What are the quality indicators of wire and cable?

The detection of wire and cable has always been an important part of the national standard wire and cable. The higher the quality inspection department within a wire and cable company, the better the quality of the wire and cable produced by this enterprise, and the more reliable it is. So what kind of cable is good quality? What are the quality inspection indicators? The following small series will be introduced for everyone.

The following are some of the key indicators for wire and cable, which are the most critical indicator points for measuring wire and cable.

1. Measurement of wire DC resistance:

The conductive core of the wire and cable mainly transmits 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 due to the skin effect and the adjacent effect surface is stronger than the DC voltage. However, when the electrical frequency is 50 Hz, the difference between the two is small. It can only be required to check whether the DC resistance or resistivity of the core exceeds the value specified in the standard. Through this inspection, some defects in the production process can be found, such as broken wires or partial single-wire breaks, and the conductor cross-section does not meet the standard. The length of the product is incorrect.

2. Test of insulation resistance:

Insulation resistance reflects the important characteristics of the insulation properties of wire and cable products, and has a close relationship with the product's electrical strength, dielectric loss, and the gradual deterioration of the insulation under working conditions. For communication cables, too low insulation resistance between lines will increase loop attenuation, crosstalk between circuits, and long-distance power supply leakage on conductive cores. Therefore, insulation resistance should be higher than the specified value.

3. Measurement of capacitance and loss factor:

When the cable is connected to the AC voltage, current flows. When the amplitude and frequency of the voltage are constant, the magnitude of the capacitor current is proportional to the capacitance of the cable (Cx). For ultra-high voltage cables, the current of such capacitors may reach a value comparable to the rated current, which is an important factor limiting cable capacity and transmission distance. Therefore, the capacitance of the cable is also one of the main electrical performance parameters of the cable. Through the measurement of capacitance and loss factor, various insulation degradation phenomena such as insulation moisture, insulation layer and shielding layer dropout can be found, so capacitance and TAN δ measurement are performed in cable manufacturing or cable operation.

4. Insulation strength test:

The insulation strength of wire and cable refers to the ability of the insulation structure and the insulation material to withstand the electric field without breakdown damage. In order to check the quality of the wire and cable products and ensure the safe operation of the products, all insulation type wires and cables are generally tested for insulation strength. . The dielectric strength test can be divided into a withstand voltage test and a breakdown test. The voltage of time is generally higher than the rated working voltage of the sample, the specific voltage value and the withstand voltage time, which are specified in the product standard. Through the withstand voltage test, the reliability of the product operating under the working voltage can be tested and the seriousness of the insulation can be found. Defects can also reveal some of the shortcomings of the production process.

5. Aging and stability test:

The aging test is a stability test that maintains stable performance under the action of stress (mechanical, electrical, and thermal).

Heat aging test: A simple heat aging test is a test of the aging characteristics of a test product under the action of heat. The test sample is placed in an environment above a certain temperature of the rated working temperature, so that at a higher temperature T, Shorter life.

6. Thermal stability test:

The thermal stability test is that the cable is heated by the current while still receiving a certain voltage. After a certain period of heating, some sensitive performance parameters are measured to evaluate the stability of the insulation. The insulation stability test is divided into two types: long-term stability test or short-term accelerated aging test.

The above is the content of the wire and cable quality inspection indicators introduced by Xiaobian for you to help you understand the quality indicators of wire and cable, so that you can have a basis when purchasing.