Important Indicators for Wire And Cable Quality Test

The detection of wire and cable has always been an important link in the national standard wire and cable, the more advanced the internal quality inspection department of a wire and cable enterprise, then, the better the quality of wire and cable produced by this enterprise is better, the more trustworthy. The more stringent the third-party quality inspection department is, the more conducive it is to the development of the industry.

The following are several important indicators of wire and cable, which are the most key indicator points to measure wire and cable:

1, Wire DC resistance measurement

The conductive wire core of the wire and cable mainly transmits electric energy or electrical signals. The resistance of the conductor is the main index of its electrical performance. Under the action of AC voltage, the core resistance has the skin effect and the adjacent effect surface, but the difference between the DC resistance or resistivity of the core exceeds the standard. Through this inspection, some defects in the production process, such as wire fracture or part of the single line broken; the wire section does not meet the standard; the length of the product is incorrect.

2. The insulation resistance test

The insulation resistance is an important index reflecting the insulation characteristics of wire and cable products, which is closely related to the electric resistance strength, dielectric loss, and the gradual deterioration of insulation materials in the working state. For communication cables, the low insulation resistance between the lines will also increase the circuit attenuation, the crosstalk between the circuits and the long-distance power supply leakage on the conductive line core, so it is required that the insulation resistance should be higher than the specified value.

3. Capacitance and loss factor measurement

Cable plus AC voltage, there is a current flow, when the amplitude and frequency of the voltage is certain, the size of the capacitance current is proportional to the capacitor of the cable (Cx). For ultra-high voltage cables, the current of this capacitor may reach a value that can be compared with the rated current, becoming an important factor limiting the cable capacity and transmission distance. Therefore, the capacitor of cable is also one of the main electrical performance parameters of cable. Through the measurement of capacitance and loss factor, we can find that insulation moisture, insulation layer and shielding layer shedding. Therefore, capacitance and TAN δ are measured in cable manufacturing or cable operation.

4. Insulation strength test

The insulation strength of wire and cable refers to the ability of insulation structure and insulation material to bear the action of electric field without breakdown and damage. In order to check the quality of wire and cable products and ensure the safe operation of products, all insulation types of wire and cable generally need to carry out insulation strength test. The insulation strength test can be divided into the voltage withstand test and the breakdown test. The time voltage is generally higher than the rated working voltage of the test product, and the specific voltage value and voltage resistance time are specified in the product standard. Through the voltage test, the reliability of the product running under the working voltage can be tested and serious defects in the insulation can be found, and some shortcomings of the production process can also be found.

5. Aging and stability test

Aging test is a stability test under the action of stress (mechanical, electrical and thermal). Thermal aging test: a simple thermal aging test is to test the aging characteristics of the test product under the action of heat. Put the test article in an environment with a certain value above the rated working temperature, so that a shorter life is obtained at a higher temperature T.

6. Thermal stability test

Thermal stability test is that the cable is heated by the current and also bears a certain voltage. After a certain period of heating, some sensitive performance parameters are measured to evaluate the stability of insulation. Insulation stability test can be divided into long-term stability test or short-term accelerated aging test.