DC fuse manufacturersย believe that the rated current of the melt is not equal to the rated current of the fuse. The rated current of the fuse is selected according to the load current of the protected equipment. The rated current of the fuse should be greater than the rated current of the fuse, which should be determined in coordination with the main electrical equipment. The fuse is mainly composed of a melt, a shell and a bracket, where the melt is the key element to control the fusing characteristics. Melting properties are determined by the material, size and shape of the melt.
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DC fuse manufacturers believe that the melt is divided into low melting point and high melting point. Low melting point materials, such as lead and lead alloys, melt easily due to their low melting point. Because of their high resistivity, the size of the melt section is large, and more metal vapor is generated when they are blown, so they are only suitable for fuses with low breaking capacity. High melting point materials, such as copper, silver, etc., have a high melting point and are not easy to fuse. However, due to their low resistivity, they can be made with smaller cross-sectional dimensions than low melting point melts and generate less metal vapour upon fusing, so they are suitable for fuses with high breaking capacity. The shape of the melt is divided into two types: filament and ribbon. Changing the shape of the variable cross-section can significantly alter the fusing characteristics of the fuse.
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DC fuse manufacturers believe that the fuses of charging pilesย have anti-delay characteristics, that is, when the overload current is small, the fuse time is long; when the overload current is large, the fuse time is short. Therefore, within a certain overload current range, when the current returns to normal, the fuse will not blow and can continue to be used. Fuses have different fusing characteristic curves, which can meet the needs of different types of protection objects.
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DC fuse manufacturers believe that the fuse RL of the spiral charging pile is equipped with quartz sand in the fuse tube, and the melt is buried in it. When the melt melts, the arc is sprayed to the quartz sand and its crevices, which can be quickly cooled and extinguished. In order to facilitate monitoring, one end of the fuse is equipped with colored dots, and different colors indicate different melt flows. When the melt melts, the color dots jump out, indicating that the melt has melted. The rated current of the spiral fuse is 5 ~ 200 A, and it is mainly used for branch circuits with large short-circuit current or places with flammable gas.
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DC fuse manufacturers consider the filled tube fuse to be a current-limiting fuse. It consists of a porcelain melting tube filled with quartz sand, contacts and a silver-plated copper mesh melt. Packaging tube fuses are mounted on special bases, such as bases with isolation knives or bases with fuses as isolation knives, operated by a manual mechanism. The rated current of the gas tube fuse is 50 ~ 1000 A, and it is mainly used in circuits with large short-circuit current or places with flammable gas.
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DC fuse manufacturers consider the fuse tubes of unfilled tubular fuses to be made of fiber. The melt used is a variable-section zinc alloy sheet. When the melt is melted, some fibers in the fiber melting tube are decomposed by heat, and high-pressure gas is generated, which quickly extinguishes the arc. Packaging-free tubular fuse has the characteristics of simple structure, good protection performance and convenient use. Generally used in conjunction with the knife switch.