SCHURTER 0034.4287 Equivalent & Substitute Parts

Part Overview

The SCHURTER 0034.4287 is a 4 A, 125 V AC/DC board mount radial fuse with fast blow response time, designed for through-hole PCB applications. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The MSF 125 series fuse provides protection in low-voltage AC/DC circuits with a breaking capacity of 300 A at rated voltage and operates across a temperature range of -25°C to 85°C.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Fast Blow
Mounting Type	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)
Package / Case	Radial, Can
Size / Dimension	0.252" Dia x 0.346" H (6.40mm x 8.80mm)
Operating Temperature	-25°C ~ 85°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the SCHURTER 0034.4287 is determined by strict equivalence across the following critical parameters: current rating (4 A), AC voltage rating (125 V), DC voltage rating (125 V), response time (fast blow), mounting type (through hole), fuse type (board mount, cartridge style excluded), and physical package dimensions (radial, can configuration). Substitute parts are grouped into three categories based on manufacturer and product status:

Parametric Equivalents (SCHURTER MSF 125 Series): Parts 0034.4227 and 0034.4257 maintain identical electrical specifications and physical dimensions as the main part. Both are active products with bulk packaging, offering direct functional replacement with improved availability compared to the obsolete 0034.4287.

Direct Manufacturer Equivalent (Littelfuse MICRO™ 273 Series): Part 0273004.H represents a direct cross-reference from an alternative manufacturer. This part meets all core electrical and mechanical requirements with enhanced breaking capacity (10 kA) and extended temperature range (-55°C to 85°C).

Similar Manufacturer Alternative (Littelfuse MICRO™ 273 and TR3® 303 Series): Parts 0273004.V and 30314000421 provide functional alternatives with minor parameter variations. Part 0273004.V is electrically identical to 0273004.H with vertical orientation capability. Part 30314000421 operates at reduced DC voltage (63 V versus 125 V) and lower breaking capacity (50 A), suitable only for applications not requiring full 125 V DC rating.

Parameter Comparison

Parameter	0034.4287 (Main)	0034.4227	0034.4257	0273004.H	0273004.V	30314000421
Manufacturer	SCHURTER Inc.	SCHURTER Inc.	SCHURTER Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse
Current Rating (A)	4	4	4	4	4	4
Voltage Rating AC (V)	125	125	125	125	125	125
Voltage Rating DC (V)	125	125	125	125	125	63
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Can	Radial, Can	Radial, Can	Radial, Can, Vertical	Radial, Can, Vertical	Radial, Can, Vertical
Size / Dimension	0.252" Dia x 0.346" H (6.40mm x 8.80mm)	0.252" Dia x 0.346" H (6.40mm x 8.80mm)	0.252" Dia x 0.346" H (6.40mm x 8.80mm)	0.250" Dia x 0.350" H (6.35mm x 8.89mm)	0.250" Dia x 0.350" H (6.35mm x 8.89mm)	0.236" Dia x 0.315" H (6.00mm x 8.00mm)
Breaking Capacity @ Rated Voltage	300 A	100 A	100 A	10 kA	10 kA	50 A
Operating Temperature	-25°C ~ 85°C	-25°C ~ 85°C	-25°C ~ 85°C	-55°C ~ 85°C	-55°C ~ 85°C	-25°C ~ 70°C
Product Status	Obsolete	Active	Active	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	cURus	cURus	cURus	CSA, QPL, UL	CSA, QPL, UL	CSA, UL

Engineering Selection Recommendations

For Direct Replacement (Preferred): Select SCHURTER 0034.4227 or 0034.4257. Both parts maintain identical electrical ratings, physical dimensions, and operating temperature range as the obsolete 0034.4287. These parts are active products with established supply chains and cURus certification matching the original specification. Packaging differences (bulk versus tape) do not affect functional compatibility.

For Enhanced Performance: Select Littelfuse 0273004.H or 0273004.V. These parts provide superior breaking capacity (10 kA versus 300 A) and extended low-temperature operation (-55°C versus -25°C). Physical dimensions are within 0.002" tolerance, ensuring PCB footprint compatibility. CSA, QPL, and UL certifications provide broader regulatory acceptance. Vertical orientation capability (0273004.V) offers design flexibility for space-constrained layouts.

For Reduced Voltage Applications Only: Part 30314000421 is suitable only for circuits operating at 63 V DC maximum. This part is not recommended as a general replacement due to reduced DC voltage rating and lower breaking capacity (50 A). Use only when application requirements confirm 63 V DC operation and 50 A breaking capacity sufficiency.

Frequently Asked Questions (FAQ)

Q: Can I use SCHURTER 0034.4227 or 0034.4257 as a direct replacement for the obsolete 0034.4287?

A: Yes. Both parts are parametric equivalents with identical current rating (4 A), voltage ratings (125 V AC/DC), response time (fast blow), mounting type (through hole), and physical dimensions (0.252" Dia x 0.346" H). The only difference is packaging format (bulk). Electrical performance and PCB compatibility are identical.

Q: What are the advantages of using Littelfuse 0273004.H over SCHURTER alternatives?

A: Littelfuse 0273004.H offers three advantages: (1) significantly higher breaking capacity (10 kA versus 100-300 A), providing enhanced protection margin in high-fault-current environments; (2) extended operating temperature range (-55°C to 85°C versus -25°C to 85°C), enabling use in cold-environment applications; (3) broader regulatory certifications (CSA, QPL, UL) supporting diverse market requirements. Physical dimensions are within tolerance for standard PCB footprints.

Q: Are 0273004.H and 0273004.V interchangeable?

A: Yes, electrically and mechanically. Both parts are identical in current rating, voltage ratings, response time, breaking capacity, and physical dimensions. The designation difference (.H versus .V) indicates orientation capability (horizontal versus vertical mounting). Select based on PCB layout requirements.

Q: Why should I avoid using Littelfuse 30314000421 as a general replacement?

A: Part 30314000421 has a reduced DC voltage rating (63 V versus 125 V) and lower breaking capacity (50 A versus 100-300 A). Use this part only in applications confirmed to operate at 63 V DC maximum. For circuits requiring full 125 V DC operation, this part will not provide adequate protection and is not suitable.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts (0034.4227, 0034.4257, 0273004.H, 0273004.V, and 30314000421) are ROHS3 compliant, matching the environmental compliance status of the original 0034.4287.

Q: What is the impact of physical dimension variations between substitute parts?

A: Littelfuse parts (0273004.H, 0273004.V, 30314000421) have minor dimensional variations. The 0273004 series measures 0.250" Dia x 0.350" H (6.35mm x 8.89mm), and the 303 series measures 0.236" Dia x 0.315" H (6.00mm x 8.00mm). These variations are within standard PCB footprint tolerances for radial through-hole components. Verify PCB hole spacing and clearance before final selection.

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