Wire and cable quality inspection-Henan Sanheng Cable Co.,Ltd

Wire and cable quality inspection

Jun 13,2018

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 reliable 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, which are the most important indicator points for measuring wire and cable.

Wire and cable quality testing requires these important indicators

Insulation resistance test:

The insulation resistance type reflects the important index of insulation properties of wire and cable products. It 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. Determination of insulation resistance can be found in the process of defects, such as insulation dry or jacket moisture damage; insulation is contaminated and mixed with conductive impurities; various causes of insulation cracking. In the operation of wires and cables, insulation resistance and leakage current are often tested as the main basis for whether or not safe operation can continue. At present, the measurement of the insulation resistance of wire and cable, in addition to using ohmmeter (rocking table), commonly used galvanometer comparison method high resistance meter method (voltage - current method).

Capacitance and loss factor measurements:

When the AC voltage is applied to the cable, current flows. When the voltage amplitude and frequency are constant, the capacitor current is proportional to the cable capacitance (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 capacity of the cable and the transmission distance. Therefore, the capacitance of the cable is also one of the main electrical performance parameters of the cable. In an AC electric field, insulators in the cable, due to leakage currents and various polarizations, generate dielectric losses, represented by the dielectric dissipation factor or loss tangent (TAN δ), which not only wastes power, but also makes the dielectric (insulator) ) Heating, accelerated insulation aging, so TANδ is also one of the main 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. For high-voltage cables, the measurements of Cx and TAN δ are carried out under their operating conditions, that is, at high power frequency, usually using high-voltage Xilin bridges. This year also began to use current-ratio transformer bridges.

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, all insulation types of wire and cable are generally tested for insulation strength. . Dielectric strength test can be divided into pressure test and breakdown test. The withstand voltage test is to apply a certain voltage to the sample under certain conditions. After a certain period of time, whether or not a breakdown occurs is used as a criterion for judging whether or not the sample is qualified. 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 be found in the production process of some shortcomings, such as: insulation has serious external damage, there are serious defects on the conductor to make a sharp distortion of the electric field; insulation in the production of penetrating defects or large conductive impurities. The breakdown test is to measure the breakdown field strength or breakdown voltage by increasing the voltage until the breakdown of the sample under certain test conditions. The breakdown test can be used to assess the safety margin between the ability of the cable to withstand voltage and the operating voltage. One of the important parameters in the cable design when breaking the field strength. The cable is generally subjected to AC voltage in operation, but it also withstands DC voltage in DC transmission systems and certain special occasions. For high voltage cables, it may also be subject to atmospheric voltage (lightning) and operation overvoltage. Therefore, according to the different experimental voltage waveform, can be divided into 1. AC (power frequency) voltage, 2. DC voltage, 3 impulse voltage three dielectric strength test.

Wire and cable quality testing requires these important indicators

Partial discharge measurement:

There is basically no local power generation for oil-filled cables; oil-paper cables are usually very weak, such as several PCs, even if there is partial discharge, so these cables may not measure partial discharge in the factory test. For the extruded cable, not only is the possibility of partial discharge generated, but also the damage of the partial discharge to the plastic and rubber is severe. With the increase of the voltage level and the improvement of the work field, this problem becomes even more serious. Extruded cables are subject to partial discharge measurements in the factory test. Partial discharge measurement methods are many, according to the instantaneous charge exchange generated by the discharge, measuring the discharge pulse (electrical measurement method); also based on the ultrasonic generated when the discharge, measure the voltage (acoustic method); also based on the discharge of light , measure the intensity of light (photometric method). Basically, electrical measurements are used for cables.

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 to consider the characteristics of aging of the test article under the effect of heat. Place the test article in an environment with a certain value higher than the rated operating temperature, and after a specified time, measure some sensitive properties. Aging characteristics were evaluated by changes before and after aging. Can also be used to increase the temperature to accelerate the aging of the test sample, coupled with moisture, vibration, electric field and other thermal, mechanical, electrical and other stress to form an aging cycle, after each aging cycle, determine certain selected sensitive performance parameters. Until the performance drops to the value of the indicated lifetime. In this way, at a higher temperature T, a shorter lifetime L (time for sample heating) is obtained. Thermal temperature test: The thermal stability of the cable is through the current while also withstand a certain voltage, after undergoing a certain period of heating, measuring some of the sensitive performance parameters to assess the stability of the insulation. The insulation stability test is divided into long-term stability test or short-term accelerated aging test. Responsible business thinking is how to improve the quality of the company's products in order to improve their own product market competitiveness, product quality is the development of the company, especially in the wire and cable industry.

Henan Sanheng Cable Co., Ltd , founded in 2000, It is one of the top wire and cable manufacturers in China's wire and cable industry for nearly 20 years. the company has more than 5 production lines.

The production cable can be divided into more than 50 varieties and subdivided into 1000 specifications.All products have passed national certification, such as China compulsory certification, bv certification, Nigerian SONCAP certificate, China national industrial certification, etc. China national industrial production license, etc.It also has the ability to produce products that meet international standards, such as iec, ce, rohs, etc.
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