Littelfuse 031801.6H Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 031801.6H is a 1.6 A, 250 V AC/DC fast-blow glass cartridge fuse in the 3AB/3AG package format (1/4" x 1-1/4" axial). This component is classified as obsolete, making equivalent substitute parts necessary for ongoing system maintenance and new design implementations. The part belongs to the Littelfuse 318 series and features a breaking capacity of 35 A at rated voltage with a melting I²t of 2.8.

Key Parameters

Parameter	Value
Current Rating	1.6 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
Size / Dimension	0.275" Dia x 1.288" L (6.99mm x 32.72mm)
Mounting Type	Through Hole
Melting I²t	2.8
DC Cold Resistance	0.093 Ohms

Substitute Part Grouping Explanation

Substitute parts for the 031801.6H are qualified based on the following critical parameters that must remain constant:

Current Rating: 1.6 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)
Melting I²t: 2.8 (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Mounting Type: Through Hole (exact match required)

All three substitute parts—031801.6HXP, 031801.6MXP, and 031801.6VXP—meet these critical parameters. The primary differences between the main part and substitutes relate to product status, regulatory compliance, and operational temperature range, which do not affect electrical or mechanical interchangeability.

Parameter Comparison

Parameter	031801.6H (Main)	031801.6HXP	031801.6MXP	031801.6VXP
Current Rating (Amps)	1.6 A	1.6 A	1.6 A	1.6 A
Voltage Rating - AC	250 V	250 V	250 V	250 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast 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
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Size / Dimension	0.275" Dia x 1.288" L (6.99mm x 32.72mm)	0.275" Dia x 1.288" L (6.99mm x 32.72mm)	0.275" Dia x 1.288" L (6.99mm x 32.72mm)	0.275" Dia x 1.288" L (6.99mm x 32.72mm)
Melting I²t	2.8	2.8	2.8	2.8
DC Cold Resistance	0.093 Ohms	0.0934 Ohms	0.0934 Ohms	0.0934 Ohms
Breaking Capacity @ Rated Voltage	35 A	100 A	100 A	100 A
Product Status	Obsolete	Active	Active	Active
Operating Temperature	Not specified	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, UL	CE, CSA, KC, PSE, UL	CE, CSA, KC, PSE, UL	CE, CSA, KC, PSE, UL

Engineering Selection Recommendations

All three substitute parts—031801.6HXP, 031801.6MXP, and 031801.6VXP—are electrically and mechanically interchangeable with the 031801.6H for applications requiring a 1.6 A, 250 V AC/DC fast-blow glass cartridge fuse in the 3AB/3AG package.

The substitute parts offer the following advantages over the obsolete 031801.6H:

Active product status ensures long-term availability and supply chain continuity
ROHS3 compliance meets current environmental and regulatory requirements
Extended regulatory certifications (CE, KC, PSE in addition to CSA and UL) support broader market applications
Defined operating temperature range (-55°C ~ 125°C) provides explicit thermal performance specifications
Increased breaking capacity (100 A versus 35 A) offers enhanced protection margins

Selection among the three substitute parts should be based on packaging requirements and inventory availability. All three parts are supplied in bulk packaging and maintain identical electrical and mechanical specifications.

Frequently Asked Questions (FAQ)

Q: Can 031801.6HXP, 031801.6MXP, and 031801.6VXP be used interchangeably with 031801.6H?

A: Yes. All three substitute parts maintain identical current rating (1.6 A), voltage rating (250 V AC), response time (Fast Blow), package format (3AB/3AG, 1/4" x 1-1/4" axial), and melting I²t (2.8). Physical dimensions and mounting type are identical, ensuring direct mechanical and electrical compatibility.

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

A: The three substitute parts—031801.6HXP, 031801.6MXP, and 031801.6VXP—are parametrically equivalent. Differences are limited to internal manufacturing specifications and packaging designations. All three are active products with identical electrical performance and regulatory compliance.

Q: Why does the 031801.6H have a lower breaking capacity (35 A) compared to the substitutes (100 A)?

A: Breaking capacity is a manufacturing specification that does not affect interchangeability for standard circuit protection applications. The substitute parts incorporate improved design specifications that provide higher breaking capacity while maintaining all critical electrical parameters required for direct substitution.

Q: Are the substitute parts RoHS compliant?

A: Yes. All three substitute parts (031801.6HXP, 031801.6MXP, 031801.6VXP) are ROHS3 compliant. The original 031801.6H is RoHS non-compliant, making the substitutes necessary for applications subject to RoHS requirements.

Q: What regulatory certifications do the substitute parts carry?

A: The substitute parts carry CE, CSA, KC, PSE, and UL certifications. The original 031801.6H carries only CSA and UL certifications. The expanded certification set of the substitutes supports compliance with international regulatory standards.

Q: Can I use these fuses in high-temperature applications?

A: The substitute parts are rated for operation from -55°C to 125°C. The original 031801.6H does not specify an operating temperature range. Confirm that your application requirements fall within the -55°C to 125°C range before selection.

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