Littelfuse 0RLS350.X Fuse Cartridge - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0RLS350.X is a 350A, 600 VAC cylindrical fuse cartridge from the POWR-GARD® RLS series, designed for electrical and industrial applications requiring fast-blow protection. This component is classified as obsolete, necessitating identification of active equivalent parts to maintain system functionality and ensure continued availability for replacement and new installations.

Substiute Parts

0RLS350.X

Littelfuse Inc.In Stock: 12080RLS350.X Datasheet

Current PartRFQ

KLSR300.X

Littelfuse Inc.In Stock: 1222KLSR300.X Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 0RLS350.X requires evaluation based on the following critical parameters:

• Current Rating: The substitute must accommodate the circuit's amperage requirement. The 0RLS350.X operates at 350A; however, lower-rated alternatives may be considered for circuits designed to operate at reduced current levels.
• Voltage Rating - AC: The substitute must maintain or exceed the 600 VAC rating to ensure safe operation in the intended electrical environment.
• Fuse Type and Package: Both the main part and substitute must be cylindrical cartridge fuses with blade terminals to ensure mechanical compatibility with existing holders.
• Response Time: Fast-blow characteristics must be preserved to maintain protection timing in the circuit.
• Approval Certifications: The substitute must retain CE, CSA, and UL certifications to comply with regulatory and safety standards.
• Product Status: Active status ensures ongoing availability and manufacturer support.

The KLSR300.X is identified as a substitute based on shared mechanical form factor, compatible voltage rating, fast-blow response, and active product status. The current rating difference (300A vs. 350A) represents a design trade-off that may be acceptable depending on circuit requirements.

Parameter Comparison

Engineering Selection Recommendations

The KLSR300.X serves as an active substitute for the obsolete 0RLS350.X based on the following engineering criteria:

Regulatory Compliance: Both parts maintain CE, CSA, and UL certifications, ensuring compliance with applicable safety standards. The KLSR300.X additionally achieves ROHS3 compliance, providing enhanced environmental compliance for new designs and installations.

Electrical Compatibility: Both fuses operate at 600 VAC with fast-blow response characteristics. The KLSR300.X provides superior breaking capacity (200kA AC versus 10kA), offering enhanced fault protection capability. The addition of 300 VDC rating on the KLSR300.X extends application flexibility without compromising AC performance.

Mechanical Compatibility: Both parts share identical cylindrical form factor with blade terminals and matching 2.594" diameter, ensuring compatibility with existing fuse holders. The KLSR300.X is longer (11.626" versus 7.878"), which must be verified against holder depth specifications.

Current Rating Consideration: The 50A reduction in current rating (300A versus 350A) represents a design trade-off. Selection of the KLSR300.X is appropriate for circuits designed to operate at or below 300A. Circuits requiring 350A operation require alternative solutions.

Product Availability: The KLSR300.X is active status with confirmed inventory, ensuring reliable procurement for replacement and new applications.

Frequently Asked Questions (FAQ)

Q: Can the KLSR300.X directly replace the 0RLS350.X in all applications?

A: Direct replacement is limited by current rating. The KLSR300.X is rated for 300A maximum, while the 0RLS350.X is rated for 350A. Substitution is valid only for circuits designed to operate at 300A or below. Circuits requiring 350A operation require alternative parts.

Q: What is the significance of the length difference between these fuses?

A: The 0RLS350.X measures 7.878" length while the KLSR300.X measures 11.626" length. Both share the same 2.594" diameter. The fuse holder must accommodate the longer KLSR300.X cartridge. Physical verification of holder depth is required before substitution.

Q: Why does the KLSR300.X have a higher breaking capacity than the 0RLS350.X?

A: Breaking capacity (10kA versus 200kA AC) reflects the fuse class designation. The 0RLS350.X is Class H; the KLSR300.X is Class RK1. Class RK1 fuses are designed for higher fault current environments. The KLSR300.X provides enhanced protection capability in circuits with higher available fault current.

Q: Does the KLSR300.X support DC applications?

A: Yes. The KLSR300.X is rated for 300 VDC in addition to 600 VAC. The 0RLS350.X does not specify DC rating. If DC operation is required, the KLSR300.X provides this capability.

Q: Are both fuses RoHS compliant?

A: No. The 0RLS350.X is RoHS non-compliant. The KLSR300.X is ROHS3 compliant. For new designs or applications with RoHS compliance requirements, the KLSR300.X is the appropriate selection.

Q: What certifications do these fuses maintain?

A: Both the 0RLS350.X and KLSR300.X are certified by CE, CSA, and UL. Certification compliance is maintained across the substitution.