Littelfuse LLSRK040 - RK1 fuses are extremely current-limiting fuses meaning they greatly reduce or eliminate damage to circuits and equipment under short-circuit conditions. Replacing existing Class H, K and RK5 fuses with RK1 fuses is one of the easiest ways to immediately improve the protection of plant workers and equipment.
Littelfuse

LLSRK040

Alternate Item Number: LSRK040.T

UPC: 079458350753

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Minimum Qty: 10

Multiplier: 10

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Overview

Littelfuse RK1 fuses (SKU: LLSRK040) are high-performance, current-limiting fuses engineered to deliver superior protection in industrial electrical systems. Designed as a direct replacement for Class H, K, and RK5 fuses, these fuses significantly reduce or eliminate damage to circuits and equipment during short-circuit conditions, ensuring immediate safety for plant workers and critical assets. With Littelfuse’s reputation for innovation and reliability, the RK1 series stands as a trusted solution for facilities prioritizing operational continuity and compliance with stringent safety standards. **Key Features and Benefits:** - **Extreme Current-Limiting Performance:** RK1 fuses are engineered to interrupt fault currents rapidly, minimizing thermal and mechanical stress on downstream equipment. This current-limiting capability is critical in preventing catastrophic failures, reducing downtime, and lowering repair costs in industrial environments. - **Direct Replacement for Outdated Fuse Classes:** The RK1 series is designed to seamlessly replace Class H, K, and RK5 fuses, offering an immediate upgrade path without requiring modifications to existing panel configurations. This compatibility simplifies retrofitting in legacy systems, ensuring compliance with modern safety codes while preserving infrastructure investments. - **Enhanced Safety and Worker Protection:** By limiting fault currents to safe levels, RK1 fuses reduce the risk of arc flash and electrical fires, creating a safer work environment for maintenance personnel. This is particularly valuable in high-risk industries such as manufacturing, chemical processing, and power generation, where electrical safety is a top priority. - **Rugged Construction for Demanding Environments:** Built to withstand harsh industrial conditions, RK1 fuses feature durable construction and are engineered to meet rigorous industry standards, including UL and IEC certifications. Their robust design ensures reliable performance in environments with extreme temperatures, vibrations, and electrical noise. - **Operational Efficiency and Reliability:** The RK1 series is optimized for high interrupting ratings, ensuring dependable operation even in systems with high prospective fault currents. This reliability translates to fewer nuisance trips, reduced maintenance, and extended equipment lifespan, ultimately improving overall system uptime. **Typical Applications:** RK1 fuses are widely used across a range of industrial sectors, including: - **Manufacturing Plants:** Protecting machinery, motor control centers, and distribution panels from short-circuit events. - **Power Generation and Distribution:** Safeguarding transformers, switchgear, and feeder circuits in utility and renewable energy facilities. - **Oil and Gas:** Ensuring safety in refineries, drilling operations, and pipeline systems where electrical faults pose significant risks. - **Mining and Metals:** Providing protection in harsh environments with heavy machinery and high fault currents. - **Commercial Buildings:** Enhancing safety in large-scale facilities such as hospitals, data centers, and airports. **Selection and Installation Considerations:** When selecting RK1 fuses, professionals should evaluate the system’s fault current ratings, voltage requirements, and coordination needs with upstream and downstream protective devices. Proper coordination ensures that the fuse operates selectively, isolating faults without disrupting entire systems. Installation should follow manufacturer guidelines and local electrical codes, with attention to proper sizing and mounting to maximize performance and safety. **Why Choose Littelfuse?** Littelfuse is a global leader in circuit protection solutions, trusted by industries worldwide for its commitment to innovation, quality, and reliability. With decades of expertise in fuse technology, Littelfuse delivers products that meet the evolving demands of modern electrical systems. The RK1 series exemplifies this dedication, offering a proven solution for upgrading electrical protection in industrial applications. By choosing Littelfuse RK1 fuses, engineers and facility managers gain peace of mind, knowing their systems are safeguarded by a product designed for excellence.
  • Extreme current-limiting performance reduces damage from short-circuit conditions
  • Direct replacement for Class H, K, and RK5 fuses with no panel modifications required
  • Enhances worker safety by limiting fault currents and reducing arc flash risk
  • Rugged construction meets rigorous UL and IEC industry standards
  • Optimized for high interrupting ratings, ensuring reliable operation in demanding environments

Specifications

Amperage Rating
40 Amp
Application
All general purpose circuits
Brand Name
Littelfuse
Series
RK1
Special Features
Time-Delay
Standard
Standard 248-12 UL Listed/CSA
Sub Brand
LLSRK Series
Type
Class RK1
Package Weight (Imperial)
0.354 L
Package Weight (Metric)
0.161 kg
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 Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20

E1062696

Fuse Holder Modulostar® Size 10x38 IEC 690VAC 690VDC 3-Pole IP20
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
9F61 Size B Clips 1.6in

9F61BWW460

9F61 Size B Clips 1.6in
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.

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.