Characteristics and performance of photovoltaic cable_Anhui Honglin Instrument Cable Co., Ltd.

Characteristics and performance of photovoltaic cable

Author：hlyb Add Time：2016-03-03 15:50:41

Photovoltaic cables are often exposed to sunlight, and solar systems are often used in harsh environmental conditions, such as high temperature and ultraviolet radiation. In Europe, sunny days will result in a field temperature of up to 100 ° C for the solar system. At present, various materials we can use include PVC, rubber, TPE and high-quality cross-linking materials. Unfortunately, rubber cables with a rated temperature of 90 ° C and even PVC cables with a rated temperature of 70 ° C are often used outdoors. At present, the national golden sun project is launched frequently, and many contractors do not choose special cables for solar system in order to save costs, Instead, ordinary PVC cables are selected to replace photovoltaic cables. Obviously, this will greatly affect the service life of the system.

The characteristics of photovoltaic cable are determined by its special insulating material and sheath material for cable. We call it cross-linked PE. After irradiation by irradiation accelerator, the molecular structure of cable material will change, so as to provide its performance in all aspects. In fact, during installation and maintenance, the cable can be routed on the sharp edge of the roof structure, and the cable must withstand pressure, bending, tension, cross tensile load and strong impact. If the strength of the cable sheath is not enough, the cable insulation will be seriously damaged, which will affect the service life of the whole cable, or lead to problems such as short circuit, fire and personal injury.

Performance of photovoltaic cable

Electrical properties

1. DC resistance

When the finished cable is 20 ℃, the DC resistance of conductor core shall not be greater than 5.09 Ω / km.

2 immersion voltage test

The finished cable (20m) will not break down after being immersed in water at (20 ± 5) ℃ for 1H and subjected to voltage test for 5min (AC 6.5kv or DC 15kV).

3 long term DC withstand voltage

The sample is 5m long, put it into distilled water containing 3% sodium chloride (NaCl) at (85 ± 2) ℃ for (240 ± 2) h, and both ends are exposed to the water surface for 30cm. A DC voltage of 0.9kv is applied between the wire core and the water (the conductive wire core is connected to the positive pole and the water is connected to the negative pole). After taking out the sample, conduct the immersion voltage test. The test voltage is AC 1KV. It is required that there is no breakdown.

4 insulation resistance

The insulation resistance of finished cable at 20 ℃ shall not be less than 1014 Ω & middot; cm，

Insulation resistance of finished cable at 90 ℃ shall not be less than 1011 Ω & middot; cm。

5 sheath surface resistance

The surface resistance of finished cable sheath shall not be less than 109 Ω.

Other properties

1. High temperature pressure test (GB / T 2951.31-2008)

Temperature (140 ± 3) ℃, time 240Min, k = 0.6, indentation depth shall not exceed 50% of the total thickness of insulation and sheath. And AC6 5kV, 5min voltage test, no breakdown is required.

2 damp heat test

After the sample is placed at 90 ℃ and 85% relative humidity for 1000h and cooled to room temperature, compared with before the test, the change rate of tensile strength is ≤ - 30%, and the change rate of elongation at break is ≤ - 30%.

3 acid base solution resistance test (GB / T 2951.21-2008)

The two groups of samples were immersed in oxalic acid solution with the concentration of 45g / L and sodium hydroxide solution with the concentration of 40g / L respectively. The temperature was 23 ℃ and the time was 168h. Compared with that before immersion, the change rate of tensile strength was ≤± 30% and the elongation at break was ≥ 100%.

4 compatibility test

Overall cable diameter 7 × After aging at (135 ± 2) ℃ for 24h, the change rate of tensile strength before and after insulation aging is ≤± 30%, and the change rate of elongation at break is ≤± 30%; The change rate of tensile strength before and after sheath aging is ≤ - 30%, and the change rate of elongation at break is ≤± 30%.

5 low temperature impact test (8.5 in GB / T 2951.14-2008)

The cooling temperature is - 40 ℃, the time is 16h, the weight of the drop hammer is 1000g, the weight of the impact block is 200g, the falling height is 100mm, and there shall be no visible cracks on the surface.

6 low temperature bending test (8.2 in GB / T 2951.14-2008)

The cooling temperature is (- 40 ± 2) ℃, the time is 16h, the diameter of the test bar is 4 ~ 5 times of the outer diameter of the cable, and it is wound for 3 ~ 4 turns. There shall be no visible cracks on the sheath surface after the test.

7 ozone resistance test

The length of the sample is 20cm and placed in a dry vessel for 16h. The diameter of the test bar used in the bending test is (2 ± 0.1) times of 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 ~ 0.5 times the volume of the test chamber / min. After the sample is placed in the test chamber for 72h, there shall be no visible cracks on the sheath surface after the test.

8 weather resistance

Ultraviolet test

Each cycle: water spraying for 18min, xenon lamp drying for 102min, temperature (65 ± 3) ℃, relative humidity 65%, * * * low power under the condition of wavelength 300 ~ 400nm: (60 ± 2) w / m2. The bending test at room temperature was carried out after 720h. The diameter of the test bar shall be 4 ~ 5 times of the outer diameter of the cable, and there shall be no visible cracks on the sheath surface after the test.

9 dynamic penetration test

At room temperature, the cutting speed is 1n / s and the number of cutting tests: 4 times. Each time, the test sample must be moved forward by 25mm and rotated clockwise by 90 °. Record the penetration force F at the moment of contact between the spring steel needle and the copper wire, and the average value is ≥ 150 & middot; DN1 / 2 n (4mm2 section DN = 2.5mm)

10 dent resistance

Take 3 sections of samples, each 25 mm apart, and rotate 90 ° to make 4 dents, the depth of which is 0.05 mm and perpendicular to the copper conductor. The three sections of samples are placed in the test chamber at - 15 ℃, room temperature and + 85 ℃ for 3h respectively, and then wound on the mandrel in their corresponding test chamber. The diameter of the mandrel is (3 ± 0.3) times the small outer diameter of the cable * * *. At least one notch of each sample is located on the outside. Perform ac0 No breakdown during 3KV immersion voltage test.

11 sheath thermal shrinkage test (11 in GB / T 2951.13-2008) cut the sample with length L1 = 300mm, place it in 120 ℃ oven for 1h, take it out to room temperature for cooling, repeat such cold and heat cycle for 5 times, and cool it to room temperature after * * *. The thermal shrinkage rate of the sample is required to be ≤ 2%.

12 vertical combustion test

After the finished cable is placed at (60 ± 2) ℃ for 4h, the vertical combustion test specified in GB / T 18380.12-2008 shall be carried out.

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 less than 0.1mg. Air flow (0.0157 & middot; D2) l & middot; H-1 ± 10%, the distance between the combustion boat and the edge of the effective heating area of the furnace shall be ≥ 300mm, the temperature at the combustion boat shall be ≥ 935 ℃, and the temperature at 300m away from the combustion boat (along the air flow direction) shall be ≥ 900 ℃.

The gas produced by the test sample contains 450ml (pH value 6.5 ± 1.0; conductivity ≤ 0.5 μ S / mm) gas bottle washing collection of distilled water, test cycle: 30min. Requirement: pH ≥ 4.3; Conductivity ≤ 10 μ S/mm。

CL and Br content

Sample placement: 16h, temperature (21 ~ 25) ℃, humidity (45 ~ 55)%. Two samples (500 ~ 1000) mg each, crushed to 0.1mg.

Air flow (0.0157 & middot; D2) l & middot; H-1 ± 10%, the sample is evenly heated to (800 ± 10) ℃ for 40min and maintained for 20min.

The gas generated by the test sample is absorbed through the gas washing bottle containing 220ml / 0.1M sodium hydroxide solution; Inject the liquid of the two gas washing bottles into the measuring bottle. At the same time, clean the gas washing bottle and its accessories with distilled water and inject it into the measuring bottle to 1000ml. After cooling to room temperature, drop 200ml of the measured solution into the measuring bottle with a straw, add 4ml of concentrated ************************** 20ml of 0.1M silver and 3ml of nitrobenzene, and then stir until white flocs are deposited; Add 40% ammonium sulfate aqueous solution and a few drops of ******* solution, mix them completely, stir them with a magnetic stirrer, and add ammonium sulfate titration solution.

Requirements: mean value of test values of two samples: HCl ≤ 0.5%; HBr≤0.5%;

The test value of each sample ≤ the mean value of the test values of two samples ± 10%.

F content

Put 25 ~ 30mg of sample material into 1L oxygen container, drop 2 ~ 3 drops of alkanol, and add 5ml of 0.5m sodium hydroxide solution. Burn out the sample block and pour the residue into a 50ml measuring cup by slight flushing.

Mix 5ml buffer solution into the sample solution and flushing solution and reach the marking line. Draw the calibration curve to obtain the fluorine concentration of the sample solution, and calculate the fluorine percentage content in the sample.

Requirement: ≤ 0.1%.

14 mechanical properties of insulation and sheath materials

Before aging, insulation tensile strength ≥ 6.5n/mm2, elongation at break ≥ 125%, sheath tensile strength ≥ 8.0n/mm2, elongation at break ≥ 125%. After (150 ± 2) ℃, 7 × After 24h aging, the change rate of tensile strength before and after aging of insulation and sheath is ≤ - 30%, and the change rate of elongation at break before and after aging of insulation and sheath is ≤ - 30%.

15 thermal elongation test

Under the load of 20n / cm2, after the sample is subjected to the thermal extension test at (200 ± 3) ℃ for 15min, the middle value of the elongation of insulation and sheath shall not be greater than 100%, and the percentage of the middle value of the increase in the distance between the marking lines after the test piece is taken out of the oven and cooled to the distance before the test piece is put into the oven shall not be greater than 25%.

16 thermal life

According to en 60

216-1, en60216-2 Arrhenius curve, temperature index is 120 ℃. Time: 5000h. Retention rate of elongation at break of insulation and sheath: ≥ 50%. Then the bending test at room temperature was carried out. The diameter of the test bar is twice the outer diameter of the cable, and there shall be no visible cracks on the sheath surface after the test. Required service life: 25 years.

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Characteristics and performance of photovoltaic cable