Cooper Bussmann FRS-R-400 Fusetron Dual Element Time Delay Fuse

FRS-R-400 is a 400 A dual-element time-delay fuse from Bussmann (now Eaton’s Bussmann series), built for RK5-class protection in 600 VAC / 300 VDC circuits. This Fusetron device is current-limiting and designed to tolerate brief inrush or motor-start surges without nuisance blows, delivering a 200 kA interrupt rating at 600 VAC and 20 kA at 300 VDC. It uses a fiberglass cartridge body with knife-blade terminals and a holder-mount configuration, and its physical size is about 11.63 inches long by 2.34 inches in diameter. The 400 A rating, dual-element construction, and time-delay characteristics make it suitable for protecting feeders, motor circuits, and panel outlets in industrial environments, especially where surges or short overloads are expected but fast disconnection is required for safety and equipment protection. This non-indicating fuse is built to meet Class RK5 requirements and is part of the Fusetron family known for reliable, long-term protection in electrical distribution systems.