Overview
The Bussmann Fusetron FRN-R-400 is a Class RK5 dual-element, time-delay (slow-blow) fuse designed for industrial power distribution and control circuits. With a current rating of 400 A, this non-indicating fuse delivers an interrupting rating of 200 kA at 250 Vac and 20 kA at 250 Vdc. This fuse is engineered to protect motors, transformers, and other inductive loads while minimizing nuisance trips from inrush currents.
Key Features
- Dual-Element Design: Provides motor overload, ground fault and short-circuit protection
- Time-Delay Technology: 10 seconds (minimum) at 500% rated amps tolerates transient inrush without nuisance operation
- Current-Limiting Performance: 200 kA interrupting rating at 250 Vac limits fault energy in downstream circuits
- Blade-Terminal Construction: Easy insertion into Class RK5 fuse holders for modular, field-replaceable protection
- Industry Standard: cULus listed; meets UL 248-12 and CSA C22.2 standards for safe deployment across North America
Technical Specifications
- Rated Current: 400 A
- Voltage Rating: 250 Vac / 125 Vdc
- Fuse Class: RK5 (dual-element, time-delay, current-limiting)
- Interrupting Rating: 200 kA (ac, symmetrical); 20 kA (dc)
- Time-Delay Response: 10 seconds minimum at 500% rated current
- Terminal Type: Blade (blade-end contact)
- Dimensions: 2.38 in. diameter × 8.63 in. length
- Indicator Type: Non-indicating
- Agency Approvals: UL 248-12, CSA C22.2, cULus Listed
Typical Applications
- Motor branch circuits and motor starters (NEMA Type 1 & 3R enclosures)
- Industrial control transformer protection in PLC, servo drive, and HMI cabinets
- Power distribution in machinery automation and assembly lines
- Equipment protection where momentary overload tolerance is required (pumps, compressors, conveyor systems)
- Compatible with Class RK5 fuse blocks in industrial electrical panels (120 V – 600 V systems)
Compatibility & Replacements
Compatible With
- Class RK5 fuse holders and fuse blocks (blade-terminal design)
- Standard industrial fuse blocks rated 250V, 400A
- Motor starter and control circuits in Allen-Bradley, Siemens, and Schneider Electric enclosures
- Industrial DC circuits up to 125 Vdc (standard ratings); 250 Vdc for higher amperage ranges
Replaces / Drop-In Replacement For
- Equivalent Class RK5 fuses with identical 250V, 400A, dual-element time-delay specifications
- Verify exact replacement compatibility with system documentation before ordering
Works With
- Eaton/Bussmann Class RK5 fuse blocks and cartridge holders
- Square D (Schneider Electric) and GE industrial enclosures
- Siemens SENTRON fuse systems (Class RK5 compatible ratings)
- Standard industrial control panels and power distribution units rated for 250V operation
