KLSR Series - UL Class RK1 Fast Acting Fuse

Series: KLSR
Questions? Contact Littelfuse Support
Littelfuse Fuse KLSR Peak Let Thru Curves
Roll Over to Zoom
Disclaimer Notice

Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

KLSR series RK1 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, KLSR series fuses must be greatly oversized to prevent opening the fuses on harmless inrush currents. In such applications, 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 fuses, or in existing applications where fast-acting RK1 or RK5 fuses have been opening on harmless system surges such as motor starting currents.

Applications:
  • Resistance heaters
  • Lighting circuits
  • Non-inductive loads
  • Molded case circuit breaker load centers and panelboards have increased interrupting ratings when “series rated” with Littelfuse KLNR/KLSR Class RK1 fuses. Refer to panelboard manufacturer’s literature for UL Listed combination of fuses and panelboards. Series ratings up to 200,000 amperes are available.
Safety:
  • 200,000 A.I.R. — Reliable interruption of all overcurrents up to 200,000 amperes.
  • Extremely current limiting — Stops damaging short-circuit current faster than any mechanical protective device.
  • Fast-acting — Provides fast-acting protection to equipment such as variable speed drives, rectifiers and other equipment containing surge-sensitive components.
Longer Equipment Life:
  • Current-limiting design reduces damage to equipment caused by heating and magnetic effects of short-circuit currents.
Economical:
  • Extremely current-limiting — often permits use of readily available, less costly equipment.
  • Used as input or output fuses for surge-sensitive components, such as variable speed drives and rectifiers, fast acting KLNR/KLSR fuses may prevent opening of expensive semiconductor fuses protecting individual components.
Easy to Use:
  • 200,000 A.I.R. rating minimizes need for short circuit calculations.
Dimensions:
  • Refer to FLNR for KLNR dimensions and FLSR for KLSR dimensions.

Product Literature

POWR-GARD Fuse Catalog - Download

Download our white paper!

Access specifications, certifications, check availability and order parts below

Catalog #Amps (A)Interrupting RatingOpeningVAC (V)VDC (V)SizeStockSamplesCompare
KLSR0011200 kA @ 600 VacFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR002220 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR003320 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR004420 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR005520 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR006620 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR008820 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR0101020 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR0121220 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR0151520 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR0202020 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR0252520 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR0303020 kA @ 250 VdcFast-Acting (F)600250Industrial CartridgeCheckOrder
KLSR0353520 kA @ 300 VdcFast-Acting (F)600300Industrial CartridgeCheckOrder
KLSR0404020 kA @ 300 VdcFast-Acting (F)600300Industrial CartridgeCheckOrder
KLSR0454520 kA @ 300 VdcFast-Acting (F)600300Industrial CartridgeCheckOrder
KLSR0505020 kA @ 300 VdcFast-Acting (F)600300Industrial CartridgeCheckOrder
KLSR0606020 kA @ 300 VdcFast-Acting (F)600300Industrial CartridgeCheckOrder
KLSR0707020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR0808020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR0909020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR10010020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR11011020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR12512520 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR15015020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR17517520 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR20020020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR22522520 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR25025020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR30030020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR35035020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR40040020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR45045020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR50050020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
KLSR60060020 kA @ 300 VdcFast-Acting (F)600300Knife-BladeCheckOrder
Catalog # Certificates
Sorting icon
KLSR001 CSAiconULiconCULicon
KLSR002 CSAiconULiconCULicon
KLSR003 CSAiconULiconCULicon
KLSR004 CSAiconULiconCULicon
KLSR005 CSAiconULiconCULicon
KLSR006 CSAiconULiconCULicon
KLSR008 CSAiconULiconCULicon
KLSR010 CSAiconULiconCULicon
KLSR012 CSAiconULiconCULicon
KLSR015 CSAiconULiconCULicon
KLSR020 CSAiconULiconCULicon
KLSR025 CSAiconULiconCULicon
KLSR030 CSAiconULiconCULicon
KLSR035 CSAiconULiconCULicon
KLSR040 CSAiconULiconCULicon
KLSR045 CSAiconULiconCULicon
KLSR050 CSAiconULiconCULicon
KLSR060 CSAiconULiconCULicon
KLSR070 CSAiconULiconCULicon
KLSR080 CSAiconULiconCULicon
KLSR090 CSAiconULiconCULicon
KLSR100 CSAiconULiconCULicon
KLSR110 CSAiconULiconCULicon
KLSR125 CSAiconULiconCULicon
KLSR150 CSAiconULiconCULicon
KLSR175 CSAiconULiconCULicon
KLSR200 CSAiconULiconCULicon
KLSR225 CSAiconULiconCULicon
KLSR250 CSAiconULiconCULicon
KLSR300 CSAiconULiconCULicon
KLSR350 CSAiconULiconCULicon
KLSR400 CSAiconULiconCULicon
KLSR450 CSAiconULiconCULicon
KLSR500 CSAiconULiconCULicon
KLSR600 CSAiconULiconCULicon


  • Showing 1 items
To request product environmental information, please complete the Product Environmental Information Request Form.