This part specifies in detail the technical requirements for polyvinyl chloride insulated shielded and unshielded control cables with rated voltages up to and including 300/500V. All cables shall comply with the corresponding requirements specified in GB 5023.1, and cables of various types shall comply with the special requirements specified in this part. GB 5023.7-1997 Polyvinyl chloride insulated cables with rated voltages up to and including 450/750V Part 7: 2-core or multi-core shielded and unshielded flexible cables GB5023.7-1997 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V
Part 7: Flexible cables screened and unscreened with two or more conductors
GB5023.7—1997
Idt IEC 227-7:1995
Part 7: Flexible cables screened and unscreened with two or more conductors1 General
1.1 Scope
Part 7 of this standard specifies in detail the technical requirements for polyvinyl chloride insulated, screened and unscreened control cables of rated voltages up to and including 300/500 V.
All cables shall comply with the corresponding requirements specified in GB5023.1, and cables of various types shall comply with the special requirements specified in this part respectively.
1.2 References
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T2951.1—1997 General test methods for cable insulation and sheathing materials Part 1: General test methods
Section 1: Measurement of thickness and overall dimensions - Mechanical properties test General test methods for cable insulation and sheathing materials GB/T 2951.2—1997
Part 1: General test methods
Section 2: Thermal aging test methods
GB/T 2951. 4—1997
General test methods for cable insulation and sheathing materials Part 1: General test methods
Section 4: Low temperature test
GB/T2951.5—1997 General test methods for cable insulation and sheathing materials Part 2: Test methods for elastomeric mixtures Section 1: Ozone resistance test - Thermal extension test - GB/T 2951.6--1997E
General test methods for cable insulation and sheath materials-mineral oil test
Part 3: Special test methods for polyvinyl chloride mixtures Section 1: High temperature pressure test-cracking resistance test GB/T 2951.7-1997F
General test methods for cable insulation and sheath materials-Part 3: Special test methods for polyvinyl chloride mixtures Section 2: Weight loss test-thermal stability test GB/T3956-1997 Cable conductors
Approved by the State Administration of Technical Supervision on July 30, 1997 and implemented on September 1, 2008
GB 5023. 7--1997
GB5023.1—1997 Polyvinyl fluoride insulated cables with rated voltages up to and including 450/750V Part 1: General requirements
GB5023.21997 Polyvinyl chloride insulated cables with rated voltages up to and including 450/750V Part 2: Test methods
GR9023—88 Shielding efficiency measurement method for radio frequency coaxial cables (transfer impedance method) GB/T12666.2—90 Burning test methods for wires and cables Part 2: Single wire and cable vertical Direct burning test method IEC502:1994 Extruded insulated power cables with rated voltage of 1~30kV IEC719:1992 Calculation of upper and lower limits of average overall dimensions of round copper core cables with rated voltage of 450/750V and below 2 Oil-resistant polyvinyl chloride sheathed shielded and unshielded flexible cables 2.1 Model
Shielded cable is 227IEC74 (RVVYP)
Unshielded cable is 227IEC75 (RVVY)
2.2 Rated voltage
300/500 V.Www.bzxZ.net
2.3 Structure
2.3.1, Conductor
Number of cores: 2~60 cores
Preferred core numbers 2, 3, 4, 5, 6, 7, 12, 18, 27, 36, 48 and 60 cores Conductors should meet the requirements of the 5th conductor specified in GB/T3956. 2.3.2 Insulation
The insulation extruded on each conductor shall be a PVC/D type polyvinyl chloride mixture. The insulation thickness shall comply with the specified value in Table 1 or Table 2, column 2. The insulation resistance shall not be less than the specified value in Table 1, column 8 or Table 2, column 6. 2.3.3 The insulated cores and fillers (if any) shall be cabled together. The insulated cores shall be arranged in appropriate concentric layers. The center of the twisted cores shall not be allowed to be placed in an insulated core, but a filler made of a suitable material may be placed in the center of the first layer of cables with 5 cores or more. There shall be an insulated core of a yellow-green combination color in the cable cores with 3 cores or more. When cabling, the layers may overlap or a layer of tape may be wrapped around the gap, and the tape shall not adhere to the insulated cores. The gap between the insulated cores of a two-core cable may be filled separately or with a sheath. 2.3.4 Inner sheath of shielded cable
The inner sheath extruded on the cable core shall be a PVC/ST5 type polyvinyl chloride mixture. The thickness of the inner sheath of all cables shall be determined by the following formula:
t=0. 02Dr + 0. 6mm
where D is the assumed diameter of the cable core after the insulated core is cabled according to A2.1, A2.2 and A2.3 in Appendix A of IEC502. The assumed diameter d of 0.5mm2, 0.75mm and 1.0mm2 conductors (not specified in A2.1) shall be 0.8mm, 1.0mm and 1.1mm respectively.
The calculated values ​​of the inner sheath thickness of the cable with the preferred number of cores are shown in the third column of Table 1. Note: When the cable consists of 10 or more cores, the specified values ​​apply to cable cores with 2 or more layers. The average value of the inner sheath layer thickness shall not be less than the calculated value. However, the thickness at any point may be less than the calculated value, as long as it is not less than 85% of the calculated value +0.1 mm.
The inner sheath can fill the gaps between the cable cores, but should not adhere to the bare cores. 2. 3. 5 Shielding
GB5023.7-1997
The shielding layer of the shielded relay should be woven on the inner sheath with bare copper wire or radiation-plated copper wire. The diameter of the braided copper wire for cables with a preferred number of cores shall comply with the specified values ​​in column 4 of Table 1. The maximum diameters of the braided copper wires for other cables are as follows:ds10.0 mm
10.0mmd≤20.0mm
20.0mm
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