3AP 15 Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The 3AP 15 is a 15A 125VAC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc., designed for through-hole mounting in 3AB/3AG package format. This component is classified as obsolete, making identification of functionally equivalent substitutes necessary for ongoing system maintenance and repair applications. The fuse provides circuit protection with a breaking capacity of 10kA at rated voltage and operates across a temperature range of -55°C to 125°C.

Substiute Parts

3AP 15

Bel Fuse Inc.In Stock: 10693AP 15 Datasheet

Current PartRFQ

0318015.MXP

Littelfuse Inc.In Stock: 10440318015.MXP Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 3AP 15 is determined by the following critical parameters:

• Current Rating: Must be 15 A to maintain circuit protection design intent
• Fuse Type & Package: Must be cartridge glass fuse in 3AB/3AG format with identical physical dimensions (1/4" x 1-1/4" axial)
• Mounting Type: Must be through-hole compatible
• Response Time: Must be fast-blow characteristic
• Operating Temperature Range: Must support -55°C to 125°C minimum
• Physical Dimensions: Must match 0.272" Dia x 1.280" L specification within tolerance

The substitute part 0318015.MXP from Littelfuse Inc. meets these core substitution criteria. However, the voltage rating differs (32V AC versus 125V AC), which represents a significant parameter variance that must be evaluated within the specific application context.

Parameter Comparison

Engineering Selection Recommendations

The 0318015.MXP from Littelfuse Inc. is an active product with current manufacturing support and ROHS3 compliance, addressing the obsolescence status of the 3AP 15. Both components share identical current rating, fuse type, package format, and operating temperature specifications.

The primary consideration is voltage rating: the 0318015.MXP operates at 32V AC, compared to the 3AP 15 at 125V AC. This voltage differential must be evaluated against the actual circuit voltage requirements. The Littelfuse component is suitable for applications operating at or below 32V AC. For circuits requiring 125V AC protection, the voltage rating of the substitute must match or exceed the circuit operating voltage.

Both components carry recognized safety approvals. The 3AP 15 holds CE, CSA, PSE, and UL certifications, while the 0318015.MXP carries cULus certification. Physical dimensions are within acceptable tolerance (0.003" diameter and 0.008" length variance).

Frequently Asked Questions (FAQ)

Q: Can the 0318015.MXP directly replace the 3AP 15 in all applications?

A: Direct replacement is possible only in circuits operating at 32V AC or lower. The voltage rating is the limiting parameter. For 125V AC circuits, the substitute voltage rating is insufficient and does not meet circuit protection requirements.

Q: What is the significance of the different breaking capacities (10 kA vs. 300 A)?

A: Breaking capacity indicates the maximum fault current the fuse can safely interrupt. The 3AP 15 has a 10 kA breaking capacity at 125V, while the 0318015.MXP has 300A at 32V. These values are rated at their respective voltage levels and are not directly comparable across different voltage ratings.

Q: Are the physical dimensions compatible?

A: Yes. Both components use the 3AB/3AG package format with 1/4" x 1-1/4" axial dimensions. Measured dimensions show minor variance (0.003" diameter, 0.008" length), which is within standard manufacturing tolerance for this package type and maintains mechanical compatibility in through-hole mounting applications.

Q: What does the difference in melting I²t values indicate?

A: Melting I²t (845 for 3AP 15 vs. 490.5 for 0318015.MXP) represents the thermal energy required to melt the fuse element. The lower value in the Littelfuse component indicates faster thermal response, which is consistent with its lower voltage rating and different fuse element design.

Q: Why is RoHS compliance status different?

A: The 3AP 15 is RoHS non-compliant (obsolete product), while the 0318015.MXP is ROHS3 compliant (active product). For new designs or systems requiring RoHS compliance, the Littelfuse component is the appropriate selection.

Q: Are the DC cold resistance values significant for substitution?

A: DC cold resistance (0.006 Ohms vs. 0.0052 Ohms) is a minor parameter difference. Both values are sufficiently low for typical circuit applications and do not represent a substitution barrier.