Method for detecting low-temperature flexibility of special cable for charging pile

Abstract

The invention discloses a low-temperature flexibility detection method for a special cable for a charging pile, and the detection method comprises the steps: fixing the end part of a cable sample, rolling, bundling, sequentially carrying out the low-temperature treatment of the rolled and bundled cable sample at the low temperature of-15 DEG C,-35 DEG C and-50 DEG C for 24 hours, carrying out a tensile test within 5 minutes after each low-temperature treatment, after the three low-temperature tensile tests are completed, the cable sample is subjected to a withstand voltage test, it is required that breakdown does not occur, and it is observed that the surfaces of a cable sheath and an insulating core wire do not have cracks or cracks or the like. According to the detection method, the flexibility of the cable in a low-temperature environment can be quickly simulated, and whether the cable cannot be bent, elongated and charged or not in the actual application of the cable at the low temperature is judged.

Description

Technical Field

[0001] The invention relates to a method for detecting the low-temperature flexibility of a cable dedicated to a charging pile, and belongs to the technical field of cable testing. Background Art

[0002] In recent years, with the rapid development of new energy electric vehicles, the construction of charging pile networks has spread across cities across the country. DC fast charging cables are an indispensable part of this, and their efficient charging speed, high reliability and high safety are also popular among electric car owners.

[0003] The charging pile network is laid over a large area in the northeast or exported to Europe, where the winter is cold. The low temperature is a big test for the actual application of cables. Although the current cable standards include low-temperature tensile and low-temperature bending performance tests at -40°C, they are only test methods and requirements for the insulation and sheath materials of cables. The purpose is to assess whether the cable materials have no cracking at -40°C, which only guarantees the safety performance of the cables. However, the charging pile cable is a cable used for mobile charging at any time. Whether it can maintain a certain degree of flexibility at low temperatures and can be used normally is more critical, especially the large outer diameter DC charging cable itself is very bulky, and if the flexibility is not good at low temperatures, it is difficult to use it for mobile charging.

[0004] At present, there are no corresponding standards for the flexibility of large-diameter DC charging cables, especially the overall flexibility of the cables at low temperatures in actual applications, and there is no verification test method. However, many charging gun and charging pile manufacturers have already required that the cables be flexible at low temperatures and have control measures and methods. Summary of the invention

[0005] The purpose of the present invention is to provide a method for detecting the low-temperature flexibility of a cable dedicated to a charging pile. The method can quickly simulate the flexibility of the cable in a low-temperature environment and determine whether the cable is unable to bend and stretch for charging in actual applications at low temperatures.

[0006] In order to achieve the above technical purpose, the technical solution of the present invention is:

[0007] A method for detecting the low temperature flexibility of a charging pile dedicated cable comprises the following steps:

[0008] (1) Take a 4m to 7m cable sample, cut both ends of the cable sample neatly, and clamp them with a clamp to prevent the two ends of the core wire from sliding after bending and curling, which will affect the subsequent test results. At present, the outer diameter of the DC charging pile cable is generally between 25mm and 42mm.

[0009] (2) Roll up the cable sample and tie it with a self-locking cable tie. The cable bending radius is 5 to 6 times the cable diameter OD. Among them: the cable bending radius of the cable with a diameter of 20 to 30 mm is 5 times the cable diameter OD, and the cable bending radius of the cable with a diameter of more than 30 mm is 6 times the cable diameter OD.

[0010] (3) Place the rolled and bundled cable samples in a low-temperature cooling box and treat them at a low temperature of -18℃ to -12℃ for 24 hours. After taking them out, conduct the first cable tensile test within 5 minutes. It is necessary to ensure that the tensile distance is greater than 90% of the original length (the original length of the cable sample) within the set maximum force value of 100N;

[0011] (4) After the cable samples that have passed the first cable tensile test are restored to room temperature, they are re-rolled and bundled, and the rolled and bundled cable samples are placed in a low-temperature cooling box and treated at a low temperature of -38℃ to -32℃ for 24 hours. After being taken out, a second cable tensile test must be carried out within 5 minutes, and it must be ensured that the stretching distance is greater than 80% of the original length within the set maximum force value of 100N;

[0012] (5) After the cable samples that have passed the second whole cable tensile test are restored to room temperature, they are re-rolled and bundled, and the rolled and bundled cable samples are placed in a low-temperature cooling box as a whole, and treated at a low temperature of -58℃ to -52℃ for 24 hours. After being taken out, the third whole cable tensile test must be carried out within 5 minutes, and it must be ensured that the stretching distance is greater than 70% of the original length within the set maximum force value of 100N;

[0013] (6) Conduct a withstand voltage test on the cable samples that have passed the third cable tensile test. The test requires no breakdown and no cracks or splits on the cable sheath and insulation core wire surface. Conduct a withstand voltage test on the cable samples at DC8.4kV / 15min for the main core wire / ground wire and DC3.6kV / 15min for the auxiliary power wire / signal control wire.

[0014] The above-mentioned whole cable tensile test method is: take out the cable sample, cut the cable tie, and immediately place the cable sample on a horizontal parallel tensile machine, with one end fixed and the other end moving and stretching.

[0015] After the sample preparation is completed, it is necessary to put the sample into a temperature box corresponding to the long-term low-temperature working temperature level of the cable for low-temperature treatment test. Only after all the samples pass the test can it be judged that the cable can be normally moved and worked with the minimum turning radius at low temperature.

[0016] The detection method of the present invention can quickly simulate the flexibility of the cable in a low temperature environment, and determine whether the cable is unable to bend and stretch for charging in actual applications at low temperatures, so as to verify the flexibility of the dedicated cable for charging piles in cold areas. The test method has the necessary conditions for actual applications and is highly operable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 Schematic diagram of cable sample rolling.

[0019] Figure 2 Schematic diagram of the overall tensile test of cable samples. DETAILED DESCRIPTION

[0020] Cable sample preparation:

[0021] Take two types of DC charging pile cables with outer diameters of 25mm and 42mm, and cut them into 4m, 5m, 6m and 7m lengths respectively. Both ends are required to be cut neatly, and both ends of each cable sample are clamped with clamps to prevent the two ends of the core wire from sliding after bending and curling, which will affect the subsequent test results.

[0022] Cable sample coiling and bundling:

[0023] Roll up each cable sample separately (such as Figure 1 The cable bending radius of a cable with an outer diameter of 25 mm is 5 times the cable diameter OD, and the cable bending radius of a cable with an outer diameter of 42 mm is 6 times the cable diameter OD.

[0024] Cable low temperature tensile test:

[0025] 1. Put the rolled and bundled cable samples into a low-temperature cooling box and treat them at a low temperature of -15℃ (±3℃) for 24 hours. After taking them out, conduct the first cable tensile test within 5 minutes. It is necessary to ensure that the stretching distance is greater than 90% of the original length (original length of the cable sample) within the set maximum force value of 100N.

[0026] Whole cable tensile test method: Take out the cable sample, cut the cable tie, and immediately place the cable sample on a horizontal parallel tensile machine (such as Figure 2 As shown), one end is fixed and the other end is moved and stretched.

[0027] 2. After the cable samples that have passed the first cable tensile test are restored to room temperature, they are re-rolled and bundled, and the rolled and bundled cable samples are placed in a low-temperature cooling box as a whole, and treated at a low temperature of -35℃ (±3℃) for 24 hours. After taking them out, a second cable tensile test must be carried out within 5 minutes, and it must be ensured that the stretching distance is greater than 80% of the original length within the set maximum force value of 100N.

[0028] 3. After the cable samples that have passed the second cable tensile test are restored to room temperature, they are re-rolled and bundled, and the rolled and bundled cable samples are placed in a low-temperature cooling box as a whole, and treated at a low temperature of -55℃ (±3℃) for 24 hours. After taking them out, they need to be subjected to the third cable tensile test within 5 minutes, and it is necessary to ensure that the stretching distance is greater than 70% of the original length within the set maximum force value of 100N.

[0029] Cable withstand voltage test:

[0030] For each cable sample that has passed the third cable tensile test, a withstand voltage test of DC8.4kV / 15min for the main core wire / ground wire and DC3.6kV / 15min for the auxiliary power wire / signal control wire is performed. The test is required not to break down, and no cracks or fissures should be found on the surface of the cable sheath and the insulating core wire.

[0031] This detection method can quickly simulate the flexibility of cables in low-temperature environments and determine whether the cables are unable to bend and stretch for charging in actual applications at low temperatures, so as to verify the flexibility of dedicated cables for charging piles in cold areas. It has the necessary conditions for actual applications and is highly operational.

[0032] The above embodiments do not limit the present invention in any way, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for detecting the low temperature flexibility of a charging pile dedicated cable, characterized in that: The following steps are involved: (1) Take a 4m to 7m cable sample and clamp both ends of the cable sample with clamps to prevent the ends of the core wire from sliding after bending and curling; (2) Roll and bundle the cable samples. The cable bending radius is 5 to 6 times the cable diameter OD; (3) Place the rolled and bundled cable samples in a low-temperature cooling box and treat them at a low temperature of -18℃ to -12℃ for 24 hours. After taking them out, conduct the first cable tensile test within 5 minutes. It is necessary to ensure that the tensile distance is greater than 90% of the original length within the maximum force of 100N; (4) After the cable samples that have passed the first cable tensile test are restored to room temperature, they are re-rolled and bundled, and the rolled and bundled cable samples are placed in a low-temperature cooling box and treated at a low temperature of -38℃ to -32℃ for 24 hours. After being taken out, a second cable tensile test must be carried out within 5 minutes, and it must be ensured that the stretching distance is greater than 80% of the original length within the set maximum force value of 100N; (5) After the cable samples that have passed the second whole cable tensile test are restored to room temperature, they are re-rolled and bundled, and the rolled and bundled cable samples are placed in a low-temperature cooling box as a whole, and treated at a low temperature of -58℃ to -52℃ for 24 hours. After being taken out, the third whole cable tensile test must be carried out within 5 minutes, and it must be ensured that the stretching distance is greater than 70% of the original length within the set maximum force value of 100N; (6) The cable samples that have passed the third cable tensile test are subjected to a voltage withstand test, which requires no breakdown, and no cracks or cracks on the surface of the cable sheath and insulating core wire.

2. A method for detecting low temperature flexibility of a charging pile dedicated cable according to claim 1, characterized in that: In step (2), the cable bending radius of a cable with a diameter of 20 to 30 mm is 5 times the cable diameter OD, and the cable bending radius of a cable with a diameter of more than 30 mm is 6 times the cable diameter OD.

3. A method for detecting low temperature flexibility of a charging pile dedicated cable according to claim 1, characterized in that: In step (6), the cable sample is subjected to a withstand voltage test of DC8.4kV / 15min for the main core wire / ground wire and DC3.6kV / 15min for the auxiliary power wire / signal control wire.

4. A method for detecting low temperature flexibility of a charging pile dedicated cable according to claim 1, characterized in that: The outer diameter of the cable is between 25mm and 42mm.

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