Littelfuse KLNR020 - KLNR/KLSR series RK1 fast-acting 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, KLNR/KLSR series fuses must be greatly oversized to prevent opening the fuses on harmless inrush currents. In such applications, KLNR/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 fast-acting 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

KLNR020

Alternate Item Number: KLNR020.T

UPC: 079458280715

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Overview

The Littelfuse KLNR020, part of the KLNR/KLSR series, represents a foundational element in industrial electrical protection. As one of the earliest current-limiting fuse designs, this RK1 fast-acting fuse utilizes a robust single-element, silver link construction to deliver rapid and reliable overload and short-circuit protection. Its primary function is to swiftly interrupt electrical circuits when fault currents exceed safe operating levels, thereby safeguarding sensitive equipment and preventing potential hazards. Engineered for demanding industrial environments, the KLNR020 is particularly effective in applications with resistive loads where predictable current draw is the norm. However, it is crucial for engineers and maintenance professionals to understand its limitations when applied to inductive loads such as motors, solenoids, and transformers. Due to the inherent inrush currents associated with these components during startup, the KLNR020 series fuses often require significant oversizing to prevent nuisance tripping. In such scenarios, the fuse may primarily offer short-circuit protection rather than comprehensive overload protection against typical startup surges. For applications demanding the superior current-limiting capabilities of UL Class RK1 fast-acting fuses, especially in new installations or existing systems experiencing nuisance tripping on harmless system surges, Littelfuse strongly recommends the advanced POWR-PRO™ LLNRK/LLSRK series. These dual-element, time-delay fuses are specifically designed to accommodate motor starting currents and other transient surges while still providing excellent short-circuit protection. This upgrade ensures optimal system performance and reliability, minimizing downtime and maintenance issues. Despite the recommendation for newer technologies in certain applications, the KLNR020 remains a viable and trusted solution for specific industrial uses where fast-acting protection is paramount and inrush current concerns are minimal or managed through careful system design. Its straightforward design and proven performance make it a reliable choice for protecting fixed industrial equipment and circuits that do not experience significant transient current demands. When selecting the KLNR020, consider the following: * **Protection Type:** Primarily designed for fast-acting overload and short-circuit protection. * **Construction:** Features a single-element, silver link for rapid response. * **Load Considerations:** Best suited for resistive loads; requires oversizing for inductive loads to mitigate nuisance tripping. * **Application Focus:** Ideal for industrial settings where rapid fault interruption is critical and inrush currents are not a primary concern. * **Manufacturer Reputation:** Littelfuse is a globally recognized leader in circuit protection, known for its quality and innovation in fuse technology. By understanding the specific characteristics and recommended applications of the Littelfuse KLNR020, industrial professionals can make informed decisions to ensure the safety, efficiency, and longevity of their electrical systems. For applications requiring enhanced surge tolerance and dual-element protection, exploring the POWR-PRO™ series is advised.
  • Littelfuse KLNR020 RK1 fast-acting fuse for industrial electrical protection.
  • Single-element, silver link design for rapid overload and short-circuit response.
  • Effective for resistive loads; requires oversizing for inductive loads (motors, transformers) to prevent nuisance tripping.
  • Provides essential fault current interruption to safeguard equipment.
  • Recommended for applications requiring fast-acting RK1 protection where inrush currents are managed.

Specifications

Amperage Rating
6 AMP
Application
DC control circuits/Solar
Brand Name
Littelfuse
Material
Silver
Series
KLNR/KLSR
Special Features
Fast-Acting
Standard
UL 2579 IEC 60269-6
Sub Brand
POWR-GARD KLKD Series
Type
UL Supplemental
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 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 Block 1500VAC 1500VDC 400A 1-Pole Stud M8

1SCM8

Fuse Block 1500VAC 1500VDC 400A 1-Pole Stud M8
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 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.