3SBP 2.5 Equivalent & Substitute Parts

Part Overview

The 3SBP 2.5 is a 2.5 A 250 V AC/DC glass cartridge fuse with 3AB/3AG form factor manufactured by Bel Fuse Inc. This component is classified as obsolete, making substitute parts necessary for ongoing system maintenance and new design implementations. The fuse features slow-blow response characteristics and is rated for through-hole mounting in standard 1/4" x 1-1/4" (6.90mm x 32.50mm) axial configurations.

Key Parameters

Parameter	Value
Current Rating	2.5 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Response Time	Slow Blow
Mounting Type	Through Hole
Operating Temperature Range	-55°C ~ 125°C
Breaking Capacity @ Rated Voltage	100 A
Melting I²t	94

Substitute Part Grouping Explanation

Substitution for the 3SBP 2.5 is determined by strict equivalence across the following critical parameters:

Current Rating: 2.5 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Response Time: Slow Blow (exact match required)
Mounting Type: Through Hole (exact match required)
Operating Temperature Range: -55°C ~ 125°C (exact match required)

All substitute parts listed below meet these criteria. Variations in secondary parameters such as Breaking Capacity, Melting I²t, DC Cold Resistance, and approval certifications do not disqualify substitution when primary electrical and mechanical parameters are identical.

Parameter Comparison

Part Number	Manufacturer	Current Rating (A)	Voltage Rating (V AC)	Response Time	Package / Case	Breaking Capacity @ Rated Voltage (A)	Melting I²t	DC Cold Resistance (Ohms)	Product Status	RoHS Status
3SBP 2.5	Bel Fuse Inc.	2.5	250	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	100	94	0.11	Obsolete	RoHS non-compliant
3SBP 2.5-R	Bel Fuse Inc.	2.5	250	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200	94	0.08	Obsolete	ROHS3 Compliant
031502.5HXP	Littelfuse Inc.	2.5	250	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	100	130	0.0811	Active	ROHS3 Compliant
031502.5MRT1BP	Littelfuse Inc.	2.5	250	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	100	130	0.0811	Active	ROHS3 Compliant
031502.5MXP	Littelfuse Inc.	2.5	250	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	100	130	0.0811	Active	ROHS3 Compliant
031502.5MXSLP	Littelfuse Inc.	2.5	250	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	100	130	0.0811	Active	ROHS3 Compliant
031502.5VXP	Littelfuse Inc.	2.5	250	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	100	130	0.0811	Active	ROHS3 Compliant

Engineering Selection Recommendations

All listed substitute parts are electrically and mechanically equivalent to the 3SBP 2.5 based on the critical parameters that define fuse interchangeability.

For new designs and ongoing maintenance where component availability is a priority, Littelfuse 315 series parts (031502.5HXP, 031502.5MRT1BP, 031502.5MXP, 031502.5MXSLP, 031502.5VXP) are preferred due to active product status and ROHS3 compliance. These parts maintain identical electrical ratings and mechanical form factors while offering improved regulatory compliance.

The 3SBP 2.5-R variant from Bel Fuse Inc. provides an intermediate option with enhanced Breaking Capacity (200 A versus 100 A) and ROHS3 compliance, though it remains classified as obsolete.

Packaging considerations: 031502.5MRT1BP is supplied in Tape & Reel format; all other substitute parts are supplied in Bulk packaging. Select packaging based on assembly process requirements.

Frequently Asked Questions (FAQ)

Q: Can I substitute a Littelfuse 315 series fuse for the 3SBP 2.5?

A: Yes. The Littelfuse 031502.5HXP, 031502.5MRT1BP, 031502.5MXP, 031502.5MXSLP, and 031502.5VXP parts are direct substitutes. All maintain the same current rating (2.5 A), voltage rating (250 V AC), response time (Slow Blow), and mechanical form factor (3AB/3AG, 1/4" x 1-1/4" axial).

Q: What is the difference between the 3SBP 2.5 and 3SBP 2.5-R?

A: Both are 2.5 A 250 V AC/DC slow-blow fuses with identical electrical ratings and mechanical dimensions. The 3SBP 2.5-R has a higher Breaking Capacity (200 A versus 100 A) and is ROHS3 compliant, whereas the original 3SBP 2.5 is RoHS non-compliant. Both are classified as obsolete.

Q: Why do the Littelfuse parts have higher Melting I²t values (130 versus 94)?

A: Melting I²t is a thermal characteristic that affects fuse response behavior. The higher value in Littelfuse parts indicates a different thermal design while maintaining the same slow-blow response classification and current rating. This difference does not prevent substitution when all primary electrical and mechanical parameters match.

Q: Does packaging format affect electrical performance?

A: No. Packaging format (Bulk versus Tape & Reel) affects handling and assembly processes only. The 031502.5MRT1BP supplied in Tape & Reel format is electrically and mechanically identical to bulk-packaged alternatives.

Q: Are all substitute parts RoHS compliant?

A: The Littelfuse 315 series parts (031502.5HXP, 031502.5MRT1BP, 031502.5MXP, 031502.5MXSLP, 031502.5VXP) and the 3SBP 2.5-R are ROHS3 compliant. The original 3SBP 2.5 is RoHS non-compliant. For applications requiring RoHS compliance, select from the compliant alternatives.

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