Study on a High-Performance Fuse against Surge Current

Fuses are often used as safety measures in the power circuits of electrical and electronic equipment. However, it is not uncommon for fuses to deteriorate or be blown out by the surges resulting from lightning or switching. Moreover, recently, a lot of electrical and electronic equipment has been downsized to save power, a trend that usually involves a lower rated current value for the fuses. When the rated current value of a fuse decreases, its ability to withstand surges also decreases. In this study, the authors propose a two-structure fuse, which does not blow out due to a surge current originating from lightning but will blow out from an overcurrent of commercial power, with an outer conductor for the passage of surges due to lightning and overcurrent in commercial power flow, and an inner conductor to allow the flow of commercial power to pass through smoothly. The characteristics of the proposed fuse were evaluated by measuring the impedance of a prototype and simulating the degree of current separation as an indicator of the proportions of current flowing through the outer and inner conductors by using electromagnetic field simulation. From this, we confirmed that the current flowing in the outer and inner conductors changes with frequency, and the degree of current separation can be changed by changing the thickness of the outer conductor.