Equivalent & Substitute Parts for 5SF 6.3 Glass Cartridge Fuse

Part Overview

The Bel Fuse Inc. 5SF 6.3 is a 6.3 A, 250 V AC/DC fast-blow glass cartridge fuse in 5mm x 20mm form factor. This part is classified as obsolete, making equivalent substitutes necessary for ongoing system maintenance and new designs. The fuse requires a compatible holder for installation and is designed for general-purpose circuit protection applications across industrial and commercial equipment.

Key Parameters

Parameter	Value
Current Rating	6.3 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Fast Blow
Package / Case	5mm x 20mm
Breaking Capacity @ Rated Voltage	63 A
Mounting Type	Requires Holder
Operating Temperature Range	-55°C to 125°C

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence across the following parameters:

Current Rating: 6.3 A (exact match required)
Voltage Rating: 250 V AC (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Fast Blow (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Breaking Capacity: 63 A (exact match required)
Mounting Type: Requires Holder (exact match required)

All substitute parts listed meet these criteria and are therefore electrically and mechanically interchangeable with the 5SF 6.3. Differences in melting I²t values, DC cold resistance, and approval agencies do not affect functional substitutability within the specified electrical parameters.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Current Rating (A)	Voltage Rating (V AC)	Response Time	Package / Case	Breaking Capacity (A)	Product Status	RoHS Status
5SF 6.3	Bel Fuse Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Obsolete	RoHS non-compliant
5SF 6.3-R	Bel Fuse Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
0034.1524	SCHURTER Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
021706.3MXBP	Littelfuse Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
021706.3MXP	Littelfuse Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
021706.3VXP	Littelfuse Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
021706.3HXP	Littelfuse Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
021706.3TXP	Littelfuse Inc.	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
BK1/S500-6.3-R	Eaton - Electronics Division	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant
GDB-6.3A	Eaton - Electronics Division	6.3	250	Fast Blow	5mm x 20mm	63	Active	Not specified
S500-6.3-R	Eaton - Electronics Division	6.3	250	Fast Blow	5mm x 20mm	63	Active	ROHS3 Compliant

Engineering Selection Recommendations

For new designs and ongoing applications, select from active-status parts with ROHS3 compliance. The 5SF 6.3-R (Bel Fuse Inc.) provides direct manufacturer continuity from the obsolete 5SF 6.3 and maintains identical electrical specifications with improved regulatory compliance. Littelfuse 021706.3 series parts (MXBP, MXP, VXP, HXP, TXP) offer broad international certification coverage including BSI, CCC, CE, CSA, KC, PSE, SEMKO, UR, and VDE. SCHURTER 0034.1524 and Eaton S500-6.3-R and BK1/S500-6.3-R variants are suitable alternatives with active product status and full RoHS3 compliance. All listed substitutes maintain identical current rating, voltage rating, response time, and mechanical form factor, ensuring direct interchangeability in existing holder assemblies.

Frequently Asked Questions (FAQ)

Q: Can I use any of these substitute parts in place of the 5SF 6.3?

A: Yes. All listed substitute parts meet the identical electrical and mechanical specifications: 6.3 A current rating, 250 V AC voltage rating, fast-blow response, 5mm x 20mm form factor, and 63 A breaking capacity. They are mechanically and electrically interchangeable when installed in compatible fuse holders.

Q: What is the difference between the Littelfuse 021706.3 variants (MXBP, MXP, VXP, HXP, TXP)?

A: All Littelfuse 021706.3 variants share identical electrical specifications and are functionally equivalent. Differences are limited to internal construction details and packaging configurations. Selection among these variants depends on availability and specific procurement requirements.

Q: Does the melting I²t value affect substitutability?

A: No. Melting I²t is a thermal characteristic that describes fuse response behavior but does not affect the ability to substitute parts with identical current, voltage, and breaking capacity ratings. All listed parts are suitable replacements.

Q: Are there any compliance differences I should consider?

A: The original 5SF 6.3 is RoHS non-compliant and obsolete. All active substitute parts are ROHS3 compliant or have equivalent regulatory status. For new designs and systems requiring RoHS compliance, any of the listed active-status parts are appropriate selections.

Q: Do I need to change my fuse holder when switching to a substitute part?

A: No. All substitute parts maintain the 5mm x 20mm form factor and require a holder for installation, identical to the original 5SF 6.3. Existing holder assemblies are compatible with all listed substitutes.

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