MS 1 Equivalent & Substitute Parts Reference

Part Overview

The MS 1 is a board mount axial fuse manufactured by Bel Fuse Inc., rated for 1 A at 125 V AC/DC with slow blow response characteristics. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement continuity. The MS 1 serves applications requiring overcurrent protection in through-hole axial configurations with moderate breaking capacity requirements.

Substiute Parts

MS 1

Bel Fuse Inc.In Stock: 907MS 1 Datasheet

Current PartRFQ

0473001.MRT1L

Littelfuse Inc.In Stock: 32700473001.MRT1L Datasheet

DirectRFQ

0473001.YRT1L

Littelfuse Inc.In Stock: 281210473001.YRT1L Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the MS 1 is based on strict electrical and mechanical parameter matching:

Primary Substitution Criteria:

• Current Rating: 1 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 (exact match required)

The substitute parts 0473001.MRT1L and 0473001.YRT1L, both from Littelfuse Inc. (PICO® II 473 series), meet all primary electrical and mechanical parameters. Both are active products with current availability, providing direct functional equivalence to the obsolete MS 1.

Parameter Comparison

Engineering Selection Recommendations

Both 0473001.MRT1L and 0473001.YRT1L are active products from Littelfuse Inc. and provide functional equivalence to the obsolete MS 1. Selection between these two substitutes should be based on packaging and inventory availability:

0473001.YRT1L is recommended as the primary substitute, with 28,100 units in stock, providing superior supply chain continuity.

0473001.MRT1L serves as a secondary substitute option with 3,210 units available.

Both substitutes carry ROHS3 compliance and CSA/PSE/UR certifications, meeting modern regulatory requirements. The slight dimensional variation (0.135" diameter versus 0.125" diameter) and lower DC cold resistance (0.267 Ohms versus 0.338 Ohms) remain within acceptable tolerance for board mount through-hole applications.

Frequently Asked Questions (FAQ)

Q: Can 0473001.YRT1L and 0473001.MRT1L be used interchangeably with MS 1?

A: Both parts meet the electrical specifications (1 A, 125 V AC/DC, slow blow response) and mechanical requirements (through-hole axial mounting). They are functionally equivalent for applications requiring these parameters.

Q: What is the difference between 0473001.YRT1L and 0473001.MRT1L?

A: Both parts are from the Littelfuse PICO® II 473 series with identical electrical and thermal characteristics. The primary difference is packaging format (Cut Tape) and inventory availability. 0473001.YRT1L has significantly higher stock levels (28,100 units versus 3,210 units).

Q: Are there dimensional compatibility concerns with the substitute parts?

A: The substitute parts have a slightly larger diameter (0.135" versus 0.125") while maintaining the same length (0.280"). Board layout and through-hole spacing must accommodate this 0.010" diameter increase.

Q: Do the substitute parts meet the same certifications as MS 1?

A: The substitute parts carry CSA, PSE, and UR certifications. The original MS 1 carried CE, CSA, and cURus certifications. Verify that your application requirements align with the available certifications on the substitute parts.

Q: What is the significance of the DC cold resistance difference?

A: The substitute parts have lower DC cold resistance (0.267 Ohms versus 0.338 Ohms). This represents improved electrical efficiency and reduced heat generation during normal operation, which is a favorable characteristic for board mount fuse applications.