Overview
The Littelfuse FLSR225 is a Class RK5 dual-element time-delay fuse engineered for industrial and commercial electrical systems. Rated 225A at 600VAC/300VDC, this blade-terminal fuse delivers 200,000A interrupting capacity and consistent performance across motor-heavy and general-purpose power distribution circuits. The time-delay characteristic minimizes nuisance trips while maintaining rapid response to true fault conditions.
Key Features
- Dual-Element Time-Delay Design: Superior UL Class RK5 fuse widely used for excellent protection, especially in circuits with motors
- High Interrupting Rating: 200,000A RMS symmetrical at 600VAC, 20,000A at 300VDC
- Knife-Blade Construction: Knife-blade-style construction for secure fitting in standard RK5 rejection blocks
- Precision Manufactured: Precision manufactured parts ensure accurate, consistent response to overloads
- Multiple Certifications: UL 248-12 Class RK5, CSA certification, QPL-W-F-1814
Technical Specifications
- Ampere Rating: 225A
- Voltage Rating: 600VAC / 300VDC
- Class: RK5 (Dual-Element Time-Delay)
- Interrupting Capacity: 200kA @ 600VAC; 20kA @ 300VDC
- Terminal Type: Knife Blade (Rejection)
- Dimensions: 2 19/32″ diameter × 11 5/8″ length
- Body Material: Fiberglass
- UPC: 079458170894
- Part Number Format: FLSR225 (also FLSR225.X)
Typical Applications
- Motor branch and feeder protection in industrial control panels
- Main service entrance protection (600V systems up to 225A)
- Power distribution boards and switchgear requiring high interrupting rating
- Manufacturing equipment, pumps, compressors, and HVAC systems
- Data centers and mission-critical facility power conditioning
Compatibility & Replacements
Compatible With
- Standard RK5 rejection-style fuse blocks and holders
- Industrial panel-mount fuse carriers (dual-element 225A rated)
- Power distribution units (PDUs) rated for Class RK5 fuses
- Motor starter disconnect switches and combination starters
- Main distribution frames and loadcenters accepting blade fuses
Replaces / Drop-In Replacement For
- FLSR225 (original Littelfuse part)
- Verify compatibility with system integrator before ordering if replacing fuses from other manufacturers
Works With
- Equivalent Class RK5 fuses: Bussmann FRS-R, Edison ECSR, Mersen TRS-R series (same class and rating)
- All UL-listed RK5 rejection block styles
- Standard industrial panel layouts and circuit protection coordination schemes
