BK/GMD-500MA Equivalent & Substitute Parts

Part Overview

The BK/GMD-500MA is a 500 mA, 250 V AC/DC slow-blow glass cartridge fuse with a 5mm x 20mm form factor, manufactured by Eaton - Electronics Division. This part is classified as obsolete and requires a fuse holder for installation. Due to its obsolete status, direct replacement with active product alternatives is necessary for new designs and ongoing procurement requirements. Substitute parts maintain identical electrical ratings and mechanical dimensions while offering improved availability and compliance certifications.

Key Parameters

Parameter	Value
Current Rating	500 mA
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Package / Case	5mm x 20mm
Fuse Type	Cartridge, Glass
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	35 A

Substitute Part Grouping Explanation

Substitution of the BK/GMD-500MA is determined by strict equivalence across the following parameters: current rating (500 mA), voltage rating (250 V AC), response time (slow blow), physical dimensions (5mm x 20mm), and breaking capacity (35 A). All substitute parts listed maintain these core electrical and mechanical specifications, ensuring direct functional compatibility within existing fuse holder assemblies.

Substitute parts are grouped into two categories:

Eaton - Electronics Division (Same Manufacturer): Parts BK/GMD-500-R, BK/GDC-500MA, BK1/GMD-500-R, GDC-500MA, GMD-500-R, BK/S506-500-R, and S506-500-R provide direct substitution with active product status and improved compliance certifications.

Cross-Manufacturer Alternatives (Littelfuse Inc.): Parts 0239.500MXP, 0239.500TXP, and 0239.500VXP offer equivalent electrical and mechanical performance from an alternative manufacturer, with extended operating temperature range (-55°C to 125°C) and active product status.

Parameter Comparison

Part Number	Manufacturer	Current Rating	Voltage Rating (AC)	Response Time	Package	Breaking Capacity	Product Status	RoHS Status
BK/GMD-500MA	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Obsolete	Non-compliant
BK/GMD-500-R	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
BK/GDC-500MA	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
BK/S506-500-R	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
BK1/GMD-500-R	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
GDC-500MA	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	Not Specified
GMD-500-R	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
S506-500-R	Eaton	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
0239.500MXP	Littelfuse	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
0239.500TXP	Littelfuse	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant
0239.500VXP	Littelfuse	500 mA	250 V	Slow Blow	5mm x 20mm	35 A	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: BK/GMD-500-R (Eaton - Electronics Division)

The BK/GMD-500-R is the direct active equivalent of the obsolete BK/GMD-500MA, maintaining identical electrical specifications and mechanical form factor. This part carries active product status, ROHS3 compliance, and CSA/UL approval certifications matching the original design requirements. Bulk packaging availability (1585 units in stock) supports production requirements.

Secondary Recommendation: BK/S506-500-R (Eaton - Electronics Division)

The BK/S506-500-R provides equivalent electrical and mechanical performance with expanded approval certifications (BSI, CCC, CSA, cULus, IMQ, SEMKO, VDE), offering broader international compliance coverage. This part is suitable for applications requiring multi-regional regulatory acceptance.

Cross-Manufacturer Alternative: 0239.500MXP (Littelfuse Inc.)

The 0239.500MXP series fuse from Littelfuse provides functional equivalence with extended operating temperature range (-55°C to 125°C) and active product status. This option is appropriate for applications requiring broader temperature performance or where Littelfuse supply chain integration is preferred. ROHS3 compliance and CSA/UL/CE/KC certifications are provided.

All substitute parts maintain the 5mm x 20mm physical dimensions and require the same fuse holder assemblies as the original BK/GMD-500MA.

Frequently Asked Questions (FAQ)

Q: Can BK/GMD-500-R be used as a direct replacement for BK/GMD-500MA?

A: Yes. The BK/GMD-500-R maintains identical current rating (500 mA), voltage rating (250 V AC), response time (slow blow), physical dimensions (5mm x 20mm), and breaking capacity (35 A). Both parts require the same fuse holder and are mechanically and electrically interchangeable.

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

A: Both series maintain identical electrical ratings and mechanical dimensions for the 500 mA, 250 V specification. The GDC series carries different approval certifications (cULus, IMQ) compared to GMD (CSA, UL). Selection between series depends on required regulatory certifications for the application.

Q: Are Littelfuse 0239 series fuses compatible with existing Eaton fuse holders?

A: Yes. The Littelfuse 0239.500MXP, 0239.500TXP, and 0239.500VXP fuses maintain the 5mm x 20mm form factor and are mechanically compatible with standard fuse holders designed for this package size. Electrical performance is equivalent across all substitute options.

Q: What is the significance of the melting I²t parameter?

A: The melting I²t value indicates the thermal energy required to melt the fuse element. While substitute parts maintain the same current rating and response time classification, variations in melting I²t (ranging from 0.827 to 1.985 across the substitute list) reflect differences in fuse element design. All values remain within acceptable ranges for 500 mA slow-blow cartridge fuses and do not affect functional compatibility in standard applications.

Q: Which substitute part offers the widest operating temperature range?

A: The Littelfuse 0239 series (0239.500MXP, 0239.500TXP, 0239.500VXP) provides an operating temperature range of -55°C to 125°C, compared to unspecified operating temperature ranges for Eaton parts. This extended range is suitable for applications subject to extreme environmental conditions.

Q: Is RoHS3 compliance required for all substitute selections?

A: The original BK/GMD-500MA is RoHS non-compliant. Most active substitute parts (BK/GMD-500-R, BK/GDC-500MA, BK/S506-500-R, BK1/GMD-500-R, GMD-500-R, S506-500-R, and all Littelfuse 0239 series) are ROHS3 compliant. Selection of RoHS-compliant alternatives is recommended for new designs and applications subject to RoHS regulatory requirements.

Q: Can substitute parts be mixed within the same circuit or assembly?

A: Yes. All substitute parts maintain identical electrical ratings and mechanical dimensions. However, for consistency in procurement, testing, and documentation, using a single substitute part number throughout an assembly is recommended.

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