How to test the product performance of new energy cable manufacturers

1、 Test basis and standard

• international standard : IEC 60245 (general cable), IEC 62899 (electric vehicle cable), UL 62 (American cable safety standard), TIA-568 (communication cable), etc;

• Domestic standards : GB/T 18487.1 (Conductive Charging System for Electric Vehicles) GB/T 30542（ PV cable ）, NB/T 10406 (wind power cable), etc;

• Industry specific requirements If the new energy vehicle cable needs to meet the specific standards of the vehicle enterprise (such as Volkswagen VW 80808, BMW GS 97026), the photovoltaic cable needs to pass the 2000 hour weathering test of T ∨ V Rhine.

2、 Core performance test items and methods

1.  Electrical performance test (ensure conductive safety)

• DC resistance test

• Objective: To detect the conductivity of conductor and avoid heating due to excessive resistance.

• Method: According to GB/T 3048.4, measure the conductor resistance with a double arm bridge at 20 ℃, and the result should be ≤ the standard value (for example, the resistance of 16mm2 copper conductor should be ≤ 1.15 Ω/km).

• Insulation resistance test

• Purpose: To evaluate the ability of insulation layer to prevent current leakage.

• Method: Apply a DC voltage (such as 1000V) between the conductor and the shielding layer with a megger to measure the insulation resistance. The PV cable should be ≥ 100M Ω・ km at room temperature and ≥ 10M Ω・ km at high temperature (120 ℃).

• Withstand voltage test (breakdown test)

• Objective: To verify the anti breakdown ability of insulation layer under high voltage.

• Methods: AC voltage (such as 3kV, lasting for 5min) is applied between the conductor and the shielding layer, without breakdown and flashover; High voltage cables of new energy vehicles need to withstand higher voltage (for example, 600V system needs to pass 10kV test).

• Partial discharge test

• Objective: To detect whether there is partial discharge in the insulation layer (which may lead to insulation aging for a long time).

• Method: When 1.73 times of rated voltage is applied to the cable, the partial discharge shall be ≤ 10pC (requirements for photovoltaic and wind power cables).

2.  Mechanical property test (suitable for mechanical stress during installation and use)

• Tensile strength and elongation at break

• Purpose: To evaluate the tensile resistance of insulation layer and sheath to avoid breakage during installation.

• Method: According to GB/T 1040, the tensile strength (insulation layer of photovoltaic cable ≥ 12MPa) and elongation at break (≥ 100%) are measured at a tensile speed of 250mm/min.

• Bending performance test

• Bending test: bend the cable around a mandrel with a diameter of 6 times the outer diameter of the cable repeatedly (for example, 10000 times), and the insulation resistance and withstand voltage still need to meet the standard after the test;

• Torsion test (wind power cable): under - 40 ℃ to+80 ℃, cycle 1000 times with a torsion angle of ± 180 °/m, without structural damage.

• Purpose: Simulate the torsion condition of new energy vehicle wiring (such as repeated bending inside the vehicle body) or wind power cable.

• method:

• Abrasion resistance test

• Purpose: to prevent sheath damage caused by long-term friction (such as friction between automobile chassis cable and components).

• Method: Use a grinding wheel (hardness 60 Shore A) to rub the sheath with 5N pressure, and the wear resistance times should be ≥ 1000 times (required for new energy vehicle cables).

• Tear resistance

• Objective: To evaluate the tear resistance of sheath and avoid cracking caused by external impact.

• Method: According to GB/T 1043, tear strength ≥ 12kN/m (photovoltaic cable sheath).

3.  Environmental adaptability test (resistance to extreme temperature, chemical corrosion, etc.)

• High and low temperature performance test

• High temperature aging: place at 120 ℃ (photovoltaic cable) or 150 ℃ (automobile cable) for 168h, test the tensile strength and elongation after cooling, and the retention rate must be ≥ 80%;

• Low temperature impact: freeze at - 40 ℃ for 4h, impact the sheath with a weight hammer, without cracks;

• Cold and hot cycle: - 40 ℃ (8h) and 120 ℃ (16h) cycles for 10 times, and the performance does not decline significantly.

• Purpose: Simulate cold (such as northern winter) or high temperature (such as automobile engine compartment) environment.

• method:

• Chemical corrosion resistance test

• Oil resistance test: in IRM 903 oil (100 ℃, 70h), the volume change rate of the sheath is ≤ 50%, and the weight change rate is ≤ 30%;

• Electrolyte resistance test (battery cable): soak in battery electrolyte (such as LiPF ₆ solution) for 72h, and the insulation resistance retention rate is ≥ 80%.

• Purpose: to resist the corrosion of oil stain, coolant, acid and alkali (such as new energy vehicle cable contacting battery electrolyte and engine oil).

• method:

• Weather resistance test (outdoor cable)

• Ultraviolet aging: when exposed to UVB-313 lamp for 168h (simulating outdoor lighting for 3 years), the tensile property retention rate is ≥ 70%;

• Ozone aging: no cracks after 96h storage at 40 ℃ with 50ppm ozone concentration.

• Objective: To resist ultraviolet, ozone, moisture and other aging (such as photovoltaic cable exposed to outdoor).

• method:

• Fire resistance and flame retardancy

• Flame retardant test: according to GB/T 18380, when burning vertically, the flame spread height is ≤ 2.5m, and the self extinguishing time is ≤ 60s;

• Fire resistance test (key circuit): it can still be powered on (voltage ≥ 0.6kV) after burning in 830 ℃ flame for 3h.

• Objective: To delay combustion in a fire and ensure escape and rescue time.

• method:

4.  Special performance test (customized requirements for new energy scenarios)

• Radiation resistance (photovoltaic cable)

• Objective: To resist the long-term radiation aging of ultraviolet and gamma rays in photovoltaic power stations.

• Methods: After 250 kGy radiation, the retention rate of tensile strength and elongation was ≥ 80%.

• Water resistance test

• Purpose: to prevent water intrusion from affecting insulation (such as underground cable or humid environment).

• Method: Immerse the cable in 2m deep water for 24h, with insulation resistance ≥ 50M Ω・ km, and the withstand voltage test is qualified.

• Shielding performance (signal and high-voltage cable)

• Purpose: to prevent electromagnetic interference (such as the interference of high-voltage cables of new energy vehicles on the on-board radar).

• Method: Measure the transfer impedance of the shielding layer (≤ 10m Ω/m @ 1MHz) to ensure the electromagnetic shielding effect.

3、 Test process and judgment criteria

1. Sampling rules : 3-5 sections of samples (length ≥ 1m) are randomly selected from each batch, covering different production periods to ensure representativeness;

2. Test sequence : Non destructive tests (such as insulation resistance) shall be carried out first, and then destructive tests (such as stretching and burning) shall be carried out;

3. Judgment criteria : All items shall comply with the corresponding product standards (for example, photovoltaic cables shall pass all tests of T ∨ V 2PfG 1169/08.15 standard). If any item is unqualified, the batch will be judged as unqualified.

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