3AP 15-R Equivalent & Substitute Parts

Part Overview

The 3AP 15-R is a 15 A, 125 V AC/DC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc. in the 3AB/3AG package format (1/4" x 1-1/4" axial). This component is classified as obsolete, making identification of functionally equivalent substitute parts essential for system maintenance, repair, and redesign applications where continued supply cannot be guaranteed.

Substiute Parts

3AP 15-R

Bel Fuse Inc.In Stock: 9173AP 15-R Datasheet

Current PartRFQ

0318015.MXP

Littelfuse Inc.In Stock: 10440318015.MXP Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

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

Mandatory Matching Parameters:

• Current Rating: 15 A (exact match required)
• Fuse Type: Cartridge, Glass (form factor and construction type)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (physical dimensions and mounting compatibility)
• Response Time: Fast Blow (thermal response characteristic)
• Mounting Type: Through Hole (circuit board integration method)

Voltage Rating Consideration: The 3AP 15-R operates at 125 V AC. Substitute parts must maintain voltage ratings equal to or greater than the original specification to ensure safe operation within the intended circuit environment.

Thermal and Electrical Characteristics: Operating temperature range, breaking capacity, melting I²t, and DC cold resistance define the electrical performance envelope. Substitutes must operate within the specified temperature range and maintain comparable thermal response characteristics.

The identified substitute part 0318015.MXP (Littelfuse Inc., Series 318) matches the mandatory parameters of current rating, fuse type, package format, response time, and mounting type. However, the voltage rating differential (32 V AC vs. 125 V AC) requires engineering evaluation based on circuit requirements.

Parameter Comparison

Engineering Selection Recommendations

The 3AP 15-R (Bel Fuse Inc.) is classified as obsolete. The 0318015.MXP (Littelfuse Inc.) provides mechanical and electrical form-factor compatibility with identical current rating, fuse type, package dimensions, response time, and mounting configuration.

Compliance Considerations: The 3AP 15-R carries CE, CSA, and cULus certifications. The 0318015.MXP carries cULus certification. Applications requiring CE or CSA compliance must evaluate whether cULus certification alone satisfies regulatory requirements for the target market and application.

Voltage Rating Differential: The 0318015.MXP operates at 32 V AC, compared to the 3AP 15-R at 125 V AC. Selection of this substitute is appropriate only for circuits operating at or below 32 V AC. For circuits requiring 125 V AC operation, this substitute is not suitable.

Electrical Performance: The 0318015.MXP exhibits lower melting I²t (490.5 vs. 845) and lower DC cold resistance (0.0052 vs. 0.006 Ohms), indicating faster thermal response and reduced resistive heating. These characteristics may affect circuit behavior in applications sensitive to fuse response time or resistive losses.

Frequently Asked Questions (FAQ)

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

A: Physical and mechanical compatibility is confirmed. However, the voltage rating difference (32 V AC vs. 125 V AC) restricts substitution to circuits operating at 32 V AC or lower. Verify circuit voltage requirements before substitution.

Q: What is the significance of the melting I²t difference between these parts?

A: Melting I²t defines the thermal energy required to melt the fuse element. The 0318015.MXP (490.5) has lower I²t than the 3AP 15-R (845), resulting in faster thermal response. This may alter circuit protection timing in applications with specific transient or inrush current profiles.

Q: Are both parts RoHS compliant?

A: Yes. Both the 3AP 15-R and 0318015.MXP are ROHS3 compliant.

Q: What certifications does each part carry?

A: The 3AP 15-R carries CE, CSA, and cULus certifications. The 0318015.MXP carries cULus certification. Applications requiring CE or CSA compliance must confirm whether cULus certification alone satisfies regulatory requirements.

Q: Are the physical dimensions identical?

A: Dimensions are nearly identical. The 3AP 15-R measures 0.272" Dia x 1.280" L (6.90mm x 32.50mm). The 0318015.MXP measures 0.275" Dia x 1.288" L (6.99mm x 32.72mm). Both fit the 3AB/3AG package standard and are mechanically compatible with through-hole mounting.

Q: What is the breaking capacity difference?

A: The 3AP 15-R has a breaking capacity of 10 kA at rated voltage. The 0318015.MXP has a breaking capacity of 300 A at rated voltage. Breaking capacity defines the maximum fault current the fuse can safely interrupt. The lower breaking capacity of the 0318015.MXP may be insufficient for high-fault-current applications.