BK1/GMD-3-R Equivalent & Substitute Parts

Part Overview

The BK1/GMD-3-R is a 3 A, 250 V AC/DC slow-blow glass cartridge fuse in a 5mm x 20mm package manufactured by Eaton - Electronics Division. This fuse requires a holder for installation and is designed for circuit protection applications requiring slow-blow response characteristics. The part is active in production status with full RoHS3 compliance and international approvals including CSA, PSE/JET, and UL certifications. Equivalent and substitute parts are identified to support procurement flexibility, inventory management, and supply chain continuity for applications requiring identical electrical and mechanical specifications.

Key Parameters

Parameter	Value
Current Rating	3 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	5mm x 20mm
Breaking Capacity @ Rated Voltage	100 A
Mounting Type	Requires Holder
RoHS Status	ROHS3 Compliant
Product Status	Active

Substitute Part Grouping Explanation

Substitute parts for the BK1/GMD-3-R are classified based on strict parametric equivalence across the following critical specifications:

Primary Equivalence Criteria:

Current Rating: 3 A
Voltage Rating (AC): 250 V
Fuse Type: Cartridge, Glass
Response Time: Slow Blow
Package / Case: 5mm x 20mm
Breaking Capacity @ Rated Voltage: 100 A
Mounting Type: Requires Holder
RoHS Status: ROHS3 Compliant

Parametric Equivalent Parts share all primary equivalence criteria with the main part and are direct functional replacements. These include BK/GMD-3-R and GMD-3-R from Eaton, as well as multiple Littelfuse 239 series variants (0239003.HXP, 0239003.MXP, 0239003.TXP, 0239003.VXP), SCHURTER FSL 5x20 series (0034.3781), and OptiFuse TSC series (TSC-3A).

Similar Parts meet the primary equivalence criteria but may have minor variations in secondary parameters such as melting I²t, DC cold resistance, or operating temperature range. The Littelfuse 0239003.HXEP is classified as similar due to through-hole mounting type and slightly different dimensional specifications (5.50mm x 21.50mm versus 5.20mm x 20.00mm).

Parameter Comparison

Manufacturer Part Number	Manufacturer	Current Rating (A)	Voltage Rating (V AC)	Response Time	Package / Case	Breaking Capacity (A)	Mounting Type	RoHS Status	Product Status
BK1/GMD-3-R	Eaton - Electronics Division	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
BK/GMD-3-R	Eaton - Electronics Division	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
GMD-3-R	Eaton - Electronics Division	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
0239003.HXP	Littelfuse Inc.	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
0239003.MXP	Littelfuse Inc.	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
0239003.TXP	Littelfuse Inc.	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
0239003.VXP	Littelfuse Inc.	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
0034.3781	SCHURTER Inc.	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
TSC-3A	OptiFuse	3	250	Slow Blow	5mm x 20mm	100	Requires Holder	ROHS3 Compliant	Active
0239003.HXEP	Littelfuse Inc.	3	250	Slow Blow	5mm x 20mm (Axial)	100	Through Hole	ROHS3 Compliant	Active

Engineering Selection Recommendations

All identified substitute parts maintain active production status and full RoHS3 compliance, ensuring regulatory conformance and long-term availability. Selection among parametric equivalent parts should be based on:

Eaton GMD Series (BK/GMD-3-R, GMD-3-R): Direct manufacturer equivalents with identical specifications to the main part BK1/GMD-3-R. These parts are recommended when maintaining single-manufacturer sourcing is a requirement.

Littelfuse 239 Series (0239003.HXP, 0239003.MXP, 0239003.TXP, 0239003.VXP): Parametric equivalents with extended operating temperature range (-55°C to 125°C) and broader international approvals (CE, CSA, KC, PSE, UL). These variants differ in melting I²t (129.51) and DC cold resistance (0.04877 Ohms) compared to the main part. Selection among these variants should be based on specific application requirements and certification needs.

SCHURTER FSL 5x20 Series (0034.3781): Parametric equivalent with cULus approval and operating temperature range of -40°C to 85°C. This part exhibits different melting I²t (17.5) and is suitable for applications requiring SCHURTER sourcing.

OptiFuse TSC Series (TSC-3A): Parametric equivalent with cULus and UL 248 approvals, operating temperature range of -55°C to 125°C, and melting I²t of 14.15. This part is suitable for applications requiring OptiFuse sourcing.

Littelfuse 0239003.HXEP (Similar Part): This part differs in mounting type (through-hole versus requires holder) and physical dimensions (5.50mm x 21.50mm versus 5.20mm x 20.00mm). This part is not recommended as a direct substitute for applications requiring holder-based mounting.

Frequently Asked Questions (FAQ)

Q: Can I substitute BK/GMD-3-R or GMD-3-R for BK1/GMD-3-R?

A: Yes. BK/GMD-3-R and GMD-3-R are parametric equivalents manufactured by Eaton - Electronics Division with identical electrical and mechanical specifications, including current rating, voltage rating, response time, package dimensions, breaking capacity, and mounting requirements.

Q: What is the difference between the Littelfuse 239 series variants (0239003.HXP, 0239003.MXP, 0239003.TXP, 0239003.VXP)?

A: All four Littelfuse 239 series variants share identical electrical and mechanical parameters with the main part. The designations (HXP, MXP, TXP, VXP) represent different product line variants within the 239 series. Selection among these variants should be based on application-specific requirements and availability.

Q: Why is 0239003.HXEP listed as a similar part rather than a parametric equivalent?

A: The 0239003.HXEP differs in two key parameters: mounting type (through-hole versus requires holder) and physical dimensions (5.50mm x 21.50mm versus 5.20mm x 20.00mm). These differences prevent direct substitution in applications requiring holder-based mounting with standard 5mm x 20mm dimensions.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All identified substitute parts maintain RoHS3 compliance, ensuring regulatory conformance with current environmental and hazardous substance restrictions.

Q: What certifications do the substitute parts carry?

A: The main part BK1/GMD-3-R carries CSA, PSE/JET, and UL approvals. Littelfuse 239 series parts carry CE, CSA, KC, PSE, and UL approvals. SCHURTER 0034.3781 carries cULus approval. OptiFuse TSC-3A carries cULus and UL 248 approvals. Application requirements should determine which certifications are necessary for your specific use case.

Q: Can I use these fuses interchangeably in the same holder?

A: Yes. All parametric equivalent parts share identical package dimensions (5mm x 20mm) and mounting type (requires holder), ensuring mechanical compatibility with standard 5mm x 20mm fuse holders.

Q: What is the significance of melting I²t values?

A: Melting I²t is a thermal characteristic that influences fuse response time and energy dissipation. While all substitute parts maintain the same slow-blow response classification, variations in melting I²t (ranging from 14.15 to 145 across the substitute list) reflect different thermal designs. Application-specific thermal requirements should guide selection when melting I²t is a critical parameter.

Q: Are there any operating temperature restrictions I should consider?

A: The main part BK1/GMD-3-R does not specify an operating temperature range. Littelfuse, OptiFuse, and some other manufacturers specify -55°C to 125°C operating ranges. SCHURTER specifies -40°C to 85°C. Applications operating outside standard temperature ranges should verify compatibility with the selected substitute part's specifications.

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