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GB/T 3048.5-2007 English PDF (GBT3048.5-2007)

GB/T 3048.5-2007 English PDF (GBT3048.5-2007)

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GB/T 3048.5-2007: Test methods for electrical properties of electric cables and wires -- Part 5: Test of insulation resistance

This Part of GB/T 3048 specifies the terms and definitions, test equipment, sample preparation, test procedures, test results and calculation, cautions, and test record of DC comparison method and voltage-current method for the measurement of insulation resistance.
GB/T 3048.5-2007
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 29.060.20
K 13
Replacing GB/T 3048.5-1994, GB/T 3048.6-1994
Test Methods for Electrical Properties
of Electric Cables and Wires - Part 5.
Test of Insulation Resistance
ISSUED ON. DECEMBER 3, 2007
IMPLEMENTED ON. MAY 1, 2008
Jointly issued by. General Administration of Quality Supervision,
Inspection and Quarantine (AQSIQ);
Standardization Administration (SAC) of the
People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 7
2 Normative References ... 7
3 Terms and Definitions ... 7
4 Test Equipment ... 8
5 Sample Preparation ... 11
6 Test Procedures ... 11
7 Test Result and Calculation ... 13
8 Precautions ... 14
9 Test Data Sheet ... 15
Foreword
GB/T 3048 "Test methods for electrical properties of electric cables and wires?€? is divided into 14 parts.
-- 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 the Part 5 of GB/T 3048.
This Part replaces GB/T 3048.6-1994 ?€?Test methods for determining electrical properties of electric cables and wires - Determining insulation resistance - Comparison-galvanometer method?€? and GB/T 3048.6-1994 "Test methods for
determining electrical properties of electric cables and wires - Determining insulation resistance - Voltmeter-ammeter method". According to GB/T 1.1 2000 "Directives for standardization - Part 1. Rules for the structure and drafting of standards", this revision adjusts this Part.
This Part integrates and adjusts the applicable contents in GB/T 3048.5-1994 and GB/T 3048.6-1994. Compared with GB/T 3048.5-1994, the main changes of this Part are as follows.
1) The specifications of "measurement of charging time" are modified (5.4.2 of GB/T 3048.5-1994 and 5.3.2 of GB/T 3048.6-1994; 6.6 of this edition); 2) The connection mode of the wire cores of multicore cables to the screen is supplemented (5.1.1 of 1994 edition, 6.1.1 of this edition);
3) The connection modes of "the samples of cables with non-metallic
sheath, unshielded cables or unarmored cables" are modified (5.1.1 of
1994 edition; 6.1.2 of this edition);
4) The test methods for insulation resistance under high temperature are added (Nil in 1994 edition; 6.4 of this edition);
-- The following modifications are made in Chapter 7 "Test result and
Calculation".
1) The calculation formulas are merged and integrated; the calculation
formula for insulation resistance is deleted (6.1 of 1994 edition; 7.1 of this edition);
2) The value of "insulation resistance coefficient K" is more-specifically specified (6.3 of 1994 edition; 7.3 of this edition);
3) The calculation formulas for "volume resistivity ??" and "insulation
resistance constant Ki" are added (Nil in 1994 edition; 7.4 of this edition); 4) The specifications of the rounding of the calculation numbers are deleted (6.4 of 1994 edition; Nil in this edition);
-- Some modifications are made in Chapter 8 "Cautions" as follows.
1) More specific expressions on the test on the sample placed in the
shielded case are made (7.2 of GB/T 3048.6-1994; 8.2 of this edition);
2) The expression on "adopt the megger of which the output end is
suspended over the ground" is modified, and the technical judgment for
utilizing a megger is supplemented (7.4 of GB/T 3048.6-1994; 8.4 of this edition);
-- Add Chapter 9 "Test Data Sheet"; Specify the detail contents that shall be recorded in test data sheet (Nil in 1994 edition; Chapter 9 of this edition). This Part was proposed by China Electrical Equipment Industrial Association. This Part shall be under the jurisdiction of the National Technical Committee on Wire and Cables of Standardization Administration of China.
Drafting organization of this Part. Shanghai Electric Cable Research Institute. Test Methods for Electrical Properties of Electric Cables
and Wires - Part 5. Test of Insulation Resistance
1 Scope
This Part of GB/T 3048 specifies the terms and definitions, test equipment, sample preparation, test procedures, test results and calculation, cautions, and test record of DC comparison method and voltage-current method for the
measurement of insulation resistance.
This Part is applicable to the measurement of the insulation resistance of electric wires and cables, including DC comparison method and voltage-current method. the measurement range of DC comparison method is (105 ~ 2??1035)??; the
measurement range of voltage-current method is (104 ~ 1016)??; in general, measurement voltage is (100 ~500)V.
For voltage-current method, if the measured voltage and current are directly expressed in resistance on the same instrument, then it can also be called "megger method".
This Part shall be used together with GB/T 3048.1.
2 Normative References
The provisions in following documents become the provisions of this Standard through reference in this Standard. For dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this Standard, however, parties who reach an agreement based on this Standard are encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies.
GB/T 2900.5-2002 Electrotechnical terminology - Insulating solids, liquids and gases [eqv IEC 60050 (212). 1990]
GB/T 3048.1 Test methods for electrical properties of electric cables and wires - Part 1. General
3 Terms and Definitions
The following terms and definitions that are established by GB/T 2900.5-2002 are 5 Sample Preparation
5.1 The effective length of the sample shall not be less than 10m, unless otherwise specified in the product standard. The coverings on the insulation at the both ends of the sample shall be peeled carefully and avoid damage to the insulating surface.
5.2 The sample shall be kept in the test environment for enough time to make the sample temperature and the test temperature in balance. Keep the
temperature stable.
5.3 When the sample is tested in the water, the exposed length of the two ends of the sample shall not be less than 250mm; the exposed length of the insulating part shall not be less than 150mm.
When the sample is tested in the air, the exposed length of the insulating part at the sample ends shall not be less than 100mm.
The exposed insulating surface shall be kept dry and clean.
6 Test Procedures
6.1 Connection of the sample
6.1.1 Cable samples with metal sheath, shielding layer or armor
For single-core cables, the insulation resistance of the conductor to the metallic sheath or shielding layers or armor layers shall be measured; as for multi-core cables, each wire core shall be connected to the metallic sheath or shielding layer or armor layer for testing against the rest wire cores. If it is required to measure the insulation resistance between the shield and the wire cores of multi-core cables, it shall measure the shield after all of the wire cores are in parallel connection.
6.1.2 Non-metallic sheathed, non-shielded or unarmored cable samples
The single-core cable shall be submerged in the water; the insulation resistance of the conductor to the water shall be measured; as for multi-core cables, each wire core shall be tested against the rest wire cores.
The sample may also be wound around the metallic test bar. For single-core cables, the insulation resistance of the conductor to the test bar shall be measured; as for multi-core cables, each wire core shall be connected to the test bar for testing against the rest. The external diameter of the test bar shall meet 6.6 Test charging time
In order to keep the measured insulation resistance stable, the test charging time shall be adequate, not less than 1min and does not exceed 5min. Generally, 1min reading is recommended.
6.7 Measuring error of the test system
The measuring error of the test system shall meet the following requirements. -- If the insulation resistance value of the tested sample is (1??1010)?? or below, the measuring error shall not be greater than ??10%;
-- If the insulation resistance value of the tested sample is above (1??1010)??, the measuring error shall not be greater than 20%.
7 Test Result and Calculation
7.1 When DC comparison method is adopted in the test, the insulation
resistance value shall be calcula...

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