Littelfuse 031501.2H Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 031501.2H is a 1.2 A, 250 V AC/DC slow-blow glass cartridge fuse in the 3AB/3AG form factor (1/4" x 1-1/4" axial). This fuse is classified as obsolete, making equivalent substitute parts necessary for ongoing circuit protection applications. Active alternatives with identical electrical and mechanical specifications are available from the same manufacturer series.

Key Parameters

Parameter	Value
Current Rating	1.2 A
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Fuse Type	Cartridge, Glass
Breaking Capacity @ Rated Voltage	100 A
Melting I²t	21.5
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.275" Dia x 1.275" L (6.99mm x 32.39mm)
Mounting Type	Through Hole

Substitute Part Grouping Explanation

Substitution of the 031501.2H is based on strict equivalence of the following critical parameters:

Current Rating: 1.2 A (exact match required)
Voltage Rating: 250 V AC (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Breaking Capacity: 100 A (exact match required)
Melting I²t: 21.5 (exact match required)
Operating Temperature Range: -55°C ~ 125°C (exact match required)

All substitute parts listed below meet these criteria. The primary distinction between the main part and substitutes is product status (obsolete vs. active) and regulatory compliance certifications.

Parameter Comparison

Parameter	031501.2H (Main)	031501.2HXP	031501.2MXP	031501.2VXP
Current Rating (Amps)	1.2 A	1.2 A	1.2 A	1.2 A
Voltage Rating - AC	250 V	250 V	250 V	250 V
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Breaking Capacity @ Rated Voltage	100 A	100 A	100 A	100 A
Melting I²t	21.5	21.5	21.5	21.5
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Size / Dimension	0.275" Dia x 1.275" L (6.99mm x 32.39mm)	0.275" Dia x 1.275" L (6.99mm x 32.39mm)	0.275" Dia x 1.275" L (6.99mm x 32.39mm)	0.275" Dia x 1.275" L (6.99mm x 32.39mm)
DC Cold Resistance	0.276 Ohms	0.278 Ohms	0.278 Ohms	0.278 Ohms
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, METI, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL

Engineering Selection Recommendations

All three substitute parts (031501.2HXP, 031501.2MXP, 031501.2VXP) are direct electrical and mechanical equivalents to the 031501.2H. Selection among these active alternatives should be based on the following factors:

Product Status: The 031501.2H is obsolete. All substitute parts are active products with ongoing manufacturer support and availability.

Regulatory Compliance: The 031501.2H carries CSA, METI, and UL certifications. All substitute parts carry CE, CSA, PSE, and UL certifications, providing broader international compliance coverage including European (CE) and Japanese (PSE) markets.

RoHS Compliance: The 031501.2H is RoHS non-compliant. All substitute parts are ROHS3 compliant, meeting current environmental and hazardous substance restrictions.

DC Cold Resistance: The main part specifies 0.276 Ohms, while all substitutes specify 0.278 Ohms. This minor variance (0.002 Ohms) is within acceptable tolerance for fuse applications and does not affect circuit protection performance.

Packaging: All parts are supplied in bulk packaging. Inventory availability is comparable across all three substitutes.

Frequently Asked Questions (FAQ)

Q: Can the 031501.2HXP, 031501.2MXP, or 031501.2VXP be used as direct replacements for the 031501.2H?

A: Yes. All three parts are electrically and mechanically equivalent. They share identical current ratings (1.2 A), voltage ratings (250 V AC), response time (slow blow), package dimensions (3AB/3AG, 1/4" x 1-1/4"), breaking capacity (100 A), and melting I²t (21.5). They are suitable for direct substitution in through-hole applications.

Q: What is the difference between the three substitute parts?

A: The 031501.2HXP, 031501.2MXP, and 031501.2VXP are parametrically identical. The part number suffix indicates internal manufacturing or packaging variations. All three are active products with equivalent electrical performance and compliance certifications.

Q: Why is the 031501.2H classified as obsolete?

A: Product obsolescence is determined by the manufacturer based on production discontinuation. Active alternatives with identical specifications are available to ensure continuity of supply for circuit protection applications.

Q: Does the difference in DC cold resistance (0.276 Ohms vs. 0.278 Ohms) affect circuit performance?

A: No. The 0.002 Ohm variance is negligible for fuse applications. Fuse performance is determined by current rating, voltage rating, and response time characteristics, all of which are identical across the main part and substitutes.

Q: Are the substitute parts RoHS compliant?

A: Yes. All three substitute parts (031501.2HXP, 031501.2MXP, 031501.2VXP) are ROHS3 compliant. The original 031501.2H is RoHS non-compliant. If RoHS compliance is required for your application, use one of the active substitutes.

Q: What certifications do the substitute parts carry?

A: All substitute parts carry CE, CSA, PSE, and UL certifications. The original part carries CSA, METI, and UL certifications. The substitutes provide broader international compliance, including European (CE) and Japanese (PSE) market approval.

Q: Can these fuses be used in both AC and DC circuits?

A: Yes. All parts are rated for 250 V AC/DC operation. The 1.2 A current rating applies to both AC and DC applications within the specified voltage range.

Q: What is the operating temperature range for these fuses?

A: All parts operate within -55°C to 125°C. This range applies to the main part and all substitutes.

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