BK/S500-40-R Equivalent & Substitute Parts

Part Overview

The BK/S500-40-R is a fast-blow glass cartridge fuse manufactured by Eaton - Electronics Division. This component is rated for 40 mA at 250 V AC/DC with a 5mm x 20mm form factor and requires a fuse holder for installation. The part is currently active in production with 796 pieces available in inventory. Glass cartridge fuses of this specification are essential protective components in electronic circuits where precise current-limiting functionality and fast response characteristics are required. Identifying equivalent substitute parts ensures design flexibility, supply chain continuity, and component availability across manufacturing cycles.

Key Parameters

Parameter	Value
Current Rating	40 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Fast Blow
Package / Case	5mm x 20mm
Breaking Capacity @ Rated Voltage	35 A
Mounting Type	Requires Holder
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the BK/S500-40-R is determined by strict equivalence across the following critical parameters:

Current Rating: Both the main part and substitute must be rated for 40 mA. This parameter directly determines circuit protection characteristics and cannot be altered.

Voltage Rating (AC): Both parts must support 250 V AC minimum. Voltage rating establishes the maximum safe operating voltage and dielectric strength.

Fuse Type: Both must be glass cartridge fuses with fast-blow response characteristics. This ensures identical electrical behavior and protection response time.

Package / Case: Both must conform to the 5mm x 20mm physical form factor. This ensures mechanical compatibility with existing fuse holders and mounting infrastructure.

Breaking Capacity: Both parts must maintain 35 A breaking capacity at rated voltage to ensure consistent fault interruption performance.

Mounting Type: Both require a fuse holder for installation. This confirms compatibility with existing circuit board and panel designs.

The substitute part 0034.1528 (SCHURTER Inc., FSF 5x20 series) meets all these criteria and is therefore a direct equivalent.

Parameter Comparison

Parameter	BK/S500-40-R (Eaton)	0034.1528 (SCHURTER)	Match Status
Current Rating (Amps)	40 mA	40 mA	Equivalent
Voltage Rating - AC	250 V	250 V	Equivalent
Fuse Type	Cartridge, Glass	Cartridge, Glass	Equivalent
Response Time	Fast Blow	Fast Blow	Equivalent
Package / Case	5mm x 20mm	5mm x 20mm	Equivalent
Size / Dimension	0.205" Dia x 0.787" L (5.20mm x 20.00mm)	0.205" Dia x 0.787" L (5.20mm x 20.00mm)	Equivalent
Breaking Capacity @ Rated Voltage	35 A	35 A	Equivalent
Mounting Type	Requires Holder	Requires Holder	Equivalent
Melting I²t	0.00011	0.000128	Within tolerance
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Equivalent
REACH Status	REACH Unaffected	REACH Unaffected	Equivalent
ECCN	EAR99	EAR99	Equivalent
HTSUS	8536.10.0020	8536.10.0020	Equivalent

Engineering Selection Recommendations

Primary Selection: BK/S500-40-R (Eaton - Electronics Division) is the specified component and should be used when available. Current inventory status shows 796 pieces in stock.

Substitute Selection: 0034.1528 (SCHURTER Inc., FSF 5x20 series) is a direct functional equivalent and may be selected when the primary part is unavailable. This substitute maintains all critical electrical and mechanical parameters. The SCHURTER part carries additional approval certifications (CCC, cURus, VDE) and an extended operating temperature range (-55°C ~ 125°C), providing enhanced compliance documentation for regulated applications. Inventory availability for the substitute is 3622 pieces.

Both parts are ROHS3 compliant, REACH unaffected, and classified under identical ECCN and HTSUS codes, confirming regulatory equivalence for procurement and export purposes.

Frequently Asked Questions (FAQ)

Q: Can the 0034.1528 be used as a direct replacement for the BK/S500-40-R in all applications?

A: Yes. Both parts are rated for 40 mA at 250 V AC/DC, feature identical 5mm x 20mm form factors, and deliver fast-blow response characteristics. Both require a fuse holder and maintain 35 A breaking capacity. All critical electrical and mechanical parameters are equivalent.

Q: What is the difference in melting I²t values between these parts?

A: The BK/S500-40-R has a melting I²t of 0.00011, while the 0034.1528 has 0.000128. Both values fall within the acceptable tolerance range for 40 mA fast-blow glass cartridge fuses and do not affect functional equivalence in standard circuit protection applications.

Q: Are there any compliance or certification differences?

A: The SCHURTER 0034.1528 carries additional approval certifications (CCC, cURus, VDE) and specifies an operating temperature range of -55°C ~ 125°C. Both parts are ROHS3 compliant and REACH unaffected. The additional certifications on the SCHURTER part may be advantageous for regulated or international applications.

Q: Will the 0034.1528 fit in existing fuse holders designed for the BK/S500-40-R?

A: Yes. Both parts conform to the identical 5mm x 20mm physical specification (0.205" Dia x 0.787" L). Mechanical compatibility with existing fuse holders is confirmed.

Q: What is the current inventory status for each part?

A: BK/S500-40-R: 796 pieces available. 0034.1528: 3622 pieces available. The SCHURTER substitute offers significantly higher inventory availability.

Q: Can these parts be used interchangeably in the same circuit design?

A: Yes. Both parts deliver identical current rating, voltage rating, response time, and breaking capacity. They are functionally interchangeable for circuit protection purposes and require no design modifications.

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