LLNRK400 - 400Amp Fuse

LLNRK400 - 400Amp Fuse

Powerful circuit protection shouldn't mean unnecessary interruptions. When your motors start, transformers energize, or industrial equipment comes online, temporary current surges are often normal. The challenge is protecting the electrical system from genuine faults without opening a fuse every time equipment starts.

The Littelfuse LLNRK400 400 Amp time-delay fuse is designed to meet that challenge. Part of the Littelfuse POWR-PRO series, this 250V Class RK1 current-limiting fuse combines dual-element construction, high interrupting capacity, and dependable overload protection for demanding commercial and industrial electrical systems.

Key Features and Benefits

• 400 Amp Continuous Rating
• Class RK1 Current-Limiting Protection
• Dual-Element Time-Delay Design
• Reduced Nuisance Openings
• High AC Interrupting Capacity
• DC Fault Protection
• Low-Resistance Construction
• Motor and Transformer Compatibility
• Versatile Circuit Protection
• Potential Class H Upgrade
• Standard Fuse Mounting

Technical Specifications

• Manufacturer: Littelfuse
  
• Catalog Number: LLNRK400
  
• Product Series: LLNRK
  
• Product Family: POWR-PRO
  
• Fuse Class: Class RK1
  
• Fuse Type: Dual-Element, Time-Delay
  
• Continuous Current Rating: 400 Amps
  
• Maximum AC Voltage: 250V AC
  
• Maximum DC Voltage: 125V DC
  
• AC Interrupting Ratings: 200,000A and 300,000A at 250V AC, as listed by the manufacturer
  
• DC Interrupting Rating: 20,000A at 125V DC
  
• Opening Characteristic: Slo-Blo / Time Lag / Time Delay
  
• Current-Limiting Design: Yes
  
• Overload Element: Thermally Reversible, Spring-Loaded Thermal Element
  
• Indicating Feature: No
  
• Mounting Method: Fuse Block / Clip / Holder
  
• Specified Holder Series: LFR25400
  

Material Compliance and Certifications

The manufacturer identifies the Littelfuse LLNRK400 as a Class RK1 POWR-PRO current-limiting fuse with dual-element time-delay operation.

• RoHS Compliance: Confirm using current Littelfuse material compliance documentation
• REACH Compliance: Confirm using current Littelfuse material compliance documentation
• UL Certification or Listing: Verify the applicable listing and conditions in current manufacturer documentation
• CSA Certification: Verify applicable certification details in current manufacturer documentation

Confirm specific material declarations, certification file numbers, and regulatory approvals against the latest manufacturer documentation when required for an installation or project.

Where It Works Best

• Service Entrance Equipment
• Main Distribution Circuits
• Feeder Circuits
• General-Purpose Branch Circuits
• Industrial Motor Circuits
• Transformer Circuits
• Solenoids and Electromagnetic Devices
• Fluorescent Lighting Systems
• Industrial Machinery
• Compatible Class H Fuse Block Upgrades