MS 500TR Equivalent & Substitute Parts Reference

Part Overview

The MS 500TR is a 500 mA, 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 500TR serves as a protective device in circuits requiring 500 mA current limiting at 125 V operating conditions with through-hole axial mounting.

Key Parameters

Parameter	Value
Current Rating	500 mA
Voltage Rating (AC)	125 V
Voltage Rating (DC)	125 V
Response Time	Slow Blow
Mounting Type	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)
Package / Case	Axial
Breaking Capacity @ Rated Voltage	50A AC, 300A DC
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitute parts for the MS 500TR are classified into two categories based on electrical and mechanical parameter alignment:

Direct Substitutes (Electrical & Mechanical Equivalence):

0474.600MRT1L (Littelfuse PICO® II 473, Cut Tape packaging)
0474.600YRT1L (Littelfuse PICO® II 473, Tape & Reel packaging)

These parts maintain identical electrical specifications: 500 mA current rating, 125 V AC/DC voltage rating, slow blow response, 50A breaking capacity at rated voltage, and -55°C ~ 125°C operating temperature. Physical dimensions differ slightly (0.135" Dia vs. 0.125" Dia), but remain compatible with standard through-hole axial mounting footprints. Both are active products with current manufacturing status.

Similar Substitute (Reduced Breaking Capacity):

0472.500NRT1L (Littelfuse PICO® II 472, Tape & Reel packaging)

This part matches all electrical specifications except breaking capacity (50A AC only, versus 50A AC/300A DC). Physical dimensions are smaller (0.110" Dia x 0.280" L). This part is suitable only for applications where DC breaking capacity is not a design requirement.

Parameter Comparison

Parameter	MS 500TR (Bel Fuse)	0474.600MRT1L (Littelfuse)	0474.600YRT1L (Littelfuse)	0472.500NRT1L (Littelfuse)
Current Rating (Amps)	500 mA	500 mA	500 mA	500 mA
Voltage Rating - AC	125 V	125 V	125 V	125 V
Voltage Rating - DC	125 V	125 V	125 V	125 V
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)
Package / Case	Axial	Axial	Axial	Axial
Breaking Capacity @ Rated Voltage	50A AC, 300A DC	50A	50A	50A
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 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)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)
DC Cold Resistance	0.99 Ohms	1.13 Ohms	1.13 Ohms	0.174 Ohms
Product Status	Obsolete	Active	Active	Active
Approval Agency	CE, CSA, cURus	CSA, UR	CSA, UR	UR

Engineering Selection Recommendations

For Direct Replacement (Preferred): Select either 0474.600MRT1L or 0474.600YRT1L. Both are active Littelfuse PICO® II 473 series products with full electrical equivalence to the MS 500TR. The choice between these two depends on procurement packaging requirements: 0474.600MRT1L is supplied in Cut Tape format, while 0474.600YRT1L is supplied in Tape & Reel format. Both maintain CSA and UR certifications. The slight increase in DC cold resistance (1.13 Ohms vs. 0.99 Ohms) and melting I²t (0.21 vs. 0.2) are within acceptable engineering tolerances for slow blow fuse applications.

For Applications Without DC Breaking Capacity Requirements: The 0472.500NRT1L may be considered only when the design does not require DC breaking capacity specification. This part offers significantly lower DC cold resistance (0.174 Ohms) and smaller physical dimensions, which may be advantageous in space-constrained layouts. However, this substitution requires explicit design review to confirm DC breaking capacity is not a functional requirement.

Frequently Asked Questions (FAQ)

Q: Can 0474.600MRT1L and 0474.600YRT1L be used interchangeably? A: Yes. Both parts are electrically and mechanically equivalent. The difference is packaging format only: Cut Tape (CT) versus Tape & Reel (TR). Selection depends on assembly line equipment compatibility and procurement volume requirements.

Q: What is the impact of the dimensional difference between MS 500TR and the Littelfuse substitutes? A: The MS 500TR has a 0.125" diameter, while 0474.600MRT1L and 0474.600YRT1L have 0.135" diameter. Both fit standard through-hole axial mounting footprints. The 0472.500NRT1L is smaller at 0.110" diameter and may require footprint verification for older PCB designs.

Q: Why does 0472.500NRT1L have lower DC cold resistance? A: The 0472.500NRT1L is from the PICO® II 472 series with a smaller physical form factor (0.110" Dia). Lower resistance is a characteristic of this design. This part is suitable only for applications where DC breaking capacity is not specified.

Q: Are all substitute parts RoHS compliant? A: The Littelfuse PICO® II 473 series (0474.600MRT1L and 0474.600YRT1L) are ROHS3 compliant. The 0472.500NRT1L does not list RoHS status in the provided specifications.

Q: What certifications should I verify for my application? A: The MS 500TR carries CE, CSA, and cURus certifications. The 0474.600MRT1L and 0474.600YRT1L carry CSA and UR certifications. The 0472.500NRT1L carries UR certification only. Verify that substitute part certifications meet your application and regional requirements.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message