MS 500 Equivalent & Substitute Parts Reference

Part Overview

The MS 500 is a 500 mA board mount axial fuse rated for 125 V AC/DC operation, manufactured by Bel Fuse Inc. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement. The MS 500 serves as a protective device in through-hole applications requiring slow-blow response characteristics and is suitable for operating environments ranging from -55°C to 125°C.

Substiute Parts

MS 500

Bel Fuse Inc.In Stock: 999MS 500 Datasheet

Current PartRFQ

0473.500MRT1L

Littelfuse Inc.In Stock: 26610473.500MRT1L Datasheet

DirectRFQ

0473.500YRT1L

Littelfuse Inc.In Stock: 482710473.500YRT1L Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the MS 500 are qualified based on the following electrical and mechanical parameters:

• Current Rating: 500 mA (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)
• Fuse Type: Board Mount, Axial configuration (exact match required)
• Operating Temperature Range: -55°C to 125°C (exact match required)

The substitute parts listed below meet all these criteria and are manufactured by Littelfuse Inc. under the PICO® II 473 series. Both substitutes are active products with current availability, addressing the obsolescence of the original MS 500.

Parameter Comparison

Engineering Selection Recommendations

Both 0474.600MRT1L and 0474.600YRT1L are functionally equivalent substitutes for the MS 500. Selection between these two Littelfuse parts should be based on procurement and assembly requirements:

• 0474.600MRT1L is supplied in Cut Tape (CT) packaging, suitable for lower-volume applications or manual assembly processes.
• 0474.600YRT1L is supplied in Tape & Reel (TR) packaging, optimized for high-volume automated assembly operations.

Both substitutes carry active product status from Littelfuse Inc., ensuring long-term availability and supply chain stability. The Littelfuse parts maintain CSA and UR certifications, meeting regulatory requirements for the application. RoHS3 compliance of the substitute parts provides environmental compliance advantages over the original MS 500.

Minor dimensional variations exist: the substitute parts have a slightly larger diameter (0.135" vs. 0.125") and marginally higher DC cold resistance (1.13 Ohms vs. 0.99 Ohms). These variations remain within acceptable tolerances for board mount axial fuse applications and do not affect functional compatibility in the specified electrical operating range.

Frequently Asked Questions (FAQ)

Q: Can 0474.600MRT1L and 0474.600YRT1L be used interchangeably with the MS 500?

A: Yes. Both Littelfuse parts meet all electrical and mechanical substitution criteria for the MS 500, including current rating, voltage rating, response time, mounting type, and operating temperature range. The primary difference is packaging format (Cut Tape vs. Tape & Reel).

Q: What is the difference between the two substitute parts?

A: 0474.600MRT1L and 0474.600YRT1L are electrically and mechanically identical. The only difference is packaging: 0474.600MRT1L uses Cut Tape (CT) format, while 0474.600YRT1L uses Tape & Reel (TR) format. Selection depends on assembly volume and equipment compatibility.

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

A: The substitute parts have a slightly larger diameter (0.135" compared to 0.125" for the MS 500) and identical length (0.280"). PCB through-hole patterns designed for the MS 500 will accommodate the substitute parts, as the increase in diameter is within standard tolerance ranges for axial component mounting.

Q: Do the substitute parts meet the same regulatory certifications?

A: The substitute parts carry CSA and UR certifications. The original MS 500 also included CE and cURus certifications. For applications requiring CE or cURus certification specifically, compliance verification with the Littelfuse substitutes is necessary.

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

A: The melting I²t values are 0.2 for the MS 500 and 0.21 for the Littelfuse substitutes. This 5% difference is negligible for slow-blow fuse applications and does not affect functional performance in standard circuit protection scenarios.

Q: Are the substitute parts RoHS compliant?

A: Yes. Both 0474.600MRT1L and 0474.600YRT1L are ROHS3 compliant. The original MS 500 RoHS status was not specified in the available data.