Bel Fuse Inc. 0651-6000-21 Equivalent & Substitute Parts

Part Overview

The Bel Fuse Inc. 0651-6000-21 is a 6A 125VAC fast-blow glass cartridge fuse in 5mm x 20mm form factor, designed for circuits requiring holder-mounted protection. This part is classified as obsolete, necessitating identification of active equivalent alternatives to maintain supply chain continuity and ensure compliance with current manufacturing standards.

Substiute Parts

0651-6000-21

Bel Fuse Inc.In Stock: 9640651-6000-21 Datasheet

Current PartRFQ

5MF 6-R

Bel Fuse Inc.In Stock: 9505MF 6-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 0651-6000-21 is determined by strict equivalence across the following electrical and mechanical parameters:

• Current Rating: 6 A (exact match required)
• Voltage Rating (AC): 125 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Fast Blow (exact match required)
• Package / Case: 5mm x 20mm (exact match required)
• Breaking Capacity @ Rated Voltage: 10kA (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)
• Mounting Type: Requires Holder (exact match required)

The substitute part 5MF 6-R meets all these criteria and is classified as active, making it a direct functional equivalent.

Parameter Comparison

Engineering Selection Recommendations

The 5MF 6-R is the direct substitute for the obsolete 0651-6000-21. Both parts are manufactured by Bel Fuse Inc. within the 5MF series and maintain identical electrical and mechanical specifications across all critical parameters.

The 5MF 6-R offers the following advantages:

• Active product status ensures ongoing availability and manufacturing support
• ROHS3 compliance aligns with current environmental and regulatory requirements
• cULus certification provides expanded North American approval coverage
• Marginal improvements in DC cold resistance (0.012 Ohms vs. 0.013 Ohms) and melting I²t (65 vs. 66) remain within acceptable tolerance for circuit protection applications
• Identical form factor, current rating, voltage rating, and breaking capacity guarantee direct functional compatibility in existing holder-based installations

Frequently Asked Questions (FAQ)

Q: Can the 5MF 6-R be used as a direct replacement for the 0651-6000-21?

A: Yes. Both parts are identical in current rating (6A), voltage rating (125VAC), fuse type (cartridge glass), response time (fast blow), package dimensions (5mm x 20mm), and breaking capacity (10kA). The 5MF 6-R is the active equivalent.

Q: What is the difference in melting I²t between the two parts?

A: The 0651-6000-21 has a melting I²t of 66, while the 5MF 6-R has 65. This minor difference does not affect circuit protection performance within standard application tolerances.

Q: Does the 5MF 6-R fit the same holder as the 0651-6000-21?

A: Yes. Both parts share identical dimensions (5.10mm diameter x 20.00mm length) and require the same holder-based mounting configuration.

Q: What regulatory compliance improvements does the 5MF 6-R provide?

A: The 5MF 6-R is ROHS3 compliant, whereas the 0651-6000-21 is RoHS non-compliant. The 5MF 6-R also carries cULus certification in addition to CE, CSA, and PSE approvals.

Q: Is the 5MF 6-R available in the same packaging as the 0651-6000-21?

A: The 0651-6000-21 was supplied in standard packaging, while the 5MF 6-R is available in bulk packaging. Both formats support the same component specifications and holder compatibility.