5MF 250-R Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The 5MF 250-R is a 250 mA, 250 V AC/DC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc. in a 5mm x 20mm form factor. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing circuit protection applications. The fuse requires a holder for installation and is designed for applications requiring fast response time protection at the specified current and voltage ratings.

Key Parameters

Parameter	Value
Current Rating	250 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	5mm x 20mm
Response Time	Fast Blow
Mounting Type	Requires Holder
Operating Temperature Range	-55°C ~ 125°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 5MF 250-R is determined by strict alignment of the following parameters:

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

All substitute parts listed below meet these criteria. Variations in secondary parameters such as breaking capacity, melting I²t, DC cold resistance, and approval agencies do not disqualify substitution but may affect performance characteristics in specific applications.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Current Rating (A)	Voltage Rating (V AC)	Fuse Type	Package / Case	Response Time	Mounting Type	Breaking Capacity @ Rated Voltage	Melting I²t	DC Cold Resistance (Ω)	Product Status
5MF 250-R	Bel Fuse Inc.	0.250	250	Cartridge, Glass	5mm x 20mm	Fast Blow	Requires Holder	200A	0.016	1.47	Obsolete
0235.250MXP	Littelfuse Inc.	0.250	250	Cartridge, Glass	5mm x 20mm	Fast Blow	Requires Holder	35A	0.0166	2.25	Active
BK/GMA-250-R	Eaton - Electronics Division	0.250	250	Cartridge, Glass	5mm x 20mm	Fast Blow	Requires Holder	35A	0.018	1.735	Active
0034.1510	SCHURTER Inc.	0.250	250	Cartridge, Glass	5mm x 20mm	Fast Blow	Requires Holder	35A	0.0159	—	Active
0217.250HXP	Littelfuse Inc.	0.250	250	Cartridge, Glass	5mm x 20mm	Fast Blow	Requires Holder	35A	0.04	1.2325	Active
0235.250HXP	Littelfuse Inc.	0.250	250	Cartridge, Glass	5mm x 20mm	Fast Blow	Requires Holder	35A	0.0166	2.25	Active
S500-250-R	Eaton - Electronics Division	0.250	250	Cartridge, Glass	5mm x 20mm	Fast Blow	Requires Holder	35A	0.28	4.3	Active

Engineering Selection Recommendations

All listed substitute parts are active products with current manufacturing status, ensuring long-term availability and supply chain reliability. Selection among these equivalents should be based on:

Compliance and Certification Requirements: The 5MF 250-R carries CE, CSA, and cULus approvals. Substitute parts offer varying certification portfolios. The 0217.250HXP provides the broadest certification coverage (CCC, CE, CSA, K-MARK, SEMKO, UL, VDE), while BK/GMA-250-R carries CSA, PSE, and UL approvals. Verify that the selected substitute meets the specific regulatory requirements of your application.

Availability and Inventory: Current stock levels vary across manufacturers. Littelfuse parts (0235.250MXP, 0217.250HXP, 0235.250HXP) and Eaton parts (BK/GMA-250-R, S500-250-R) maintain substantial inventory positions, supporting consistent supply.

Secondary Performance Parameters: While all parts meet the core substitution criteria, differences in breaking capacity, melting I²t, and DC cold resistance exist. The original 5MF 250-R specifies 200A breaking capacity and 0.016 melting I²t. Most active substitutes provide 35A breaking capacity with comparable melting I²t values (0.0159 to 0.0166), with the exception of S500-250-R (0.28 melting I²t). These variations do not affect basic circuit protection function but may influence performance in high-fault-current environments.

Frequently Asked Questions (FAQ)

Q: Can I use any of these substitute parts directly in place of the 5MF 250-R?

A: Yes. All listed parts meet the core electrical and mechanical parameters: 250 mA current rating, 250 V AC voltage rating, fast-blow response, 5mm x 20mm package, and holder-mount configuration. Physical installation is identical.

Q: What is the difference between "Direct" and "Similar" substitute classifications?

A: Direct substitutes (0235.250MXP, BK/GMA-250-R) are explicitly listed in the 5MF 250-R substitution cross-reference. Similar substitutes (0034.1510, 0217.250HXP, 0235.250HXP, S500-250-R) meet all core parameter requirements but are not explicitly cross-referenced. Both categories are electrically and mechanically compatible.

Q: Why do breaking capacity values differ between the original part and substitutes?

A: The 5MF 250-R specifies 200A breaking capacity, while most active substitutes specify 35A. Both values are valid for the 250 mA, 250 V rating. Breaking capacity indicates the maximum fault current the fuse can safely interrupt. Selection depends on your circuit's maximum available fault current. Consult your application's fault analysis to determine the required breaking capacity.

Q: Does the difference in melting I²t affect compatibility?

A: Melting I²t is a thermal characteristic that influences fuse response time under specific fault conditions. The 5MF 250-R specifies 0.016, while substitutes range from 0.0159 to 0.28. Variations within this range do not affect basic circuit protection function. If your application has strict thermal coordination requirements, verify that the selected substitute's melting I²t is acceptable for your system design.

Q: Are there mounting differences between these parts?

A: The 5MF 250-R and all direct/similar substitutes require a fuse holder for installation. One variant, 0034.1510.PT, features through-hole axial mounting (5.40mm diameter, 22.50mm length) and is not compatible with standard 5mm x 20mm holders. Use only 0034.1510 (not .PT variant) for direct holder compatibility.

Q: Which substitute offers the best regulatory coverage?

A: The 0217.250HXP (Littelfuse 217 series) carries the broadest certification portfolio: CCC, CE, CSA, K-MARK, SEMKO, UL, and VDE. Select this part if your application requires multiple regional certifications.

Q: Can I mix different substitute parts in the same circuit?

A: Yes, provided all parts meet your application's electrical, mechanical, and regulatory requirements. However, for consistency and simplified inventory management, using a single substitute part number across identical circuit positions is recommended.

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