LSRK125.X Equivalent & Substitute Parts

Part Overview

The LSRK125.X is a 125A cartridge fuse manufactured by Littelfuse Inc., rated for 600 VAC and 300 VDC applications. Designed for electrical and industrial protection circuits, this slow-blow fuse operates within the RK1 class and requires a dedicated holder for installation. The product maintains active status with full compliance to CE, CSA, QPL, and UL standards. Substitute parts become necessary when application requirements demand alternative mounting configurations, enhanced breaking capacity, or specific series compatibility within the same electrical ratings.

Substiute Parts

LSRK125.X

Littelfuse Inc.In Stock: 1211LSRK125.X Datasheet

Current PartRFQ

LPS-RK-125SP

Eaton - Bussmann Electrical DivisionIn Stock: 944LPS-RK-125SP Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The LPS-RK-125SP qualifies as a direct substitute based on the following matching electrical parameters:

• Current Rating: 125A (identical)
• Voltage Rating AC: 600 VAC (identical)
• Voltage Rating DC: 300 VDC (identical)
• Fuse Type: Cartridge (identical)
• Response Time: Slow Blow (identical)
• Class: RK1 (identical)
• Approval Agencies: CE, CSA, UL (subset of main part certifications)

The primary difference lies in mounting configuration: the LPS-RK-125SP uses bolt mount instead of requiring a separate holder, and features enhanced breaking capacity (300kA AC, 100kA DC versus 200kA AC, 20kA DC). These differences do not prevent substitution when the application environment and circuit protection requirements align with the substitute's specifications.

Parameter Comparison

Engineering Selection Recommendations

Both the LSRK125.X and LPS-RK-125SP maintain active product status with full regulatory compliance. The LSRK125.X carries QPL certification in addition to CE, CSA, and UL approvals, making it suitable for applications requiring qualified parts lists. The LPS-RK-125SP provides equivalent electrical protection with higher breaking capacity ratings, beneficial in circuits subject to higher fault currents. Selection between these parts depends on circuit architecture: applications using dedicated fuse holders align with LSRK125.X, while installations with bolt-mount infrastructure favor LPS-RK-125SP. Both parts satisfy RoHS compliance requirements for modern industrial and electrical applications.

Frequently Asked Questions (FAQ)

Q: Can the LPS-RK-125SP directly replace the LSRK125.X in existing installations?

A: Direct replacement requires compatible mounting infrastructure. The LSRK125.X requires a separate holder, while the LPS-RK-125SP uses bolt mount. If the circuit already incorporates a bolt-mount fuse block, the LPS-RK-125SP is compatible. If the circuit uses a cartridge holder, the LSRK125.X must remain unless the holder is replaced with a bolt-mount assembly.

Q: Are the electrical protection characteristics identical?

A: Both parts provide identical current rating (125A), voltage ratings (600 VAC / 300 VDC), response time (slow blow), and class (RK1). The LPS-RK-125SP offers higher breaking capacity (300kA AC / 100kA DC) compared to the LSRK125.X (200kA AC / 20kA DC), providing enhanced protection in high-fault-current environments.

Q: What certifications apply to both parts?

A: Both parts carry CE, CSA, and UL certifications. The LSRK125.X additionally includes QPL certification for applications requiring qualified parts documentation.

Q: Does packaging differ between these parts?

A: The LSRK125.X ships in box packaging, while the LPS-RK-125SP uses bulk packaging. This distinction affects inventory management and procurement processes but does not impact electrical performance.

Q: Are both parts RoHS compliant?

A: Yes. The LSRK125.X meets ROHS3 compliance, and the LPS-RK-125SP meets RoHS compliance standards, both suitable for modern industrial applications.