Equivalent & Substitute Parts for S505-6.3-R Ceramic Fuse Cartridge

Part Overview

The S505-6.3-R is a 6.3 A, 250 V AC ceramic fuse cartridge manufactured by Eaton - Electronics Division. This slow-blow fuse operates in a 5mm x 20mm form factor and requires a compatible holder for installation. The part is active in production with 961 pieces in current inventory. Equivalent and substitute parts are identified based on matching electrical ratings, mechanical dimensions, response characteristics, and approval certifications to ensure functional interchangeability in circuit protection applications.

Key Parameters

Parameter	Value
Current Rating	6.3 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Ceramic
Response Time	Slow Blow
Package / Case	5mm x 20mm
Breaking Capacity @ Rated Voltage	1.5 kA
Mounting Type	Requires Holder
Product Status	Active

Substitute Part Grouping Explanation

Substitute parts for the S505-6.3-R are classified into two categories based on electrical and mechanical parameter alignment:

Direct Equivalents (Identical Parameters): Parts that match all critical electrical specifications (6.3 A current rating, 250 V AC voltage rating, slow-blow response, 5mm x 20mm package) and maintain the same breaking capacity of 1.5 kA. These parts are functionally interchangeable without design modification.

Parametric Equivalents (Matching Core Ratings with Acceptable Variations): Parts that maintain identical current, voltage, and package specifications but may differ in melting I²t values, DC cold resistance, or operating temperature ranges. These parts satisfy the primary circuit protection function while offering alternative compliance certifications or inventory availability.

The following parameters determine substitution eligibility:

Current Rating: 6.3 A (mandatory match)
Voltage Rating (AC): 250 V (mandatory match)
Package / Case: 5mm x 20mm (mandatory match)
Fuse Type: Cartridge, Ceramic (mandatory match)
Response Time: Slow Blow (mandatory match)
Breaking Capacity: 1.5 kA (mandatory match)

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage AC (V)	Package	Breaking Capacity (kA)	Melting I²t	DC Cold Resistance (Ω)	Response Time	RoHS Status
S505-6.3-R	Eaton	6.3	250	5x20mm	1.5	111	0.0102	Slow Blow	RoHS Compliant
BK/S505-6.3-R	Eaton	6.3	250	5x20mm	1.5	111	0.0102	Slow Blow	ROHS3 Compliant
BK1/S505-6.3-R	Eaton	6.3	250	5x20mm	1.5	111	0.0102	Slow Blow	ROHS3 Compliant
021506.3MXP	Littelfuse	6.3	250	5x20mm	1.5	128.75	0.0108	Slow Blow	ROHS3 Compliant
021506.3HXP	Littelfuse	6.3	250	5x20mm	1.5	128.75	0.0108	Slow Blow	ROHS3 Compliant
021506.3TXP	Littelfuse	6.3	250	5x20mm	1.5	128.75	0.0108	Slow Blow	ROHS3 Compliant
0001.2512	SCHURTER	6.3	250	5x20mm	1.5	171	Not Specified	Slow Blow	ROHS3 Compliant
0001.2512.G	SCHURTER	6.3	250	5x20mm	1.5	171	Not Specified	Slow Blow	ROHS3 Compliant
0001.2712.11	SCHURTER	6.3	250	5x20mm	1.5	171	Not Specified	Slow Blow	ROHS3 Compliant
028506.3HXP	Littelfuse	6.3	250	5x20mm	1.5	130.977	0.0107	Slow Blow	ROHS3 Compliant

Engineering Selection Recommendations

Eaton S505 Series (Direct Manufacturer Equivalents): BK/S505-6.3-R and BK1/S505-6.3-R are direct equivalents from the same manufacturer with identical electrical and mechanical specifications. Both parts carry ROHS3 compliance and maintain the same melting I²t value of 111. These parts are recommended when maintaining consistency within the Eaton product line is required. Inventory availability is higher for BK/S505-6.3-R (2768 pieces) and BK1/S505-6.3-R (2064 pieces) compared to the original S505-6.3-R (961 pieces).

Littelfuse 215 Series (Parametric Equivalents): 021506.3MXP, 021506.3HXP, and 021506.3TXP are parametric equivalents from Littelfuse with matching core electrical ratings and 5mm x 20mm package. These parts feature a melting I²t of 128.75 and operating temperature range of -55°C to 125°C. All three variants carry comprehensive approval certifications including CCC, CE, CSA, KC, PSE, SEMKO, UL, and VDE. Littelfuse 215 series parts offer higher inventory availability (20100 pieces for 021506.3MXP, 6887 pieces for 021506.3HXP, 1175 pieces for 021506.3TXP).

Littelfuse 285 Series (Parametric Equivalent): 028506.3HXP is a parametric equivalent with matching electrical specifications and a melting I²t of 130.977. This part carries PSE approval and operates across -55°C to 125°C. Inventory is limited to 990 pieces.

SCHURTER SPT Series (Parametric Equivalents): 0001.2512, 0001.2512.G, and 0001.2712.11 are parametric equivalents with matching current and voltage ratings in the 5mm x 20mm package. These parts feature a higher melting I²t of 171 and support both 250 V AC and 150 V DC operation. SCHURTER parts carry CCC, cURus, KC, PSE/JET, and VDE certifications. Inventory levels are substantial: 6423 pieces for 0001.2512, 9642 pieces for 0001.2512.G, and 1302 pieces for 0001.2712.11.

Non-Standard Package (Limited Compatibility): 083506.3MXP from Littelfuse is classified as a similar part but features a non-standard cartridge package and higher melting I²t of 300. This part is not recommended as a direct substitute due to package incompatibility with standard 5mm x 20mm holders.

Frequently Asked Questions (FAQ)

Q: Can I substitute BK/S505-6.3-R for S505-6.3-R without circuit modification?

A: Yes. BK/S505-6.3-R is a direct equivalent from Eaton with identical current rating (6.3 A), voltage rating (250 V AC), package dimensions (5mm x 20mm), breaking capacity (1.5 kA), and response time (slow blow). No circuit modification is required.

Q: What is the difference between Littelfuse 021506.3MXP and 021506.3HXP?

A: Both parts are parametric equivalents with identical electrical specifications (6.3 A, 250 V AC, 5mm x 20mm package, 1.5 kA breaking capacity, slow-blow response). The designations MXP, HXP, and TXP indicate different internal construction variants within the Littelfuse 215 series, but all three maintain the same melting I²t of 128.75 and DC cold resistance of 0.0108 Ohms. Selection between these variants depends on specific application requirements and holder compatibility.

Q: Why do SCHURTER parts have a higher melting I²t value (171) compared to the original S505-6.3-R (111)?

A: Melting I²t is a thermal characteristic that affects the time-current response curve of the fuse. SCHURTER SPT series parts (0001.2512, 0001.2512.G, 0001.2712.11) maintain the same 6.3 A current rating and 250 V AC voltage rating but have different internal resistance and thermal mass characteristics. These parts are parametric equivalents because they meet the mandatory electrical and mechanical specifications. Application-specific thermal analysis may be required if precise time-current coordination is critical.

Q: Can I use 083506.3MXP as a substitute?

A: No. Although 083506.3MXP matches the current rating (6.3 A), voltage rating (250 V AC), and response time (slow blow), it features a non-standard cartridge package that is incompatible with standard 5mm x 20mm fuse holders. This part is not suitable for direct substitution.

Q: What certifications should I verify when selecting a substitute part?

A: The original S505-6.3-R carries approvals from BSI, CCC/CQC, CSA, cULus, IMQ, KC, PSE/JET, SEMKO, and VDE. When selecting substitute parts, verify that the replacement part carries certifications required by your application's regulatory framework. Littelfuse 215 series parts (021506.3MXP, 021506.3HXP, 021506.3TXP) and SCHURTER SPT series parts maintain comprehensive certification coverage. Littelfuse 285 series (028506.3HXP) carries PSE approval only and may have limited applicability in regions requiring broader certification.

Q: Are all substitute parts RoHS compliant?

A: Yes. All listed substitute parts carry ROHS3 compliance status. The original S505-6.3-R is RoHS Compliant. All equivalent and parametric equivalent parts meet RoHS3 requirements, ensuring environmental compliance across all options.

Q: Which substitute part offers the best inventory availability?

A: Littelfuse 021506.3MXP offers the highest inventory availability with 20100 pieces in stock, followed by SCHURTER 0001.2512.G with 9642 pieces. If immediate availability is a priority, these parts are recommended.

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