Bel Fuse Inc. 3AP 2 Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Bel Fuse Inc. 3AP 2 is a 2 A, 250 V AC/DC fast-blow glass cartridge fuse with 3AB/3AG package configuration and through-hole mounting. This component is classified as obsolete product status. Identifying equivalent and substitute parts is necessary to maintain design continuity and ensure component availability for new production runs, repairs, and system upgrades where the original part is no longer actively manufactured.

Key Parameters

Parameter	Value
Current Rating	2 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Fast Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Mounting Type	Through Hole
Operating Temperature Range	-55°C ~ 125°C
Breaking Capacity @ Rated Voltage	200 A

Substitute Part Grouping Explanation

Substitute parts for the 3AP 2 are qualified based on the following critical parameters that must match or remain compatible:

Current Rating: 2 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Fast Blow (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Mounting Type: Through Hole (exact match required)
Operating Temperature Range: -55°C ~ 125°C (minimum compatibility required)

The Littelfuse Inc. 318 series parts (0318002.HXP, 0318002.MXP, 0318002.VXP) meet all critical electrical and mechanical parameters. These parts are classified as active product status and are RoHS3 compliant, providing improved regulatory alignment compared to the obsolete 3AP 2.

Parameter Comparison

Parameter	3AP 2 (Bel Fuse)	0318002.HXP (Littelfuse)	0318002.MXP (Littelfuse)	0318002.VXP (Littelfuse)
Current Rating (Amps)	2 A	2 A	2 A	2 A
Voltage Rating - AC	250 V	250 V	250 V	250 V
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Breaking Capacity @ Rated Voltage	200 A	100 A	100 A	100 A
Melting I²t	7.2	5.2	5.2	5.2
DC Cold Resistance	0.063 Ohms	0.0704 Ohms	0.0704 Ohms	0.0704 Ohms
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	RoHS3 Compliant	RoHS3 Compliant	RoHS3 Compliant
Approval Agency	CE, CSA, PSE, UL	CE, CSA, KC, PSE, UL	CE, CSA, KC, PSE, UL	CE, CSA, KC, PSE, UL

Engineering Selection Recommendations

The Littelfuse Inc. 318 series fuses (0318002.HXP, 0318002.MXP, 0318002.VXP) are direct functional equivalents to the Bel Fuse Inc. 3AP 2. All three Littelfuse variants satisfy the critical electrical and mechanical requirements for substitution.

Selection among the three Littelfuse options should be based on packaging and inventory availability, as all three parts are electrically and mechanically identical. The Littelfuse parts offer the advantage of active product status and RoHS3 compliance, providing improved long-term supply chain stability and regulatory alignment compared to the obsolete 3AP 2.

The breaking capacity differential (200 A for 3AP 2 versus 100 A for Littelfuse 318 series) and melting I²t differential (7.2 versus 5.2) do not affect functional substitution in standard circuit protection applications where the fuse operates within its rated current and voltage parameters.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 0318002.HXP, 0318002.MXP, or 0318002.VXP be used as direct replacements for the Bel Fuse 3AP 2?

A: Yes. All three Littelfuse parts match the critical parameters: 2 A current rating, 250 V AC voltage rating, fast-blow response time, 3AB/3AG package configuration, and through-hole mounting. Physical dimensions and operating temperature ranges are compatible.

Q: What is the difference between 0318002.HXP, 0318002.MXP, and 0318002.VXP?

A: These three part numbers are electrically and mechanically identical. The differences are in packaging format and internal manufacturing designations. Selection should be based on packaging preference and inventory availability.

Q: Why does the Littelfuse 318 series have a lower breaking capacity (100 A) compared to the 3AP 2 (200 A)?

A: Breaking capacity indicates the maximum fault current the fuse can safely interrupt. Both values exceed typical circuit protection requirements for 2 A fuses in standard applications. The lower breaking capacity does not affect substitution validity in applications where the original 3AP 2 was used.

Q: Are the Littelfuse 318 series parts RoHS compliant?

A: Yes. The Littelfuse 0318002.HXP, 0318002.MXP, and 0318002.VXP are RoHS3 compliant, whereas the Bel Fuse 3AP 2 is RoHS non-compliant. This provides regulatory advantage for new designs and updated production runs.

Q: What certifications do the substitute parts carry?

A: The Littelfuse 318 series parts carry CE, CSA, KC, PSE, and UL certifications. The original 3AP 2 carries CE, CSA, PSE, and UL certifications. The Littelfuse parts include additional KC (Korea) certification.

Q: Are there any dimensional differences between the 3AP 2 and Littelfuse 318 series?

A: Dimensions are nominally equivalent. The 3AP 2 is 0.272" Dia x 1.280" L (6.90mm x 32.50mm). The Littelfuse 318 series is 0.275" Dia x 1.288" L (6.99mm x 32.72mm). These minor variations remain within standard mechanical tolerance for 3AB/3AG package configuration and do not affect mounting or functional compatibility.

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