Overview
The Littelfuse FLSR90 is a Class RK5 dual-element, time-delay fuse designed for reliable overcurrent and short-circuit protection in commercial and industrial power distribution. With a current rating of 90A and voltage rating of 600VAC, this Powr-Gard blade-type fuse combines fast fault response with tolerance for harmless inrush currents. The time-delay design eliminates nuisance tripping, making it ideal for circuits with motor loads, transformers, and service entrance switches.
Key Features
- Dual-element, time-delay design for superior inrush tolerance and fault protection
- Current-limiting Class RK5 construction — most widely used fuse class
- Blade-type terminal for standard fuse holders
- 200,000A interrupting rating (symmetrical RMS @ 600VAC)
- Precision-manufactured for consistent, accurate response to overloads and short circuits
- UL-listed for commercial and industrial applications
Technical Specifications
- Voltage Rating: 600VAC / 300VDC
- Current Rating: 90A
- Interrupting Rating: 200,000A symmetrical RMS
- Fuse Class: RK5
- Type: Dual-Element, Time-Delay (Slow-Blow)
- Terminal Type: Blade
- Dimensions: 1⁵⁄₁₆″ diameter × 7⁷⁄₈″ length
- UL Listing: UL 248-6
Typical Applications
The FLSR90 is engineered for protection in:
- Service entrance switches and distribution panelboards
- Transformer primary and secondary circuits
- Motor branch circuits and feeder protection
- Fluorescent and LED lighting circuits
- Industrial feeder and main bus protection
Compatibility & Replacements
Compatible With
- Standard North American fuse holders rated for Class RK5 fuses
- 600V distribution panels and switchgear
- Motor control centers (MCC) rated for 600VAC
- All electrical systems requiring Class RK5 protection
- UL-listed electrical equipment rated for dual-element fuses
Replaces / Drop-In Replacement For
- Earlier versions of Littelfuse FLSR 90A fuses
- Equivalent Class RK5 90A dual-element fuses from other manufacturers (verify compatibility with system integrator)
- Verify with your system integrator before replacing fuses in critical circuits
Works With
- All 600VAC three-phase and single-phase industrial power systems
- Electrical maintenance and troubleshooting software (component-level compatibility)
- Standard fuse pullers and insertion tools for RK5 blade-type fuses
- Motor overload relays and protection coordination schemes
