Overview
The Bussmann FRN-R-25 is a Class RK5 dual-element, time-delay, current-limiting cartridge fuse designed for motor branch-circuit and equipment protection. Rated 25A at 250VAC and 125VDC, this fuse provides coordinated overload and short-circuit protection for industrial control panels, motor circuits, and HVAC systems. The time-delay characteristic allows temporary motor inrush currents while protecting against sustained overloads and faults.
Key Features
- Dual-element construction: Dual-element, current limiting fuse — thermal element for overload protection, fission element for short-circuit protection
- Time-delay operation: 8 seconds for 1/10-30A sizes at 500% rated current, allowing safe motor starts without nuisance trips
- UL and CSA listed: UL Listed, Std. 248-12, Class RK-5, Guide JDDZ, File E4273 and CSA Certified, C22.2 No. 248.12, Class 1422-02, File 53787
- Ferule-terminal design: Standard cartridge format for use in rejection-type fuse holders and blocks rated for Class R fuses
- Energy efficient: Fusetron fuses are on average 23% more energy efficient than the next leading brand
Technical Specifications
- Fuse Type: Dual-element, time-delay cartridge
- Current Rating: 25A
- Voltage Rating: 250Vac, 125Vdc
- Interrupting Rating: 200kA Vac RMS Sym., 20kA Vdc
- Class: RK5
- Response Time: 8 seconds (minimum) at 500% of rated current
- Dimensions: 0.56" Dia x 2" L (14.22×50.8mm)
- Terminal Type: Ferrule-to-ferrule ends
- Body Material: Ceramic (fiberglass reinforced)
- Certifications: UL, CSA, CE
Typical Applications
- Motor branch-circuit protection in NEMA-compliant control panels
- AC and DC equipment protection in industrial and commercial facilities
- HVAC compressor and fan motor circuits
- Pump and conveyor system protection
- General-purpose equipment protection in circuits subject to temporary overloads
Compatibility & Replacements
Compatible With
- Class R rejection-type fuse blocks rated for Class RK5
- Standard cartridge fuse holders with ferrule-terminal configuration (0.56″ × 2″ size)
- Fuse reducers for 60A and 100A disconnect switches (Bussmann No. 263-R, No. 213-R)
- AC and DC circuits rated 250VAC or 125VDC or lower
Replaces / Drop-In Replacement For
- Other 25A Class RK5 dual-element fuses with ferrule terminals, such as Littelfuse FLN-R-25 or Mersen TR 25R (verify with system integrator before substitution)
- Bussmann FRN-R-25 non-indicating variant
Works With
- Class RK5 series fuses compatible with Class R rejection fuse blocks
- Eaton/Bussmann recommended fuse blocks: RM25030 series (up to 30A), RM25060 series (35–60A)
- Standard ferrule-terminal cartridge fuse holders in industrial control equipment
