What is the meaning of the main detection means of the power cord

The universal meter tests the on-off, and if you want to measure the magnitude of the resistance-current, you must do the power-on test. Generally, if the destructive test is not done, the quality of the power supply line must be judged by the increase in temperature after the current increases.

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Clause. First, first of all, we must look at the wire brand, the quality of the general big brand wire will not be bad, these brand manufacturers will not do inferior products to smash their own signboards, but must buy authentic products, can not buy fake or imitation brand-name wires.

Clause. Second, it is necessary to look at the certificate of conformity, and the general problem is not big if the factory is qualified and there is a national standard standard on the certificate.

Clause. 3. Check the cross-section of the power cord to see if it is the marked material and cross-sectional area thickness.

Clause. Fourth, look at the appearance of the plastic, whether the surface is shiny, whether the material is flexible, etc.

Clause. 5. Check the flexibility of the copper wire, the copper wire should not be too hard, and the copper wire should be shiny; The black copper wire is generally produced because it contains many impurities or is produced by ** copper.

Clause. Sixth, you must buy it from a regular store, and you can't buy it from an untrustworthy store for the sake of being cheap.

According to the relevant provisions of the national standard, the testing items of wires and cables mainly include the testing of electrical properties and mechanical properties, of which the electrical performance testing mainly includes DC resistance testing, insulation resistance testing and power frequency withstand voltage testing.

1) DC resistance detection. There are clear provisions in the relevant national standards: the DC resistance of wires and cables must be based on the conductor resistance per kilometer, and the measured DC resistance data of wires and cables must be converted into the DC resistance value per kilometer at a temperature of 20.

After converting the measured DC resistance value into the DC resistance value under 20 conditions, if its value is less than the specified standard value, then the wire and cable sample is a qualified product, otherwise it is a unqualified product. At present, the relevant departments in China usually use two methods: bridge method and current method to determine the DC resistance of wires and cables. The measurement range of the bridge method is relatively narrow, and can be divided into single-arm bridge method and double-arm bridge method, and the single-arm bridge method is used when the resistance value of the wire and cable is about 1 or more; When the resistance value of the wire and cable is less than 1, the double-arm bridge method is used.

The current method, also known as the micro-ohmmeter method, is based on the size of the resistance value of the wire and cable, using a constant current source to output different constant currents, and then accurately measuring the voltage at both ends of the wire and cable to be measured, and the measured data can be calculated according to Ohm's law to obtain the DC resistance of the measured wire and cable.

The rapid development of the power industry is an important guarantee for the economic development of a country, and wire and cable are indispensable products in the process of power construction. At present, China's wire and cable industry has jumped to the first manufacturing country. However, the quality problems of domestic wires and cables are also more prominent, and the resulting fires or other safety accidents are not uncommon, which is worrying, and it is necessary to do a good job in the testing of each project in the production process according to national standards and scientific methods, so as to provide a scientific and accurate basis for strengthening supervision.

At present, there are many domestic wire and cable manufacturers, the production technology level is uneven, and the quality assurance system of the industry is not perfect, resulting in a large gap between the quality of wire and cable products produced in China and other developed countries. In addition, in order to pursue high profits, some manufacturers use substandard raw materials and production processes, which further leads to counterfeit and shoddy wire and cable products flooding the domestic market. In recent years, the state has gradually attached importance to the detection of wires and cables, and has formulated some strict production and quality regulations, which has promoted the improvement of the quality of wires and cables in China to a certain extent.

A domestic quality inspection agency has investigated the wires and cables of some electrical appliances, and the results show that the qualified rate of wires and cables that can be achieved by ISO9000 certification in the production enterprises is below 90%, and those small-scale wire and cable manufacturers who have not passed the certification have a product qualification rate of not even 30%. According to the investigation report issued by the quality inspection agency, the wire and cable sold by the various franchise stores on the market, the overall pass rate is about 70%, and the pass rate of the wire and cable sold by those smaller hardware stores is not even 10%. The quality of domestic wires and cables is worrying.