BK/MDL-1/2 Equivalent & Substitute Parts

Part Overview

The BK/MDL-1/2 is a 500 mA, 250 V AC/DC glass cartridge fuse manufactured by Eaton - Electronics Division. This component is classified as obsolete and requires a fuse holder for installation. The 3AB/3AG form factor (1/4" × 1-1/4") is a standard configuration for industrial and commercial circuit protection applications.

Due to the obsolete product status of BK/MDL-1/2, direct replacement with active production equivalents is necessary to ensure supply chain continuity and access to current manufacturing certifications. Active substitute parts maintain identical electrical and mechanical parameters while offering improved compliance standards and availability.

Key Parameters

Parameter	Value
Current Rating	500 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" × 1-1/4"
Breaking Capacity @ Rated Voltage	35 A
Size / Dimension	0.250" Dia × 1.250" L (6.35 mm × 31.75 mm)
Mounting Type	Requires Holder

Substitute Part Grouping Explanation

Substitution of BK/MDL-1/2 is determined by strict equivalence across the following critical parameters:

Electrical Parameters:

Current Rating: 500 mA (exact match required)
Voltage Rating: 250 V AC (exact match required)
Response Time: Slow Blow (exact match required)
Breaking Capacity: 35 A @ rated voltage (exact match required)

Mechanical Parameters:

Fuse Type: Cartridge, Glass (exact match required)
Package / Case: 3AB, 3AG, 1/4" × 1-1/4" (exact match required)
Mounting Type: Requires Holder (exact match required)

All substitute parts listed maintain these parameters without deviation. Substitutes are grouped into two categories: direct manufacturer equivalents from Eaton - Electronics Division (MDL and MDQ series) and parametric equivalents from Littelfuse Inc. (313 series). All listed substitutes are active production parts with current certifications.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating	Voltage (AC)	Response Time	Breaking Capacity	Package	Product Status	RoHS Status
BK/MDL-1/2	Eaton	MDL	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Obsolete	Non-compliant
BK/MDL-1/2-R	Eaton	MDL	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	ROHS3 Compliant
MDL-1/2-R	Eaton	MDL	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	RoHS Compliant
BK/MDL-1/2BB	Eaton	MDL	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	RoHS Compliant
BK/MDQ-1/2	Eaton	MDQ	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	Non-compliant
MDQ-1/2	Eaton	MDQ	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	Not specified
0313.500HXIDP	Littelfuse	313	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	ROHS3 Compliant
0313.500HXP	Littelfuse	313	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	ROHS3 Compliant
0313.500MXP	Littelfuse	313	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	ROHS3 Compliant
0313.500VXIDP	Littelfuse	313	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	ROHS3 Compliant
0313.500VXP	Littelfuse	313	500 mA	250 V	Slow Blow	35 A	3AB, 3AG, 1/4" × 1-1/4"	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation - Eaton Direct Equivalents:

BK/MDL-1/2-R and MDL-1/2-R are the preferred substitutes for BK/MDL-1/2. Both parts are manufactured by Eaton - Electronics Division and maintain identical electrical and mechanical specifications. These parts carry active product status and current RoHS compliance certifications (ROHS3 or RoHS Compliant). Selection between BK/MDL-1/2-R and MDL-1/2-R depends on packaging requirements; both are available in bulk packaging with high inventory levels (1130 and 1068 units respectively).

BK/MDL-1/2BB is an alternative Eaton equivalent with active status and RoHS compliance. This part is suitable for applications requiring the same electrical performance with current manufacturing standards.

Secondary Recommendation - Eaton MDQ Series:

BK/MDQ-1/2 and MDQ-1/2 are parametric equivalents from Eaton's MDQ series. These parts maintain all critical electrical and mechanical parameters. Both carry active product status. Note that RoHS compliance status differs: BK/MDQ-1/2 is non-compliant, while MDQ-1/2 status is not specified. These parts are suitable for applications where RoHS compliance is not a requirement.

Tertiary Recommendation - Littelfuse 313 Series:

The Littelfuse 313 series (0313.500HXIDP, 0313.500HXP, 0313.500MXP, 0313.500VXIDP, 0313.500VXP) provides parametric equivalence with active production status and ROHS3 compliance. All Littelfuse parts carry CE, CSA, and UL certifications. These parts are suitable for applications requiring cross-manufacturer sourcing or where Littelfuse supply chain integration is preferred. The 0313.500MXP variant has the highest inventory availability (4917 units).

Compliance Considerations:

For applications requiring RoHS compliance, select from: BK/MDL-1/2-R, MDL-1/2-R, BK/MDL-1/2BB, or any Littelfuse 313 series part.

For applications without RoHS compliance requirements, all listed substitutes are acceptable.

Frequently Asked Questions (FAQ)

Q: Can BK/MDL-1/2 be directly replaced with BK/MDL-1/2-R?

A: Yes. BK/MDL-1/2-R is a direct manufacturer equivalent with identical electrical ratings (500 mA, 250 V AC, Slow Blow response) and mechanical form factor (3AB/3AG, 1/4" × 1-1/4"). The primary difference is product status (Active vs. Obsolete) and RoHS compliance (ROHS3 Compliant vs. Non-compliant). No circuit modifications are required.

Q: What is the difference between Eaton MDL and MDQ series substitutes?

A: Both MDL and MDQ series maintain identical electrical parameters (500 mA, 250 V, 35 A breaking capacity, Slow Blow response) and mechanical specifications (3AB/3AG package). The series designation reflects internal Eaton product line organization. Selection between MDL and MDQ is based on availability and RoHS compliance requirements rather than electrical performance.

Q: Are Littelfuse 313 series parts fully compatible with BK/MDL-1/2?

A: Yes. Littelfuse 313 series parts (0313.500HXIDP, 0313.500HXP, 0313.500MXP, 0313.500VXIDP, 0313.500VXP) are parametric equivalents that maintain all critical electrical and mechanical specifications. They fit the same 3AB/3AG holder and provide identical circuit protection performance. Littelfuse parts carry CE, CSA, and UL certifications and are ROHS3 compliant.

Q: Which substitute has the best availability?

A: 0313.500MXP (Littelfuse) has the highest inventory level at 4917 units. Among Eaton parts, BK/MDL-1/2-R has 1130 units in stock.

Q: Do all substitutes require the same fuse holder?

A: Yes. All listed substitutes are 3AB/3AG cartridge fuses with dimensions 0.250" Dia × 1.250" L (6.35 mm × 31.75 mm). They are mechanically interchangeable and require the same holder type as BK/MDL-1/2.

Q: What is the difference between Littelfuse part variants (HXP, HXIDP, VXP, VXIDP, MXP)?

A: All Littelfuse variants listed maintain identical electrical specifications (500 mA, 250 V, Slow Blow, 35 A breaking capacity) and mechanical form factor (3AB/3AG). The suffix designations reflect internal Littelfuse product line organization and packaging configurations. Selection among variants is based on availability and supply chain preference rather than electrical performance differences.

Q: Can BK/MDL-1/2 be used in new designs, or must substitutes be used?

A: BK/MDL-1/2 is classified as obsolete. For new designs and ongoing production, use active substitute parts. BK/MDL-1/2-R, MDL-1/2-R, or Littelfuse 313 series parts are recommended for new applications.

Q: Are there any temperature rating differences among substitutes?

A: Littelfuse 313 series parts specify operating temperature range of -55°C to 125°C. Eaton parts do not specify operating temperature limits in the provided data. For applications requiring defined temperature specifications, Littelfuse parts provide explicit thermal performance documentation.

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