Bel Fuse Inc. 5ST 5 Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The Bel Fuse Inc. 5ST 5 is a 5 A, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm package format, designed for circuits requiring holder-mounted protection. This part is classified as obsolete, necessitating identification of active equivalent and substitute components to maintain design continuity and ensure supply chain availability. Substitute parts must maintain identical electrical ratings, mechanical dimensions, and functional characteristics to ensure direct interchangeability in existing applications.

Key Parameters

Parameter	Value
Current Rating	5 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	5mm x 20mm
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	50 A
Operating Temperature Range	-55°C to 125°C
DC Cold Resistance	0.011 Ohms

Substitute Part Grouping Explanation

Substitution of the 5ST 5 is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

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

Acceptable Variation Parameters:

Breaking Capacity: Parts with 50 A or higher breaking capacity are acceptable
Melting I²t: Variations within thermal characteristics are acceptable provided electrical ratings remain identical
DC Cold Resistance: Minor variations (±0.002 Ohms) are acceptable
Approval Agencies: Substitutes must maintain equivalent or expanded certification coverage

Parts are grouped into two categories: Direct Manufacturer Substitutes (same manufacturer, active status) and Cross-Manufacturer Equivalents (alternative manufacturers, identical electrical specifications).

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage (V)	Package	Breaking Capacity (A)	Melting I²t	DC Resistance (Ω)	Status	RoHS
5ST 5	Bel Fuse Inc.	5	250	5x20mm	50	95	0.011	Obsolete	Non-compliant
5ST 5-R	Bel Fuse Inc.	5	250	5x20mm	50	95	0.011	Active	ROHS3 Compliant
5ET 5-R	Bel Fuse Inc.	5	250	5x20mm	150	444	0.012	Active	ROHS3 Compliant
0218005.MXBP	Littelfuse Inc.	5	250	5x20mm	50	111	0.0104	Active	ROHS3 Compliant
0218005.MXP	Littelfuse Inc.	5	250	5x20mm	50	111	0.0104	Active	ROHS3 Compliant
0218005.VXP	Littelfuse Inc.	5	250	5x20mm	50	111	0.0104	Active	ROHS3 Compliant
0213005.MXP	Littelfuse Inc.	5	250	5x20mm	50	314	0.0116	Active	ROHS3 Compliant
0218005.HXP	Littelfuse Inc.	5	250	5x20mm	50	111	0.0104	Active	ROHS3 Compliant
0218005.MXF11P	Littelfuse Inc.	5	250	5x20mm	50	111	0.0104	Active	ROHS3 Compliant
0218005.MXF14P	Littelfuse Inc.	5	250	5x20mm	50	111	0.0104	Active	ROHS3 Compliant
0218005.TXP	Littelfuse Inc.	5	250	5x20mm	50	111	0.0104	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: Bel Fuse Inc. 5ST 5-R

The 5ST 5-R is the direct active equivalent from the original manufacturer. It maintains identical electrical specifications (5 A, 250 V, 50 A breaking capacity) and mechanical form factor. This part carries ROHS3 compliance and expanded certification coverage (CCC, CE, CSA, cURus, IMQ, SEMKO, VDE) compared to the obsolete 5ST 5. With 53,399 units in stock, supply continuity is assured.

Secondary Recommendation: Bel Fuse Inc. 5ET 5-R

The 5ET 5-R is a parametric equivalent from Bel Fuse Inc. with identical current and voltage ratings. It features enhanced breaking capacity (150 A versus 50 A) and higher melting I²t (444 versus 95), providing superior fault protection capability. This part is suitable for applications where increased fault tolerance is beneficial. ROHS3 compliant with active product status.

Cross-Manufacturer Alternatives: Littelfuse Inc. Series 218 and 213

Littelfuse 0218005.MXP, 0218005.MXBP, 0218005.VXP, 0218005.HXP, 0218005.MXF11P, 0218005.MXF14P, and 0218005.TXP are direct electrical and mechanical equivalents. All maintain 5 A, 250 V ratings with 5mm x 20mm package dimensions. DC cold resistance values (0.0104 Ohms) are within acceptable tolerance of the original specification. These parts carry comprehensive international certifications (CCC, CE, CSA, K-MARK, PSE, SEMKO, UL, VDE) and ROHS3 compliance.

The Littelfuse 0213005.MXP (Series 213) is functionally equivalent with identical electrical ratings but exhibits higher melting I²t (314 versus 95), indicating different thermal response characteristics within the slow-blow classification.

Compliance Consideration:

The original 5ST 5 is RoHS non-compliant. All recommended substitutes are ROHS3 compliant, meeting current regulatory requirements for new designs and production runs.

Frequently Asked Questions (FAQ)

Q: Can the 5ST 5-R be used as a direct replacement for the obsolete 5ST 5?

A: Yes. The 5ST 5-R is electrically and mechanically identical to the 5ST 5, with the same 5 A current rating, 250 V voltage rating, 5mm x 20mm package, and slow-blow response time. The primary difference is product status (active versus obsolete) and enhanced RoHS compliance.

Q: What is the difference between the 5ST 5-R and the 5ET 5-R?

A: Both parts share identical current (5 A) and voltage (250 V) ratings and package dimensions. The 5ET 5-R provides higher breaking capacity (150 A versus 50 A) and higher melting I²t (444 versus 95). Selection depends on application fault current requirements. For direct replacement in existing designs, the 5ST 5-R is preferred.

Q: Are Littelfuse parts interchangeable with Bel Fuse parts?

A: Littelfuse Series 218 parts (0218005.MXP, 0218005.MXBP, 0218005.VXP, 0218005.HXP, 0218005.MXF11P, 0218005.MXF14P, 0218005.TXP) are electrically and mechanically equivalent to the 5ST 5. All maintain identical current, voltage, and package specifications. DC cold resistance values are within acceptable tolerance. These parts are suitable for direct substitution.

Q: What certifications should I verify for regulatory compliance?

A: The original 5ST 5 carries CE, CSA, IMQ, SEMKO, UL, and VDE approvals. All recommended substitutes maintain equivalent or expanded certification coverage. For applications requiring specific regional compliance (CCC for China, K-MARK for Korea, PSE for Japan), verify the substitute part's certification list against your regulatory requirements.

Q: Does package dimension variation affect interchangeability?

A: No. All substitute parts maintain the 5mm x 20mm package specification. Physical dimensions are identical, ensuring compatibility with existing fuse holders and mounting hardware.

Q: What is the significance of melting I²t variation among substitutes?

A: Melting I²t defines the thermal energy required to melt the fuse element. Variations (95 to 444 across the substitute list) indicate different thermal response characteristics within the slow-blow classification. For direct replacement, parts with similar I²t values (5ST 5-R at 95, Littelfuse 218 series at 111) are preferred. Higher I²t values (5ET 5-R at 444, 0213005.MXP at 314) provide extended thermal tolerance.

Q: Is DC cold resistance variation significant?

A: DC cold resistance values across substitutes range from 0.0104 to 0.012 Ohms, representing less than 10% variation from the original 0.011 Ohms specification. This variation is within acceptable engineering tolerance and does not affect functional interchangeability in standard applications.

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