GMD-3A Equivalent & Substitute Parts

Part Overview

The GMD-3A is a 1.25 A 250 V AC DC fuse cartridge manufactured by Eaton - Electronics Division. This glass fuse operates in a 5mm x 20mm form factor and requires a compatible holder for installation. The part is currently in stock with 981 pieces available. Equivalent and substitute parts are identified based on matching electrical ratings, mechanical dimensions, and functional characteristics to ensure direct interchangeability in circuit protection applications.

Key Parameters

Parameter	Value
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
Size / Dimension	0.205" Dia x 0.787" L (5.20mm x 20.00mm)

Substitute Part Grouping Explanation

Substitution of the GMD-3A is determined by equivalence in the following critical parameters:

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

All substitute parts listed maintain these core electrical and mechanical specifications. Variations in breaking capacity, melting I²t, DC cold resistance, and approval agencies do not prevent functional substitution when the above parameters are identical. Parts are grouped by manufacturer and series designation.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Series	Current Rating (A)	Voltage Rating - AC (V)	Fuse Type	Package / Case	Response Time	Breaking Capacity @ Rated Voltage (A)	Melting I²t	DC Cold Resistance (Ohms)	Approval Agency	Inventory (Pcs)
GMD-3A	Eaton - Electronics Division	GMD	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	100	16	0.1995	CSA, PSE/JET, UL	981
BK/GDC-1.25A	Eaton - Electronics Division	GDC	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	35	10.05	0.06	cULus, IMQ, MITI/JET	1775
BK/GMD-1.25-R	Eaton - Electronics Division	GMD	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	100	16	0.1995	CSA, PSE/JET, UL	1115
BK/S506-1.25-R	Eaton - Electronics Division	S506	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	35	10.05	0.06	BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, VDE	2930
BK1/GMD-1.25-R	Eaton - Electronics Division	GMD	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	100	16	0.1995	CSA, PSE/JET, UL	1859
GDC-1.25A	Eaton - Electronics Division	GDC	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	35	10.05	0.06	cURus, IMQ, MITI/JET	975
GMD-1.25-R	Eaton - Electronics Division	GMD	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	100	16	0.1995	CSA, PSE/JET, UL	926
S506-1.25-R	Eaton - Electronics Division	S506	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	35	10.05	0.06	BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, VDE	624
0034.3118	SCHURTER Inc.	FST 5x20	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	35	5.5	Not Provided	CCC, cURus, PSE/JET, VDE	13782
0034.3776	SCHURTER Inc.	FSL 5x20	1.25	250	Cartridge, Glass	5mm x 20mm	Slow Blow	100	1.54	Not Provided	cULus	631

Engineering Selection Recommendations

All listed substitute parts maintain electrical and mechanical compatibility with the GMD-3A based on matching current rating, voltage rating, fuse type, and package dimensions. Selection among equivalent parts should be based on the following factors:

Eaton - Electronics Division GMD Series: Parts BK/GMD-1.25-R, BK1/GMD-1.25-R, and GMD-1.25-R provide direct series equivalence with identical breaking capacity (100 A) and melting I²t (16). These parts carry CSA, PSE/JET, and UL approvals consistent with the main part.

Eaton - Electronics Division GDC Series: Parts BK/GDC-1.25A and GDC-1.25A are functionally equivalent with lower breaking capacity (35 A) and melting I²t (10.05). These parts carry cULus, IMQ, and MITI/JET approvals.

Eaton - Electronics Division S506 Series: Parts BK/S506-1.25-R and S506-1.25-R provide broad international approval coverage including BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, and VDE. Breaking capacity is 35 A with melting I²t of 10.05.

SCHURTER Inc. FST 5x20 Series: Part 0034.3118 is a cross-manufacturer equivalent with CCC, cURus, PSE/JET, and VDE approvals. Operating temperature range is specified as -55°C to 125°C. Breaking capacity is 35 A with melting I²t of 5.5.

SCHURTER Inc. FSL 5x20 Series: Part 0034.3776 is a cross-manufacturer equivalent with cULus approval. Operating temperature range is specified as -40°C to 85°C. Breaking capacity is 100 A with melting I²t of 1.54.

Selection should account for required approval agencies for the target application and any specific breaking capacity or thermal characteristics required by the circuit design.

Frequently Asked Questions (FAQ)

Q: Can I substitute the GMD-3A with any of the listed parts?

A: All listed parts are electrically and mechanically equivalent to the GMD-3A. They share identical current rating (1.25 A), voltage rating (250 V AC), fuse type (Cartridge, Glass), and package dimensions (5mm x 20mm). Substitution is valid from a functional standpoint. Approval agency requirements for your specific application should be verified.

Q: What is the difference between the Eaton GMD series and GDC series?

A: Both series maintain identical electrical ratings and package dimensions. The GMD series has a breaking capacity of 100 A and melting I²t of 16. The GDC series has a breaking capacity of 35 A and melting I²t of 10.05. Approval agencies differ between the two series.

Q: Are SCHURTER parts direct replacements for Eaton parts?

A: SCHURTER parts 0034.3118 and 0034.3776 are functionally equivalent to the GMD-3A in terms of current rating, voltage rating, fuse type, and package dimensions. However, they are manufactured by a different company and carry different approval agencies. Verify that SCHURTER approvals meet your application requirements before substitution.

Q: What does "Requires Holder" mean?

A: All listed parts are cartridge fuses that must be installed in a compatible fuse holder. The fuse itself does not include a holder. Ensure your application uses a 5mm x 20mm fuse holder rated for 250 V AC operation.

Q: Why do some parts have different melting I²t values?

A: Melting I²t is a thermal characteristic that affects the speed at which the fuse element melts under overcurrent conditions. While all listed parts are classified as Slow Blow fuses, variations in melting I²t reflect differences in fuse element design between manufacturers and series. This parameter does not prevent substitution but may affect circuit protection response characteristics.

Q: Which substitute part has the highest inventory availability?

A: SCHURTER Inc. part 0034.3118 (FST 5x20 series) has the highest inventory with 13,782 pieces in stock.

Q: Do all substitute parts have RoHS3 compliance?

A: RoHS3 compliance is confirmed for all Eaton parts and SCHURTER parts listed. This information is provided in the detailed specifications for each part.

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