GMD-2A Glass Cartridge Fuse 1.25A 250VAC 5x20mm Equivalent & Substitute Parts

Part Overview

The GMD-2A is a 1.25 A, 250 V AC/DC glass cartridge fuse manufactured by Eaton - Electronics Division. This slow-blow fuse cartridge requires a holder and is housed in a 5mm x 20mm package. The part is currently in active production with 937 pieces in new original stock inventory. Glass cartridge fuses of this specification are essential protective components in electrical circuits where overcurrent protection and circuit isolation are required. Equivalent and substitute parts are identified based on matching electrical ratings, mechanical dimensions, response characteristics, and regulatory compliance standards.

Key Parameters

Parameter	Value
Manufacturer Part Number	GMD-2A
Manufacturer	Eaton - Electronics Division
Series	GMD
Current Rating	1.25 A
Voltage Rating - AC	250 V
Fuse Type	Cartridge, Glass
Package / Case	5mm x 20mm
Response Time	Slow Blow
Mounting Type	Requires Holder
Product Status	Active

Substitute Part Grouping Explanation

Substitution of the GMD-2A is determined by the following critical parameters:

Electrical Equivalence Requirements:

Current Rating: 1.25 A (exact match required)
Voltage Rating - AC: 250 V (exact match required)
Response Time: Slow Blow (exact match required)

Mechanical Compatibility Requirements:

Package / Case: 5mm x 20mm (exact match required)
Mounting Type: Requires Holder (exact match required)
Fuse Type: Cartridge, Glass (exact match required)

Substitute parts are grouped into two categories based on these parameters:

Category 1: Direct Parametric Equivalents Parts that match all electrical and mechanical parameters with the GMD-2A. These parts differ only in manufacturer, series designation, or internal specifications such as breaking capacity, melting I²t, or DC cold resistance. These variations do not affect functional interchangeability in standard applications.

Category 2: Functional Equivalents from Alternative Manufacturers Parts from manufacturers other than Eaton that meet all electrical and mechanical requirements. These parts provide equivalent circuit protection performance within the specified electrical and mechanical constraints.

Parameter Comparison

Part Number	Manufacturer	Series	Current Rating (A)	Voltage Rating - AC (V)	Response Time	Package / Case	Breaking Capacity @ Rated Voltage (A)	Melting I²t	DC Cold Resistance (Ohms)	RoHS Status
GMD-2A	Eaton - Electronics Division	GMD	1.25	250	Slow Blow	5mm x 20mm	100	Not Specified	Not Specified	Not Specified
BK/GDC-1.25A	Eaton - Electronics Division	GDC	1.25	250	Slow Blow	5mm x 20mm	35	10.05	0.06	ROHS3 Compliant
BK/GMD-1.25-R	Eaton - Electronics Division	GMD	1.25	250	Slow Blow	5mm x 20mm	100	16	0.1995	ROHS3 Compliant
BK/S506-1.25-R	Eaton - Electronics Division	S506	1.25	250	Slow Blow	5mm x 20mm	35	10.05	0.06	ROHS3 Compliant
BK1/GMD-1.25-R	Eaton - Electronics Division	GMD	1.25	250	Slow Blow	5mm x 20mm	100	16	0.1995	ROHS3 Compliant
GDC-1.25A	Eaton - Electronics Division	GDC	1.25	250	Slow Blow	5mm x 20mm	35	10.05	0.06	Not Specified
GMD-1.25-R	Eaton - Electronics Division	GMD	1.25	250	Slow Blow	5mm x 20mm	100	16	0.1995	ROHS3 Compliant
S506-1.25-R	Eaton - Electronics Division	S506	1.25	250	Slow Blow	5mm x 20mm	35	10.05	0.06	ROHS3 Compliant
0034.3118	SCHURTER Inc.	FST 5x20	1.25	250	Slow Blow	5mm x 20mm	35	5.5	Not Specified	ROHS3 Compliant
0034.3776	SCHURTER Inc.	FSL 5x20	1.25	250	Slow Blow	5mm x 20mm	100	1.54	Not Specified	ROHS3 Compliant

Engineering Selection Recommendations

Eaton GMD Series (Direct Manufacturer Match): Parts BK/GMD-1.25-R, BK1/GMD-1.25-R, and GMD-1.25-R are direct series equivalents from Eaton - Electronics Division. These parts maintain the GMD series designation and provide 100A breaking capacity at rated voltage. All variants are ROHS3 compliant and carry CSA, PSE/JET, and UL approvals. These parts are recommended for applications requiring continuity with the original GMD-2A specification and certification profile.

Eaton Alternative Series (GDC and S506): Parts BK/GDC-1.25A, GDC-1.25A, BK/S506-1.25-R, and S506-1.25-R are parametric equivalents from Eaton with reduced breaking capacity (35A at rated voltage). The GDC series carries cURus, IMQ, and MITI/JET approvals. The S506 series carries broader international approvals including BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, and VDE. These parts are suitable for applications where the lower breaking capacity is acceptable and where the expanded certification profile is beneficial.

SCHURTER Inc. Alternatives: Parts 0034.3118 (FST 5x20 series) and 0034.3776 (FSL 5x20 series) are functional equivalents from SCHURTER Inc. The FST series (0034.3118) carries CCC, cURus, PSE/JET, and VDE approvals with operating temperature range -55°C to 125°C. The FSL series (0034.3776) carries cULus approval with operating temperature range -40°C to 85°C and 100A breaking capacity. These parts are suitable for applications where SCHURTER certification and supply chain diversity are required.

Frequently Asked Questions (FAQ)

Q: Can I substitute GMD-2A with a different current rating fuse? A: No. The current rating must remain 1.25 A. Substituting with a different current rating will alter circuit protection characteristics and violate the electrical design specification.

Q: What is the significance of breaking capacity differences between substitute parts? A: Breaking capacity indicates the maximum fault current the fuse can safely interrupt. The GMD-2A specification does not provide breaking capacity data. Substitute parts with 100A breaking capacity (GMD series and SCHURTER FSL series) provide higher fault current handling than those with 35A breaking capacity (GDC and S506 series). Selection depends on the actual fault current levels in the application circuit.

Q: Are all substitute parts physically compatible with GMD-2A holders? A: Yes. All substitute parts maintain the 5mm x 20mm package dimension and require a holder for mounting. Physical installation compatibility is confirmed across all listed substitutes.

Q: What is the difference between Slow Blow and other fuse response types? A: Slow Blow fuses tolerate temporary current surges and inrush currents before opening. All listed substitutes maintain the Slow Blow characteristic, ensuring equivalent response behavior to the GMD-2A.

Q: Can I use SCHURTER parts as direct replacements for Eaton parts? A: Yes, provided the application does not require specific Eaton certifications. SCHURTER parts 0034.3118 and 0034.3776 meet all electrical and mechanical parameters. Verify that the application's regulatory requirements do not mandate Eaton-specific approvals.

Q: What does ROHS3 compliance mean? A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, mercury, cadmium, and other hazardous materials. Most substitute parts carry ROHS3 compliance, supporting environmental and regulatory requirements.

Q: How do I determine which substitute part is best for my application? A: Selection criteria include: (1) Required certifications and approvals for your market; (2) Breaking capacity requirements based on circuit fault current levels; (3) Operating temperature range requirements; (4) Supply chain and inventory availability; (5) Cost considerations. All listed parts meet the core electrical and mechanical requirements of the GMD-2A.

Q: What is melting I²t and why does it vary between substitutes? A: Melting I²t is a measure of the thermal energy required to melt the fuse element. Lower values indicate faster response to overcurrent. Variations in melting I²t between substitutes reflect different internal element designs but do not affect compatibility in standard applications where the 1.25 A rating and Slow Blow response are the controlling factors.

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