3JS 4 Equivalent & Substitute Parts Reference

Part Overview

The 3JS 4 is a 4A 350VAC/140VDC glass cartridge fuse in 2AG form factor (5mm x 15mm axial) manufactured by Bel Fuse Inc. This component is classified as obsolete, making identification of active equivalent parts essential for ongoing system maintenance and new design implementations. The slow-blow response characteristic and through-hole mounting configuration define its application scope in circuit protection applications requiring moderate current ratings and dual voltage operation.

Substiute Parts

3JS 4

Bel Fuse Inc.In Stock: 7013JS 4 Datasheet

Current PartRFQ

3JS 4-R

Bel Fuse Inc.In Stock: 17693JS 4-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 3JS 4 is determined by strict equivalence across the following critical parameters:

• Current Rating: 4 A (exact match required)
• Voltage Rating - AC: 350 V (exact match required)
• Voltage Rating - DC: 140 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Slow Blow (exact match required)
• Package / Case: 2AG, 5mm x 15mm (Axial) (exact match required)
• Mounting Type: Through Hole (exact match required)
• Breaking Capacity @ Rated Voltage: 100A AC, 150A DC (exact match required)
• Melting I²t: 86 (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)
• Approval Agencies: CE, CSA, cURus, PSE (exact match required)

The 3JS 4-R qualifies as a direct substitute based on complete parameter alignment across all electrical and mechanical specifications.

Parameter Comparison

Engineering Selection Recommendations

The 3JS 4-R is the direct functional equivalent to the obsolete 3JS 4. Both components maintain identical electrical and mechanical specifications across all critical parameters including current rating, voltage ratings, response time, package configuration, and breaking capacity.

The 3JS 4-R carries active product status, ensuring ongoing availability and supply chain continuity. The substitute part holds ROHS3 compliance, whereas the original 3JS 4 is RoHS non-compliant. Both components maintain equivalent approval certifications (CE, CSA, cURus, PSE) required for regulatory compliance in target applications.

The DC cold resistance differential (0.026 Ohms versus 0.031 Ohms) falls within acceptable tolerance for circuit protection applications and does not affect functional equivalence.

Frequently Asked Questions (FAQ)

Q: Can the 3JS 4-R be used as a direct replacement for the 3JS 4?

A: Yes. The 3JS 4-R meets all electrical and mechanical specifications of the 3JS 4, including current rating, voltage ratings, response time, package configuration, and breaking capacity. Both components are identical in form, fit, and function for circuit protection applications.

Q: What is the difference between the 3JS 4 and 3JS 4-R?

A: The primary differences are product status and regulatory compliance. The 3JS 4 is obsolete with RoHS non-compliant status, while the 3JS 4-R is active with ROHS3 compliance. The DC cold resistance is slightly lower in the 3JS 4-R (0.026 Ohms versus 0.031 Ohms), which does not affect circuit protection performance.

Q: Are the approval certifications identical between both parts?

A: Yes. Both the 3JS 4 and 3JS 4-R hold identical approval certifications: CE, CSA, cURus, and PSE.

Q: Is the 2AG package configuration the same for both parts?

A: Yes. Both components use the 2AG form factor with 5mm x 15mm axial dimensions, ensuring identical through-hole mounting compatibility.

Q: What is the operating temperature range for these fuses?

A: Both the 3JS 4 and 3JS 4-R operate across the temperature range of -55°C to 125°C.