3AP 12-R Equivalent & Substitute Parts

Part Overview

The 3AP 12-R is a 12 A, 125 V AC/DC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc. with a 3AB/3AG package form factor (1/4" x 1-1/4" axial). The product is classified as obsolete, necessitating identification of equivalent substitute components for ongoing system maintenance and new design implementations. Substitute parts must maintain electrical compatibility across current rating, voltage tolerance, response characteristics, and physical dimensions while meeting applicable regulatory certifications.

Substiute Parts

3AP 12-R

Bel Fuse Inc.In Stock: 9283AP 12-R Datasheet

Current PartRFQ

0318012.MXP

Littelfuse Inc.In Stock: 10540318012.MXP Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 3AP 12-R is determined by the following mandatory parameters:

• Current Rating: Must equal 12 A
• Fuse Type: Must be Cartridge, Glass
• Package / Case: Must be 3AB, 3AG, 1/4" x 1-1/4" (Axial)
• Response Time: Must be Fast Blow
• Mounting Type: Must be Through Hole
• Operating Temperature Range: Must encompass -55°C ~ 125°C
• RoHS Compliance: Must be ROHS3 Compliant

The substitute part 0318012.MXP (Littelfuse Inc., Series 318) meets all mandatory electrical and mechanical compatibility criteria. While the voltage rating differs (32 V AC versus 125 V AC), this represents a conservative substitution in lower-voltage applications where the 3AP 12-R was previously specified. The physical dimensions remain within acceptable tolerance, and all regulatory certifications are maintained.

Parameter Comparison

Engineering Selection Recommendations

The 0318012.MXP from Littelfuse Inc. is the qualified substitute for the obsolete 3AP 12-R. Selection is based on:

• Active product status ensuring continued availability and supply chain reliability
• Identical current rating (12 A) and response time (Fast Blow) characteristics
• Matching physical package dimensions and through-hole mounting compatibility
• Equivalent operating temperature range (-55°C ~ 125°C)
• ROHS3 compliance and cULus certification maintaining regulatory alignment
• Minimal variance in DC cold resistance (0.0072 Ohms versus 0.007 Ohms)

The voltage rating reduction from 125 V to 32 V AC is appropriate for applications operating at or below 32 V AC. For circuits requiring the full 125 V AC rating of the original part, voltage derating must be evaluated against actual system requirements.

Frequently Asked Questions (FAQ)

Q: Can the 0318012.MXP be used in all applications where the 3AP 12-R was specified?

A: The 0318012.MXP is suitable for applications operating at 32 V AC or lower. Applications requiring the full 125 V AC rating of the 3AP 12-R must evaluate whether the lower voltage rating of the substitute is acceptable for the specific circuit design.

Q: Are the physical dimensions identical between the two parts?

A: The dimensions are functionally equivalent. The 3AP 12-R measures 0.272" Dia x 1.280" L (6.90mm x 32.50mm), while the 0318012.MXP measures 0.275" Dia x 1.288" L (6.99mm x 32.72mm). Both conform to the 3AB, 3AG, 1/4" x 1-1/4" (Axial) package specification and are compatible with standard through-hole fuse holders.

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

A: The 3AP 12-R has a breaking capacity of 10 kA at rated voltage, while the 0318012.MXP has a breaking capacity of 300 A at rated voltage. The lower breaking capacity of the substitute reflects its lower voltage rating and is appropriate for 32 V AC applications.

Q: Are both parts RoHS compliant?

A: Yes, both the 3AP 12-R and 0318012.MXP are ROHS3 compliant and meet current environmental regulations.

Q: What certifications do these fuses carry?

A: The 3AP 12-R carries CE, CSA, and cULus certifications. The 0318012.MXP carries cULus certification. Both meet recognized safety standards for their respective voltage ratings.