Miniature Fuses Hesitate Before Blowing To Skirt False Alarms

A range of miniature fuses has been expanded to include "time-lag" versions, which provide a slower reaction time to allow harmless pulse currents to pass through without opening the fuse. The fuses are offered in through-hole and SMT packages and are rated for primary voltage protection at 250 vdc or 125 vdc as outlined in IEC/EN60127-4 and UL 248-14. While built to standards for primary circuit protection, the fuses' voltage rating, performance characteristics, miniature size, and ease of mounting make them suitable for protection of dc sub-circuits as well.The time-lag fuses are especially useful in applications exposed to the effects of higher inrush currents caused by motor loads, or to pc-board transients caused by atmospheric influences such as lightning. The radial-leaded MST250 (round version) is now complemented by the FRT250 (square version), which has a slightly wider pin spacing of 7.5 mm. It exhibits excellent pulse-withstand performance.