Overview
The Bussmann FRS-R-90 is a Class RK5 dual-element, time-delay fuse engineered for industrial circuit protection where motor inrush and temporary overload surges demand reliable, coordinated protection. This 90-amp Fusetron fuse provides current-limiting short-circuit protection combined with time-delay overload response, making it ideal for motor-driven equipment and distribution systems subject to temporary surge currents.
Key Features
- Dual-element design: Delivers 10 seconds (minimum) of time-delay at 500% of rated current, preventing nuisance trips on motor startup
- Current-limiting protection: Interrupting rating of 200 kA at 600 Vac and 20 kA at 300 Vdc, protecting downstream components from high fault currents
- Class RK5 rated: UL Class RK5 Fusetron product offering provides energy efficient advanced protection with recognized rejection characteristics
- Non-indicating design: Non-indicating with blade end terminals and is CE marked, UL listed, and CSA certified
- Compact cylindrical form: Fits standard Class RK5 fuse holders and blocks
Technical Specifications
- Part Number: FRS-R-90
- Manufacturer: Eaton Bussmann (formerly Cooper Bussmann)
- Current Rating: 90 A
- Voltage Rating: 600 VAC / 300 VDC
- Fuse Classification: Class RK5
- Fuse Type: Dual Element, Time-Delay (Slow-Blow)
- Interrupting Rating: 200 kA @ 600 Vac; 20 kA @ 300 Vdc
- Time-Delay Response: 10 seconds minimum at 500% of rated current
- Terminal Type: Blade end x blade end
- Body Material: Fiberglass (ceramic body variant also available)
- Physical Dimensions: 1.11″ diameter × 7.88″ length (28.19 × 200.15 mm)
- Certifications: UL Listed, CSA Certified, CE Marked
- Series: Fusetron FRS-R
Typical Applications
The Bussmann FRS-R-90 is widely applied in:
- Motor circuits: Provides reliable overload and short-circuit protection for AC motors subject to inrush current
- Industrial distribution panels: Protects feeder circuits in manufacturing and plant electrical systems
- Transformer secondary protection: Coordinates with primary overcurrent devices for reliable system selectivity
- Machine tool and process equipment: Safeguards circuits in automated production and control systems
- HVAC systems: Protects compressor and motor branch circuits
Compatibility & Replacements
Compatible With
- Class RK5 fuse holders and blocks (standard industrial electrical enclosures)
- Motor control circuits rated 600 VAC/300 VDC
- Industrial distribution systems with dual-element fuse coordination requirements
- UL 508 industrial control panels
Replaces / Drop-In Replacement For
- Bussmann FRS-R-90 (direct equivalent; same part number across distributors)
- Cooper Bussmann FRS-R-90 (legacy brand designation)
- Industry-standard 90A Class RK5 time-delay fuses in equivalent voltage ratings
Works With
- Class RK5 fuse rejection bases and holders
- Littelfuse FLSR equivalent fuses (verify compatibility with system integrator)
- Mersen TRS-R equivalent fuses (verify compatibility with system integrator)
- Standard industrial motor starter and distribution architectures
