GMD-1.25-R Equivalent & Substitute Parts

Part Overview

The GMD-1.25-R is a 1.25 A, 250 V AC/DC glass cartridge fuse with a 5mm x 20mm form factor manufactured by Eaton - Electronics Division. This slow-blow fuse cartridge requires a holder for installation and is designed for circuit protection applications requiring a 100 A breaking capacity at rated voltage. The part maintains Active product status and is RoHS3 compliant. Equivalent and substitute parts are identified to support procurement flexibility, inventory management, and application-specific performance requirements where parametric or functional compatibility exists.

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
Breaking Capacity @ Rated Voltage	100 A
Melting I²t	16
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the GMD-1.25-R are grouped based on strict parametric equivalence across the following criteria:

Primary Equivalence Parameters:

Current Rating: 1.25 A (exact match required)
Voltage Rating: 250 V AC (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Mounting Type: Requires Holder (exact match required)

Secondary Consideration Parameters:

Breaking Capacity @ Rated Voltage
Melting I²t
DC Cold Resistance
Approval Agency certifications
Operating Temperature range
RoHS compliance status

Parts are classified as Direct Manufacturer equivalents when manufactured by the same supplier with identical electrical and mechanical specifications. Parametric equivalents are parts from alternative manufacturers that meet all primary equivalence parameters. Similar parts meet primary parameters but may differ in secondary characteristics such as breaking capacity or melting I²t values.

Parameter Comparison

Part Number	Manufacturer	Current Rating (A)	Voltage (V AC)	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ohms)	Response Time	RoHS Status
GMD-1.25-R	Eaton	1.25	250	5x20mm	100	16	0.1995	Slow Blow	ROHS3
BK/GMD-1.25-R	Eaton	1.25	250	5x20mm	100	16	0.1995	Slow Blow	ROHS3
BK1/GMD-1.25-R	Eaton	1.25	250	5x20mm	100	16	0.1995	Slow Blow	ROHS3
BK/GDC-1.25A	Eaton	1.25	250	5x20mm	35	10.05	0.06	Slow Blow	ROHS3
GDC-1.25A	Eaton	1.25	250	5x20mm	35	10.05	0.06	Slow Blow	ROHS3
BK/S506-1.25-R	Eaton	1.25	250	5x20mm	35	10.05	0.06	Slow Blow	ROHS3
02391.25MXP	Littelfuse	1.25	250	5x20mm	100	19.525	0.198	Slow Blow	ROHS3
02131.25MXP	Littelfuse	1.25	250	5x20mm	35	27.15	0.0817	Slow Blow	ROHS3
0034.3118	SCHURTER	1.25	250	5x20mm	35	5.5	—	Slow Blow	ROHS3
0034.5044	SCHURTER	1.25	250	5x20mm	35	33.3	—	Slow Blow	ROHS3
0034.5618.11	SCHURTER	1.25	250	5x20mm	35	5.5	—	Slow Blow	ROHS3

Engineering Selection Recommendations

Direct Manufacturer Equivalents (Eaton - Electronics Division):

BK/GMD-1.25-R and BK1/GMD-1.25-R are direct equivalents to GMD-1.25-R with identical electrical and mechanical specifications. These parts share the same 100 A breaking capacity and 16 melting I²t rating. Selection among these three Eaton GMD series variants is based on packaging designation and inventory availability without performance differentiation.

Parametric Equivalents with Reduced Breaking Capacity (Eaton - Electronics Division):

BK/GDC-1.25A, GDC-1.25A, and BK/S506-1.25-R are parametric equivalents that maintain the 1.25 A current rating, 250 V voltage rating, and 5mm x 20mm package. These parts feature a reduced breaking capacity of 35 A and lower melting I²t of 10.05. Selection of these variants is appropriate for applications where the 35 A breaking capacity is sufficient and where the lower melting I²t provides faster response characteristics. Approval agencies differ: GDC series carries cULus, IMQ, and MITI/JET certifications, while S506 series carries broader international certifications including BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, and VDE.

Littelfuse Equivalents:

02391.25MXP (Series 239) matches the GMD-1.25-R with 100 A breaking capacity and operates across -55°C to 125°C. Melting I²t is 19.525, slightly elevated from the GMD reference. Approval agencies include CE, CSA, KC, PSE, and UL.

02131.25MXP (Series 213) provides a 35 A breaking capacity variant with extended operating temperature range of -55°C to 125°C and higher melting I²t of 27.15. Approval agencies include BSI, CCC, CE, CSA, PSE, SEMKO, UR, and VDE.

SCHURTER Equivalents:

0034.3118 (FST 5x20 series) and 0034.5618.11 (SMD-FST series) both feature 35 A breaking capacity and 5.5 melting I²t with operating temperature range of -55°C to 125°C. 0034.5044 (FTT 5x20 series) provides 35 A breaking capacity with higher melting I²t of 33.3 and operates across -40°C to 85°C. SCHURTER parts carry certifications from CCC, cURus, PSE/JET, and VDE.

Selection Basis:

Part selection is determined by application requirements for breaking capacity, melting I²t response characteristics, operating temperature range, and required approval agency certifications. All listed parts maintain RoHS3 compliance and the 5mm x 20mm cartridge form factor requiring a holder for installation.

Frequently Asked Questions (FAQ)

Q: Can BK/GMD-1.25-R be used as a direct replacement for GMD-1.25-R?

A: Yes. BK/GMD-1.25-R is a direct manufacturer equivalent with identical current rating, voltage rating, breaking capacity, melting I²t, DC cold resistance, and approval agencies. The parts are interchangeable without performance differentiation.

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

A: Both series maintain 1.25 A current rating and 250 V voltage rating in the 5mm x 20mm package. The GMD series provides 100 A breaking capacity with 16 melting I²t, while the GDC series provides 35 A breaking capacity with 10.05 melting I²t. Selection depends on the application's breaking capacity requirement and desired response speed.

Q: Can a 35 A breaking capacity fuse replace a 100 A breaking capacity fuse?

A: Breaking capacity is the maximum fault current the fuse can safely interrupt. A 35 A breaking capacity fuse cannot replace a 100 A breaking capacity fuse in applications where fault currents may exceed 35 A. The fuse may fail to interrupt the circuit safely. Application fault current analysis is required to determine the minimum acceptable breaking capacity.

Q: What does melting I²t indicate?

A: Melting I²t is a thermal characteristic that describes the fuse's response time to overcurrent. Lower melting I²t values indicate faster response to overcurrent conditions. Higher values indicate slower response. Selection is based on the application's tolerance for transient overcurrents and desired protection speed.

Q: Are SCHURTER fuses compatible with Eaton fuse holders?

A: All listed substitute parts maintain the 5mm x 20mm cartridge form factor and require a holder for installation. Physical compatibility with existing holders is determined by the holder's design specifications. Electrical compatibility is confirmed by matching current rating, voltage rating, and fuse type (cartridge, glass, slow-blow).

Q: What is the operating temperature range for GMD-1.25-R?

A: The GMD-1.25-R does not specify an operating temperature range in the provided data. Littelfuse and SCHURTER equivalents specify operating ranges of -55°C to 125°C or -40°C to 85°C depending on the series. Operating temperature requirements should be confirmed with application specifications before part selection.

Q: Do all substitute parts carry the same approval certifications?

A: No. Approval agencies vary by manufacturer and series. GMD-1.25-R carries CSA, PSE/JET, and UL certifications. Littelfuse 02391.25MXP carries CE, CSA, KC, PSE, and UL. SCHURTER parts carry CCC, cURus, PSE/JET, and VDE certifications. Application requirements for specific regional certifications must be verified before part selection.

Q: Is RoHS3 compliance consistent across all substitute parts?

A: Yes. All listed substitute parts maintain RoHS3 compliance status, confirming restriction of hazardous substances in accordance with applicable regulations.

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