MJS 3 Equivalent & Substitute Parts

Part Overview

The MJS 3 is a 3A 250VAC slow-blow glass cartridge fuse in 2AG package format (5mm x 15mm axial). Manufactured by Bel Fuse Inc., this through-hole component is designed for circuit protection applications requiring moderate current interruption. The main part (MJS 3) carries an obsolete product status, making identification of active equivalent alternatives essential for ongoing procurement and design continuity.

Substiute Parts

MJS 3

Bel Fuse Inc.In Stock: 910MJS 3 Datasheet

Current PartRFQ

MJS 3-R

Bel Fuse Inc.In Stock: 779MJS 3-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MJS 3 is determined by strict equivalence across the following critical parameters:

• Current Rating: 3 A (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Package / Case: 2AG, 5mm x 15mm (Axial) (exact match required)
• Response Time: Slow Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Breaking Capacity @ Rated Voltage: 200A (exact match required)
• Melting I²t: 55 (exact match required)

The MJS 3-R qualifies as a direct substitute, maintaining identical electrical and mechanical specifications while offering active product status and improved compliance characteristics.

Parameter Comparison

Engineering Selection Recommendations

The MJS 3-R is the direct equivalent for the obsolete MJS 3. Selection of MJS 3-R is supported by:

• Product Status: MJS 3-R maintains active status, ensuring continued availability and supply chain reliability.
• Electrical Equivalence: Identical current rating (3A), voltage rating (250V AC), breaking capacity (200A), and melting I²t (55) ensure functional interchangeability in circuit protection applications.
• Mechanical Compatibility: Identical 2AG package dimensions (5mm x 15mm axial) and through-hole mounting enable direct board-level substitution without layout modifications.
• Compliance Enhancement: MJS 3-R achieves ROHS3 compliance, whereas the main part is RoHS non-compliant. MJS 3-R certifications include cULus in addition to CE, CSA, and PSE.
• Resistance Improvement: The DC cold resistance of MJS 3-R (0.036 Ohms) is lower than the main part (0.045 Ohms), representing a marginal improvement in electrical performance.

Frequently Asked Questions (FAQ)

Q: Can MJS 3-R be used as a direct replacement for MJS 3 in existing designs?

A: Yes. MJS 3-R maintains identical electrical specifications (3A, 250V AC, slow-blow response, 200A breaking capacity) and mechanical form factor (2AG, 5mm x 15mm axial, through-hole mounting). No circuit modifications are required.

Q: What is the primary reason to transition from MJS 3 to MJS 3-R?

A: The MJS 3 is obsolete. MJS 3-R is the active equivalent from the same manufacturer, ensuring ongoing procurement availability and supply chain continuity.

Q: Are there compliance differences between MJS 3 and MJS 3-R?

A: Yes. MJS 3-R is ROHS3 compliant, whereas MJS 3 is RoHS non-compliant. MJS 3-R also includes cULus certification in addition to CE, CSA, and PSE approvals.

Q: Do the fuses have identical thermal characteristics?

A: Both parts operate across the same temperature range (-55°C ~ 125°C) and share identical melting I²t values (55). MJS 3-R exhibits slightly lower DC cold resistance (0.036 Ohms vs. 0.045 Ohms).

Q: Is the 2AG package format standard for both parts?

A: Yes. Both MJS 3 and MJS 3-R use the 2AG cartridge format with dimensions of 5mm diameter x 15mm length in axial configuration, ensuring mechanical interchangeability in standard fuse holders.