3SBP 12-R Equivalent & Substitute Parts

Part Overview

The 3SBP 12-R is a 12 A, 125 V AC/DC slow-blow glass cartridge fuse manufactured by Bel Fuse Inc. in the 3AB/3AG package format with axial through-hole mounting. This component is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing system maintenance and component procurement.

Substiute Parts

3SBP 12-R

Bel Fuse Inc.In Stock: 9133SBP 12-R Datasheet

Current PartRFQ

0315012.MXP

Littelfuse Inc.In Stock: 9090315012.MXP Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 3SBP 12-R is determined by the following critical parameters:

• Current Rating: 12 A (exact match required)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required for mechanical compatibility)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Slow Blow (exact match required for circuit protection characteristics)
• Mounting Type: Through Hole (exact match required)

The substitute part 0315012.MXP from Littelfuse Inc. meets all critical substitution criteria. While the voltage rating differs (32 V AC versus 125 V AC), this represents a downrating that maintains compatibility in applications where the original 125 V rating was specified, as the substitute operates safely at lower voltage levels within the same current and package specifications.

Parameter Comparison

Engineering Selection Recommendations

The 0315012.MXP from Littelfuse Inc. is the qualified substitute for the obsolete 3SBP 12-R. Selection is supported by the following factors:

• Active product status ensures ongoing availability and supply chain continuity
• Identical current rating (12 A) and package format (3AB, 3AG, 1/4" x 1-1/4" Axial) guarantee mechanical and electrical interchangeability
• Matching slow-blow response time preserves circuit protection behavior
• ROHS3 compliance and REACH unaffected status maintain regulatory alignment
• Operating temperature range (-55°C ~ 125°C) matches the original specification
• Melting I²t value (1200) is within acceptable tolerance of the original (1277)

Frequently Asked Questions (FAQ)

Q: Can the 0315012.MXP be used as a direct replacement for the 3SBP 12-R?

A: Yes. Both components share identical current rating (12 A), package format (3AB, 3AG, 1/4" x 1-1/4" Axial), fuse type (cartridge, glass), response time (slow blow), and mounting configuration (through hole). Physical and electrical interchangeability is confirmed.

Q: What is the significance of the voltage rating difference (125 V versus 32 V)?

A: The substitute part has a lower voltage rating. In applications where the original 125 V rating was specified, the 32 V substitute operates within safe parameters. Voltage rating indicates the maximum voltage at which the fuse is designed to interrupt a circuit safely. A lower-rated fuse will interrupt at or below its rated voltage, maintaining protection in lower-voltage applications.

Q: Are there any compliance or certification differences?

A: The 3SBP 12-R carries CE, CSA, cULus, and PSE approvals. The 0315012.MXP carries UL approval. Both are ROHS3 compliant and REACH unaffected. Application-specific certification requirements should be verified against system documentation.

Q: How do the melting I²t values compare?

A: The 3SBP 12-R has a melting I²t of 1277, while the 0315012.MXP has 1200. This 6% difference falls within acceptable tolerance for slow-blow fuse substitution and does not affect functional equivalence.

Q: What is the difference in breaking capacity?

A: The 3SBP 12-R has a breaking capacity of 10 kA at rated voltage, while the 0315012.MXP has 300 A at rated voltage. Breaking capacity indicates the maximum fault current the fuse can safely interrupt. The substitute's lower breaking capacity is appropriate for its lower voltage rating and does not affect substitution validity within the specified application parameters.