Littelfuse 0318.187H Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0318.187H is a 187 mA, 250 V AC/DC fast-blow glass cartridge fuse in the 3AB/3AG package format (1/4" x 1-1/4" axial). This component is classified as obsolete, making equivalent substitute parts necessary for ongoing circuit protection applications. Active production alternatives maintain identical electrical and mechanical specifications while offering improved compliance status and extended operating temperature range.

Substiute Parts

0318.187H

Littelfuse Inc.In Stock: 7740318.187H Datasheet

Current PartRFQ

0318.187HXP

Littelfuse Inc.In Stock: 10530318.187HXP Datasheet

DirectRFQ

0318.187MXP

Littelfuse Inc.In Stock: 11210318.187MXP Datasheet

Parametric EquivalentRFQ

0318.187VXP

Littelfuse Inc.In Stock: 10590318.187VXP Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the Littelfuse 0318.187H is determined by strict equivalence across the following parameters:

• Current Rating: 187 mA (exact match required)
• Voltage Rating: 250 V AC (exact match required)
• Response Time: Fast Blow (exact match required)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" Axial (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Mounting Type: Through Hole (exact match required)
• Breaking Capacity: 35 A (exact match required)
• Melting I²t: 0.0128 (exact match required)

All three substitute parts—0318.187HXP, 0318.187MXP, and 0318.187VXP—meet these criteria and are direct functional equivalents. The primary distinction is product status: the original part is obsolete, while all substitutes are active production items.

Parameter Comparison

Engineering Selection Recommendations

All three substitute parts—0318.187HXP, 0318.187MXP, and 0318.187VXP—are electrically and mechanically equivalent to the Littelfuse 0318.187H. Selection among these active production alternatives should be based on the following factors:

Product Status: The original 0318.187H is obsolete. All substitute parts are active production items with confirmed inventory availability.

Regulatory Compliance: The original part carries CSA and UL approvals but is RoHS non-compliant. All substitute parts achieve ROHS3 compliance and CE certification in addition to CSA and UL approvals, meeting current regulatory requirements for new designs and procurement.

Operating Temperature Range: The original part does not specify an operating temperature range. All substitute parts are rated for -55°C to 125°C operation, providing defined thermal performance boundaries.

DC Cold Resistance: The original part specifies 3.4 Ohms; substitute parts specify 3.42 Ohms. This 0.02 Ohm variance is negligible for circuit protection applications and does not affect functional equivalence.

For new designs, procurement, or replacement applications requiring current regulatory compliance, any of the three substitute parts is suitable. Selection may be based on packaging preferences, supplier availability, or inventory considerations, as all three are functionally identical.

Frequently Asked Questions (FAQ)

Q: Can the 0318.187HXP, 0318.187MXP, or 0318.187VXP be used as direct replacements for the 0318.187H?

A: Yes. All three substitute parts are direct functional equivalents. They share identical current ratings (187 mA), voltage ratings (250 V AC), response time (fast blow), package format (3AB/3AG, 1/4" x 1-1/4" axial), breaking capacity (35 A), and melting I²t (0.0128). Physical dimensions and mounting type are identical, enabling direct board-level substitution.

Q: What is the difference between the three substitute parts?

A: The 0318.187HXP, 0318.187MXP, and 0318.187VXP are electrically and mechanically identical. All three are active production items with identical specifications, approvals, compliance status, and operating temperature range. Differences are limited to part number designation and may reflect internal Littelfuse product line management or packaging batch variations. All three are suitable for equivalent substitution.

Q: Why is the original 0318.187H marked as obsolete?

A: Product obsolescence typically reflects manufacturer discontinuation decisions. The substitute parts represent current production alternatives that maintain full electrical and mechanical compatibility while offering improved regulatory compliance (ROHS3, CE certification) and defined operating temperature specifications.

Q: Are there any compatibility concerns with the substitute parts?

A: No. The substitute parts are mechanically compatible with existing 3AB/3AG fuse holders and electrically compatible with circuits designed for 187 mA, 250 V fast-blow protection. The negligible DC cold resistance variance (3.4 Ohms vs. 3.42 Ohms) does not affect circuit operation.

Q: What certifications do the substitute parts carry?

A: All substitute parts carry CE, CSA, and UL certifications. They are ROHS3 compliant and REACH unaffected, meeting current regulatory requirements for electronic component procurement and use in regulated markets.

Q: Can I use these fuses in applications requiring RoHS compliance?

A: Yes. The substitute parts (0318.187HXP, 0318.187MXP, 0318.187VXP) are ROHS3 compliant, unlike the original 0318.187H. They are suitable for applications and markets requiring RoHS compliance.