Overview
The Bussmann FRS-R-4 is a Fusetronâ„¢ Class RK5 time-delay fuse engineered for advanced electrical protection in industrial circuits. This 4 A, non-indicating fuse has an interrupting rating of 200 kA at 600 Vac and 20 kA at 300 Vdc. Bussmann’s UL Class RK5 Fusetron product offering provides energy efficient advanced protection with its dual-element, time-delay construction. This lot includes four units ready for immediate deployment.
Key Features
- Dual-Element Construction: Fusetron’s deliver 10 seconds (minimum) of time-delay at 500% of rated current (8 seconds for 1/10-30A sizes). This allows nuisance trip-free protection during transient inrush currents common in motor circuits.
- Current-Limiting Technology: Provides motor overload, ground fault and short-circuit protection.
- Compact Cylindrical Design: Ferrule terminal type, 0.81 in diameter × 5 in length, fiberglass body—fits standard cartridge fuse holders.
- High Interrupting Rating: 200 kA RMS symmetrical at 600VAC ensures safe fault clearance even in heavy-duty industrial environments.
- Dual Voltage Rating: Rated for both 600VAC and 300VDC applications, expanding compatibility across DC and AC circuits.
Technical Specifications
The FRS-R-4 meets stringent UL and CSA standards for branch-circuit and motor-circuit protection:
- Rated Amperage: 4 A
- Voltage Rating: 600VAC / 300VDC
- Interrupting Rating: 200 kA (600VAC), 20 kA (300VDC)
- Time-Delay Response: 10 seconds minimum at 500% rated current
- Fuse Class: RK5 (Class R, current-limiting)
- Body Type: Cylindrical, fiberglass
- Terminal Type: Ferrule
- Physical Dimensions: 0.81 in Dia × 5 in L
- Certifications: UL, CSA Class RK5
- Quantity in Lot: 4 units
Typical Applications
- AC and DC motor branch-circuit protection
- Transformer overload and short-circuit protection
- Industrial control cabinets and switchboards
- HVAC equipment circuits
- Machine tool circuits requiring motor inrush tolerance
- Any industrial application requiring Class RK5 fuse protection
Compatibility & Replacements
Compatible With
- Standard cartridge fuse holders with ferrule terminals
- Industrial motor control centers and switchgear
- 600VAC and 300VDC circuits (dual-voltage rated)
- Any control system requiring Class RK5 current-limiting fuses
Replaces / Drop-In Replacement For
- FRS-R-4 (original Bussmann part number)
- Littelfuse FLS-R-4 (equivalent Class RK5 fuse)
- Other generic 4A Class RK5 fuses in standard ferrule cartridges
Works With
- 600VAC industrial power systems
- 300VDC battery-backed circuits
- Motor starters and contactors rated 4A+ branch protection
- Transformer primary circuits in industrial settings
- Any UL/CSA-compliant control cabinet or electrical enclosure
