Bussmann FRN-400 Dual-Element Time Delay Fuse

Bussmann FRN-R-400 Fusetron dual-element time-delay fuse is a 250 V, 400 A cartridge fuse built for current-limiting protection in RK5-class power circuits. Its dual-element construction provides time-delay response to inrush currents while still offering fast short-circuit protection, with an interrupting rating of 200 kA at 250 VAC and 20 kA at 250 VDC. As part of the energy-efficient Fusetron FRN-R family, this non-indicating fuse delivers reliable protection with reduced energy loss in operation, helping minimize heat buildup in densely packed control panels and switchgear. It is suitable for protecting 250 VAC circuits that encounter inrush or surge loads and is commonly used in power distribution panels and equipment protection where dependable, time-delayed discrimination is needed. The FRN-R design is a Class RK5 device (current-limiting, dual-element) in Bussmann's line, widely used in industrial controls, motor drives, and other 250 VAC applications requiring coordination with upstream protective devices, such as circuit breakers and other fuses.