The Bussmann FRN‑R‑20 Fusetron fuse is a premium dual‑element, time‑delay, current‑limiting fuse designed to provide superior protection for industrial and commercial electrical systems. Part of Bussmann’s FRN‑R Series (Class RK5), this fuse is engineered to handle temporary overloads—such as motor starting or transformer energizing—while still reacting quickly to dangerous fault currents.

With its dual‑element construction, the FRN‑R‑20 offers advanced overload protection and excellent short‑circuit clearing performance, making it the ideal choice for combination starters, motor control centers, disconnect switches, HVAC equipment, and power panelboards.

Key Features

• Dual‑element construction provides separate overload and short‑circuit protection.
• Time‑delay performance: holds 8 seconds at 500% of rated current for 20A size (1/10–30A).
• Current‑limiting fuse reduces fault energy and protects downstream equipment.
• Class RK5 rating ensures compatibility with RK5 fuse blocks and rejection‑type holders.
• Ferrule end × ferrule end terminals for easy installation in standard clips.
• Energy‑efficient design, reducing heat and system loads (Fusetron line performance).
• Non‑indicating type (no blown‑fuse window).
• UL and CSA listed for safety compliance.

Specifications

• Catalog Number: FRN‑R‑20
• Amp Rating: 20A
• Voltage Ratings:
  • 250 VAC
  • 125 VDC
• Interrupting Ratings:
  • 200 kAIC @ 250 VAC
  • 20 kAIC @ 125 VDC
• Response Time:
  • 8 seconds minimum at 500% overload
• Fuse Class: RK5 (Rejection‑type, current‑limiting)
• Dimensions:
  • Length: 2 in
  • Diameter: 1.56 in
• Body Material: Fiberglass tube
• Terminals: Ferrule
• Mounting: Clip/holder mount
• Package Type: Retail blister (BP‑version)

Applications

The FRN‑R‑20 is ideal for systems requiring dependable time‑delay protection, including:

• Combination starters
• Motor control centers (MCCs)
• Machinery disconnects
• Power panelboards
• HVAC systems, pumps, fans, compressors
• Industrial and commercial branch circuits

Because of its ability to withstand motor inrush without nuisance blowing, the FRN‑R‑20 is superior to standard fast‑acting fuses in motor and inductive load applications.