BK/MDL-3/4SX-R Equivalent & Substitute Parts

Part Overview

The BK/MDL-3/4SX-R is a 750 mA, 250 V AC/DC slow-blow glass fuse cartridge manufactured by Eaton - Electronics Division. This component operates within the 3AB, 3AG package format with dimensions of 0.250" diameter by 1.250" length (6.35mm x 31.75mm). The part is currently active in production status with 674 pieces available in inventory.

Identifying equivalent and substitute parts becomes necessary when the primary part number experiences supply constraints, extended lead times, or when design flexibility permits component standardization across multiple suppliers. The substitute parts listed maintain electrical and mechanical compatibility through identical or functionally equivalent parameter specifications.

Substiute Parts

BK/MDL-3/4SX-R

Eaton - Electronics DivisionIn Stock: 773BK/MDL-3/4SX-R Datasheet

Current PartRFQ

BK/MDL-3/4-R

Eaton - Electronics DivisionIn Stock: 1037BK/MDL-3/4-R Datasheet

Parametric EquivalentRFQ

0034.5223

SCHURTER Inc.In Stock: 8320034.5223 Datasheet

Parametric EquivalentRFQ

0313.750HXP

Littelfuse Inc.In Stock: 15090313.750HXP Datasheet

Parametric EquivalentRFQ

0313.750MXP

Littelfuse Inc.In Stock: 56670313.750MXP Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BK/MDL-3/4SX-R is determined by strict equivalence across the following critical parameters:

Mandatory Matching Parameters:

• Current Rating: 750 mA
• Voltage Rating (AC): 250 V
• Response Time: Slow Blow
• Fuse Type: Cartridge, Glass
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4"
• Size / Dimension: 0.250" Dia x 1.250" L (6.35mm x 31.75mm)
• Breaking Capacity @ Rated Voltage: 35A
• Mounting Type: Requires Holder

All substitute parts identified in this reference maintain these exact specifications. Variations in secondary parameters such as melting I²t, DC cold resistance, operating temperature range, and RoHS compliance status do not disqualify substitution eligibility but are documented for engineering review.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute - BK/MDL-3/4-R (Eaton): This part maintains identical electrical and mechanical specifications to the BK/MDL-3/4SX-R with the addition of CE certification. Both parts are manufactured by Eaton - Electronics Division and carry active product status. The BK/MDL-3/4-R offers 961 pieces in inventory, providing superior availability. ROHS3 compliance and MSL 1 (Unlimited) rating provide enhanced environmental and moisture handling characteristics.

Secondary Substitutes - 0313.750HXP and 0313.750MXP (Littelfuse): Both Littelfuse 313 series parts meet all mandatory electrical and mechanical parameters with active product status and CE, CSA, UL certifications. The 0313.750MXP variant offers the highest inventory level at 5623 pieces. These parts include specified operating temperature range (-55°C ~ 125°C) and ROHS3 compliance. DC cold resistance differs at 0.6215 Ohms compared to the primary part's 0.397 Ohms, and melting I²t is specified at 7.16 compared to 4.343.

Tertiary Substitute - 0034.5223 (SCHURTER): This part maintains all mandatory electrical and mechanical specifications but carries obsolete product status. While 730 pieces remain in inventory, the obsolete designation indicates this part is no longer in active production. Selection of this part should be limited to applications where existing inventory depletion is the objective or where long-term supply is not a requirement. Melting I²t is specified at 9.04, and operating temperature range is -55°C ~ 125°C.

Frequently Asked Questions (FAQ)

Q: Can BK/MDL-3/4-R be used as a direct replacement for BK/MDL-3/4SX-R?

A: Yes. Both parts are manufactured by Eaton - Electronics Division and maintain identical current rating (750 mA), voltage rating (250 V AC), response time (Slow Blow), fuse type (Cartridge, Glass), package format (3AB, 3AG, 1/4" x 1-1/4"), and breaking capacity (35A). The BK/MDL-3/4-R includes additional CE certification and ROHS3 compliance status.

Q: What is the difference between the Littelfuse 0313.750HXP and 0313.750MXP?

A: Both parts are electrically and mechanically identical. They share the same current rating, voltage rating, response time, package format, and breaking capacity. The primary difference is inventory availability, with 0313.750MXP offering 5623 pieces compared to 0313.750HXP at 1440 pieces.

Q: Why does the SCHURTER 0034.5223 show obsolete status?

A: Obsolete status indicates the manufacturer has discontinued active production of this part. While 730 pieces remain in current inventory, future availability cannot be assured. This part should be selected only when existing stock depletion is acceptable or when long-term supply is not required.

Q: Are there differences in melting I²t values between substitute parts?

A: Yes. The BK/MDL-3/4SX-R and BK/MDL-3/4-R specify melting I²t at 4.343. The Littelfuse parts (0313.750HXP and 0313.750MXP) specify 7.16, and the SCHURTER part specifies 9.04. These variations reflect different thermal response characteristics but do not disqualify substitution when all mandatory electrical and mechanical parameters match.

Q: Do all substitute parts require the same holder?

A: Yes. All parts in this reference maintain the 3AB, 3AG package format with 0.250" diameter by 1.250" length dimensions. All require a compatible fuse holder designed for this package specification.

Q: What certifications apply to each substitute part?

A: BK/MDL-3/4SX-R carries CSA and UL certifications. BK/MDL-3/4-R, 0313.750HXP, and 0313.750MXP carry CE, CSA, and UL certifications. The SCHURTER 0034.5223 carries CSA and UL certifications. All parts meet the approval requirements for the primary part's CSA and UL certifications.