KLLU900 - 600 VAC, Time-Delay, 601-4000 A Series

Series: KLLU
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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.

KLLU series UL Listed, time-delay, Class L are quality fuses in every sense of the word. They were developed to provide a somewhat lower priced alternate to the POWR-PRO™ KLPC series fuses. KLLU series fuses meet or exceed all UL requirements for Class L fuses. For superior protection and performance, specification-grade POWR-PRO™ KLPC series fuses are the recommended fuses.


  • Service switches
  • Switchboard mains and feeders
  • Bolted pressure contact switches
  • Motor control center mains
  • Large motor branch circuits
  • UL Listed series-rated protection for molded case circuit breaker panelboards and loadcenters. See panelboard manufacturer’s literature for recommended fuse rating.


  • 200,000 A.I.R. — Provides reliable interruption of all overcurrents up to 200,000 amperes.
  • When used for motor branch circuit protection, KLLU fuses may be sized close to the motor full-load current, providing excellent protection to branch circuit conductors, motor control equipment and motors.

Longer Equipment Life:

  • Current limiting — Reduces short circuit damage to systems and equipment.
  • Reduced downtime
  • Ten second minimum time delay at 500 percent of rating eliminates needless downtime caused by heavy starting currents of large motors and other inductive loads.
  • Selective coordination — KLLU fuses coordinate well with other Class L fuses and with all current-limiting Littelfuse fuses rated 600 amps or less. This means less time spent trying to locate short circuits or overloaded equipment, because only the fuse immediately on the line side of the affected circuit opens.

Easy to Use:

  • 200,000 A.I.R. rating minimizes need for short circuit calculations…meets present and future system requirements.
  • KLLU fuse time-current characteristics closely match typical time-current curves of circuit breakers. Although fuse/circuit breaker systems can seldom be 100% coordinated , KLLU series fuses permit use of a wider range of breaker setting than fast-acting Class L fuses. Excellent protection for a single breaker or a group of breakers.
Property (Mouseover for details) Value
Ampere Rating (A) 900
VAC (V) 600
VDC (V) 300
Interrupting Rating 200 kA @ 600 Vac
Opening Slo-Blo/Time Lag (T)/Time Delay
Size Bolt-In
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