Littelfuse 0RLS125.X Fuse Cartridge - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0RLS125.X is a 125A, 600 VAC cylindrical fuse cartridge from the POWR-GARD® RLS series, designed for electrical and industrial applications requiring fast-blow protection. This part is classified as obsolete, making identification of suitable substitute components essential for system maintenance and replacement scenarios. The 0RLS125.X requires a dedicated fuse holder for installation and provides 10kA breaking capacity at rated voltage.

Substiute Parts

0RLS125.X

Littelfuse Inc.In Stock: 11620RLS125.X Datasheet

Current PartRFQ

KLSR125.X

Littelfuse Inc.In Stock: 1224KLSR125.X Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 0RLS125.X is determined by the following critical parameters:

• Current Rating: Must be 125A to maintain circuit protection design specifications
• Voltage Rating - AC: Must be rated for 600 VAC minimum to ensure safe operation in the intended electrical environment
• Fuse Type: Must be cartridge type with cylindrical, blade terminal configuration for mechanical compatibility with existing holders
• Response Time: Fast-blow characteristic must be preserved for application-specific protection requirements
• Mounting Configuration: Must require holder-based installation to match existing infrastructure
• Approval Certifications: Must maintain CE, CSA, and UL certifications for regulatory compliance

The Littelfuse KLSR125.X meets all substitution criteria while offering enhanced specifications including DC voltage capability and improved breaking capacity.

Parameter Comparison

Engineering Selection Recommendations

The KLSR125.X is the designated manufacturer substitute for the obsolete 0RLS125.X. Both components share identical current and AC voltage ratings, fuse type, response characteristics, and holder-based mounting requirements. The KLSR125.X maintains all required certifications (CE, CSA, UL) and provides direct functional compatibility.

The KLSR125.X offers additional technical advantages: active product status ensures ongoing availability, ROHS3 compliance meets current environmental standards, and enhanced breaking capacity (200kA AC versus 10kA) provides superior fault protection margins. The RK1 class designation reflects improved performance characteristics compared to the Class H specification of the original part.

Physical dimensions differ slightly: the KLSR125.X measures 1.843" Dia x 9.626" L (46.80mm x 244.50mm) compared to the 0RLS125.X at 1.843" Dia x 6.878" L (46.80mm x 174.70mm). Verification of holder compatibility with the increased length is required before installation.

Frequently Asked Questions (FAQ)

Q: Can the KLSR125.X be used as a direct replacement for the 0RLS125.X?

A: The KLSR125.X is the manufacturer-designated substitute and provides equivalent protection at 125A, 600 VAC with identical fast-blow response. Physical dimension differences require confirmation that the fuse holder accommodates the longer cartridge length (244.50mm versus 174.70mm).

Q: What is the difference between Class H and Class RK1 fuses?

A: Class H and Class RK1 are distinct fuse classifications with different breaking capacities and application profiles. The KLSR125.X (RK1) provides 200kA breaking capacity at 600 VAC compared to the 0RLS125.X (Class H) at 10kA. Verify that the circuit protection scheme accepts RK1 class components.

Q: Are both parts certified for the same regulatory standards?

A: Both the 0RLS125.X and KLSR125.X carry CE, CSA, and UL certifications, meeting equivalent regulatory requirements for electrical and industrial applications.

Q: Does the KLSR125.X support DC applications?

A: The KLSR125.X is rated for 300 VDC operation in addition to 600 VAC, providing expanded application flexibility. The original 0RLS125.X does not specify DC voltage capability.

Q: What is the significance of ROHS3 compliance on the KLSR125.X?

A: ROHS3 compliance indicates the KLSR125.X meets current environmental standards for restricted hazardous substances. The 0RLS125.X is RoHS non-compliant, reflecting its obsolete status and older manufacturing standards.

Q: Must the fuse holder be replaced when switching from 0RLS125.X to KLSR125.X?

A: Both cartridges use cylindrical, blade terminal configurations and require holder-based mounting. Verify that the existing holder dimensions accommodate the KLSR125.X length of 244.50mm before installation.