5STP 6.3 Equivalent & Substitute Parts

Part Overview

The 5STP 6.3 is a 6.3 A, 250 V AC/DC slow-blow glass cartridge fuse with a 5mm x 20mm axial form factor, manufactured by Bel Fuse Inc. This part is classified as obsolete. Due to its obsolete status, equivalent and substitute parts from active product lines are necessary for ongoing circuit protection applications requiring identical electrical and mechanical specifications.

Key Parameters

Parameter	Value
Current Rating	6.3 A
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Package / Case	5mm x 20mm (Axial)
Fuse Type	Cartridge, Glass
Mounting Type	Through Hole
Breaking Capacity @ Rated Voltage	63 A
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitution for the 5STP 6.3 is determined by strict equivalence across the following critical parameters:

Current Rating: 6.3 A (exact match required)
Voltage Rating: 250 V AC (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 5mm x 20mm axial form factor (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Mounting Type: Through Hole (exact match required)

Substitute parts are grouped into two categories:

Direct Manufacturer Equivalent: 5STP 6.3-R (Bel Fuse Inc.) — identical part number series with active product status and enhanced RoHS3 compliance.

Parametric Equivalents: 5ETP 6.3-R (Bel Fuse Inc.), 0034.3125.PT (SCHURTER Inc.), and 021806.3MXEP (Littelfuse Inc.) — meet all critical electrical and mechanical parameters with active product status.

Parameter Comparison

Parameter	5STP 6.3	5STP 6.3-R	5ETP 6.3-R	0034.3125.PT	021806.3MXEP
Manufacturer	Bel Fuse Inc.	Bel Fuse Inc.	Bel Fuse Inc.	SCHURTER Inc.	Littelfuse Inc.
Current Rating (Amps)	6.3	6.3	6.3	6.3	6.3
Voltage Rating - AC	250 V	250 V	250 V	250 V	250 V
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Package / Case	5mm x 20mm (Axial)	5mm x 20mm (Axial)	5mm x 20mm (Axial)	5mm x 20mm (Axial)	5mm x 20mm (Axial)
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Breaking Capacity @ Rated Voltage	63 A	63 A	150 A	63 A	63 A
Melting I²t	160	160	658	190	198.5
DC Cold Resistance (Ohms)	0.008	0.008	0.009	—	0.0076
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

5STP 6.3-R (Bel Fuse Inc.) is the primary direct equivalent. It maintains identical electrical specifications and mechanical form factor while offering active product status and ROHS3 compliance. This part is the preferred replacement for the obsolete 5STP 6.3.

5ETP 6.3-R (Bel Fuse Inc.) is a parametric equivalent with higher breaking capacity (150 A vs. 63 A) and elevated melting I²t (658 vs. 160). This part is suitable for applications where enhanced fault current handling is acceptable or beneficial. Active product status and ROHS3 compliance are confirmed.

0034.3125.PT (SCHURTER Inc.) meets all critical electrical parameters with identical breaking capacity. Physical dimensions show minor variation (5.40mm x 22.50mm vs. 5.50mm x 21.00mm). This part is suitable for applications with mechanical tolerance for dimensional variation. Active product status and ROHS3 compliance are confirmed.

021806.3MXEP (Littelfuse Inc.) meets all critical electrical parameters with identical breaking capacity. Physical dimensions show minor variation (5.80mm x 22.50mm vs. 5.50mm x 21.00mm). This part carries the broadest approval agency certifications (CCC, CE, CSA, K-MARK, PSE, SEMKO, UL, VDE). Active product status and ROHS3 compliance are confirmed.

Frequently Asked Questions (FAQ)

Q: Can 5STP 6.3-R be used as a direct replacement for 5STP 6.3?

A: Yes. The 5STP 6.3-R maintains identical current rating, voltage rating, response time, package form factor, and fuse type. It is the direct manufacturer equivalent with active product status.

Q: What is the difference between 5STP 6.3-R and 5ETP 6.3-R?

A: Both parts share identical current rating (6.3 A), voltage rating (250 V), response time (slow blow), and package form factor. The 5ETP 6.3-R has higher breaking capacity (150 A vs. 63 A) and higher melting I²t (658 vs. 160). Selection depends on circuit fault current requirements.

Q: Are there mechanical compatibility concerns with SCHURTER 0034.3125.PT or Littelfuse 021806.3MXEP?

A: Both parts have nominal form factors within the 5mm x 20mm category but show minor dimensional variations. The 0034.3125.PT measures 5.40mm x 22.50mm and the 021806.3MXEP measures 5.80mm x 22.50mm, compared to the original 5.50mm x 21.00mm. Verify mechanical fit in the target fuse holder before deployment.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts listed (5STP 6.3-R, 5ETP 6.3-R, 0034.3125.PT, and 021806.3MXEP) are ROHS3 compliant. The original 5STP 6.3 is RoHS non-compliant.

Q: Which substitute part has the broadest regulatory approval?

A: The Littelfuse 021806.3MXEP carries certifications from CCC, CE, CSA, K-MARK, PSE, SEMKO, UL, and VDE, providing the widest regulatory coverage for international applications.

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