Cooper Bussmann NSB FRS-R-4-1 Industrial Fuses

Bussmann NSB FRS-R-4-1 Industrial Fuses are part of the Bussmann Fusetron FRS-R family, a dual-element, time-delay fuse designed for industrial protection. The FRS-R-4-1 is a 4 ampere, Class RK5 device rated for up to 600 VAC or 300 VDC, making it suitable for both AC mains and DC power feeds in control panels, power supplies, and motor-control circuits. It uses ferrule-end terminations to fit standard RK5 fuse holders, enabling straightforward replacement in rugged industrial environments. As a time-delay fuse, it tolerates brief inrush conditions common to motors and transformers while still interrupting fault currents to protect downstream components. The NSB designation identifies a specific Bussmann catalog variant within the FRS-R series, a lineup widely used in applications requiring reliable circuit protection. Typical uses include protecting power distribution lines, rectifier modules, and electrical drives in industrial equipment, where a balance of surge tolerance and fast fault interruption is essential for system safety and continuity.