Equivalent & Substitute Parts for 5MT 2.5-R Glass Cartridge Fuse

Part Overview

The Bel Fuse Inc. 5MT 2.5-R is a 2.5 A, 250 V AC/DC glass cartridge fuse with a 5mm x 20mm form factor and medium blow response time. This part is classified as obsolete. Due to its discontinued status, equivalent substitute parts from active manufacturers are necessary to maintain system functionality and ensure continued availability for new designs and field replacements.

Key Parameters

Parameter	Value
Current Rating	2.5 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	5mm x 20mm
Mounting Type	Requires Holder
Response Time	Medium Blow
Breaking Capacity @ Rated Voltage	100 A
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitution for the 5MT 2.5-R is determined by strict equivalence across the following parameters:

Current Rating: 2.5 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)
Mounting Type: Requires Holder (exact match required)

Substitute parts are grouped into two categories based on response time characteristics:

Medium Blow Substitutes: Parts with medium blow response time matching the original 5MT 2.5-R specification. These provide direct functional equivalence.

Slow Blow Substitutes: Parts with slow blow response time. These differ in response characteristics and melting I²t values but maintain all other core electrical and mechanical parameters. Selection of slow blow alternatives requires circuit-level evaluation.

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage (V AC)	Response Time	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ω)	Product Status
5MT 2.5-R	Bel Fuse Inc.	2.5	250	Medium Blow	5mm x 20mm	100	35	0.039	Obsolete
023402.5MXP	Littelfuse Inc.	2.5	250	Medium Blow	5mm x 20mm	100	17.045	0.0521	Active
023202.5MXP	Littelfuse Inc.	2.5	250	Medium Blow	5mm x 20mm	100	13.875	0.0291	Active
BK1/GMC-2.5-R	Eaton - Electronics Division	2.5	250	Medium Blow	5mm x 20mm	100	13	0.035	Active
021802.5HXP	Littelfuse	2.5	250	Slow Blow	5mm x 20mm	35	23.25	0.0219	Active
021802.5TXP	Littelfuse Inc.	2.5	250	Slow Blow	5mm x 20mm	35	23.25	0.0219	Active
BK1/GMD-2.5-R	Eaton - Electronics Division	2.5	250	Slow Blow	5mm x 20mm	100	94	0.0905	Active
GDC-2.5A	Eaton - Electronics Division	2.5	250	Slow Blow	5mm x 20mm	35	59.4	0.0255	Active

Engineering Selection Recommendations

Primary Substitutes (Medium Blow, Direct Equivalence):

The 023402.5MXP (Littelfuse Inc., Series 234) and BK1/GMC-2.5-R (Eaton - Electronics Division, Series GMC) are active production parts with medium blow response time matching the original 5MT 2.5-R specification. Both maintain 100 A breaking capacity and are certified to CE, CSA, and UL standards. The 023402.5MXP carries additional K-MARK and PSE approvals. The 023202.5MXP (Littelfuse Inc., Series 232) is also medium blow with 100 A breaking capacity and CE, KC, PSE certifications.

Secondary Substitutes (Slow Blow, Response Time Variation):

The 021802.5HXP, 021802.5TXP (Littelfuse, Series 218), BK1/GMD-2.5-R (Eaton, Series GMD), and GDC-2.5A (Eaton, Series GDC) are slow blow alternatives. These parts differ in response characteristics and melting I²t values. The 021802.5HXP and 021802.5TXP feature 35 A breaking capacity, while BK1/GMD-2.5-R maintains 100 A breaking capacity. The GDC-2.5A also provides 35 A breaking capacity. Slow blow substitutes are suitable only where circuit protection requirements explicitly call for delayed response characteristics.

All substitute parts are ROHS3 compliant and operate across the -55°C to 125°C temperature range.

Frequently Asked Questions (FAQ)

Q: Can I use a slow blow fuse as a direct replacement for the medium blow 5MT 2.5-R?

A: Slow blow and medium blow fuses have different response time characteristics and melting I²t values. Substitution requires verification that the circuit protection scheme accommodates the delayed response time of slow blow fuses. Direct replacement without circuit evaluation is not recommended.

Q: Are all substitute parts mechanically compatible with the original 5mm x 20mm holder?

A: Yes. All listed substitute parts maintain the 5mm x 20mm form factor and require a holder for mounting, matching the mechanical requirements of the 5MT 2.5-R.

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 at rated voltage. The 5MT 2.5-R specifies 100 A breaking capacity. Substitute parts with 100 A breaking capacity (023402.5MXP, 023202.5MXP, BK1/GMC-2.5-R, BK1/GMD-2.5-R) provide equivalent fault protection capability. Parts with 35 A breaking capacity (021802.5HXP, 021802.5TXP, GDC-2.5A) have reduced fault interruption capability and require circuit-level assessment.

Q: Which substitute offers the best certification coverage?

A: The 021802.5HXP carries the broadest approval agency coverage: CCC, CE, CSA, K-MARK, PSE, SEMKO, UL, and VDE. The 021802.5TXP adds KC certification. For applications requiring specific regional certifications, verify the substitute part's approval list against your compliance requirements.

Q: How do melting I²t values affect fuse selection?

A: Melting I²t characterizes the thermal energy required to melt the fuse element. The 5MT 2.5-R specifies 35 I²t. Substitute parts vary: 023402.5MXP (17.045), 023202.5MXP (13.875), BK1/GMC-2.5-R (13), 021802.5HXP and 021802.5TXP (23.25), BK1/GMD-2.5-R (94), and GDC-2.5A (59.4). Lower I²t values indicate faster response to overcurrent conditions. Selection must align with circuit protection requirements.

Q: Is the obsolete status of the 5MT 2.5-R a concern for new designs?

A: Yes. The 5MT 2.5-R is no longer in production. For new designs, select from active production substitutes: 023402.5MXP, 023202.5MXP, BK1/GMC-2.5-R (medium blow), or 021802.5HXP, 021802.5TXP, BK1/GMD-2.5-R, GDC-2.5A (slow blow).

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