Littelfuse L70S Series Very Fa...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$220.30
Littelfuse L70S Series Very Fast-Acting Semiconductor Fuse, 700VAC/650VDC

Littelfuse L70S Series Very Fast-Acting Semiconductor Fuse, 700VAC/650VDC

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Model: L70S070

In Stock (leaves warehouse same day if ordered before 3pm ET)

$220.30
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Littelfuse L70S Series Very Fast-Acting Semiconductor Fuse, 700VAC/650VDC

The Littelfuse L70S Series Very Fast-Acting Semiconductor Fuse delivers extremely fast-acting, current-limiting protection for solid-state semiconductor devices, available in ampere ratings from 70A to 300A. Rated 700VAC and 650VDC, this Very Fast-Acting (FF) fuse is engineered for supplementary protection of SCRs, diodes, thyristors, triacs, transistors, and similar solid-state devices used in variable speed drives, power rectifiers, UPS systems, DC power supplies, and other power electronic equipment. Littelfuse-developed metallurgical, polymer, and materials technology delivers accuracy, consistent quality, and predictable performance, and the L70S Series is UL Recognized for use in UL listed equipment.

Key Features

  • Ampere Rating Range: Available from 70A to 300A, allowing precise overcurrent protection selection for a range of high-power semiconductor circuits.
  • Dual Voltage Rating: Rated 700VAC and 650VDC, supporting both AC and DC semiconductor protection applications.
  • Very Fast-Acting (FF) Opening: Extremely fast-acting, current-limiting design with no time delay for sensitive solid-state devices.
  • Interrupting Rating: Rated 20000A@650VDC (AC: 200 kAIC / DC: 20 kAIC) for reliable interruption of present and future overcurrents.
  • Extremely Current-Limiting: Low I2t and peak let-through currents meet most semiconductor manufacturer requirements.
  • L70S Series Engineering: Built using Littelfuse-developed metallurgical, polymer, and materials research plus mathematical modeling and computerized statistical analysis for consistent, predictable performance.
  • UL Recognized: May be used to provide supplementary protection in UL listed equipment.

Certifications & Compliance

  • UL Recognized

Technical Specifications

  • Refer to manufacturer documentation for complete technical specifications.

Typical Applications

  • Variable Speed Drives
  • Power Rectifiers
  • UPS Systems and DC Power Supplies
  • Protection of SCRs, Diodes, Thyristors, Triacs, and Transistors
  • Solid-State Device Protection Circuits
  • Electronic Equipment Requiring Fast-Acting, Current-Limiting Fuses

Why Littelfuse?

Littelfuse engineers apply advanced metallurgical, polymer, and materials research along with mathematical modeling and computerized statistical analysis to every L70S Series fuse, delivering accuracy, consistent quality, and reliability. With extremely current-limiting performance and UL Recognized status across the 70A to 300A range, the L70S Series provides dependable, code-compliant overcurrent protection for demanding semiconductor and power electronics applications.

Product Specs

Series:
L70S
Listing:
UL Recognized
Product Type:
Semiconductor Fuse
Voltage Rating:
700VAC/650VDC
Amperage Rating:
70A - 300A
Department:
Electrical
Product Group:
Circuit Protection
Product Subgroup:
Fuses

Littelfuse L70S070 – Frequently Asked Questions

1) Will a Littelfuse L70S fuse work on a 600V DC drive bus?
Yes. The L70S Series is rated 700VAC and 650VDC, so a 600V DC bus sits inside its DC rating. Interrupting capacity is 20,000A at 650VDC (200 kAIC on AC, 20 kAIC on DC). Don't apply it above 650VDC, DC rating is the binding limit on rectifier and drive bus work.
2) Can I use a semiconductor fuse like the L70S as the branch circuit overcurrent device?
No. The L70S Series is UL Recognized for supplementary protection inside UL listed equipment, protecting SCRs, diodes, thyristors, triacs and transistors. Branch circuit protection still has to come from a listed branch circuit fuse or breaker ahead of the equipment. The semiconductor fuse clears far faster than a branch device so the silicon survives the fault.
3) Is a very fast-acting fuse the right choice, or should I use a time-delay fuse for my drive?
For solid-state protection, very fast-acting is the choice. The L70S is an FF (very fast-acting) current-limiting fuse with no time delay, and its low I2t and peak let-through meet most semiconductor manufacturer requirements. A time-delay fuse rides through inrush and will let a fault energy level through that destroys an SCR or diode first. Use time-delay on motor and transformer circuits, not on the rectifier bridge.
4) What is the Bussmann equivalent to a Littelfuse L70S semiconductor fuse?
The closest Bussmann counterparts are the KAW Series and the FBP Series semiconductor fuses. The Littelfuse L70S is rated 700VAC/650VDC and covers 70A to 300A, so when cross-referencing to either Bussmann series you need to confirm the voltage class, ampere rating, and body/mounting style match the holder or busbar prep already in the drive or rectifier cabinet. The Bussmann FBP Series is a blade-end, non-indicating construction, which is a different termination style than you may be replacing.
5) My DC bus runs above 650V - what should I use instead of the L70S?
The Littelfuse L70S is rated 650VDC, so it is not the right choice for a DC link above that. For higher DC bus voltages, look at the Bussmann KAX Series semiconductor fuse, which is rated 1000VDC, or the Bussmann SF100X1000HP Series. Confirm the ampere rating and mounting arrangement against your existing fuse block before ordering, since the body style differs between series.
6) Is a standard fast-acting branch circuit fuse an acceptable substitute for the L70S?
No. The L70S is a Very Fast-Acting (FF) semiconductor fuse with low I2t and peak let-through currents, intended for supplementary protection of SCRs, diodes, thyristors, triacs, and transistors in drives, rectifiers, and UPS equipment. A general-purpose branch circuit fuse does not clear fast enough to keep a solid-state device inside its withstand curve. If the L70S does not fit your voltage or mounting, stay within semiconductor-rated families such as the Bussmann KAW, KAX, FBP, or SF100X1000HP Series rather than dropping to a general-purpose fuse.
7) What else could I buy instead of the Littelfuse L70S semiconductor fuse?
ZenSupply carries Bussmann semiconductor fuses as alternatives: the KAW Series, the KAX Series (a 1000VDC non-indicating fuse), the FBP Series with blade ends, and the SF100X1000HP Series. If your bus runs above the L70S 650VDC ceiling, the Bussmann KAX at 1000VDC is the direction to go. Mounting style matters as much as rating, blade-end and bolt-in bodies are not interchangeable in the same holder.
8) I need the exact part number for a 200 amp Littelfuse semiconductor fuse at 700V.
That is L70S200, the 200A rating in the Littelfuse L70S Series at 700VAC/650VDC. The 70A is L70S070 and the 300A is L70S300.
9) Can I use a blade-end Bussmann FBP in place of an L70S fuse?
Only if the holder accepts it. The Bussmann FBP Series is a blade-end, non-indicating semiconductor fuse, so the termination has to match the clips or bolted pads in your existing mount. Electrically, the L70S is a very fast-acting, current-limiting fuse rated 700VAC/650VDC in 70A to 300A, and any substitute needs to meet the same voltage class and the I2t and peak let-through limits the semiconductor manufacturer calls out for the SCRs or diodes you are protecting.
10) What equipment are L70S fuses typically installed in?
Variable speed drives, power rectifiers, UPS systems and DC power supplies, plus general power electronic equipment where the semiconductors need current-limiting protection. In practice that is the fuse in the rectifier bridge, the DC link, or the input of a drive panel.
11) I need a fuse that shows when it has opened - does the L70S do that?
If a visual blown-fuse indication is part of your maintenance routine, note that the Bussmann FBP Series and the Bussmann KAX Series are both non-indicating constructions, so neither gives you that cue either. For the L70S, selection is driven by its 700VAC/650VDC rating, the 70A to 300A ampere range, and its UL Recognized status for supplementary protection in UL listed equipment. Specify a holder or panel with a separate blown-fuse microswitch or monitoring relay if indication is required.
How fast can I get the Littelfuse L70S070 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Littelfuse L70S070 come with a warranty?
Absolutely. The Littelfuse L70S070 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Littelfuse L70S070?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
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