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
GB/T 3048.5-2007
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 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 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.
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)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 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 insu...