Bussmann FRN-300 Dual-Element Time-Delay Fuse

FRN‑R‑300 Fusetron is Eaton Bussmann’s high‑current, dual‑element, time‑delay fuse designed for motor protection in Class RK5 circuits. It is rated 300 A at 250 VAC, with 125 VDC ratings for 110–200 A and 250 VDC ratings for 225–600 A, providing current‑limiting protection while tolerating brief overloads to prevent nuisance trips. The cartridge‑style fiberglass body measures 2.38 in in diameter by 8.63 in long, with blade terminals and a non‑indicating design. It delivers an interrupting rating of 200 kA RMS at 250 VAC and 20 kA DC, and a minimum 10‑second time delay at 500% of rated current. As part of the FRN‑R RK5 family, it is UL 248‑12 listed for Class RK5, CSA and CE certified, with optional open fuse indication available on select ratings. Typical applications include motor protection in industrial control panels, where selective coordination and reliable protection against short circuits and overloads are required.