Overview
The Bussmann Fusetron FRS-R-400 is a Class RK5 dual-element, time-delay, current-limiting fuse engineered for industrial and commercial electrical systems. Rated at 400 amperes, 600VAC/300VDC, this fuse delivers 200kA interrupting capacity at 600V and 20kA at 300V, providing dependable protection against motor overloads, ground faults, and short circuits. The blade terminal design enables quick installation in standard fuse holders while the rejection feature prevents mismatched replacements.
Key Features
- Dual-element construction — combines overload and short-circuit protection in a single cartridge
- Time-delay response — holds 5× rated current for 10 seconds minimum, permitting temporary inrush surges from motors and transformers without nuisance blowouts
- Current-limiting action — reduces let-through energy to protect downstream components and equipment from high-fault-current damage
- Rejection design — physically prevents insertion of incorrect amperage fuses, reducing installation errors
- Fiberglass body — durable, non-flammable cartridge construction with blade terminals for reliable contact
- UL listed, CSA certified — meets electrical safety standards for North American applications
Technical Specifications
- Current Rating: 400 amperes
- Voltage Rating: 600VAC / 300VDC
- Class: RK5 (dual-element, current-limiting)
- Type: Time-delay, non-indicating
- Interrupting Rating: 200,000A @ 600VAC; 20,000A @ 300VDC
- Time-Delay Response: Holds 5× rated amperes minimum 10 seconds
- Body Material: Fiberglass (non-flammable)
- Terminal Style: Blade end × blade end (rejection design)
- Dimensions: 2.34″ diameter × 11.63″ length
- Weight: 3 lbs
- Series: FRS-R
- Certifications: UL 248-12 Guide JDDZ, CSA Class 1422-01, CE marked
Typical Applications
The Bussmann FRS-R-400 is suitable for a broad range of industrial and commercial installations where time-delay fuse protection is required:
- Power distribution panelboards and switchboards
- Motor control centers and combination starters
- Machinery disconnects and branch circuit protection
- Three-phase systems requiring motor overload and single-phasing protection
- Industrial feeder circuits with inductive loads (transformers, motors, solenoids)
The time-delay characteristic allows engineers to size the fuse closer to full-load amperage, permitting use of smaller, more cost-effective disconnecting switches while maintaining coordinated protection.
Compatibility & Replacements
Compatible With
- Standard RK5 cartridge fuse holders (blade terminal 400A rated)
- Eaton/Bussmann distribution and motor control equipment
- Any equipment listed for Class RK5 fuse protection at 600VAC or 300VDC
- National Electrical Code (NEC) compliant branch circuits and feeder circuits
Replaces / Drop-In Replacement For
Verify compatibility with your system integrator before ordering. Common equivalent models include Littlefuse FLSR-400 and Mersen/Ferraz Shawmut TRS-R-400, though direct replacement should be confirmed with application data.
Works With
- Class RK5 UL-listed fuse holder assemblies
- Motor overload relay coordination per NEMA ICS 2
- Standard electrical disconnects and panelboards rated 600V or less
- Industrial control systems and machinery disconnect assemblies
