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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 Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB/T 3048.5: Historical versions
Similar standardsGB/T 3048.5-2007: Test methods for electrical properties of electric cables and wires -- Part 5: Test of insulation resistance---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT3048.5-2007 GB NATIONAL STANDARD OF THE PEOPLE’S 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 ContentsForeword... 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... 15ForewordGB/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. -- The Chinese name of the Standard is changed to "Test methods for electrical properties of electric cables and wires - Part 5.Test of insulation resistance "; -- The English name of the Standard is changed to “Test methods for electrical properties of electric cables and wires - Part 5.Test of insulation resistance”; -- The overall structure and compilation of this Part are modified according to GB/T 1.1-2000. 1) Chapter 1."Scope" (Chapter 1 of 1994 edition, Chapter 1 of this edition); 2) Chapter 2.Normative References (Chapter 2 of 1994 edition, Chapter 2 of this edition); 3) Chapter 3.Terms and Definitions (Nil in 1994 edition, Chapter 3 of this edition); 4) Chapter 4.Test Equipment (Chapter 3 of 1994 edition, Chapter 4 of this edition); 5) Chapter 5.Sample Preparation (Chapter 4 of 1994 edition, Chapter 5 of this edition); 6) Chapter 6.Test Procedures (Chapter 5 of 1994 edition, Chapter 6 of this edition); 7) Chapter 7.Test Result and Calculation (Chapter 6 of 1994 edition, Chapter 7 of this edition); 8) Chapter 8.Cautions (Chapter 7 of 1994 edition, Chapter 8 of this edition); 9) Chapter 9.Test Data Sheet (Nil in 1994 edition, Chapter 9 of this edition); -- In Chapter 1 "Scope", the parts containing requirements are deleted; comparison-galvanometer method is changed to DC comparison method, and its measurement range is modified (Chapter 1 of 1994 edition; Chapter 1 of this edition); -- GB/T 2900.5-2002 quoted in Chapter 3 is listed in Chapter 2 "Normative References" (Chapter 2 of 1994 edition; Chapter 2 of this edition); -- Tester for digital DC comparison method is clearly supplemented in Chapter 4 "Test Equipment" (Nil in 1994 edition; 4.3 of this edition); -- The following modifications are made in Chapter 6 "Test Procedures". 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 ρ" 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. Chief drafting staffs of this Part. Wan Shude, Xia Kairong, Yu Zhenming, Zhu Zhongzhu, and Jin Biaoyi. The previous editions replaced by this Part are as follows. -- GB 765-1965, GB3048.5-1983, and GB/T 3048.5-1994; -- GB3048.6-1983, and GB/T 3048.6-1994. Test Methods for Electrical Properties of Electric Cables and Wires - Part 5.Test of Insulation Resistance1 ScopeThis 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)Ω; the measurement range of voltage-current method is (104 ~ 1016)Ω; 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 ReferencesThe 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]3 Terms and DefinitionsThe following terms and definitions that are established by GB/T 2900.5-2002 are applicable to this Part of GB/T 3048. 3.1 Insulation resistance It is the electric resistance of the insulating material located between two conductors under specified conditions. 3.2 Volume resistance It is the insulation resistance part determined by the volume conduction after the surface current is eliminated. 3.3 Volume resistivity It is the volume resistance in per unit of cubic volume.4 Test Equipment4.1 The typical principle of DC comparison method is shown in Figure 1.The main components shall meet the following requirements. 4.1.1 The current constant of the galvanometer shall not be larger than 10-9 A/mm. 4.1.4 The output voltage of the DC power supply shall be stable; the change of the voltage value at the output end shall not exceed ±1%. 4.2 The connection of the typical test system in voltage-current method is shown in Figure 2; the main components shall meet the following requirements. 4.2.1 The accuracy of the DC voltmeter shall not be less than Grade 1.0. 4.2.2 The zero point drift of the high resistance DC amplifier, galvanometer or the microammeter under rated operating voltage within 8h shall not exceed 4% of the full scale of the instrument. 4.2.3 The input resistance of the DC amplifier shall be at least 100 times smaller than the insulation resistance of the sample. 4.3 Other measuring instruments can be used, as long as the measuring error meets those specified in 6.7.If a bridge circuit is measured according to similar relational expression for high voltage bridge and analog-digital converter technology is adopted, then the tester in digital DC comparison method which has anti-interference and high stability shall be adopted.5 Sample Preparation5.1 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.6 Test Procedures6.1 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. 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. 6.2 Length measurement of the sample Connect the sample to the test system. The measuring error of the effective length of the sample shall not exceed ±1％. 6.3 Test environment conditions In the type test, the measurement shall be conducted in the room, where the environment temperature is (20±5)°C; the relative temperature of the air is not larger than 80%, or be conducted in water, unless otherwise specified in the product standard for electric wires and cables. In the routine test, the measurement shall be conducted in the room where the environment temperature is (0~35) °C. 6.4 Test methods for the insulation resistance of the cables under high temperature 6.4.1 Cut a sample of 1.40m long from the tested single-core cable; shielding layers shall be cladded at the center of the sample. Metallic knit or metal bar may be taken as the shielding layers. The cladding way shall enable the effective length to 1.0m at least. 6.5 Test voltage Select the test voltage for the sample according the requirements in the product standard. 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.7 Test Result and Calculation7.1 When DC comparison method is adopted in the test, the insulation resistance value shall be calculated according to the formula provided by the instrument instructions. 7.2 The insulation resistance of per kilometer length shall be calculated according to Formula (1). 7.4 Volume resistivity shall be calculated according to Formula (3) with the measured insulation resistance.8 Precautions8.1 If necessary, a protection ring may be provided to the two ends of the insulating surface. The protection ring shall be clung to the insulating surface and be connected with the shield of the test system or be grounded. 8.3 When the test is repeated, the sample shall be short-circuited and discharged before voltage application; the discharge time shall not be less than 4 times of the charging time of the sample. If the measurement results have apparent disparities due to residual charge in the sample, the sample must be discharged sufficiently first. For such samples, sufficient discharging is required in the first test or in repeated test. 8.4 When the insulation resistance is measured by adopting a megger whose output end is suspended over the ground, it is recommended that the measuring end (low voltage end) of the megger to be connected to the conductor of the tested insulated core, and the high voltage end to be connected to the other pole (water, it is permitted to be grounded) of the sample. 8.5 Attention shall be drawn to the connection methods for the internal and external shield of the whole set apparatus used by the DC comparison method, so as to avoid to enlarge the measuring error.9 Test Data SheetThe following contents shall be recorded in the test data sheet. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. 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