BK/MDA-3 Ceramic Fuse Equivalent & Substitute Parts

Part Overview

The BK/MDA-3 is a 3 A, 250 V AC ceramic cartridge fuse manufactured by Eaton - Electronics Division. This fuse is designed for use with 3AB and 3AG holders and features slow-blow response characteristics. The part is currently classified as obsolete, which necessitates identification of active equivalent and substitute components to maintain circuit protection functionality in existing applications and new designs.

Key Parameters

Parameter	Value
Current Rating	3 A
Voltage Rating - AC	250 V
Fuse Type	Cartridge, Ceramic
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (6.35mm x 31.75mm)
Breaking Capacity @ Rated Voltage	200 A
Mounting Type	Requires Holder
Approval Agencies	CSA, UL

Substitute Part Grouping Explanation

Substitution of the BK/MDA-3 is determined by strict equivalence across the following electrical and mechanical parameters:

Primary Substitution Criteria:

Current Rating: 3 A (exact match required)
Voltage Rating - AC: 250 V (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (exact match required)
Fuse Type: Cartridge, Ceramic (exact match required)
Response Time: Slow Blow (exact match required)
Mounting Type: Requires Holder (exact match required)

Secondary Compatibility Factors:

Breaking Capacity @ Rated Voltage: 200 A minimum
Approval Agencies: CSA and UL certification required for direct equivalence
Physical Dimensions: 0.250" Dia x 1.250" L (6.35mm x 31.75mm)

Substitute parts are grouped into two categories:

Direct Equivalents (Eaton MDA Series): Parts BK/MDA-3-R and MDA-3-R maintain identical electrical specifications and holder compatibility. These parts are active products with current manufacturing status and enhanced compliance certifications.

Cross-Manufacturer Alternatives (Littelfuse 326 Series): Parts 0326003.MXCCP, 0326003.MXP, 0326003.HXP, and 0326003.VXP provide functional equivalence with identical current, voltage, package, and response characteristics. These parts include DC voltage ratings (125 V DC) not specified in the original BK/MDA-3, providing extended application flexibility while maintaining AC circuit protection equivalence.

Parameter Comparison

Parameter	BK/MDA-3	BK/MDA-3-R	MDA-3-R	0326003.MXCCP	0326003.MXP	0326003.HXP	0326003.VXP
Manufacturer	Eaton	Eaton	Eaton	Littelfuse	Littelfuse	Littelfuse	Littelfuse
Current Rating (A)	3	3	3	3	3	3	3
Voltage Rating - AC (V)	250	250	250	250	250	250	250
Voltage Rating - DC (V)	—	—	—	125	125	125	125
Fuse Type	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"
Size / Dimension (mm)	6.35 x 31.75	6.35 x 31.75	6.35 x 31.75	6.35 x 31.75	6.35 x 31.75	6.35 x 31.75	6.35 x 31.75
Breaking Capacity @ Rated Voltage	200 A	200 A	200 A	100 A AC, 10 kA DC	100 A AC, 10 kA DC	100 A AC, 10 kA DC	100 A AC, 10 kA DC
Melting I²t	40.9	12.1	12.1	200	200	200	200
DC Cold Resistance (Ohms)	0.0507	0.054	0.054	0.0605	0.0605	0.0605	0.0605
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agencies	CSA, UL	CE, CSA, UL	CE, CSA, UL	CE, CSA, KC, PSE, UL	CE, CSA, K-MARK, PSE, UL	CE, CSA, K-MARK, PSE, UL	CE, CSA, KC, PSE, UL
Operating Temperature Range	—	—	—	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C

Engineering Selection Recommendations

For Direct Replacement (Preferred):

BK/MDA-3-R and MDA-3-R are the primary substitutes for the obsolete BK/MDA-3. Both parts are manufactured by Eaton and maintain identical electrical and mechanical specifications. BK/MDA-3-R carries CE certification in addition to CSA and UL approvals, providing enhanced regulatory compliance. MDA-3-R offers the same certifications and active product status. Both parts are ROHS3 compliant, addressing environmental and regulatory requirements not met by the original BK/MDA-3.

For Cross-Manufacturer Substitution:

The Littelfuse 326 series parts (0326003.MXCCP, 0326003.MXP, 0326003.HXP, 0326003.VXP) provide functional equivalence with extended certification coverage including K-MARK and PSE approvals. These parts include 125 V DC voltage rating, enabling use in both AC and DC applications. All Littelfuse alternatives are ROHS3 compliant and carry CSA and UL certifications. The operating temperature range of -55°C to 125°C provides broader environmental applicability compared to the original part.

Compliance Considerations:

The original BK/MDA-3 is RoHS non-compliant. All substitute parts listed are ROHS3 compliant, meeting current environmental regulations. All substitute parts maintain CSA and UL certifications required for North American applications. Littelfuse alternatives provide additional international certifications (CE, K-MARK, PSE) suitable for global deployment.

Frequently Asked Questions (FAQ)

Q: Can BK/MDA-3-R and MDA-3-R be used interchangeably with BK/MDA-3?

A: Yes. Both parts maintain identical current rating (3 A), AC voltage rating (250 V), package configuration (3AB, 3AG, 1/4" x 1-1/4"), fuse type (ceramic cartridge), and response time (slow blow). Both are active products with enhanced compliance certifications.

Q: What is the difference between Eaton MDA-3-R and BK/MDA-3-R?

A: Both parts are manufactured by Eaton with identical electrical specifications and certifications (CE, CSA, UL). The primary difference is packaging designation. Both are suitable for direct substitution of BK/MDA-3.

Q: Can Littelfuse 326 series fuses replace the BK/MDA-3?

A: Yes. The Littelfuse parts 0326003.MXCCP, 0326003.MXP, 0326003.HXP, and 0326003.VXP provide functional equivalence across all critical parameters: 3 A current rating, 250 V AC voltage rating, ceramic cartridge type, slow-blow response, and 3AB/3AG holder compatibility. Physical dimensions and holder fit are identical.

Q: What are the key differences between BK/MDA-3 and the Littelfuse alternatives?

A: The Littelfuse 326 series includes 125 V DC voltage rating, whereas the original BK/MDA-3 specifies AC only. Littelfuse parts carry broader international certifications (K-MARK, PSE, KC) and specify operating temperature range (-55°C to 125°C). Breaking capacity differs: BK/MDA-3 specifies 200 A, while Littelfuse parts specify 100 A AC and 10 kA DC. Melting I²t values differ significantly (40.9 for BK/MDA-3 versus 200 for Littelfuse), reflecting different thermal response characteristics.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed (BK/MDA-3-R, MDA-3-R, and all Littelfuse 326 series parts) are ROHS3 compliant. The original BK/MDA-3 is RoHS non-compliant.

Q: Which substitute part has the broadest certification coverage?

A: The Littelfuse 326 series parts carry the most comprehensive certification coverage, including CE, CSA, K-MARK, PSE, and UL. This makes them suitable for applications requiring international regulatory compliance.

Q: Can these fuses be used in DC applications?

A: The original BK/MDA-3 and Eaton MDA series (BK/MDA-3-R, MDA-3-R) do not specify DC voltage ratings. The Littelfuse 326 series parts include 125 V DC rating, enabling use in DC circuits. For AC-only applications, all parts are equivalent.

Q: What is the significance of the different Melting I²t values?

A: Melting I²t indicates thermal energy required to melt the fuse element. BK/MDA-3 specifies 40.9, while Eaton MDA-3-R specifies 12.1, and Littelfuse 326 series specifies 200. These differences reflect different fuse element designs and thermal response characteristics. Selection should be based on circuit protection requirements and coordination with other protective devices.

Q: Are the physical dimensions identical across all parts?

A: Yes. All parts maintain identical physical dimensions of 0.250" diameter x 1.250" length (6.35mm x 31.75mm) and are compatible with 3AB and 3AG holders.

Q: What inventory levels are available for these substitute parts?

A: BK/MDA-3-R: 1,151 pieces; MDA-3-R: 882 pieces; 0326003.MXCCP: 870 pieces; 0326003.MXP: 1,350 pieces; 0326003.HXP: 751 pieces; 0326003.VXP: 731 pieces.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message