SCHURTER 0034.4277 Board Mount Fuse – Equivalent & Substitute Parts

Part Overview

The SCHURTER 0034.4277 is a 630 mA, 125 V AC/DC board mount fuse in radial, can package format, designed for through-hole mounting applications. This part operates within the MSF 125 series and features fast-blow response characteristics with a breaking capacity of 300 A at rated voltage. The component is currently classified as obsolete, necessitating identification of active equivalent and substitute parts for ongoing design requirements and procurement needs.

Substiute Parts

0034.4277

SCHURTER Inc.In Stock: 7490034.4277 Datasheet

Current PartRFQ

0034.4217

SCHURTER Inc.In Stock: 10980034.4217 Datasheet

DirectRFQ

0034.4247

SCHURTER Inc.In Stock: 8970034.4247 Datasheet

Parametric EquivalentRFQ

30306300421

LittelfuseIn Stock: 90430306300421 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the SCHURTER 0034.4277 is determined by strict alignment of the following electrical and mechanical parameters:

Critical Parameters for Direct Substitution:

• Current Rating: 630 mA (exact match required)
• Voltage Rating – AC: 125 V (exact match required)
• Voltage Rating – DC: 125 V (exact match required)
• Fuse Type: Board Mount (Cartridge Style Excluded)
• Mounting Type: Through Hole
• Package / Case: Radial, Can
• Response Time: Fast Blow

Substitute Categories:

Direct Manufacturer Equivalents (SCHURTER): Parts 0034.4217 and 0034.4247 meet all critical electrical parameters and mechanical specifications. Both are active products within the MSF 125 series, offering identical current, voltage, and response characteristics. These parts differ only in breaking capacity (100 A versus 300 A for the main part) and product status (active versus obsolete).

Parametric Equivalent (Cross-Manufacturer): Part 30306300421 (Littelfuse TR3® 303 series) matches the current rating (630 mA) and AC voltage rating (125 V). However, this part exhibits a reduced DC voltage rating (63 V versus 125 V), lower breaking capacity (50 A), reduced melting I²t (0.015 versus 0.045), and different physical dimensions (0.236" Dia x 0.315" H versus 0.252" Dia x 0.346" H). This part is suitable only for applications where DC voltage does not exceed 63 V.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Preferred): Parts 0034.4217 and 0034.4247 are recommended as primary substitutes. Both are active SCHURTER products within the MSF 125 series with identical electrical specifications and mechanical compatibility. These parts maintain full compliance with cURus approval and ROHS3 requirements. The reduced breaking capacity (100 A versus 300 A) does not affect circuit protection function in standard applications where the original 300 A specification was not a critical design constraint.

For Cross-Manufacturer Substitution (Conditional): Part 30306300421 (Littelfuse) is suitable only for applications where the DC voltage requirement does not exceed 63 V. This part carries CSA and UL approvals and maintains ROHS3 compliance. The reduced melting I²t (0.015 versus 0.045) and lower breaking capacity (50 A) must be evaluated against specific circuit protection requirements. Physical dimension differences (0.236" Dia x 0.315" H) require PCB layout verification for through-hole mounting compatibility.

Compliance Considerations: All substitute parts maintain ROHS3 compliance and REACH unaffected status. Approval agencies differ between SCHURTER (cURus) and Littelfuse (CSA, UL) options; design certification requirements should determine the appropriate selection.

Frequently Asked Questions (FAQ)

Q: Can 0034.4217 or 0034.4247 be used as direct replacements for 0034.4277?

A: Yes. Both parts are direct electrical and mechanical equivalents within the MSF 125 series. They match the 630 mA current rating, 125 V AC/DC voltage ratings, fast-blow response, and through-hole radial can package. Both are active products, addressing the obsolescence of the original part.

Q: What is the significance of the breaking capacity difference between the main part (300 A) and the SCHURTER equivalents (100 A)?

A: Breaking capacity defines the maximum fault current the fuse can safely interrupt. The reduction from 300 A to 100 A does not affect normal circuit operation. Selection depends on the maximum prospective short-circuit current in the application. If the circuit design requires 300 A breaking capacity, the original specification must be maintained.

Q: Can the Littelfuse 30306300421 be used in all applications requiring the 0034.4277?

A: No. The Littelfuse part has a reduced DC voltage rating (63 V versus 125 V). It is suitable only for applications where DC voltage does not exceed 63 V. Additionally, the reduced melting I²t (0.015 versus 0.045) and breaking capacity (50 A) must be verified against circuit protection requirements. Physical dimensions also differ, requiring PCB layout confirmation.

Q: Are there packaging differences between these substitute parts?

A: The SCHURTER equivalents (0034.4217 and 0034.4247) are supplied in bulk packaging and are mechanically identical to the main part. The Littelfuse 30306300421 features a vertical orientation option within the radial can package and has slightly smaller physical dimensions (0.236" Dia x 0.315" H versus 0.252" Dia x 0.346" H), which may affect PCB footprint compatibility.

Q: What compliance certifications apply to each substitute part?

A: SCHURTER parts 0034.4217 and 0034.4247 carry cURus approval. Littelfuse part 30306300421 carries CSA and UL approvals. All parts are ROHS3 compliant and REACH unaffected. Design certification requirements should guide the selection between cURus and CSA/UL approved options.

Q: What is the operating temperature range for each substitute?

A: SCHURTER parts 0034.4217 and 0034.4247 operate from -25°C to 85°C, matching the original part. Littelfuse part 30306300421 operates from -25°C to 70°C, a 15°C reduction in maximum operating temperature. Applications requiring operation above 70°C must use SCHURTER equivalents.