On the important indicators of wire and cable quality testing.

The detection of wire and cable has always been an important link in the national standard wire and cable. The higher the quality inspection department within a wire and cable company, the better the quality of wire and cable produced by the company and the more trustworthy it is. The stricter the third-party quality inspection department is, the more favorable it is to the development of this industry.

The following are some important indicators of wire and cable. These are the most important indicators for measuring wire and cable:

1, the measurement of the direct current resistance of the wire

Wire and cable conductive cores mainly transmit electrical energy or electrical signals. The resistance of the wire is the main indicator of its electrical performance. When the AC voltage is applied, the core resistance is larger than the DC voltage due to the skin effect, but when the frequency of the eye is 50Hz, the difference between the two is very small. All that can only be required to check whether the DC resistance or resistivity of the wire core exceeds the value specified in the standard. Through this check, you can find some defects in the production process, such as wire breakage or part of the single wire breakage; wire cross-section is not Meet the standards; the length of the product is not correct.

2, insulation resistance test

The insulation resistance type reflects the important index of insulation properties of wire and cable products, and is closely related to the strength of the product, dielectric loss, and the gradual deterioration of the insulation material under working conditions. For communication cables, too low insulation resistance between lines will also increase loop attenuation, crosstalk between loops, and long-distance power supply leaks on conductive cores, etc. Therefore, the insulation resistance should be higher than the specified value.

3, the measurement of capacitance and loss factor

When the AC voltage is applied to the cable, the current flows. When the voltage amplitude and frequency are constant, the capacitor current is proportional to the capacitance of the cable (Cx). For ultra-high voltage cables, the current of this capacitor may reach a value comparable to the rated current, which becomes an important factor limiting the cable capacity and transmission distance. Therefore, the capacitance of the cable is also one of the main electrical performance parameters of the cable. The measurement of capacitance and loss factor can reveal that the insulation is damp, the insulation layer and the shielding layer fall off, and other insulation degradation phenomena. Therefore, capacitance and TANδ are measured both in cable manufacturing and cable operation.

4, insulation strength test

The insulation strength of wire and cable refers to the ability of insulation structure and insulation material to withstand the effect of electric field without breakdown. In order to check the quality of wire and cable products and ensure the safe operation of products, the insulation strength test is generally required for all insulation type wire and cable. . Dielectric strength test can be divided into pressure test and breakdown test. The time voltage is generally higher than the rated working voltage of the test product. The specific voltage value and withstand voltage time are stipulated in the product standards. The withstand voltage test can test the reliability of the product under the working voltage and find the seriousness of the insulation. Defects can also reveal some of the disadvantages of the production process.

5, aging and stability test

Aging test is the stability test that can maintain stable performance under stress (mechanical, electrical, and thermal). Heat Aging Test: A simple heat aging test is a test of the aging property of a sample under the effect of heat. The test product is placed in an environment with a certain value higher than the rated operating temperature, so that it is obtained at a higher temperature T. Shorter life.

6, thermal stability test

The thermal stability test is that the cable is heated by the current and also withstands a certain voltage. After a certain period of heating, certain sensitive performance parameters are measured to assess the stability of the insulation. The insulation stability test is divided into long-term stability test or short-term accelerated aging test.