5HFP 125-R Equivalent & Substitute Parts

Part Overview

The 5HFP 125-R is a 125 mA ceramic cartridge fuse rated for 250 V AC/DC operation in a 5mm x 20mm axial package. Manufactured by Bel Fuse Inc., this component is classified as obsolete. Due to its discontinued status, identifying equivalent substitute parts with matching electrical and mechanical specifications is essential for system maintenance, repair, and redesign applications.

Substiute Parts

5HFP 125-R

Bel Fuse Inc.In Stock: 8945HFP 125-R Datasheet

Current PartRFQ

0216.125MXEP

Littelfuse Inc.In Stock: 156540216.125MXEP Datasheet

DirectRFQ

BK/S501-V-125-R

Eaton - Electronics DivisionIn Stock: 1241BK/S501-V-125-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 5HFP 125-R are qualified based on the following critical parameters:

• Current Rating: 125 mA (exact match required)
• Voltage Rating: 250 V AC (exact match required)
• Fuse Type: Cartridge, Ceramic (exact match required)
• Response Time: Fast Blow (exact match required)
• Breaking Capacity: 1.5 kA (exact match required)
• Mounting Type: Through Hole (exact match required)
• Package Dimensions: 5mm x 20mm nominal (minor dimensional tolerance acceptable within standard specifications)

The substitute parts listed below meet all critical electrical and mechanical parameters. Variations in secondary characteristics such as DC cold resistance and melting I²t are within acceptable engineering tolerances for this component category.

Parameter Comparison

Engineering Selection Recommendations

Both substitute parts are active products with current manufacturing support, addressing the obsolescence of the 5HFP 125-R.

The 0216.125MXEP (Littelfuse Inc.) maintains full electrical equivalence with comprehensive approval certifications including CCC, CE, CSA, SEMKO, UL, and VDE. This part is available in high inventory (15,595 pcs) and is ROHS3 compliant.

The BK/S501-V-125-R (Eaton - Electronics Division) provides electrical equivalence with CSA and cULus certifications. This part is available in moderate inventory (1,141 pcs) and is RoHS compliant. The higher DC cold resistance (12.3 Ohms) and lower melting I²t (0.0037) represent measurable differences that may affect performance in specific circuit applications.

Selection between these substitutes should be based on certification requirements for the target application, inventory availability, and circuit-specific tolerance for resistance and thermal characteristics.

Frequently Asked Questions (FAQ)

Q: Can the 0216.125MXEP directly replace the 5HFP 125-R in existing designs?

A: Yes. Both parts share identical current rating (125 mA), voltage rating (250 V AC), fuse type (ceramic cartridge), response time (fast blow), and breaking capacity (1.5 kA). The package designation is 5mm x 20mm (axial) for both. Dimensional variations (0.236" Dia x 0.886" L vs. 0.217" Dia x 0.827" L) fall within standard mechanical tolerances for this component category and do not prevent direct substitution in through-hole mounting applications.

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

A: DC cold resistance affects circuit behavior during normal operation and fault conditions. The 5HFP 125-R exhibits 2.78 Ohms, the 0216.125MXEP exhibits 3.675 Ohms, and the BK/S501-V-125-R exhibits 12.3 Ohms. These variations may influence voltage drop across the fuse element and thermal response characteristics. Circuit designs with tight tolerance requirements should account for these differences.

Q: Are all substitute parts RoHS compliant?

A: Yes. The 0216.125MXEP is ROHS3 compliant. The BK/S501-V-125-R is RoHS compliant. Both meet environmental compliance requirements for modern electronics manufacturing.

Q: Which substitute has the broadest certification coverage?

A: The 0216.125MXEP (Littelfuse) carries certifications from CCC, CE, CSA, SEMKO, UL, and VDE. The BK/S501-V-125-R (Eaton) carries CSA and cULus certifications. Application requirements determine which certification set is necessary.

Q: Is the melting I²t parameter critical for substitution?

A: Melting I²t characterizes the thermal energy required to melt the fuse element and is a secondary specification. The 5HFP 125-R specifies 0.005, the 0216.125MXEP specifies 0.00546, and the BK/S501-V-125-R specifies 0.0037. These values are within acceptable ranges for 125 mA fast-blow ceramic fuses and do not prevent substitution. Circuit-specific thermal analysis may be warranted for applications with stringent fault-current timing requirements.