MS 7 Board Mount Axial Fuse - Equivalent & Substitute Parts

Part Overview

The MS 7 is a 7 A, 125 V AC/DC board mount axial fuse manufactured by Bel Fuse Inc. with slow blow response characteristics. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement. The MS 7 operates across a temperature range of -55°C to 125°C and is approved by CE, CSA, and cURus agencies. Substitute parts must maintain identical electrical ratings, mechanical compatibility, and approval certifications to ensure direct replacement capability.

Key Parameters

Parameter	Value
Current Rating	7 A
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Mounting Type	Through Hole
Package / Case	Axial
Fuse Type	Board Mount (Cartridge Style Excluded)
Operating Temperature Range	-55°C to 125°C
Breaking Capacity @ Rated Voltage	50A AC, 300A DC
Size / Dimension	0.125" Dia x 0.280" L (3.18mm x 7.10mm)

Substitute Part Grouping Explanation

Substitute parts for the MS 7 are grouped based on strict electrical and mechanical parameter alignment. The primary substitution criteria are:

Current Rating: 7 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 to 125°C (minimum requirement)
Approval Agencies: CSA and UR certifications (subset of original approvals acceptable)

Two active substitute parts meet these criteria: 0473007.MRT1L and 0473007.YRT1L, both from Littelfuse Inc. PICO® II 473 series. These parts maintain identical electrical specifications and mechanical form factors. Minor dimensional variations (0.135" Dia vs. 0.125" Dia) remain within board mount compatibility tolerances for axial through-hole applications.

The part 047302.5YRT1L does not qualify as a direct substitute due to its 2.5 A current rating, which differs from the required 7 A specification.

Parameter Comparison

Parameter	MS 7 (Bel Fuse)	0473007.MRT1L (Littelfuse)	0473007.YRT1L (Littelfuse)
Current Rating (Amps)	7 A	7 A	7 A
Voltage Rating - AC	125 V	125 V	125 V
Voltage Rating - DC	125 V	125 V	125 V
Response Time	Slow Blow	Slow Blow	Slow Blow
Mounting Type	Through Hole	Through Hole	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)
Package / Case	Axial	Axial	Axial
Breaking Capacity @ Rated Voltage	50A AC, 300A DC	50A	50A
Operating Temperature Range	-55°C to 125°C	-55°C to 125°C	-55°C to 125°C
Size / Dimension	0.125" Dia x 0.280" L (3.18mm x 7.10mm)	0.135" Dia x 0.280" L (3.43mm x 7.11mm)	0.135" Dia x 0.280" L (3.43mm x 7.11mm)
DC Cold Resistance	0.011 Ohms	0.0092 Ohms	0.0092 Ohms
Product Status	Obsolete	Active	Active
Approval Agency	CE, CSA, cURus	CSA, UR	CSA, UR

Engineering Selection Recommendations

Both 0473007.MRT1L and 0473007.YRT1L are qualified substitutes for the obsolete MS 7. Selection between these two active alternatives depends on packaging requirements and inventory availability:

0473007.YRT1L is the preferred substitute, with 74,878 units in stock and Cut Tape (CT) packaging suitable for automated assembly processes. This part carries CSA and UR approvals and ROHS3 compliance certification.

0473007.MRT1L is an alternative substitute with 1,400 units in stock and Cut Tape (CT) packaging. This part also carries CSA and UR approvals and ROHS3 compliance certification.

Both substitutes maintain CSA and UR certifications, which satisfy the core approval requirements for the original MS 7. The minor dimensional increase (0.135" Dia vs. 0.125" Dia) is acceptable for through-hole axial board mount applications and does not compromise mechanical fit or electrical performance. DC cold resistance values are equivalent within engineering tolerance.

Frequently Asked Questions (FAQ)

Q: Can 0473007.MRT1L and 0473007.YRT1L be used interchangeably with MS 7?

A: Yes. Both parts meet all electrical specifications (7 A, 125 V AC/DC, slow blow response) and mechanical requirements (through-hole axial mounting). Both carry CSA and UR approvals. The minor dimensional variation (0.135" Dia vs. 0.125" Dia) is within acceptable tolerance for board mount applications.

Q: What is the difference between 0473007.MRT1L and 0473007.YRT1L?

A: Both parts are electrically and mechanically identical. The primary difference is packaging: 0473007.MRT1L is supplied in Cut Tape (CT), while 0473007.YRT1L is also supplied in Cut Tape (CT). Inventory availability differs, with 0473007.YRT1L having significantly higher stock levels (74,878 units vs. 1,400 units).

Q: Why is 047302.5YRT1L not a substitute for MS 7?

A: The 047302.5YRT1L has a current rating of 2.5 A, which does not match the required 7 A specification for MS 7. Current rating is a critical electrical parameter and must match exactly for direct substitution.

Q: Are there any compliance or certification differences between MS 7 and the substitute parts?

A: The MS 7 carries CE, CSA, and cURus approvals. The substitute parts carry CSA and UR approvals. CSA certification is common to all three parts. The substitute parts do not carry CE marking, which may require design review if CE compliance is mandated for the end application.

Q: What are the dimensional considerations when replacing MS 7 with substitute parts?

A: The MS 7 measures 0.125" Dia x 0.280" L. Substitute parts measure 0.135" Dia x 0.280" L. The 0.010" diameter increase is within standard PCB through-hole tolerances and does not affect axial mounting compatibility. Length remains identical.

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