SPXI04.5TXB Equivalent & Substitute Parts

Part Overview

The SPXI04.5TXB is a 4.5A 1.5 kVDC fast-blow fuse cartridge manufactured by Littelfuse Inc. as part of the POWR-GARD® SPXI series. This free-hanging inline cartridge fuse is designed for solar photovoltaic applications requiring DC protection at elevated voltages. The part is currently classified as obsolete, necessitating identification of active equivalent alternatives that maintain identical electrical and mechanical specifications for continued system support and new installations.

Substiute Parts

SPXI04.5TXB

Littelfuse Inc.In Stock: 1119SPXI04.5TXB Datasheet

Current PartRFQ

SPXI04.5T

Littelfuse Inc.In Stock: 924SPXI04.5T Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the obsolete SPXI04.5TXB is determined by strict equivalence across all critical electrical and mechanical parameters. The substitute must maintain:

Electrical Parameters:

• Current Rating: 4.5A (exact match required)
• Voltage Rating: 1.5 kVDC (exact match required)
• Response Time: Fast Blow (exact match required)
• Breaking Capacity: 30kA @ rated voltage (exact match required)
• Melting I²t: 34 (exact match required)
• DC Cold Resistance: 0.1023 Ohms (exact match required)

Mechanical Parameters:

• Fuse Type: Cartridge (exact match required)
• Mounting Type: Free Hanging (In-Line) (exact match required)
• Package / Case: Cartridge, Inline, Double Ended (exact match required)

Compliance Parameters:

• Approval Agencies: CE, gPV, UL, UR (all certifications required)
• RoHS Compliance: Required

The SPXI04.5T meets all substitution criteria and is classified as an active product, providing continuity for applications previously using the SPXI04.5TXB.

Parameter Comparison

Engineering Selection Recommendations

The SPXI04.5T is the direct active equivalent for the obsolete SPXI04.5TXB. Both parts are manufactured by Littelfuse Inc. within the POWR-GARD® SPXI series and maintain identical electrical specifications across all critical parameters: 4.5A current rating, 1.5 kVDC voltage rating, fast-blow response, 30kA breaking capacity, and 0.1023 Ohms DC cold resistance.

The SPXI04.5T carries active product status and holds all required certifications: CE, gPV, UL, and UR. The part meets ROHS3 compliance, representing an advancement over the RoHS compliance of the obsolete SPXI04.5TXB. Both parts are housed in identical cartridge, inline, double-ended packages suitable for free-hanging mounting in solar photovoltaic applications.

The minor dimensional difference in length (4.490" versus 4.333") does not affect electrical performance or mechanical compatibility in standard inline fuse holder installations. The SPXI04.5T is the appropriate selection for replacement of the SPXI04.5TXB in all solar DC protection circuits.

Frequently Asked Questions (FAQ)

Q: Can the SPXI04.5T directly replace the SPXI04.5TXB in existing installations?

A: Yes. The SPXI04.5T is electrically and mechanically equivalent to the SPXI04.5TXB across all critical parameters. Both parts share identical current rating (4.5A), voltage rating (1.5 kVDC), response time (fast blow), breaking capacity (30kA), and DC cold resistance (0.1023 Ohms). The parts are compatible with standard inline fuse holders designed for POWR-GARD® SPXI series cartridges.

Q: What is the significance of the product status change from Obsolete to Active?

A: The SPXI04.5T is currently in active production by Littelfuse Inc., ensuring continued availability for new designs and replacement applications. The SPXI04.5TXB is obsolete and no longer manufactured. Transitioning to the SPXI04.5T provides supply chain continuity and access to current manufacturing quality standards.

Q: Are there compliance differences between the SPXI04.5TXB and SPXI04.5T?

A: Both parts hold identical certifications from CE, gPV, UL, and UR. The SPXI04.5T carries ROHS3 compliance, which supersedes the RoHS compliance of the SPXI04.5TXB. This represents an advancement in environmental compliance standards.

Q: Does the dimensional difference between the two parts affect installation?

A: The SPXI04.5T is 0.157" (approximately 4mm) shorter in length than the SPXI04.5TXB. Both parts maintain the same 0.406" diameter and double-ended cartridge configuration. This dimensional difference does not affect compatibility with standard inline fuse holders used in solar photovoltaic systems.

Q: What applications are these fuses designed for?

A: Both the SPXI04.5TXB and SPXI04.5T are designed for solar photovoltaic applications requiring DC protection at 1.5 kVDC. The fast-blow response and 4.5A current rating provide circuit protection in string-level or combiner-box configurations typical of solar array installations.

Q: Are there any electrical performance differences between these parts?

A: No. Both parts are electrically identical. The melting I²t value (34), DC cold resistance (0.1023 Ohms), and breaking capacity (30kA) are identical. The fast-blow response time classification is the same for both parts.