Equivalent & Substitute Parts for 5ST 250 Glass Cartridge Fuse

Part Overview

The Bel Fuse Inc. 5ST 250 is a 250 mA, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm form factor, designed for applications requiring overcurrent protection in low-voltage circuits. This part is classified as obsolete, necessitating identification of active equivalent and substitute components that maintain functional compatibility within the specified electrical and mechanical parameters.

Key Parameters

Parameter	Value
Current Rating	250 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	5mm x 20mm
Mounting Type	Requires Holder
Operating Temperature Range	-55°C ~ 125°C
Breaking Capacity @ Rated Voltage	35A

Substitute Part Grouping Explanation

Substitution of the 5ST 250 is determined by strict equivalence across the following critical parameters: current rating (250 mA), voltage rating (250 V AC), fuse type (cartridge glass), response time (slow blow), and physical package (5mm x 20mm). All substitute parts must maintain these core electrical and mechanical specifications to ensure functional compatibility within the original circuit application.

Substitute parts are categorized as follows:

Direct Manufacturer Equivalents: Parts with identical electrical specifications and active product status, differing only in packaging or minor manufacturing revisions.

Parametric Equivalents: Parts with identical core electrical parameters but different breaking capacity or melting I²t characteristics, suitable for applications where these secondary parameters do not impose circuit constraints.

Similar Parts: Components with matching primary electrical and mechanical parameters but variations in operating temperature range, DC cold resistance, or melting I²t that may require application-level verification.

Parameter Comparison

Part Number	Manufacturer	Current Rating (mA)	Voltage (V AC)	Response Time	Package	Breaking Capacity (A)	Melting I²t	Operating Temp (°C)	Product Status	RoHS Status
5ST 250	Bel Fuse Inc.	250	250	Slow Blow	5x20mm	35	0.26	-55 ~ 125	Obsolete	Non-compliant
5ST 250-R	Bel Fuse Inc.	250	250	Slow Blow	5x20mm	35	0.26	-55 ~ 125	Active	ROHS3 Compliant
5TT 250-R	Bel Fuse Inc.	250	250	Slow Blow	5x20mm	100	0.719	-55 ~ 125	Active	ROHS3 Compliant
0034.3111	SCHURTER Inc.	250	250	Slow Blow	5x20mm	35	0.238	-55 ~ 125	Active	ROHS3 Compliant
0218.250MXBP	Littelfuse Inc.	250	250	Slow Blow	5x20mm	35	0.5405	-55 ~ 125	Active	ROHS3 Compliant
0218.250MXP	Littelfuse Inc.	250	250	Slow Blow	5x20mm	35	0.5405	-55 ~ 125	Active	ROHS3 Compliant
0218.250TXP	Littelfuse Inc.	250	250	Slow Blow	5x20mm	35	0.5405	-55 ~ 125	Active	ROHS3 Compliant
0218.250VXP	Littelfuse Inc.	250	250	Slow Blow	5x20mm	35	0.5405	-55 ~ 125	Active	ROHS3 Compliant
0034.3768	SCHURTER Inc.	250	250	Slow Blow	5x20mm	35	0.29	-40 ~ 85	Active	ROHS3 Compliant
0218.250HXP	Littelfuse Inc.	250	250	Slow Blow	5x20mm	35	0.5405	-55 ~ 125	Active	ROHS3 Compliant
0239.250HXP	Littelfuse Inc.	250	250	Slow Blow	5x20mm	35	0.34	-55 ~ 125	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: 5ST 250-R (Bel Fuse Inc.) is the direct active equivalent of the obsolete 5ST 250, maintaining identical electrical specifications, breaking capacity, and melting I²t characteristics. This part carries ROHS3 compliance and active product status, making it the preferred replacement for direct substitution.

Alternative Direct Equivalents: The Littelfuse 0218.250MXBP, 0218.250MXP, 0218.250TXP, and 0218.250VXP all meet the core electrical and mechanical requirements with identical current, voltage, and package specifications. These parts carry broader international certifications (CCC, CE, CSA, KC, SEMKO, UL, VDE) and are suitable for applications requiring multi-regional compliance.

Secondary Equivalent: SCHURTER 0034.3111 provides functional equivalence with matching electrical parameters and breaking capacity. This part is suitable for applications where SCHURTER component qualification is required.

Parametric Alternative: Bel Fuse 5TT 250-R maintains identical electrical ratings but features increased breaking capacity (100A vs. 35A) and higher melting I²t (0.719 vs. 0.26). This part is suitable only for applications where higher breaking capacity does not introduce unintended circuit behavior.

Temperature-Constrained Alternative: SCHURTER 0034.3768 operates within a reduced temperature range (-40°C to 85°C) compared to the standard range (-55°C to 125°C). Selection of this part requires confirmation that the application does not require full temperature range coverage.

Frequently Asked Questions (FAQ)

Q: Can the 5ST 250-R directly replace the obsolete 5ST 250?

A: Yes. The 5ST 250-R is the direct active equivalent, maintaining identical current rating (250 mA), voltage rating (250 V AC), response time (slow blow), package (5mm x 20mm), breaking capacity (35A), and melting I²t (0.26). It is the recommended replacement.

Q: What is the difference between the Littelfuse 0218.250MXBP and 0218.250MXP variants?

A: Both parts are electrically and mechanically identical, with matching current, voltage, package, and thermal characteristics. The designation difference reflects packaging or manufacturing revision. Both are suitable for direct substitution.

Q: Can the 5TT 250-R be used as a substitute for the 5ST 250?

A: The 5TT 250-R maintains identical current, voltage, and package specifications but differs in breaking capacity (100A vs. 35A) and melting I²t (0.719 vs. 0.26). Substitution is permissible only if the application does not require the specific breaking capacity and thermal characteristics of the original part.

Q: Does the SCHURTER 0034.3768 have any limitations compared to other substitutes?

A: The 0034.3768 operates within a reduced temperature range (-40°C to 85°C) versus the standard -55°C to 125°C. It is suitable only for applications that do not require operation at the full temperature extremes.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts listed carry ROHS3 compliance. The original 5ST 250 is RoHS non-compliant. Substitution with any active equivalent automatically upgrades compliance status.

Q: What certifications should I prioritize when selecting a substitute?

A: Selection depends on regional requirements. The 5ST 250-R carries CCC, CE, CSA, cURus, IMQ, SEMKO, and VDE certifications. Littelfuse variants (0218 series) carry CCC, CE, CSA, K-MARK, SEMKO, and UL certifications. SCHURTER 0034.3111 carries CCC, cURus, and VDE certifications. Confirm that the selected part's certification portfolio meets your application's regulatory requirements.

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