Equivalent & Substitute Parts for 3AP 12 Fuse

Part Overview

The 3AP 12 is a 12A 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 alternatives necessary for ongoing system maintenance and new design implementations where legacy specifications must be maintained or adapted.

Substiute Parts

3AP 12

Bel Fuse Inc.In Stock: 7833AP 12 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 is determined by the following critical parameters:

• Current Rating: 12 A (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
• Mounting Type: Through Hole (exact match required)
• Response Time: Fast Blow (exact match required)
• Operating Temperature Range: -55°C to 125°C (minimum requirement)

The substitute part 0318012.MXP from Littelfuse Inc. meets all critical dimensional and functional parameters. The voltage rating difference (32 V AC vs. 125 V AC) represents a design consideration rather than a disqualification, as the substitute operates at a lower voltage specification while maintaining identical current and package characteristics.

Parameter Comparison

Engineering Selection Recommendations

The 0318012.MXP from Littelfuse Inc. is an active product with current manufacturing support and ROHS3 compliance, addressing the obsolescence status of the 3AP 12. Both components share identical current ratings, package dimensions, and response characteristics, ensuring mechanical and electrical compatibility in through-hole circuit applications.

The voltage rating differential (32 V vs. 125 V) must be evaluated against circuit requirements. The substitute operates at a lower voltage specification; applications requiring the full 125 V rating should confirm that 32 V operation is acceptable for the intended circuit topology.

The Littelfuse component carries cULus certification, providing regulatory coverage for North American markets. The original Bel Fuse component includes broader international certifications (CE, CSA, PSE, UL); applications requiring specific regional compliance should cross-reference certification requirements.

Frequently Asked Questions (FAQ)

Q: Can the 0318012.MXP directly replace the 3AP 12 in existing designs?

A: Physical and electrical compatibility exists for current rating, fuse type, and package format. The voltage rating difference (32 V vs. 125 V) requires circuit-level evaluation to confirm acceptability.

Q: What is the significance of the voltage rating difference?

A: The 3AP 12 operates at 125 V AC, while the 0318012.MXP operates at 32 V AC. The substitute is rated for lower voltage operation. Circuits designed for 125 V operation must confirm that 32 V specification meets application requirements.

Q: Are there dimensional differences between these components?

A: Dimensions are functionally equivalent. The 3AP 12 measures 0.272" Dia x 1.280" L (6.90mm x 32.50mm); the 0318012.MXP measures 0.275" Dia x 1.288" L (6.99mm x 32.72mm). These variations fall within standard manufacturing tolerances for 3AB/3AG package specifications.

Q: What certifications apply to each component?

A: The 3AP 12 carries CE, CSA, PSE, and UL certifications. The 0318012.MXP carries cULus certification. Applications requiring specific regional compliance should verify that cULus certification satisfies project requirements.

Q: How do the melting I²t values compare?

A: The 3AP 12 has a melting I²t of 501, while the 0318012.MXP has a melting I²t of 234.6. This difference indicates different thermal response characteristics; circuit protection coordination should be re-evaluated if this component is substituted.

Q: What is the RoHS compliance status?

A: The 3AP 12 is RoHS non-compliant. The 0318012.MXP is ROHS3 compliant, making it suitable for applications with RoHS requirements.