Equivalent & Substitute Parts for 3AP 3-R Glass Cartridge Fuse

Part Overview

The 3AP 3-R is a 3 A, 250 V AC/DC glass cartridge fuse manufactured by Bel Fuse Inc., designed for through-hole mounting in 3AB and 3AG package formats. This component is classified as obsolete, making identification of functionally equivalent substitutes necessary for ongoing system maintenance and repair applications. The fuse provides fast-blow response characteristics suitable for circuit protection in industrial and commercial equipment.

Key Parameters

Parameter	Value
Current Rating	3 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Response Time	Fast Blow
Mounting Type	Through Hole
Operating Temperature Range	-55°C ~ 125°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 3AP 3-R is determined by strict equivalence across the following parameters:

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

All three substitute parts—0318003.HXP, 0318003.MXP, and 0318003.VXP—manufactured by Littelfuse Inc., meet these criteria. These components are classified as active products, ensuring continued availability and supply chain reliability compared to the obsolete 3AP 3-R.

Parameter Comparison

Parameter	3AP 3-R (Bel Fuse)	0318003.HXP (Littelfuse)	0318003.MXP (Littelfuse)	0318003.VXP (Littelfuse)
Current Rating (Amps)	3 A	3 A	3 A	3 A
Voltage Rating - AC	250 V	250 V	250 V	250 V
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
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"
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow
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	21	14	14	14
DC Cold Resistance	0.035 Ohms	0.0427 Ohms	0.0427 Ohms	0.0427 Ohms
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active

Engineering Selection Recommendations

The three Littelfuse substitute parts (0318003.HXP, 0318003.MXP, 0318003.VXP) are functionally equivalent to the 3AP 3-R across all critical electrical and mechanical parameters. All substitute parts maintain active product status, ensuring long-term availability and supply chain continuity. Both the original and substitute components carry ROHS3 compliance and equivalent approval certifications (CE, CSA, PSE). The Littelfuse variants include additional certifications (KC, UL) beyond those of the original part.

Minor variations exist in breaking capacity (100 A versus 200 A) and melting I²t (14 versus 21), as well as DC cold resistance (0.0427 Ohms versus 0.035 Ohms). These differences do not affect functional substitution for standard circuit protection applications within the specified electrical ratings.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 0318003 series parts directly replace the 3AP 3-R?

A: Yes. The 0318003.HXP, 0318003.MXP, and 0318003.VXP are direct functional equivalents. All match the required current rating (3 A), voltage rating (250 V AC), package format (3AB, 3AG, 1/4" x 1-1/4"), response time (fast blow), and operating temperature range (-55°C ~ 125°C).

Q: What is the difference between the three Littelfuse substitute part numbers?

A: The 0318003.HXP, 0318003.MXP, and 0318003.VXP variants are electrically and mechanically identical. Differences in part number designation reflect internal Littelfuse product line categorization and do not affect performance or compatibility.

Q: Are there any compliance or certification differences?

A: The substitute parts carry additional certifications (KC, UL) compared to the original 3AP 3-R. Both the original and substitute components maintain ROHS3 compliance and equivalent environmental standards.

Q: Does the lower breaking capacity of the substitute parts affect compatibility?

A: The substitute parts specify 100 A breaking capacity versus 200 A for the original. For applications operating within the 3 A rated current, this difference does not impact circuit protection performance. System design parameters should be reviewed if breaking capacity is a critical specification.

Q: What packaging options are available for the substitute parts?

A: The Littelfuse substitute parts are supplied in bulk packaging, compared to the original part's unspecified packaging format. Confirm packaging requirements for your procurement process.

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