3JS 350-R Equivalent & Substitute Parts

Part Overview

The 3JS 350-R is a 350 mA slow-blow glass cartridge fuse manufactured by Bel Fuse Inc., rated for 350 V AC and 140 V DC operation. This component is classified as obsolete, necessitating identification of equivalent substitute parts for ongoing system maintenance and new designs. The 2AG form factor (5mm x 15mm axial) and slow-blow response characteristic define the functional requirements for suitable alternatives.

Substiute Parts

3JS 350-R

Bel Fuse Inc.In Stock: 12183JS 350-R Datasheet

Current PartRFQ

0230.350MXP

Littelfuse Inc.In Stock: 7350230.350MXP Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 3JS 350-R is determined by the following critical parameters:

• Current Rating: Must match 350 mA exactly
• Response Time: Must be Slow Blow
• Fuse Type: Must be Cartridge, Glass
• Mounting Type: Must be Through Hole
• Operating Temperature Range: Must support -55°C ~ 125°C minimum
• Voltage Ratings: AC and DC voltage ratings must meet or exceed the application requirements
• Approval Agencies: Must maintain compliance certifications appropriate to the application

The substitute part 0230.350MXP meets the current rating, response time, fuse type, mounting type, and temperature range requirements. However, voltage ratings differ and must be evaluated against specific application constraints.

Parameter Comparison

Engineering Selection Recommendations

The 0230.350MXP from Littelfuse Inc. is an active product suitable for applications where the reduced voltage ratings (250 V AC, 125 V DC) are acceptable. This substitute maintains the same current rating, response time, and temperature operating range as the 3JS 350-R. Both components carry ROHS3 compliance and CE/CSA certifications.

Selection of the 0230.350MXP requires verification that the application voltage requirements do not exceed 250 V AC or 125 V DC. The melting I²t value of 0.49 is lower than the original 0.8, indicating faster thermal response. The breaking capacity differs significantly, with the substitute providing lower AC breaking capacity (35A versus 100A) but higher DC breaking capacity (10kA versus 150A).

The non-standard package dimension (4.50mm x 14.50mm versus 5.50mm x 15.00mm) may require mechanical evaluation for board layout compatibility.

Frequently Asked Questions (FAQ)

Q: Can the 0230.350MXP directly replace the 3JS 350-R in all applications?

A: Direct replacement is possible only when the application voltage does not exceed 250 V AC or 125 V DC. The original 3JS 350-R supports higher voltage ratings (350 V AC, 140 V DC). Verify application requirements before substitution.

Q: What is the significance of the different melting I²t values?

A: The melting I²t value (0.8 for 3JS 350-R versus 0.49 for 0230.350MXP) indicates the thermal energy required to melt the fuse element. The lower value of the substitute means it will respond to thermal stress more quickly. This difference must be evaluated against circuit protection requirements.

Q: Are there mechanical compatibility concerns with the package dimensions?

A: The 0230.350MXP has slightly smaller dimensions (4.50mm x 14.50mm) compared to the 3JS 350-R (5.50mm x 15.00mm). While both are axial cartridge formats, the dimensional difference may affect fit in legacy fuse holders. Physical verification is necessary.

Q: Do both parts carry the same regulatory approvals?

A: Both components are CE and CSA certified. The 3JS 350-R carries cURus approval, while the 0230.350MXP carries UL approval. Verify that the substitute's certification profile meets application regulatory requirements.

Q: What is the difference in breaking capacity between these parts?

A: The 3JS 350-R provides 100A AC and 150A DC breaking capacity, while the 0230.350MXP provides 35A AC and 10kA DC breaking capacity. Breaking capacity defines the maximum fault current the fuse can safely interrupt. Application fault current levels must be evaluated against these specifications.