5TT 1 Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The 5TT 1 is a 1 A, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm form factor manufactured by Bel Fuse Inc. This part is classified as obsolete. Due to its obsolete status, direct equivalents and parametric substitutes are available from the same manufacturer to ensure continued circuit protection functionality in applications requiring 1 A rated protection at 250 V.

Key Parameters

Parameter	Value
Current Rating	1 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	5mm x 20mm
Response Time	Slow Blow
Mounting Type	Requires Holder
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitution for the 5TT 1 is determined by matching the following critical parameters: current rating (1 A), voltage rating (250 V AC), fuse type (cartridge glass), physical dimensions (5mm x 20mm), response characteristic (slow blow), and mounting requirement (holder-based installation). All substitute parts listed maintain these core electrical and mechanical specifications, ensuring functional compatibility within the same circuit protection application.

The 5TT 1-R serves as a direct manufacturer equivalent with active product status. The 5ET 1-R and 5ST 1-R are parametric equivalents that meet the same electrical ratings and physical form factor while differing in breaking capacity and melting I²t characteristics, which do not affect substitutability for standard circuit protection applications at the specified current and voltage ratings.

Parameter Comparison

Parameter	5TT 1 (Main)	5TT 1-R	5ET 1-R	5ST 1-R
Manufacturer	Bel Fuse Inc.	Bel Fuse Inc.	Bel Fuse Inc.	Bel Fuse Inc.
Current Rating (Amps)	1 A	1 A	1 A	1 A
Voltage Rating - AC	250 V	250 V	250 V	250 V
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Package / Case	5mm x 20mm	5mm x 20mm	5mm x 20mm	5mm x 20mm
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Mounting Type	Requires Holder	Requires Holder	Requires Holder	Requires Holder
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Breaking Capacity @ Rated Voltage	100 A	100 A	150 A	35 A
DC Cold Resistance	0.3 Ohms	0.27 Ohms	0.11 Ohms	0.095 Ohms
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

The 5TT 1-R is the primary substitute for the obsolete 5TT 1, offering identical electrical ratings and physical form factor with active product status and ROHS3 compliance. This part maintains the same 100 A breaking capacity and provides the most direct replacement path.

The 5ET 1-R and 5ST 1-R are parametric equivalents suitable for applications where the specified current and voltage ratings are the primary selection criteria. The 5ET 1-R provides higher breaking capacity (150 A) and lower DC cold resistance (0.11 Ohms), while the 5ST 1-R offers lower breaking capacity (35 A) and the lowest DC cold resistance (0.095 Ohms). Selection between these alternatives depends on the specific circuit protection requirements and breaking capacity specifications of the target application.

All substitute parts carry active product status and ROHS3 compliance, supporting modern procurement and environmental regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can the 5TT 1-R directly replace the obsolete 5TT 1?

A: Yes. The 5TT 1-R maintains identical current rating (1 A), voltage rating (250 V AC), fuse type (cartridge glass), physical dimensions (5mm x 20mm), response characteristic (slow blow), and operating temperature range (-55°C ~ 125°C). It is the direct manufacturer equivalent with active product status.

Q: What is the difference between the 5TT 1-R, 5ET 1-R, and 5ST 1-R?

A: All three parts share the same electrical ratings (1 A, 250 V AC) and physical form factor (5mm x 20mm). They differ in breaking capacity and DC cold resistance. The 5TT 1-R has 100 A breaking capacity with 0.27 Ohms resistance. The 5ET 1-R has 150 A breaking capacity with 0.11 Ohms resistance. The 5ST 1-R has 35 A breaking capacity with 0.095 Ohms resistance. Selection depends on the circuit's breaking capacity requirement.

Q: Are all substitute parts compatible with existing 5mm x 20mm fuse holders?

A: Yes. All substitute parts maintain the 5mm x 20mm physical dimensions and require holder-based mounting, ensuring mechanical compatibility with existing fuse holder installations.

Q: What certifications do the substitute parts carry?

A: The 5TT 1-R carries CE, CSA, cULus, and PSE certifications. The 5ET 1-R carries CCC, CE, CSA, cURus, SEMKO, and VDE certifications. The 5ST 1-R carries CCC, CE, CSA, cURus, IMQ, SEMKO, and VDE certifications. All parts are ROHS3 compliant and REACH unaffected.

Q: Is the 5TT 1 still available for procurement?

A: The 5TT 1 is classified as obsolete. The 5TT 1-R, 5ET 1-R, and 5ST 1-R are active products available for new procurement and should be used for replacement applications.

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