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What are the properties of solar cables

Published by admin September 25,2021

Electrical properties

1. DC resistance: The DC resistance of the conductive core of the finished solar cables at 20℃ is not more than 5.09Ω/km.


2 Water immersion voltage test: solar cables (20m) will not breakdown after being immersed in (20±5)℃ water for 1h after 5min voltage test (AC 6.5kV or DC 15kV).


3 Long-term DC voltage resistance: The sample is 5m long and placed in distilled water containing 3% sodium chloride (NaCl) at (85±2)℃ for (240±2)h, and the two ends are exposed to the water surface for 30cm. Apply a DC 0.9kV voltage between solar cables core and the water (the conductive wire core is connected to the positive electrode, and the water is connected to the negative electrode). After taking out the sample, perform a water immersion voltage test. The test voltage is AC 1kV, and no breakdown is required.


4 Insulation resistance: the insulation resistance of solar cables at 20°C are not less than 1014Ω·cm.


5 Sheath surface resistance: The surface resistance of solar cables sheath should not be less than 109Ω.

Other Properties


1. High temperature pressure test (GB/T 2951.31-2008): temperature (140±3) ℃, time 240min, k=0.6, the depth of indentation does not exceed 50% of the total thickness of insulation and sheath. And carry out AC6.5kV, 5min voltage test, solar cables are no breakdown is required.


2 Damp heat test: The sample is placed in an environment with a temperature of 90℃ and a relative humidity of 85% for 1000h. After cooling to room temperature, the change rate of tensile strength is ≤-30%, and the solar cables change rate of elongation at break ≤-30. %.


3 Acid and alkali resistance test (GB/T 2951.21-2008): Two sets of samples were immersed in an oxalic acid solution with a concentration of 45g/L and a sodium hydroxide solution with a concentration of 40g/L. The temperature was 23°C, and the time was 168h. Compared with before immersion in the solution, the tensile strength change rate is ≤±30%, and the elongation at break ≥100%.


4 Compatibility test: After the cable as a whole is aged at (135±2)℃ for 7×24h, the change rate of tensile strength before and after insulation aging is ≤±30%, the change rate of elongation at break ≤±30%; before and after the sheath is aged The rate of change of tensile strength is ≤-30%, and the rate of change of elongation at break is ≤±30%.


5 Low-temperature impact test (GB/T 2951.14-2008, 8.5): cooling temperature -40℃, time 16h, weight of drop weight 1000g, weight of impact block 200g, height of drop 100mm, and there should be no visible cracks on the surface.


6 Low temperature bending test (GB/T 2951.14-2008, 8.2): cooling temperature (-40±2) ℃, time 16h, the diameter of the test rod is 4 to 5 times the outer diameter of the cable, winding 3 to 4 times, after the test There should be no visible cracks on the surface of the sheath.


7 Ozone resistance test: The length of the solar cables sample is 20cm, and it is placed in a drying vessel for 16h. The diameter of the test rod used in the bending test is (2±0.1) times the outer diameter of the cable. The test chamber: temperature (40±2)℃, relative humidity (55±5)%, ozone concentration (200±50)×10-6% , Air flow: 0.2 to 0.5 times the chamber volume/min. After the sample is placed in the test box for 72 hours, there should be no visible cracks on the surface of the sheath after the test.

 

8 Weather resistance/ultraviolet test: each cycle: water spray for 18min, xenon lamp drying for 102min, temperature (65±3)℃, relative humidity 65%, wavelength 300~400nm, minimum power: (60±2)W/m2 . After 720h, the bending test at room temperature was carried out. The diameter of the test rod is 4 to 5 times the outer diameter of the cable. After the test, there should be no visible cracks on the surface of the sheath.


9 Dynamic penetration test: At room temperature, the cutting speed is 1N/s, and the number of cutting tests: 4 times. Each time you continue to test the sample must be moved forward by 25mm and rotated 90° clockwise. Record the penetration force F at the moment the spring steel needle contacts the copper wire, and the average value obtained is ≥150·Dn1/2 N (4mm2 section Dn=2.5mm)


10. Dent resistance: Take 3 sections of samples, each section is 25mm apart, and rotate 90° to make a total of 4 dents. The depth of the dents is 0.05mm and is perpendicular to the copper wire. The three sections of samples were placed in a test box at -15°C, room temperature, and +85°C for 3 hours, and then wound on a mandrel in the corresponding test box. The diameter of the mandrel was (3±0.3) times the minimum outer diameter of the cable. At least one score for each sample is located on the outside. It does not break down in AC0.3kV water immersion voltage test.


11 Thermal shrinkage test of sheath (No. 11 in GB/T 2951.13-2008): The sample is cut to length L1=300mm, placed in an oven at 120℃ for 1h, and then taken out to room temperature to cool down. Repeat this heat and cold cycle 5 times, and finally cool to At room temperature, the thermal shrinkage of the sample is required to be ≤2%.


12 Vertical combustion test: After the solar cables are placed at (60±2)°C for 4 hours, perform the vertical combustion test specified in GB/T 18380.12-2008.


13 Halogen content test: PH and conductivity sample placement: 16h, temperature (21~25)℃, humidity (45~55)%. Two samples, each (1000±5) mg, crushed to particles below 0.1 mg. Air flow rate (0.0157·D2)l·h-1±10%, the distance between the combustion boat and the edge of the effective heating zone of the furnace is ≥300mm, the temperature at the combustion boat must be ≥935℃, 300m away from the combustion boat (in the direction of air flow ) The temperature must be ≥900℃.
The gas generated by the test sample is collected through a gas washing bottle containing 450ml (PH value 6.5±1.0; conductivity ≤0.5μS/mm) of distilled water. Test cycle: 30min. Requirements: PH≥4.3; conductivity≤10μS/mm.
Cl and Br content
Sample placement: 16h, temperature (21~25)℃, humidity (45~55)%. Two samples, each (500-1000) mg, crushed to 0.1 mg.
The air flow rate is (0.0157·D2)l·h-1±10%, and the sample is uniformly heated for 40min to (800±10)℃ and kept for 20min.


15 Thermal extension test:  Under a load of 20N/cm2, after the sample is subjected to a thermal extension test at (200±3)°C for 15 minutes, the median value of the elongation of the insulation and sheath should not be greater than 100%, and the specimen should be taken out of the oven and cooled The median value of the increase in the distance between the back marking lines shall not exceed 25% of the distance before the test piece is placed in the oven.


16.Thermal life: According to EN 60216-1, EN60216-2 Arrhenius curve, the temperature index is 120℃. Time is 5000h. Retention rate of insulation and sheath breaking elongation: ≥50%. Afterwards, a bending test at room temperature was carried out. The diameter of the test rod is twice the outer diameter of the cable, and solar cables should be no visible cracks on the surface of the sheath after the test. Required lifespan: 25 years.