Authorized Littelfuse Distributor
Littelfuse KLSR450 - KLSR series RK1 fuses were the earliest type of current-limiting fuse developed. Their single-element, silver link design enables them to provide fast-acting overload and short-circuit protection. When used to protect inductive loads such as motors, solenoids, and transformers, KLSR series fuses must be greatly oversized to prevent opening the fuses on harmless inrush currents. In such applications, KLSR series fuses may only provide short-circuit protection. We recommend using POWR-PRO™ LLNRK/LLSRK series RK1, dual-element, time-delay fuses in all new applications requiring the current-limiting ability of UL Class RK1 fuses, or in existing applications where fast-acting RK1 or RK5 fuses have been opening on harmless system surges such as motor starting currents.

Littelfuse KLSR450 KLSR series RK1 fuses were the earliest type of current-limiting fuse developed. Their…

Alternate Item Number: KLSR450.X

UPC: 079458290950


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Contact for Pricing

Call +1 (262) 252-1600 (toll-free 877-268-3700) or email [email protected] for pricing and availability.

Overview

The Littelfuse KLSR450 RK1 fuse is a single-element, silver link current-limiting fuse designed for fast-acting overload and short-circuit protection in industrial electrical systems. Part of Littelfuse’s pioneering KLSR series, this 450 ampere fuse delivers rapid fault interruption to minimize damage during electrical disturbances. Its single-element construction ensures immediate response to excessive current, making it ideal for protecting sensitive equipment where swift fault clearance is critical. The KLSR450 is engineered to meet UL Class RK1 standards, providing high-performance current limitation that significantly reduces or eliminates damage to circuits and connected components during short-circuit events. Unlike dual-element fuses, the KLSR450 is not designed to accommodate harmless inrush currents common in inductive loads such as motors, solenoids, and transformers. In such applications, oversizing is often required to prevent nuisance openings, limiting its protective role to short-circuit scenarios. For comprehensive protection of inductive loads, Littelfuse recommends their POWR-PRO™ LLNRK/LLSRK series RK1 dual-element, time-delay fuses, which differentiate between inrush and fault currents. The KLSR450 remains an excellent choice for legacy systems originally designed for fast-acting RK1 or RK5 fuses, ensuring compatibility and continued safety without modification. Backed by Littelfuse’s reputation for quality, the KLSR450 offers reliable, immediate protection in environments where operational continuity and fault response speed are paramount. Its adherence to established performance standards makes it a trusted solution for industrial applications requiring robust short-circuit protection.
  • 450A current rating for high-load industrial applications
  • Single-element silver link design for fast-acting fault interruption
  • UL Class RK1 current-limiting fuse reduces circuit damage during short circuits
  • Compatible with legacy systems designed for RK1/RK5 fuses
  • Minimizes downtime by rapidly clearing faults to protect equipment

Specifications

Application
Non-Inductive Loads
Brand Name
Littelfuse
Current Rating
450 A
Material
Silver
Material
Silver link
Series
KLSR
Special Features
Fast-Acting
Standard
Standard 248-12 UL Listed/CSA
Sub Brand
KLSR Series
Type
Class RK1
Fuse Block 600VAC 600VDC Class CC 30A 1/4in Quick Connect / Solder 90 angle screw Knob Panel Mount

GPM-SRR90

Fuse Block 600VAC 600VDC Class CC 30A 1/4in Quick Connect / Solder 90 angle screw Knob Panel Mount
Fuse Block 600VAC 600VDC Class CC 30A 3-Pole Pressure Plate with Reinforced Clip

30323R

Fuse Block 600VAC 600VDC Class CC 30A 3-Pole Pressure Plate with Reinforced Clip
Fuse Holder UltraSafe™ 800VAC 1000VDC UL Fuse size 14x51 1-Pole Visual Indicator Microswitch Pressure Plate IP20

C331156

Fuse Holder UltraSafe™ 800VAC 1000VDC UL Fuse size 14x51 1-Pole Visual Indicator Microswitch Pressure Plate IP20
Fuse Holder Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20

E1062696

Fuse Holder Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20
POWR-JAW clamps improve the contact between fuse and clip. The unnecessary heat from poor contact due to the loss of spring force in the clips can cause nuisance fuse opening and premature aging of surrounding components. High temperature phenolic resin knob designed for the most severe environments 7 sizes to provide effective coverage. Simple design makes installation easy.

LCC5

POWR-JAW clamps improve the contact between fuse and clip. The unnecessary heat from poor contact due to the loss of spring force in the clips can cause nuisance fuse opening and premature aging of surrounding components. High temperature phenolic resin knob designed for the most severe environments 7 sizes to provide effective coverage. Simple design makes installation easy.
9F61 Size B Clips 1.6in

9F61BWW460

9F61 Size B Clips 1.6in

Frequently Asked Questions

What is the MROplus program and its benefits?

The MROplus program helps customers lower costs, increase plant safety, decrease downtime, and reduce inventory by analyzing fuse inventories and optimizing circuit protection.

How does MROplus help reduce electrical hazards?

It identifies inadequate fuses and upgrades them to current-limiting circuit protection, reducing Hazard Risk Categories (HRC) and allowing workers to wear less Personal Protective Equipment (PPE).

How can MROplus improve productivity?

By converting to indicating fuses and consolidating inventory, MROplus provides fast, visible identification for fuse replacement, saving time and money.

What reports are included in the FREE MROplus Program?

The program includes a Total Cost Savings Report, Consolidated Part Number Report, SKU Reduction Report, and Fuse Performance Summaries.

How do I get started with the MROplus program?

Complete a request form with your current fuse inventory and contact your local Littelfuse Sales Representative, 1-800-TEC-FUSE, or [email protected].

What Littelfuse fuse should I use if I have a Littelfuse KLSR* fuse?

If you have a Littelfuse KLSR* fuse, you should use the Littelfuse LLSRK_ID fuse.

What are Littelfuse high-speed fuses for?

Littelfuse high-speed semiconductor fuses protect critical power electronics from over-currents that may cause damage to equipment.

What does Littelfuse POWR-GARD offer?

POWR-GARD offers a complete circuit protection portfolio, including time-saving indication products for immediate visual blown-fuse identification.

What is the purpose of Littelfuse protection relays?

Electronic and microprocessor-based protection relays safeguard equipment and personnel to prevent damage, downtime, or injury due to electrical faults.

When should I consult Article 430 of the NEC?

Consult Article 430 of the NEC when substituting for loads with motors, or call 1-800-TEC-FUSE.

Frequently Asked Questions about Littelfuse

What certifications and standards do Littelfuse products comply with?

Littelfuse products are certified to multiple international standards, including UL (Underwriters Laboratories), CSA (Canadian Standards Association), CCC (China Compulsory Certification), and EAC (Eurasian Conformity). Customers can verify specific product certifications by consulting individual product datasheets on Littelfuse.com, which provide comprehensive details about standards compliance for each component.

What industries and applications are Littelfuse products used for?

Littelfuse products are critical for electrical protection and safety across multiple industrial sectors, including manufacturing, automation, power distribution, and electrical control systems. Their comprehensive product portfolio serves industries that require robust electrical protection, including motor and pump applications, solar installations, programmable logic controllers (PLCs), electrical switch panels, and critical infrastructure environments. Key product lines protect against overcurrent, voltage transients, ground faults, and temperature-related electrical risks, ensuring equipment safety and operational reliability.

What technical support does Littelfuse offer?

Littelfuse offers comprehensive technical support through multiple channels. Their Technical Hotline (800-TEC-FUSE) provides direct access to engineers who can help identify issues and recommend solutions. Additionally, Littelfuse offers extensive online Technical Resources at Littelfuse.com, including datasheets, product manuals, whitepapers, application guides, and online design tools. Their experienced product and application engineers also provide step-by-step support from design to installation.

What are the main product lines offered by Littelfuse?

Littelfuse offers comprehensive industrial protection and control product lines, including fuses, fuse holders, protection relays, temperature sensors, and electrical safety components. Their key product categories span surge protective devices, custom OEM products, electrical switch panels, medium voltage fuses, ground-fault protection relays, motor and pump protection devices, and temperature sensors. These products are designed to minimize electrical safety hazards, limit equipment damage, improve productivity, and safeguard personnel from electrical faults.

What are the key features of Littelfuse products?

Littelfuse products feature exceptional circuit protection technologies with key characteristics including UL/IEC safety standard compliance, low internal resistance, and advanced protective capabilities across multiple product lines. Their components provide critical protection for industrial systems, offering features like overcurrent protection, voltage transient suppression, and resettable protection devices with ultra-low resistance and compact designs. Key product lines include fuses, metal oxide varistors (MOVs), TVS diodes, PolySwitch devices, and specialized electronic protection components that enhance system reliability and safety.

What environmental ratings do Littelfuse products have?

Littelfuse products feature comprehensive environmental ratings, including NEMA Type 1, 2, 3, 3R, 4/4X, 12, and 13 certifications, as well as IP65 protection. These ratings ensure superior protection in diverse industrial environments, with an operating temperature range of -40°F to +131°F (-40°C to +55°C). Many products also include UV-stabilized materials and neoprene gaskets for enhanced durability in outdoor and challenging conditions.

What accessories are available for Littelfuse products?

Littelfuse offers several key accessories across their product lines, including fuse holders, voltage monitoring modules, and terminal connectors. Specific accessories include the LPSM003ZXID (indicating) and LPSM003Z (non-indicating) POWR-SAFE Dead Front fuse holders for Class CC and Midget-Style fuses, the VRM6048 voltage monitor accessory module, and female quick connect terminals (P1015 series) in various wire gauge sizes. These accessories are designed to enhance protection, monitoring, and connectivity for Littelfuse electrical components.

What is Littelfuse's warranty policy?

Littelfuse provides comprehensive warranty details on their official website at www.littelfuse.com/warranty. Customers should visit this page to review the specific warranty terms and conditions for their specific product lines. For direct warranty support or questions, customers can contact Littelfuse Technical Support at 1-800-TEC-FUSE or email [email protected].

What communication protocols do Littelfuse products support?

Littelfuse supports a comprehensive range of industrial communication protocols, including PROFIBUS, PROFINET, EtherNet/IP, DeviceNet, Modbus RTU, and CANopen. Our products provide flexible connectivity solutions across multiple industrial automation platforms, enabling seamless integration with various control systems and network architectures.

How are Littelfuse products typically installed?

Littelfuse products are typically installed using specialized mounting hardware like fuse holders, blocks, and panels designed for specific industrial applications. The POWR-SAFE Dead Front holders, for example, provide optimum protection for Class CC and Midget-Style fuses, supporting installations up to 600 VAC/DC. Installation often involves using precision terminals with strain relief, such as 0.25 in. female quick connect terminals, to ensure secure and safe electrical connections in industrial control systems.