BK/GMD-315MA Equivalent & Substitute Parts

Part Overview

The BK/GMD-315MA is a 315 mA, 250 V AC/DC glass cartridge fuse with a 5mm x 20mm form factor, manufactured by Eaton - Electronics Division. This component is classified as obsolete, requiring identification of active equivalent and substitute parts for ongoing circuit protection applications. The slow-blow response characteristic and 35A breaking capacity at rated voltage establish the functional baseline for substitution analysis. Direct replacements and parametric equivalents are available from both Eaton and alternative manufacturers, with varying compliance certifications and electrical characteristics.

Key Parameters

Parameter	Value
Current Rating	315 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	5mm x 20mm
Response Time	Slow Blow
Breaking Capacity @ Rated Voltage	35A
Mounting Type	Requires Holder
Size / Dimension	0.205" Dia x 0.787" L (5.20mm x 20.00mm)

Substitute Part Grouping Explanation

Substitution of the BK/GMD-315MA is determined by strict equivalence across the following electrical and mechanical parameters: current rating (315 mA), voltage rating (250 V AC), fuse type (cartridge glass), package dimensions (5mm x 20mm), response time (slow blow), and breaking capacity (35A). All substitute parts listed maintain these core specifications, ensuring functional interchangeability within the circuit protection application.

Eaton-manufactured substitutes are grouped into two categories: direct manufacturer replacements (BK/GMD-315-R) and parametric equivalents across different series (BK/GDC-315MA, BK/S506-315-R, BK1/GMD-315-R, BK1/S506-315-R, GMD-315-R, S506-315-R). Alternative manufacturer substitutes from Littelfuse Inc. (0213.315MXP, 0218.315HXP, 0218.315TXP) maintain identical electrical ratings and mechanical form factors while offering different melting I²t characteristics and approval agency certifications.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating	Voltage Rating (AC)	Response Time	Breaking Capacity	Melting I²t	DC Cold Resistance (Ohms)	Product Status	RoHS Status
BK/GMD-315MA	Eaton	GMD	315 mA	250 V	Slow Blow	35A	0.89	Not Specified	Obsolete	Non-compliant
BK/GMD-315-R	Eaton	GMD	315 mA	250 V	Slow Blow	35A	0.89	2.4	Active	ROHS3 Compliant
BK/GDC-315MA	Eaton	GDC	315 mA	250 V	Slow Blow	35A	0.621	0.45	Active	RoHS Compliant
BK/S506-315-R	Eaton	S506	315 mA	250 V	Slow Blow	35A	0.621	0.45	Active	ROHS3 Compliant
BK1/GMD-315-R	Eaton	GMD	315 mA	250 V	Slow Blow	35A	0.89	2.4	Active	ROHS3 Compliant
BK1/S506-315-R	Eaton	S506	315 mA	250 V	Slow Blow	35A	0.621	0.45	Active	ROHS3 Compliant
GMD-315-R	Eaton	GMD	315 mA	250 V	Slow Blow	35A	0.89	2.4	Active	ROHS3 Compliant
S506-315-R	Eaton	S506	315 mA	250 V	Slow Blow	35A	0.621	0.45	Active	ROHS3 Compliant
0213.315MXP	Littelfuse Inc.	213	315 mA	250 V	Slow Blow	35A	1.14	0.8475	Active	ROHS3 Compliant
0218.315HXP	Littelfuse Inc.	218	315 mA	250 V	Slow Blow	35A	1.11	0.8475	Active	ROHS3 Compliant
0218.315TXP	Littelfuse Inc.	218	315 mA	250 V	Slow Blow	35A	1.11	0.8475	Active	ROHS3 Compliant

Engineering Selection Recommendations

Eaton Direct Replacements (Preferred for Eaton-based systems):

BK/GMD-315-R, BK1/GMD-315-R, and GMD-315-R represent direct series equivalents with identical melting I²t (0.89) and DC cold resistance (2.4 Ohms) to the original BK/GMD-315MA. All three are active products with ROHS3 compliance. These parts maintain CSA and UL approval agency certifications consistent with the original specification.

Eaton Parametric Equivalents (Lower DC Resistance):

BK/GDC-315MA, BK/S506-315-R, BK1/S506-315-R, and S506-315-R offer reduced melting I²t (0.621) and lower DC cold resistance (0.45 Ohms) compared to the GMD series. The GDC series carries cULus and IMQ certifications, while S506 series parts carry expanded international certifications (BSI, CCC, CSA, IMQ, SEMKO, UR, VDE). These parts are suitable for applications where lower resistance characteristics are acceptable.

Littelfuse Alternatives (Cross-manufacturer substitution):

0213.315MXP, 0218.315HXP, and 0218.315TXP from Littelfuse Inc. maintain the 315 mA, 250 V, 5mm x 20mm specification with higher melting I²t values (1.11–1.14) and elevated DC cold resistance (0.8475 Ohms). These parts carry expanded international certifications and operate across -55°C to 125°C temperature range. Selection of Littelfuse alternatives requires confirmation that circuit protection characteristics align with application requirements.

All substitute parts are active products with current manufacturing status and RoHS compliance, eliminating obsolescence risk associated with the original BK/GMD-315MA.

Frequently Asked Questions (FAQ)

Q: Can BK/GMD-315-R directly replace BK/GMD-315MA?

A: Yes. BK/GMD-315-R is the active direct replacement from Eaton, maintaining identical electrical ratings (315 mA, 250 V), response time (slow blow), breaking capacity (35A), and mechanical form factor (5mm x 20mm). The primary difference is product status (active versus obsolete) and RoHS compliance (ROHS3 versus non-compliant).

Q: What is the difference between GMD and S506 series fuses?

A: Both series maintain identical current rating, voltage rating, response time, and breaking capacity. The primary differences are melting I²t (GMD: 0.89 versus S506: 0.621) and DC cold resistance (GMD: 2.4 Ohms versus S506: 0.45 Ohms). S506 series carries broader international approval certifications (BSI, CCC, CSA, IMQ, SEMKO, UR, VDE) compared to GMD series (CSA, UL).

Q: Are Littelfuse 0213.315MXP and 0218.315HXP interchangeable with Eaton parts?

A: Both Littelfuse parts maintain the 315 mA, 250 V, 5mm x 20mm specification and 35A breaking capacity. However, melting I²t values differ (Littelfuse: 1.11–1.14 versus Eaton GMD: 0.89 versus Eaton S506: 0.621) and DC cold resistance is higher (Littelfuse: 0.8475 Ohms). Interchangeability depends on circuit protection requirements and whether the application tolerates these electrical characteristic variations.

Q: What does melting I²t indicate?

A: Melting I²t is the thermal energy required to melt the fuse element, expressed in ampere-squared seconds. Lower values indicate faster thermal response. Eaton S506 series (0.621) responds faster than GMD series (0.89), which responds faster than Littelfuse alternatives (1.11–1.14). Selection must align with circuit protection coordination requirements.

Q: Does the 5mm x 20mm form factor fit all standard fuse holders?

A: Yes. All substitute parts maintain the 5mm x 20mm mechanical specification (0.205" Dia x 0.787" L), ensuring physical compatibility with standard cartridge fuse holders. Mounting type remains "Requires Holder" across all substitutes.

Q: Which substitute offers the broadest international certification coverage?

A: BK/S506-315-R and S506-315-R carry the most extensive approval agency certifications: BSI, CCC, CSA, IMQ, SEMKO, UR, and VDE. These certifications support deployment across multiple international markets and regulatory jurisdictions.

Q: Is RoHS compliance mandatory for my application?

A: The original BK/GMD-315MA is RoHS non-compliant. All active substitutes (Eaton and Littelfuse) are ROHS3 compliant. If your application or supply chain requires RoHS compliance, any active substitute listed satisfies this requirement.

Q: Can I use BK/GDC-315MA as a drop-in replacement?

A: BK/GDC-315MA maintains identical current rating, voltage rating, response time, breaking capacity, and mechanical form factor. However, it exhibits lower melting I²t (0.621 versus 0.89) and significantly lower DC cold resistance (0.45 Ohms versus unspecified). Substitution is valid only if the circuit protection scheme accommodates these electrical characteristic changes.

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