The new standard electrical performance test adopts alternating current test, that is, the power frequency voltage value is applied to the inner and outer electrodes of safety shoes, and the measured leakage current does not differ greatly from the original standard.

In European standards, the leakage current increases with the height of the upper. Because European and international standards use wet methods to measure leakage currents, water electrodes are used inside and outside the shoe and are maintained at a certain height level. As the height of the upper increases, the water injection amount of the water electrode increases, and the leakage current through the safety shoe also increases. This is because the capacitance determined by the size of the safety medium and the test electrode geometry greatly affects the current of the alternating current test. Therefore, for the same sample, the leakage current values ​​obtained by the wet test and the dry test are very different and are not comparable.

The function of the electric safety shoes is to prevent the electric current from forming a passage between the human body and the earth when people accidentally receive electric shock, thereby causing electric shock damage to the human body. People usually ground through their feet, so the key part of an electric safety shoe is the outsole of the shoe. Considering that the technical requirements and test methods of the original standard have been practiced for many years, it has been shown to be adaptable to domestic demand, with feasibility and ease of operation. Therefore, this revision still uses the original standard electrical performance test method, ie dry test, only Made editorial changes, technical requirements remain unchanged.

The changes to the test method are as follows:

The wet sponge pad in the inner electrode was removed. Tests have shown that sponge mats impregnated with 1% sodium chloride solution can easily oxidize the beads, affecting the test results;

Use copper sheet instead of metal sheet, and increase the requirements for stainless steel beads;

With reference to foreign standards, the height of the steel ball in shoes and all-rubber all-polymer shoes was increased from the original standard of 15 mm to 30 mm in the test step;

Increase the indication accuracy of the recording ammeter to 0.01mA.

5 Research Summary

During the revision of the standard, some non-electrical properties of several types of products were tested. Although it is only part of the physical and mechanical tests, there are still test data that do not meet the requirements of the new standard. This requires domestic enterprises to pay attention and pay attention to the production process in place. Use appropriate materials and accessories to improve product quality.

The dry and wet tests on electrical properties are also not unified in China. The main requirement for power departments is that all-rubber shoes and all-polymer shoes require wet testing because they are mainly used in wet environments. Considering the safety of the upper, the dry test cannot explain whether the upper is safe, or whether there is a material defect that may be conductive. However, in the standard, how to balance dry and wet methods needs to continue to be studied. After all, the test results of the two methods differ greatly. For electric safety shoes, dry testing cannot be used, and manufacturers cannot use the wet method to test each one. . However, international standards only have low-voltage test requirements. For high voltage, the leakage current should reach a value that cannot be referenced. This requires further research and resolution.

The rapid development of economic globalization has brought pressure and challenges to the development of all countries in the world, and has also pushed standard competition to the forefront of international market competition. The continuous economic growth, overall social progress, and continuous improvement of the people’s living standards in China also raise higher and newer demands on the standards. We must master the rules of the WTO based on the one hand, we must actively adopt international standards and foreign advanced standards to improve product quality, break foreign technical barriers, and promote product exports; on the other hand, we must fully study domestic and foreign products. Differences in standards, targeted to establish standardized technical measures to curb unnecessary product imports in order to protect China's economic interests and national security.

China Labor Insurance Network