GB/T 3048.4-2007 English PDF (GB/T3048.4-2007)

GB/T 3048.4-2007: Test methods for electrical properties of electric cables and wires -- Part 4: Test of DC resistance of conductors
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GB/T 3048.4-2007
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.060
K 13
Replacing GB/T 3048.4-1994
Test methods for electrical properties of electric
cables and wires - Part 4. Test of DC resistance of
conductors
ISSUED ON. DECEMBER 03, 2007
IMPLEMENTED ON. MAY 01, 2008
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1  Scope ... 6 
2  Normative References ... 6 
3  Test Apparatus ... 6 
4  Specimen Preparation ... 8 
5  Test Procedure ... 9 
6  Test Results and Calculation ... 11 
7  Test Record ... 12 
Foreword
GB/T 3084 Test methods for electrical properties of electric cables and wires is divided
into 14 parts as follows [Translator note. Parts 6 and 15 do not exist].
— Part 1. General;
— Part 2. Test of electrical resistivity of metallic materials;
— Part 3. Test of volume resistivity of semi conducting rubbers and plastics;
— Part 4. Test of DC resistance of conductors;
— Part 5. Test of insulation resistance;
— Part 7. Tracking resistance test;
— Part 8. AC voltage test;
— Part 9. Spark test of insulated cores;
— Part 10. Spark test of extruded protective sheaths;
— Part 11. Test for dielectric dissipation factor;
— Part 12. Partial discharge test;
— Part 13. Impulse voltage test;
— Part 14. DC voltage test;
— Part 16. Surface resistance test.
This part is part 4 of GB/T 3084.
This part replaces GB/T 3048.4-1994 Test Methods for Determining Electrical Properties
of Electric Cables and Wires-Measurement of D.C. Resistance of Conductors. This
revision makes modifications based on GB/T 1.1-2000 Directives for Standardization -
Part 1. Rules for the Structure and Drafting of Standards.
The main changes in this part, compared with GB/T 3048.4-1994, are as follows.
- The title of the standard in English has been changed to “Test methods for electrical
properties of electric cables and wires - Part 4. Test of DC resistance of conductors”;
- The general structure and layout of this part have been changed according to GB/T
1.1-2000.
1) Clause 1 is “scope” (Clause 1 in 1994 edition; Clause 1 in this edition);
2) Clause 2 is “normative references” (Clause 2 in 1994 edition; Clause 2 in this
edition);
3) Clause 3 is “testing equipment” (Clause 3 in 1994 edition; Clause 3 in this
edition);
4) Clause 4 is “sample preparation” (Clause 4 in 1994 edition; Clause 4 in this
edition);
5) Clause 5 is “test procedure” (Clause 5 in 1994 edition; Clause 5 in this edition);
6) Clause 6 is “test result and calculation” (Clause 6 in 1994 edition; Clause 6 in this
edition);
7) Clause 7 is “test record” (none in 1994 edition, clause 7 in this edition);
- Some content, including requirements, is deleted from Clause 1 “scope” (Clause 1 in
1994 edition; Clause 1 in this edition);
- Relevant standards are supplemented in Clause 2 “normative references” (Clause 2
in 1994 edition; Clause 2 in this edition);
- Digital test instruments are explicitly added to Clause 3 “testing equipment” (3.3 in
1994 edition; 3.3 in this edition);
- Technical adjustment is made; and the requirements of preparing water-blocked
conductor samples is added to Clause 4 “sample preparation” (Clause 4 in 1994
edition; Clause 4, 4.3 in this edition);
- The requirements on ambient temperature in Clause 1 and 4.5 in 1994 edition are
incorporated into 5.1 in Clause 5 “test procedure” (Clause 1, 4.5 in 1994 edition, 5.1
in this edition);
- Clause 6 “test result and calculation” is altered as follows.
1) The calculation formula of the bridge method is deleted, and regulations on digital
instrument readings are added (6.1, 6.2 in 1994 edition, 6.1.1, 6.1.2 in this
edition);
2) The calculation formula of temperature correction for routine tests is added (none
in 1994 edition, 6.2.2 in this edition);
3) The requirements for rules for rounding-off of computing results are deleted (6.4
in 1994 edition, none in this edition);
Test methods for electrical properties of electric cables
and wires - Part 4. Test of DC resistance of conductors
1 Scope
This Standard specifies the test apparatus, specimen preparation, test procedure for test
of DC resistance of conductors as well as calculation and test record.
This Standard is applicable to measure DC resistance of conductors of electric wires and
cables, the measuring range is as follows.
– Kelvin (double) bridge (2×105 ~ 99.9)Ω.
– Wheatstone (single) bridge 1Ω ~ 100Ω and above.
The test methods specified in this Standard is not applicable to measure DC resistance of
electric wires and cables which have been installed.
This Standard shall be used together with GB/T 3048.1.
2 Normative References
The articles contained in the following documents have become part of this part when they
are quoted herein. For the dated documents so quoted, all the modifications (excluding
corrections) or revisions made thereafter shall not be applicable to this part. For the
undated documents so quoted, the latest editions shall be applicable to this part.
GB/T 3048.1 Test methods for electrical properties of electric cables and wires - Part 1.
General
3 Test Apparatus
3.1 Schematic diagram of bridge is given in Figure 1 and Figure 2.
4.1 Sampling
Cut the specimen of which the length is not less than 1m from measured electric wires
and cables; or take the electric wire and cables of coil as specimen. Remove the surface
insulation, sheath or other covers for specimen; the covers of connection position with
measuring system can be used and exposure to conductor. Cover shall be removed
carefully to prevent damage conductor.
4.2 Straightening of specimen
If needed to straighten the specimen, it shall not cause the specimen any distortion which
changes of cross-section of conduction; it shall not lead to elongation of the conductor of
specimen.
4.3 Surface treatment of specimen
Before connecting to measuring system, the surface of conductor shall be cleared, free
from attachments, dirt and grime. The oxide coating of surface of connection position shall
be removed. After treatment by reagent, the remaining shall be cleaned with water. For
water-blocked specimen, it shall be poured with low melting point alloy.
4.4 Aluminium conductor specimen with large-section
4.4.1 Specimen length of type test
Specimen length are recommended. 3m for (95-185) mm2 of section; 5m for 240 mm2 of
section. Whenever there is dispute, 5m for 185 mm2 of section and below, 10m for 240
mm2 and above.
4.4.2 Current terminal and potential terminal
Aluminum connecting terminals can be used for leading-in end of aluminium strand and
pressure welding with routine method, so as to integrate conductor with joint together. Soft
copper wire of which the diameter is 1.0mm or so can be used for potential electrode and
avoid of loosing
5 Test Procedure
5.1 Environment temperature of test
5.1.1 Whenever type test, it shall place the specimen at test environments of which the
temperature is (15-25)°C and air humidity is not greater than 85%; under testing, the
changes of environment temperature shall not exceed ±1°C.
Measuring the environment temperature by thermometer with division value of 0.1°C;
thermometer distance to ground shall not lower than 1m; distance to wall shall not be
lower than 10cm; distance to specimen shall not exceed 1m; and at the same height, it
shall prevent thermal radiation and cross-ventilation.
5.1.2 Whenever routine test, it shall place the specimen at test environment of which the
temperature is (5-35)°C, so as to achieve the equilibrium temperature. Test results shall
be carried out resistance conversion according to 6.2.2.
5.2 Connection of specimen
5.2.1 Connect the specimen to be tested with two special clamps whenever measuring
with Wheatstone bridge.
5.2.2 Connect the specimen to be tested with four-terminal measuring clamps or four
chucks whenever measuring with Kelvin bridge or other resistance test instruments.
5.2.3 Single-wire of stranded conductor shall be connected with current clamp of
measuring system. For measuring conductor resistance of electric wires and cables with
two cores and above, two clamps of Wheatstone bridge or a pair of electric potential
clamps of Kelvin bridge shall be connected with specimen to be tested at actual marked
line position of length measurement.
5.3 Measuring error of resistance
Measuring error of resistance shall not exceed ±0.5% for type test; measuring error of
resistance shall not exceed ±0.2% for routine test.
5.4 Measurement of specimen length
Measure the the specimen length between clamps of Wheatstone bridge or a pair of
clamps of Kelvin bridge. Measuring error shall not exceed ±0.15% for type test; measuring
error shall not exceed ±0.5% for routine test.
5.5 Measurements of low resistance
Whenever the resistance of specimen is lower than 0.1Ω, measuring error caused by
contact potential and thermoelectrical potential shall be elim...
GB/T 3048.4-2007
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.060
K 13
Replacing GB/T 3048.4-1994
Test methods for electrical properties of electric
cables and wires - Part 4. Test of DC resistance of
conductors
ISSUED ON. DECEMBER 03, 2007
IMPLEMENTED ON. MAY 01, 2008
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword ... 3 
1  Scope ... 6 
2  Normative References ... 6 
3  Test Apparatus ... 6 
4  Specimen Preparation ... 8 
5  Test Procedure ... 9 
6  Test Results and Calculation ... 11 
7  Test Record ... 12 
Foreword
GB/T 3084 Test methods for electrical properties of electric cables and wires is divided
into 14 parts as follows [Translator note. Parts 6 and 15 do not exist].
— Part 1. General;
— Part 2. Test of electrical resistivity of metallic materials;
— Part 3. Test of volume resistivity of semi conducting rubbers and plastics;
— Part 4. Test of DC resistance of conductors;
— Part 5. Test of insulation resistance;
— Part 7. Tracking resistance test;
— Part 8. AC voltage test;
— Part 9. Spark test of insulated cores;
— Part 10. Spark test of extruded protective sheaths;
— Part 11. Test for dielectric dissipation factor;
— Part 12. Partial discharge test;
— Part 13. Impulse voltage test;
— Part 14. DC voltage test;
— Part 16. Surface resistance test.
This part is part 4 of GB/T 3084.
This part replaces GB/T 3048.4-1994 Test Methods for Determining Electrical Properties
of Electric Cables and Wires-Measurement of D.C. Resistance of Conductors. This
revision makes modifications based on GB/T 1.1-2000 Directives for Standardization -
Part 1. Rules for the Structure and Drafting of Standards.
The main changes in this part, compared with GB/T 3048.4-1994, are as follows.
- The title of the standard in English has been changed to “Test methods for electrical
properties of electric cables and wires - Part 4. Test of DC resistance of conductors”;
- The general structure and layout of this part have been changed according to GB/T
1.1-2000.
1) Clause 1 is “scope” (Clause 1 in 1994 edition; Clause 1 in this edition);
2) Clause 2 is “normative references” (Clause 2 in 1994 edition; Clause 2 in this
edition);
3) Clause 3 is “testing equipment” (Clause 3 in 1994 edition; Clause 3 in this
edition);
4) Clause 4 is “sample preparation” (Clause 4 in 1994 edition; Clause 4 in this
edition);
5) Clause 5 is “test procedure” (Clause 5 in 1994 edition; Clause 5 in this edition);
6) Clause 6 is “test result and calculation” (Clause 6 in 1994 edition; Clause 6 in this
edition);
7) Clause 7 is “test record” (none in 1994 edition, clause 7 in this edition);
- Some content, including requirements, is deleted from Clause 1 “scope” (Clause 1 in
1994 edition; Clause 1 in this edition);
- Relevant standards are supplemented in Clause 2 “normative references” (Clause 2
in 1994 edition; Clause 2 in this edition);
- Digital test instruments are explicitly added to Clause 3 “testing equipment” (3.3 in
1994 edition; 3.3 in this edition);
- Technical adjustment is made; and the requirements of preparing water-blocked
conductor samples is added to Clause 4 “sample preparation” (Clause 4 in 1994
edition; Clause 4, 4.3 in this edition);
- The requirements on ambient temperature in Clause 1 and 4.5 in 1994 edition are
incorporated into 5.1 in Clause 5 “test procedure” (Clause 1, 4.5 in 1994 edition, 5.1
in this edition);
- Clause 6 “test result and calculation” is altered as follows.
1) The calculation formula of the bridge method is deleted, and regulations on digital
instrument readings are added (6.1, 6.2 in 1994 edition, 6.1.1, 6.1.2 in this
edition);
2) The calculation formula of temperature correction for routine tests is added (none
in 1994 edition, 6.2.2 in this edition);
3) The requirements for rules for rounding-off of computing results are deleted (6.4
in 1994 edition, none in this edition);
Test methods for electrical properties of electric cables
and wires - Part 4. Test of DC resistance of conductors
1 Scope
This Standard specifies the test apparatus, specimen preparation, test procedure for test
of DC resistance of conductors as well as calculation and test record.
This Standard is applicable to measure DC resistance of conductors of electric wires and
cables, the measuring range is as follows.
– Kelvin (double) bridge (2×105 ~ 99.9)Ω.
– Wheatstone (single) bridge 1Ω ~ 100Ω and above.
The test methods specified in this Standard is not applicable to measure DC resistance of
electric wires and cables which have been installed.
This Standard shall be used together with GB/T 3048.1.
2 Normative Re...