General requirements for cable structure 6.1 Number of conductor cores: 1 core. The conductor shall comply with the requirements specified in GB/T3956 and JB/T8734:
——Type 1 solid conductor;
——Type 2 stranded conductor;
——BVR conductor. The resistance value of each conductor at 20°C shall not exceed the maximum value specified in Table 1, Table 2 and Table 3. Table 1 Nominal cross-sectional area of solid conductors of type 1 (mm2) Maximum resistance of conductor at 20°C (Ω/km) Unplated Metal-plated 0.5 36.0 36.7 0.75 24.5 24.8 1.0 18.1 18.2 1.5 12.1 12.2 2.5 7.41 7.56 4 4.61 4.70 6 3.08 3.11 10 1.83 1.84 16 1.15 1.16 25 0.727 — 35 0.524 — 50 0.387 — 70 0.268 — 95 0.193 — 120 0.153 — 150 0.124 — 185 0.101 — 240 0.0775 — 300 0.0620 — 400 0.0465 — Table 2 Nominal cross-sectional area of the second type of stranded conductors (mm2) Minimum number of single wires of the conductor Maximum resistance of the conductor at 20℃ Ω/km Round Compressed Round Unmetallized Metallized 0.5 7 — 36.0 36.7 0.75 7 — 24.5 24.8 1.0 7 — 18.1 18.2 1.5 7 6 12.1 12.2 2.5 7 6 7.41 7.56 4 7 6 4.61 4.70 6 7 6 3.08 3.11 10 7 6 1.83 1.84 16 7 6 1.15 1.16 25 7 6 0.727 0.734 35 7 6 0.524 0.529 185 37 30 0.0991 0.100 240 37 34 0.0754 0.0762 300 61 34 0.0601 0.0607 400 61 53 0.0470 500 61 34 0.0504 0.0506 600 61 53 0.0470 700 61 34 0.0603 0.0607 800 61 53 0.0470 0.0475 35 133 0.524 0.529 50 133 0.387 0.391 70 189 0.268 0.270 95 259 0.193 0.195 120 259 0.153 0.154 150 336 0.264 0.266 140 336 0.264 0.266 151 336 0.264 0.266 141 336 0.264 0.266 143 336 0.124 0.126 185 427 0.0991 0.100 6.2 Insulation 6.2.1 Materials The insulation extruded on the conductor shall be the following polyvinyl chloride mixtures: PVC/C type for fixed laying heat-resistant 70℃ cable PVC/E type for internal wiring heat-resistant 90℃ cable The test requirements of different types of polyvinyl chloride mixtures are specified in Table 6. 6.2.2 Extruded insulation The insulation shall be tightly extruded on the conductor. When stripping the insulation, the insulation, conductor or tinned layer (if any) shall not be damaged. It shall be checked by inspection and manual measurement to see if it meets the requirements. 6.2.3 Thickness The average value of the insulation thickness shall comply with the specified values in Table 4 and Table 5, column 3. However, the thickness at any point may be less than the specified value, as long as it is not less than 90% of the specified value - 0.1mm. The thickness measurement result shall be rounded to one decimal place in accordance with the provisions of GB/T5023.2. The insulation resistance shall not be less than the specified value in Table 4 and Table 5, column 4. Table 4 Nominal insulation thickness of 300/500V cables and wires Nominal cross-sectional area of conductor mm2 Type of conductor Specified value of insulation thickness mm Minimum insulation resistance at 70℃ MΩ·km 0.5 1 0.6 0.015 0.75 1 0.6 0.012 1.0 1 0.6 0.011 Table 5 Nominal insulation thickness of 450/750V cables and wires Nominal cross-sectional area of conductor mm2 Type of conductor Specified value of insulation thickness mm Minimum insulation resistance at 70℃ MΩ·km 1.5 1 0.7 0.011 1.5 2 0.7 0.010 2.5 1 0.8 0.010 2.5 2 0.8 0.009 4 1 0.8 0.0085 4 2 0.8 0.0077 6 1 0.8 0.0070 6 2 0.8 0.0065 10 2 1.0 0.0070 16 2 1.0 0.0050 25 2 1.2 0.0050 35 2 1.2 0.0043 50 2 1.4 0.0043 70 2 1.4 0.0035 95 2 1.6 0.0035 120 2 1.6 0.0032 150 2 1.8 0.0032 185 2 2.0 0.0032 240 2 2.2 0.0032 300 2 2.4 0.0030 400 2 2.6 0.0028 6.2.4 Mechanical properties before and after aging Insulating polyvinyl chloride should have sufficient mechanical strength and elasticity to ensure normal operation. It should be tested and inspected according to the test specified in Table 6 and meet the requirements of Table 6. Table 6 Test requirements for non-electrical properties of polyvinyl chloride (PVC) insulation No. Test item Unit Type of mixture Test method PVC/C PVC/E Standard No. Clause No. 1.1.1 Tensile strength and elongation at break Delivery state Original properties Tensile strength Original value - minimum middle value Elongation at break Original value - minimum middle value Properties after air oven aging Aging conditions - temperature - time Tensile strength after aging - minimum middle value - maximum rate of change a Elongation at break after aging - minimum middle value - maximum rate of change a N/mm2 % ℃ h N/mm2 % % % 12.5 125 80±2 7×24 12.5 ±20 125 ±20 15.0 150 135±2 10×24 15.0 ±25 150 ±25 GB/T2951.11 GB/T2951.11 GB/T2951.12 9.1 9.1 8.1.3.1 2 2.1 2.2 Weight loss test Aging conditions — Temperature — Time Weight loss — Maximum value °C h mg/cm2 80±2 7×24 2.0 115±2 10×24 2.0 GB/T2951.32 8.1 3 3.1 3.2 Non-contamination test b Aging conditions — Temperature — Time Mechanical properties after aging °C h 80±2 7×24 100±2 7×24 GB/T2951.32 8.1.4 Same as 1.2.2 and 1.2.3 4 4.1 4.2 Thermal shock test Test conditions — Temperature — Time Test results °C h 150±2 1 150±2 1 GB/T2951.31 9.1 No cracking Table 6 (continued) No. Test item Unit Model of mixture Test method PVC/C PVC/E Standard No. Clause No. 5 5.1 High temperature pressure test Test conditions — Pressure applied on the blade — Heating time under load — Temperature Test result — Indentation depth (maximum median value) ℃ % See 8.1.4 in GB/T2951.13-2008 See 8.1.5 in GB/T2951.13-2008 GB/T2951.31 8.1 80±2 50 90±2 50 6 6.1 6.2 Low temperature bending test Test conditions — Temperature c — Time of application of low temperature Test result ℃ -15±2 -15±2 GB/T2951.14 8.1 See 8.1.4 and 8.1.5 in GB/T2951.14-2008 No cracking 7 7.1 7.2 Low-temperature tensile test Test conditions — Temperature c — Time of application of low temperature — Test results — Minimum elongation °C % -15±2 — GB/T2951.14 8.3 See 8.3.4 and 8.3.5 of GB/T2951.14-2008 20 — 8 8.1 8.2 Low-temperature impact test Test conditions — Temperature c — Time of application of low temperature — Drop weight test results °C -15±2 — GB/T2951.14 8.5 See 8.5.5 of GB/T2951.14-2008 See 8.5.4 of GB/T2951.14-2008 See 8.5.6 of GB/T2951.14-2008 9 9.1 9.2 Thermal stability test Test conditions — Temperature — Test results — Minimum average thermal stability time °C min — — — — 200±0.5 180 GB/T2951.32 9 a The rate of change is the ratio of the difference between the median value after aging and the median value before aging to the median value before aging, expressed as a percentage. b If applicable. c According to China's climatic conditions, the low temperature test temperature is specified as -15℃, but the test temperature can be adjusted after consultation between the supply and demand parties. 6.2.5 Identification of insulated cores The insulated cores of the cable shall be identified by colored insulation or other appropriate methods. Except for the insulated cores identified by yellow/green combination colors, each insulated core of the cable shall only use one color. The two-color distribution of the yellow/green combination color insulated core shall meet the following conditions: For each 15mm section of two-color insulated core, one color shall cover at least 30% of the surface of the insulated core and not more than 70%, while the other color shall cover the rest of the insulated core. 7 Marking 7.1 Origin marking and cable identification The cable shall have a continuous mark of the manufacturer's name, product model and rated voltage. The manufacturer's name mark is the mark of the manufacturer's name or trademark. The markings can be printed on the insulation by ink printing, embossing or other suitable methods. 7.2 Marking continuity The distance between the end of a complete mark and the beginning of the next mark shall not exceed 275mm. 7.3 Abrasion resistance The markings printed with ink shall be resistant to abrasion and shall meet the requirements when tested according to the test method specified in GB/T5023.2. 7.4 Clarity All markings shall be legible. 8 Finished cable tests 8.1 Cable withstand voltage test 300/500V finished cables shall be subjected to AC50Hz2000V/5min immersion test, without breakdown and discharge flashover. 450/750V finished cables shall be subjected to AC50Hz2500V/5min immersion test, without breakdown and discharge flashover. 8.2 Combustion performance requirements 8.2.1 Single vertical performance The flame retardant performance of a single cable shall meet the requirements of Table 7. Table 7 Single Flame Retardant Performance Code Sample Outer Diameter d mm Fire Time s Qualified Index Test Method Z d≤25 60±2 1) The distance between the lower edge of the upper fixture and the upper carbonization starting point should be greater than 50mm; 2) The distance between the lower edge of the upper fixture and the upper carbonization starting point is not greater than 540mm; 3) The burning falling objects do not ignite the filter paper under the sample during the test. GB/T18380.12a and GB/T18380.13 25＜d≤50 120±2 50＜d≤75 240±2 d＞75 480±2 a Thin wire or cable or thin optical cable with a total cross-sectional area of less than 0.5mm2 may be melted when the GB/T18380.12 test method is used. The GB/T 18380.22 test method should be used, and the GB/T18380.13 test is not performed. 8.2.2 Bundle combustion performance The bundle flame retardant performance shall meet the requirements of Table 8. Table 8 Bundle flame retardant performance Code Sample outer diameter d mm Fire supply time s Qualified index Test method ZA 7 40 The carbonization range on the sample shall not exceed 2.5m above the bottom edge of the blowtorch. GB/T18380.33 ZB 3.5 40 GB/T18380.34 ZC 1.5 20 GB/T18380.35 ZDa 0.5 20 GB/T18380.36 a Applicable to small wires and cables or optical cables with an outer diameter less than or equal to 12mm and wires and cables with a conductor nominal cross-sectional area less than or equal to 35mm2. 8.3 Fire resistance performance The fire resistance performance shall meet the requirements of Table 9. Note: Under special working conditions, the test time can be determined by negotiation between the manufacturer and the purchaser. Table 9 Fire resistance performance code Test time Test voltage Qualified index Test method N 90min fire supply + 15min cooling Rated voltage 1) 2A fuse is not broken 2) Indicator light is not extinguished GB/T19216.21 8.4 Delivery length 100m, loop without joints. If the length is greater than 100m, the delivery method can be determined by negotiation according to customer needs. The length error should not be less than 0%.
T/DXDLDQCT 001-2024 history
2024T/DXDLDQCT 001-2024 PVC insulated flame retardant and fire-resistant cables with rated voltage 450/750V and below