MS 3TR Board Mount Axial Fuse Equivalent & Substitute Parts

Part Overview

The MS 3TR is a 3 A, 125 V AC/DC board mount axial fuse manufactured by Bel Fuse Inc. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The MS 3TR serves as a protective device in circuits requiring slow-blow response characteristics with through-hole axial mounting configuration.

Substiute Parts

MS 3TR

Bel Fuse Inc.In Stock: 1277MS 3TR Datasheet

Current PartRFQ

0473002.YRT1L

Littelfuse Inc.In Stock: 254850473002.YRT1L Datasheet

DirectRFQ

0473003.MRT1L

Littelfuse Inc.In Stock: 24630473003.MRT1L Datasheet

DirectRFQ

0473003.YRT1L

LittelfuseIn Stock: 201860473003.YRT1L Datasheet

DirectRFQ

0471003.NRT1L

Littelfuse Inc.In Stock: 64200471003.NRT1L Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MS 3TR is determined by the following critical parameters:

• Current Rating: 3 A (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (exact match required)
• Response Time: Slow Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Package / Case: Axial (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (minimum requirement)

Parts are classified into two categories:

Direct Equivalents: Parts meeting all critical parameters with identical electrical and mechanical specifications.

Similar Alternatives: Parts meeting all critical parameters but with variations in physical dimensions, melting I²t characteristics, or approval agencies. These require mechanical fit verification and thermal performance evaluation in the target application.

Parameter Comparison

Engineering Selection Recommendations

Direct Equivalents (Recommended Primary Choices):

0473003.MRT1L and 0473003.YRT1L are active production parts from Littelfuse Inc. with identical electrical ratings to the MS 3TR. Both parts carry CSA and UR approvals, supporting North American and international regulatory requirements. The 0473003.YRT1L variant offers higher inventory availability (20,100 units) compared to 0473003.MRT1L (2,400 units). Both parts are ROHS3 compliant and suitable for direct substitution in applications where the MS 3TR was originally specified.

Similar Alternative (Secondary Choice):

0471003.NRT1L is a Littelfuse PICO® II 471 series part meeting all critical electrical parameters. This part differs in physical diameter (0.110" vs. 0.125"), melting I²t (6.96 vs. 8), and approval agencies (PSE, UR vs. CE, CSA, cURus). Selection of this part requires verification of mechanical fit within the PCB footprint and thermal performance validation in the target circuit. The lower melting I²t may result in faster response to overcurrent conditions.

Compliance Considerations:

All substitute parts maintain the -55°C to 125°C operating temperature range and slow-blow response characteristic. Littelfuse parts provide ROHS3 compliance, addressing modern environmental and regulatory requirements. Approval agency differences should be evaluated against specific regional certification requirements for the end application.

Frequently Asked Questions (FAQ)

Q: Can 0473003.YRT1L be used as a direct replacement for MS 3TR?

A: Yes. Both parts share identical current rating (3 A), voltage ratings (125 V AC/DC), response time (slow blow), mounting type (through hole), and operating temperature range (-55°C to 125°C). The primary difference is physical diameter (0.135" vs. 0.125"), which requires verification that the PCB footprint accommodates the larger diameter.

Q: What is the difference between 0473003.MRT1L and 0473003.YRT1L?

A: Both parts are electrically identical 3 A, 125 V AC/DC slow-blow axial fuses from Littelfuse PICO® II 473 series. The primary distinction is inventory availability, with 0473003.YRT1L offering significantly higher stock (20,100 units vs. 2,400 units). Both are suitable for MS 3TR replacement.

Q: Why does 0471003.NRT1L have different physical dimensions?

A: 0471003.NRT1L belongs to the Littelfuse PICO® II 471 series, which uses a smaller diameter (0.110" vs. 0.125"). While electrically equivalent for the 3 A, 125 V AC/DC application, the reduced diameter may allow use in space-constrained PCB designs. However, the lower melting I²t (6.96 vs. 8) indicates faster thermal response, requiring application-specific thermal performance validation.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All Littelfuse substitute parts (0473003.MRT1L, 0473003.YRT1L, and 0471003.NRT1L) are ROHS3 compliant. The original MS 3TR does not specify RoHS status.

Q: Which substitute part has the best inventory availability?

A: 0473003.YRT1L offers the highest inventory with 20,100 units in stock, followed by 0471003.NRT1L (6,361 units) and 0473003.MRT1L (2,400 units).

Q: Do all substitute parts support the same approval agencies as MS 3TR?

A: No. The MS 3TR carries CE, CSA, and cURus approvals. Littelfuse substitutes carry CSA and UR approvals (0473003.MRT1L and 0473003.YRT1L) or PSE and UR approvals (0471003.NRT1L). Regional certification requirements should be verified for the target application.