5TT 300 Equivalent & Substitute Parts

Part Overview

The 5TT 300 is a 300 mA, 250 V AC/DC slow-blow glass cartridge fuse in a 5mm x 20mm package manufactured by Bel Fuse Inc. This component is classified as obsolete, making identification of suitable substitutes necessary for ongoing system maintenance and component sourcing. The fuse requires a dedicated holder for installation and is designed for applications requiring moderate overcurrent protection with delayed response characteristics.

Substiute Parts

5TT 300

Bel Fuse Inc.In Stock: 8695TT 300 Datasheet

Current PartRFQ

5TT 300-R

Bel Fuse Inc.In Stock: 16895TT 300-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

The 5TT 300-R qualifies as a direct substitute based on the following critical parameters:

• Current Rating: 300 mA (identical)
• Voltage Rating (AC): 250 V (identical)
• Fuse Type: Cartridge, Glass (identical)
• Package / Case: 5mm x 20mm (identical)
• Response Time: Slow Blow (identical)
• Breaking Capacity @ Rated Voltage: 100 A (identical)
• Operating Temperature Range: -55°C ~ 125°C (identical)
• Mounting Type: Requires Holder (identical)

The 5TT 300-R maintains full electrical and mechanical compatibility with the original 5TT 300, with the primary distinction being product status and regulatory compliance.

Parameter Comparison

Engineering Selection Recommendations

The 5TT 300-R is the direct substitute for the obsolete 5TT 300. Selection of the 5TT 300-R is based on:

• Identical electrical ratings and mechanical dimensions ensure drop-in compatibility
• Active product status guarantees ongoing availability and supply chain continuity
• ROHS3 compliance and cULus certification provide enhanced regulatory alignment compared to the original part
• Marginal variations in DC cold resistance (2.14 Ohms vs. 2.1 Ohms) and melting I²t (0.885 vs. 1.09) remain within acceptable engineering tolerances for this component class

Frequently Asked Questions (FAQ)

Q: Can the 5TT 300-R be used as a direct replacement for the 5TT 300?

A: Yes. Both parts share identical current ratings (300 mA), voltage ratings (250 V AC), fuse type (cartridge, glass), package dimensions (5mm x 20mm), response characteristics (slow blow), and operating temperature ranges (-55°C ~ 125°C). Physical and electrical compatibility is complete.

Q: What are the differences between the 5TT 300 and 5TT 300-R?

A: The primary differences are product status (obsolete vs. active), RoHS compliance (non-compliant vs. ROHS3 compliant), and certifications (UL vs. cULus). Minor variations exist in DC cold resistance and melting I²t values, which do not affect functional substitution.

Q: Does the 5TT 300-R require the same holder as the 5TT 300?

A: Yes. Both fuses are cartridge-type components requiring a dedicated holder. The 5mm x 20mm package dimensions are identical, ensuring compatibility with existing holder installations.

Q: Are there any compliance considerations when switching from 5TT 300 to 5TT 300-R?

A: The 5TT 300-R offers improved compliance status with ROHS3 certification and cULus approval, making it suitable for applications with stricter regulatory requirements. The original 5TT 300 holds CE, CSA, and UL certifications.

Q: What is the significance of the melting I²t difference?

A: The melting I²t value (0.885 for 5TT 300-R vs. 1.09 for 5TT 300) indicates slightly faster thermal response in the substitute part. Both values remain within the slow-blow fuse classification and do not affect compatibility for standard 300 mA applications.