Littelfuse LA70QS125-4 - LA70 VERY FAST-ACT SEMICOND FUSE QS125-4. Littelfuse LA70QS semiconductor fuses were developed to provide improved performance required by today’s new equipment. The LA70QS features lower I2t, improved cycling, and lower watts loss. It is the best choice for the protection of dynamic solid-state equipment. Features: Very low I2t improved protection of equipment. Superior cycling ability for long, reliable life on high cycling loading. Lower watts loss for cooler operation. 700 Volt AC/DC rating provides greater design versatility. Compact sizes allow downsizing of equipment. Applications: Protection of 700 volt or less solid state equipment such as motor drives, UPS, inverters, etc.
Littelfuse

LA70QS125-4

Alternate Item Number: LA70QS1254

UPC: 079458152715


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Overview

The Littelfuse LA70QS125-4 semiconductor fuse is a high-performance, very fast-acting protection solution engineered for modern solid-state equipment operating at 700V AC/DC or below. Designed to meet the demanding requirements of today’s dynamic industrial environments, this fuse delivers superior performance where rapid fault response and long-term reliability are critical. The LA70QS125-4 is part of Littelfuse’s advanced LA70QS series, which has been optimized to address the evolving needs of power electronics, motor drives, and renewable energy systems by offering lower I²t values, improved cycling capability, and reduced power loss. This semiconductor fuse is specifically developed for the protection of sensitive solid-state components in applications such as motor drives, uninterruptible power supplies (UPS), inverters, and other high-frequency switching equipment. Its very fast-acting characteristic ensures rapid interruption of fault currents, minimizing stress on downstream components and preventing catastrophic failure. The reduced I²t value allows for more precise fault detection and faster response times compared to conventional fuses, which is essential in protecting IGBTs, thyristors, and other semiconductor devices that are highly susceptible to thermal and electrical stress. One of the standout features of the LA70QS125-4 is its superior cycling ability, which enables it to withstand repeated high-current surges without degradation. This makes it ideal for applications with frequent load variations or regenerative braking, such as in variable frequency drives (VFDs) and solar inverters. Additionally, the fuse’s lower watts loss translates to cooler operation, reducing the need for additional cooling systems and improving overall system efficiency. The compact design of the LA70QS125-4 allows for easier integration into space-constrained equipment, enabling engineers to downsize their designs without compromising protection. The 700V AC/DC rating of the LA70QS125-4 provides exceptional versatility, making it suitable for both AC and DC applications across a wide range of voltages. This dual-rated capability simplifies inventory management and reduces the need for multiple fuse types in mixed-voltage systems. Professionals in industries such as industrial automation, renewable energy, and transportation rely on Littelfuse’s semiconductor fuses for their proven reliability and adherence to strict safety standards. When selecting a semiconductor fuse, engineers must consider factors such as interrupting rating, I²t value, cycling performance, and thermal characteristics. The LA70QS125-4 excels in all these areas, offering a balance of speed, durability, and efficiency that is unmatched in its class. Installation is straightforward, with standard mounting options compatible with most industrial fuse holders and disconnect switches. Littelfuse provides comprehensive technical documentation, including time-current curves and application notes, to assist engineers in selecting the optimal fuse for their specific requirements. Littelfuse, a global leader in circuit protection, has built a reputation for innovation and quality in the industrial and power electronics markets. With decades of experience in developing solutions for semiconductor protection, Littelfuse’s semiconductor fuses are trusted by professionals worldwide to safeguard critical infrastructure. The LA70QS125-4 is no exception, offering a robust, high-performance option for protecting today’s most advanced power conversion systems. Whether deployed in a motor drive protecting a conveyor belt in a manufacturing plant or safeguarding a solar inverter in a utility-scale installation, the LA70QS125-4 delivers the reliability and performance that engineers demand.
  • Very fast-acting response for superior semiconductor protection
  • 700V AC/DC rating for versatile application support
  • Lower I²t and watts loss for improved efficiency and cooler operation
  • Superior cycling capability for high-frequency switching environments
  • Compact design enables equipment downsizing without compromising protection

Specifications

Application
Protection of Semiconductors
Brand Name
Littelfuse
Current Rating
125 A
Series
LA70QS
Special Features
Very-Fast Acting
Standard
UL Recognized
Sub Brand
LA Series
Type
Semiconductor Fuse
Voltage Rating
700 V AC/DC
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.