company news about Characteristics of DC fuse

        With the increasing demand for DC fuses in industry, rail transit and even electric vehicles, how to correctly select DC fuses for effective protection is a problem that users and manufacturers should seriously deal with.

        Since the DC current has no current zero crossing point, when breaking the fault current, the arc can only be quickly extinguished by itself under the effect of forced cooling of quartz sand packing. The reasonable design and welding mode of the melt sheet, the purity and particle size ratio of quartz sand, the melting point, the curing mode and other factors all determine the effectiveness and role of DC arc forced extinction.

        Under the same rated voltage, the arc energy generated by DC arc is more than twice that of AC arc. In order to ensure that each arc can be limited to a controllable distance and extinguished rapidly at the same time, there will be no huge energy collection caused by the direct series connection of each arc, which will lead to the fuse explosion accident due to the long duration of arc burning. The tube body of DC fuse is generally longer than that of AC fuse.

        According to the recommended data of the International Fuse Technical Organization, the length of the fuse body shall be increased by 10mm for every 150V increase in DC voltage.

        When the fuse is used in the DC circuit, the complex influence caused by the existence of inductance and capacitance energy must be considered. Therefore, the time constant L/R is an important parameter that cannot be ignored. It should be accurately evaluated according to the occurrence and attenuation rate of the short-circuit fault current of the specific line system. It is not optional to select large or small. Since the time constant L/R of DC fuse determines the breaking arc energy, breaking time and allowable voltage, the thickness and length of the tube must be selected reasonably and safely.

        Because some manufacturers do not have self-contained DC fuse products, it is feasible from a practical point of view to replace them with AC fuses. However, for the safety reasons mentioned above, when AC fuses are used in DC circuits, they should be used with reduced voltage.