Equivalent & Substitute Parts for BK/S506-40-R Glass Cartridge Fuse

Part Overview

The BK/S506-40-R is a 40 mA, 250 V AC/DC slow-blow glass cartridge fuse manufactured by Eaton - Electronics Division. This fuse is designed for circuits requiring overcurrent protection in a 5mm x 20mm form factor with holder mounting. The part is currently active in production with 844 units in stock. Substitute parts are identified to support procurement flexibility, inventory management, and supply chain continuity for applications requiring equivalent electrical and mechanical performance.

Substiute Parts

BK/S506-40-R

Eaton - Electronics DivisionIn Stock: 886BK/S506-40-R Datasheet

Current PartRFQ

S506-40-R

Eaton - Electronics DivisionIn Stock: 1137S506-40-R Datasheet

Parametric EquivalentRFQ

0218.040MXP

Littelfuse Inc.In Stock: 13310218.040MXP Datasheet

DirectRFQ

0218.040HXP

Littelfuse Inc.In Stock: 7600218.040HXP Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the BK/S506-40-R are qualified based on the following electrical and mechanical parameters:

Primary Substitution Criteria:

• Current Rating: 40 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Slow Blow (exact match required)
• Package / Case: 5mm x 20mm (exact match required)
• Mounting Type: Requires Holder (exact match required)
• Breaking Capacity @ Rated Voltage: 35 A (exact match required)

All identified substitute parts meet these criteria. Variations in secondary parameters such as DC cold resistance, melting I²t, operating temperature range, and approval agency certifications do not disqualify substitution eligibility when primary electrical and mechanical parameters are identical.

Parameter Comparison

Engineering Selection Recommendations

All four parts listed—BK/S506-40-R, S506-40-R, 0218.040MXP, and 0218.040HXP—are functionally equivalent for applications requiring a 40 mA, 250 V AC/DC slow-blow glass cartridge fuse in a 5mm x 20mm form factor.

Eaton S506 Series (BK/S506-40-R and S506-40-R): Both Eaton parts carry identical electrical specifications and hold approvals from BSI, CCC, IMQ, SEMKO, UL, and VDE. The S506-40-R variant shows higher inventory availability (1081 units) compared to the BK/S506-40-R (844 units).

Littelfuse 218 Series (0218.040MXP and 0218.040HXP): Both Littelfuse parts meet all primary substitution criteria and carry approvals from CCC, CE, CSA, K-MARK, SEMKO, UL, and VDE. The 0218.040MXP variant has the highest inventory level (1286 units), while 0218.040HXP provides 720 units. Both Littelfuse parts specify an operating temperature range of -55°C to 125°C, whereas Eaton parts do not specify operating temperature limits in the provided data.

Selection between manufacturers and variants should be based on procurement requirements, existing supply agreements, and inventory availability rather than electrical performance, as all parts are equivalent within the specified parameters.

Frequently Asked Questions (FAQ)

Q: Can I substitute a Littelfuse 0218.040MXP for an Eaton BK/S506-40-R?

A: Yes. Both parts share identical electrical ratings (40 mA, 250 V AC/DC), fuse type (cartridge, glass), response time (slow blow), mechanical dimensions (5mm x 20mm), and breaking capacity (35 A). Both are ROHS3 compliant and hold relevant international approvals.

Q: What is the difference between the Eaton S506-40-R and BK/S506-40-R?

A: Both are Eaton S506 series parts with identical electrical and mechanical specifications. The primary difference is inventory availability: S506-40-R has 1081 units in stock versus 844 units for BK/S506-40-R.

Q: Are there differences in operating temperature between substitute parts?

A: The Littelfuse 218 series parts (0218.040MXP and 0218.040HXP) specify an operating temperature range of -55°C to 125°C. The Eaton S506 series parts do not include operating temperature specifications in the provided data. For applications with specific temperature requirements, verify compatibility with the application environment.

Q: Do all substitute parts require the same holder?

A: Yes. All parts are 5mm x 20mm cartridge fuses requiring a holder for mounting. Mechanical compatibility is ensured across all four part numbers.

Q: What approval agencies certify these fuses?

A: Eaton S506 parts hold approvals from BSI, CCC, IMQ, SEMKO, UL, and VDE. Littelfuse 218 series parts hold approvals from CCC, CE, CSA, K-MARK, SEMKO, UL, and VDE. Both sets of approvals cover major international standards.

Q: Can I mix different manufacturers in the same circuit or application?

A: All four parts are electrically and mechanically equivalent. Circuit design and application requirements determine compatibility. Consult application documentation and design specifications for any manufacturer-specific requirements.