5STP 125-R Equivalent & Substitute Parts

Part Overview

The 5STP 125-R is a 125 mA, 250 V AC/DC fuse cartridge manufactured by Bel Fuse Inc. This slow-blow glass fuse is designed for through-hole mounting in 5mm x 20mm form factor applications. The part is currently active in production with 1715 units in stock. Substitute parts are identified when equivalent electrical ratings, mechanical dimensions, and approval certifications align with the original specification, enabling direct replacement in circuit protection applications.

Substiute Parts

5STP 125-R

Bel Fuse Inc.In Stock: 17935STP 125-R Datasheet

Current PartRFQ

0034.3108.PT

SCHURTER Inc.In Stock: 13140034.3108.PT Datasheet

DirectRFQ

BK/S506-V-125-R

Eaton - Electronics DivisionIn Stock: 1020BK/S506-V-125-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the 5STP 125-R are qualified based on the following electrical and mechanical parameters:

• Current Rating: 125 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Slow Blow (exact match required)
• Package / Case: 5mm x 20mm (Axial) (exact match required)
• Mounting Type: Through Hole (exact match required)
• Breaking Capacity @ Rated Voltage: 35A (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (minimum requirement)
• RoHS Status: ROHS3 Compliant (exact match required)

All identified substitutes meet these criteria and are approved for direct replacement in applications requiring the 5STP 125-R specification.

Parameter Comparison

Engineering Selection Recommendations

All three parts are active products with ROHS3 compliance and meet the core electrical and mechanical specifications for 125 mA, 250 V AC/DC slow-blow fuse cartridges in 5mm x 20mm form factor.

The 5STP 125-R (Bel Fuse Inc.) carries the broadest approval agency coverage including CCC, CE, CSA, cULus, IMQ, SEMKO, and VDE certifications.

The BK/S506-V-125-R (Eaton) provides equivalent certifications with BSI, CCC, CSA, IMQ, SEMKO, UR, and VDE approvals and offers the lowest DC cold resistance at 1.97 Ohms.

The 0034.3108.PT (SCHURTER Inc.) meets all core substitution criteria with cURus certification and maintains the specified operating temperature range of -55°C ~ 125°C.

Physical dimensions vary slightly across all three parts within the 5mm x 20mm nominal specification. Melting I²t values range from 0.05 to 0.064, all within acceptable slow-blow fuse characteristics.

Frequently Asked Questions (FAQ)

Q: Can the 0034.3108.PT substitute for the 5STP 125-R in all applications?

A: Yes. Both parts share identical electrical ratings (125 mA, 250 V AC/DC), fuse type (cartridge, glass), response time (slow blow), package dimensions (5mm x 20mm), and mounting type (through hole). Both are ROHS3 compliant and active products. Physical dimensions are within nominal tolerance for the 5mm x 20mm form factor.

Q: What is the difference in approval certifications between these parts?

A: The 5STP 125-R carries CCC, CE, CSA, cULus, IMQ, SEMKO, and VDE certifications. The BK/S506-V-125-R carries BSI, CCC, CSA, IMQ, SEMKO, UR, and VDE certifications. The 0034.3108.PT carries cURus certification. Selection should align with the specific regulatory requirements of the target application.

Q: Are there dimensional differences that affect mechanical fit?

A: All three parts conform to the 5mm x 20mm (Axial) package specification. Measured dimensions show minor variations: 5STP 125-R is 5.50mm x 21.00mm, 0034.3108.PT is 5.40mm x 22.50mm, and BK/S506-V-125-R is 5.54mm x 21.10mm. These variations are within standard tolerance for through-hole cartridge fuses and do not affect mechanical compatibility in standard fuse holders.

Q: How do the melting I²t values differ?

A: The 5STP 125-R has a melting I²t of 0.05, the 0034.3108.PT has 0.064, and the BK/S506-V-125-R has 0.063. All values are consistent with slow-blow fuse characteristics at 125 mA rating. The slight variations reflect different manufacturing processes but do not affect functional equivalence for circuit protection applications.

Q: Which part has the best availability?

A: The 5STP 125-R has the highest inventory at 1715 units, followed by the 0034.3108.PT at 1218 units, and the BK/S506-V-125-R at 916 units.