- Jul 25, 2020-
Wire and cable testing has always been an important part of the national standard wire and cable. The higher the quality inspection department of a wire and cable company, the better the quality of the wire and cable produced by the company and the more trustworthy it is. So what kind of cable is of good quality? What are the quality inspection indicators? The following editor will give you a specific introduction.
The following are several important indicators of wire and cable, which are the most critical indicator points for measuring wire and cable.
1. Measurement of DC resistance of wire:
The conductive core of the wire and cable mainly transmits electric energy or electric signal. 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 than when the DC voltage is applied, but the difference between the two is very small when the electrical frequency is 50Hz. The current standard stipulates It can only be required to detect whether the DC resistance or resistivity of the wire core exceeds the value specified in the standard. Through this inspection, certain defects in the production process can be found, such as wire breakage or partial single wire breakage, and the wire section does not meet the standard , The length of the product is incorrect, etc.
2. Test of insulation resistance:
Insulation resistance is an important index reflecting the insulation characteristics of wire and cable products, and is closely related to the product's electrical strength, dielectric loss, and the gradual deterioration of insulating materials under working conditions. For communication cables, too low insulation resistance between lines will increase loop attenuation, crosstalk between loops, 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 AC voltage is applied to the cable, current will flow. When the voltage amplitude and frequency are constant, the capacitance current is proportional to the capacitance (Cx) of the cable. 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. Through the measurement of capacitance and dissipation factor, various insulation degradation phenomena such as insulation dampness, insulation layer and shielding layer falling off can be found. Therefore, capacitance and TANδ are measured whether in cable manufacturing or cable operation.
4. Dielectric strength test:
The insulation strength of wires and cables refers to the ability of the insulation structure and insulation materials to withstand the action of an electric field without breakdown. In order to check the quality of the wire and cable products and ensure the safe operation of the products, all insulation types of wires and cables are generally subjected to an insulation strength test . Dielectric strength test can be divided into withstand voltage 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 standard. The withstand voltage test can test the reliability of the product running under the working voltage and find the seriousness of the insulation Defects, some shortcomings of the production process can also be found.
5. Aging and stability test:
The aging test is a stability test to maintain stable performance under stress (mechanical, electrical, thermal). Thermal aging test: A simple thermal aging test is to test the aging characteristics of the sample under the action of heat. The sample is placed in an environment with a certain value higher than the rated working temperature, so that at a higher temperature T, Short life.
6. Thermal stability test:
The thermal stability test is that the cable is heated by current while also withstanding a certain voltage. After a certain period of heating, certain sensitive performance parameters are measured to evaluate the insulation stability. Insulation stability test is divided into 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 the editor to help you understand the quality indicators of the wire and cable, so that you can have a basis when purchasing.