Littelfuse FLNR250 - FLNR250 is a Class RK5 fuse with an ampere rating of 250 and knife-blade-style construction.
Littelfuse

FLNR250

Alternate Item Number: FLNR250.X

UPC: 079458150902


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Overview

The Littelfuse FLNR250 is a high-performance Class RK5 fuse engineered for the most demanding industrial environments where reliable overcurrent protection is critical. Designed with a 250A ampere rating and knife-blade-style construction, this fuse delivers robust circuit protection in power distribution systems, motor control panels, and other high-demand applications. Class RK5 fuses are widely recognized in the industry for their superior interrupting ratings and time-current characteristics, making them ideal for protecting sensitive equipment from damaging fault currents. The FLNR250’s knife-blade connection ensures secure, low-resistance installation, minimizing the risk of loose connections that can lead to overheating or downtime. This design also simplifies replacement, reducing maintenance costs and operational disruptions in critical systems. Industrial professionals rely on Class RK5 fuses like the FLNR250 for applications where consistent performance and compliance with safety standards are non-negotiable. Typical use cases include manufacturing plants, data centers, commercial buildings, and utility substations, where electrical systems must operate continuously without interruption. The FLNR250 meets or exceeds industry standards such as UL 248 and CSA certification, ensuring compatibility with a wide range of electrical panels and switchgear. Its high interrupting rating (typically 200kA) provides peace of mind in systems with high prospective fault currents, while its time-delayed response allows for temporary overloads common in motor starting and inrush conditions. Selecting the right fuse for an industrial application requires careful consideration of ampere rating, interrupting capacity, and physical dimensions. The FLNR250’s 250A rating makes it suitable for medium to large-scale systems, such as branch circuits feeding heavy machinery or distribution panels serving multiple loads. Professionals should verify compatibility with the specific panel or enclosure, as Class RK5 fuses require compatible fuse blocks or holders designed to accommodate their knife-blade terminals. Installation is straightforward with proper tools, and Littelfuse provides clear guidelines to ensure safe and efficient mounting. Littelfuse, a global leader in circuit protection solutions, has built a reputation for innovation and reliability over decades. The company’s Class RK5 series, including the FLNR250, is trusted by engineers and maintenance teams worldwide for its durability, precision, and adherence to stringent quality controls. With a focus on reducing unplanned downtime and enhancing system safety, Littelfuse fuses are a preferred choice for facilities where electrical reliability directly impacts productivity and profitability. Whether protecting transformers, motors, or distribution equipment, the FLNR250 delivers the performance and peace of mind that industrial operators demand.
  • 250A ampere rating for medium to large industrial systems
  • Class RK5 classification for superior overcurrent protection
  • Knife-blade-style construction for secure, low-resistance connections
  • High interrupting rating (200kA typical) for fault current protection
  • UL 248 and CSA certified for compliance with industry standards
  • Time-delayed response to handle temporary overloads and inrush currents
  • Designed for power distribution, motor control, and high-demand applications
  • Compatibility with standard Class RK5 fuse blocks and holders
  • Manufactured by Littelfuse, a leader in circuit protection solutions

Specifications

Application
General Purpose
Brand Name
Littelfuse
Special Features
Time-Delay
Standard
Standard 248-12 UL Listed/CSA
Sub Brand
POWR-GARD FLNR Series
Type
Class RK5
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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

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9F61 Size B Clips 1.6in

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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.