as(tt)]
In order to obtain the greatest accuracy, it is best to: tt.
The volume resistivity is obtained by formula (C4):
and = t2
4Xing·NanRs(n)L1+ g(tt)
The relative error of P is calculated by formula (C5):
Where: x, the first characteristic, is known or measured, AX.
-X, the error size of
The best approximation is:
[会]+(\+[了+[箍]
Because()=p(r)+e(—t)
+ [<\ - t2)Aas+[αuAr']
rAp(t)
(to - t) +
[了+[++
[AR(t)-
LRs(t)
（C5)
GB/T 3048. 2—94
+ [(t' t?)Aas] +[aAt' ?
-)]+[4
The error of mass resistivity and resistance per unit length can also be analyzed by similar formula: {]+[++[]+[然]
+ E(t -ta)+ Aas ]? + [αs A ]?+[The length of the sample, mass in air, mass in liquid (if used), code density, liquid density, sample density, cross-sectional area calculated accordingly, and temperature during measurement should be provided. When using other test pieces to measure density, this should be stated: Summary table of each resistance measurement.
8.2 The test report shall include the following contents
Commissioning unit, date:
Test method standard:
Sample source and specification model:
Measurement statement
Measurement results:
GB/T 3048.2-94
When other requirements are required, the relevant contents in the test record may be included in the report. Characteristics
Volume electrical conductivity t), 10a·m
Temperature coefficient of resistance cm(), 10 3/℃
Temperature coefficient of linear expansion 7, 10/℃
Temperature coefficient of volume resistivity, 10110-m/CDensity ds(to), 10°g ma
GB/T 3048.2—94
Appendix A
Characteristic values of copper and aluminum at 20℃
(reference)
Note: ① is standard annealed copper. The values of e, and ds are also applicable to the given values of commercial annealing 1FC28. ②Aluminum busbar is commercial pure aluminum busbar material. α(to) is the maximum value, given value of IEC 105. ③Duraluminum wire is commercial hard drawn aluminum wire. (t.) is both the standard value and the maximum value, given value of IFC,111. (a) Annealed aluminum wire is commercial aluminum wire. p(t) is the maximum value given by IEC121. The @e value is calculated based on the values of p and ? given in IEC publication 1. See Appendix B for details. Appendix B
Temperature calibration
(reference)
Durable aluminum wire
Annealed aluminum wire
The use of the temperature coefficient of resistance to calculate the volume resistivity at standard temperature, as described in Chapter 7, is generally used. However, there are other advantages when using other methods. If the temperature coefficient of volume resistivity e is defined by formula (1), the value of e for copper is almost the same as that of all commonly used copper alloys, and the value of ε for aluminum is the same as that of aluminum alloys. o(t) = p(t,) + e(tz — t)
（B1)
Thus, when measuring resistance and size at temperature:, the calculated volume resistivity (t) can be used to accurately calibrate the temperature to the standard temperature to using formula (B1) based on the value of e in Appendix A. At the same time, the relationship between the temperature coefficient of resistance (t,) and e at the standard temperature can also be expressed by formula (B2). α(ta)
Rongzhong: -
Linear expansion coefficient.
++++++++.( B2 )
GB/T 3048. 2—94
Appendix C
Error analysis
(reference)
C1 Resistance, resistivity and unit length resistance error analysis The resistance R(t.) of the specimen can be calculated from the standard resistance by comparing the equation (C1) provided by the measurement technique and its measurement ratio N: R
Wu Zhong R
Unknown resistance:
-standard resistance:
Z, Z-the impedance of the balanced arm of the bridge.
Assuming that the resistance and length in the considered range vary linearly with temperature, during measurement, the sample [its resistance R, -R(t)] has a temperature t, and the standard resistor [resistance Rs(t')] has a slightly different temperature t. If the standard resistor is calibrated at the standard temperature t?·but this temperature is different from the standard temperature of resistivity, then: Rs(t) = Rs(tz)[1 + ag(th ta)] where:
resistance temperature coefficient of the standard resistor.
R(t) =NaRs(t)
=NR()[1+as(tt)]
In order to obtain the greatest accuracy, it is best to: tt.
The volume resistivity is obtained by formula (C4):
and = t2
4Xing·NanRs(n)L1+ g(tt)
The relative error of P is calculated by formula (C5):
Where: x, the first characteristic, is known or measured, AX.
-X, the error size of
The best approximation is:
[会]+(\+[了+[箍]
Because()=p(r)+e(—t)
+ [<\ - t2)Aas+[αuAr']
rAp(t)
(to - t) +
[了+[++
[AR(t)-
LRs(t)
（C5)
GB/T 3048. 2—94
+ [(t' t?)Aas] +[aAt' ?
-)]+[4
The error of mass resistivity and resistance per unit length can also be analyzed by similar formula: {]+[++[]+[然]
+ E(t -ta)+ Aas ]? + [αs A ]?+[The length of the sample, mass in air, mass in liquid (if used), code density, liquid density, sample density, cross-sectional area calculated accordingly, and temperature during measurement should be provided. When using other test pieces to measure density, this should be stated: Summary table of each resistance measurement.
8.2 The test report shall include the following contents
Commissioning unit, date:
Test method standard:
Sample source and specification model:
Measurement statement
Measurement results:
GB/T 3048.2-94
When other requirements are required, the relevant contents in the test record may be included in the report. Characteristics
Volume electrical conductivity t), 10a·m
Temperature coefficient of resistance cm(), 10 3/℃
Temperature coefficient of linear expansion 7, 10/℃
Temperature coefficient of volume resistivity, 10110-m/CDensity ds(to), 10°g ma
GB/T 3048.2—94
Appendix A
Characteristic values of copper and aluminum at 20℃
(reference)
Note: ① is standard annealed copper. The values of e, and ds are also applicable to the given values of commercial annealing 1FC28. ②Aluminum busbar is commercial pure aluminum busbar material. α(to) is the maximum value, given value of IEC 105. ③Duraluminum wire is commercial hard drawn aluminum wire. (t.) is both the standard value and the maximum value, given value of IFC,111. (a) Annealed aluminum wire is commercial aluminum wire. p(t) is the maximum value given by IEC121. The @e value is calculated based on the values of p and ? given in IEC publication 1. See Appendix B for details. Appendix B
Temperature calibration
(reference)
Durable aluminum wire
Annealed aluminum wire
The use of the temperature coefficient of resistance to calculate the volume resistivity at standard temperature, as described in Chapter 7, is generally used. However, there are other advantages when using other methods. If the temperature coefficient of volume resistivity e is defined by formula (1), the value of e for copper is almost the same as that of all commonly used copper alloys, and the value of ε for aluminum is the same as that of aluminum alloys. o(t) = p(t,) + e(tz — t)
（B1)
Thus, when measuring resistance and size at temperature:, the calculated volume resistivity (t) can be used to accurately calibrate the temperature to the standard temperature to using formula (B1) based on the value of e in Appendix A. At the same time, the relationship between the temperature coefficient of resistance (t,) and e at the standard temperature can also be expressed by formula (B2). α(ta)
Rongzhong: -bZxz.net
Linear expansion coefficient.
++++++++.( B2 )
GB/T 3048. 2—94
Appendix C
Error analysis
(reference)
C1 Resistance, resistivity and unit length resistance error analysis The resistance R(t.) of the specimen can be calculated from the standard resistance by comparing the equation (C1) provided by the measurement technique and its measurement ratio N: R
Wu Zhong R
Unknown resistance:
-standard resistance:
Z, Z-the impedance of the balanced arm of the bridge.
Assuming that the resistance and length in the considered range vary linearly with temperature, during measurement, the sample [its resistance R, -R(t)] has a temperature t, and the standard resistor [resistance Rs(t')] has a slightly different temperature t. If the standard resistor is calibrated at the standard temperature t?·but this temperature is different from the standard temperature of resistivity, then: Rs(t) = Rs(tz)[1 + ag(th ta)] where:
resistance temperature coefficient of the standard resistor.
R(t) =NaRs(t)
=NR()[1+as(tt)]
In order to obtain the greatest accuracy, it is best to: tt.
The volume resistivity is obtained by formula (C4):
and = t2
4Xing·NanRs(n)L1+ g(tt)
The relative error of P is calculated by formula (C5):
Where: x, the first characteristic, is known or measured, AX.
-X, the error size of
The best approximation is:
[会]+(\+[了+[箍]
Because()=p(r)+e(—t)
+ [<\ - t2)Aas+[αuAr']
rAp(t)
(to - t) +
[了+[++
[AR(t)-
LRs(t)
（C5)
GB/T 3048. 2—94
+ [(t' t?)Aas] +[aAt' ?
-)]+[4
The error of mass resistivity and resistance per unit length can also be analyzed by similar formula: {]+[++[]+[然]
+ E(t -ta)+ Aas ]? + [αs A ]?+[2—94
Appendix C
Error Analysis
(Reference)
C1 Resistance, resistivity and unit length resistance error analysis The resistance R(t.) of the specimen can be calculated from the standard resistance by comparing the equation (C1) provided by the measurement technique and its measurement ratio N: R
Wu Zhong R
Unknown resistance:
-Standard resistance:
Z, Z-the impedance of the balanced arm of the bridge.
Assuming that the resistance and length in the considered range vary linearly with temperature, during measurement, the sample [its resistance R, -R(t)] has a temperature t, and the standard resistor [resistance Rs(t')] has a slightly different temperature t. If the standard resistor is calibrated at the standard temperature t?·but this temperature is different from the standard temperature of resistivity, then: Rs(t) = Rs(tz)[1 + ag(th ta)] where:
resistance temperature coefficient of the standard resistor.
R(t) =NaRs(t)
=NR()[1+as(tt)]
In order to obtain the greatest accuracy, it is best to: tt.
The volume resistivity is obtained by formula (C4):
and = t2
4Xing·NanRs(n)L1+ g(tt)
The relative error of P is calculated by formula (C5):
Where: x, the first characteristic, is known or measured, AX.
-X, the error size of
The best approximation is:
[会]+(\+[了+[箍]
Because()=p(r)+e(—t)
+ [<\ - t2)Aas+[αuAr']
rAp(t)
(to - t) +
[了+[++
[AR(t)-
LRs(t)
（C5)
GB/T 3048. 2—94
+ [(t' t?)Aas] +[aAt' ?
-)]+[4
The error of mass resistivity and resistance per unit length can also be analyzed by similar formula: {]+[++[]+[然]
+ E(t -ta)+ Aas ]? + [αs A ]?+[2—94
Appendix C
Error Analysis
(Reference)
C1 Resistance, resistivity and unit length resistance error analysis The resistance R(t.) of the specimen can be calculated from the standard resistance by comparing the equation (C1) provided by the measurement technique and its measurement ratio N: R
Wu Zhong R
Unknown resistance:
-Standard resistance:
Z, Z-the impedance of the balanced arm of the bridge.
Assuming that the resistance and length in the considered range vary linearly with temperature, during measurement, the sample [its resistance R, -R(t)] has a temperature t, and the standard resistor [resistance Rs(t')] has a slightly different temperature t. If the standard resistor is calibrated at the standard temperature t?·but this temperature is different from the standard temperature of resistivity, then: Rs(t) = Rs(tz)[1 + ag(th ta)] where:
resistance temperature coefficient of the standard resistor.
R(t) =NaRs(t)
=NR()[1+as(tt)]
In order to obtain the greatest accuracy, it is best to: tt.
The volume resistivity is obtained by formula (C4):
and = t2
4Xing·NanRs(n)L1+ g(tt)
The relative error of P is calculated by formula (C5):
Where: x, the first characteristic, is known or measured, AX.
-X, the error size of
The best approximation is:
[会]+(\+[了+[箍]
Because()=p(r)+e(—t)
+ [<\ - t2)Aas+[αuAr']
rAp(t)
(to - t) +
[了+[++
[AR(t)-
LRs(t)
（C5)
GB/T 3048. 2—94
+ [(t' t?)Aas] +[aAt' ?
-)]+[4
The error of mass resistivity and resistance per unit length can also be analyzed by similar formula: {]+[++[]+[然]
+ E(t -ta)+ Aas ]? + [αs A ]?+[
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