BK/ETF-2 Equivalent & Substitute Parts Reference

Part Overview

The BK/ETF-2 is a 2 A, 277 V AC board mount fuse in radial, can, vertical package configuration designed for through-hole mounting applications. This component is classified as obsolete, necessitating identification of active equivalent parts for ongoing design support and procurement continuity. The fuse features slow-blow response characteristics with a breaking capacity of 100 A at rated voltage and operates across a temperature range of -55°C to 125°C.

Substiute Parts

BK/ETF-2

Eaton - Electronics DivisionIn Stock: 864BK/ETF-2 Datasheet

Current PartRFQ

SR-5-2A-BK

Eaton - Electronics DivisionIn Stock: 5007SR-5-2A-BK Datasheet

SimilarRFQ

0034.6618

SCHURTER Inc.In Stock: 55800034.6618 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the BK/ETF-2 is determined by strict alignment of electrical and mechanical parameters. The primary substitution criteria are:

Mandatory Matching Parameters:

• Current Rating: 2 A (exact match required)
• Fuse Type: Board Mount (Cartridge Style Excluded)
• Mounting Type: Through Hole
• Package / Case: Radial, Can, Vertical
• Response Time: Slow Blow

Voltage Compatibility Consideration: The BK/ETF-2 operates at 277 V AC. Substitute parts must maintain voltage ratings that support the original application voltage or higher. Parts rated at 250 V AC are acceptable for applications where the circuit voltage does not exceed 250 V AC; however, direct substitution in 277 V AC circuits requires parts rated at 277 V AC or higher.

Identified Substitute Parts:

1. SR-5-2A-BK (Eaton - Electronics Division): Active status, 2 A, 250 V AC, slow-blow, through-hole radial mount. Voltage rating is lower than original specification.

2. 0034.6618 (SCHURTER Inc.): Active status, 2 A, 250 V AC / 125 V DC, slow-blow, through-hole radial mount. Dual voltage rating with DC capability. Voltage rating is lower than original specification.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement in 277 V AC Circuits: No active substitute part with 277 V AC rating is available from the provided data. The BK/ETF-2 cannot be directly replaced with SR-5-2A-BK or 0034.6618 in applications requiring 277 V AC operation, as both substitute parts are rated at 250 V AC maximum.

For Circuits Operating at 250 V AC or Lower:

SR-5-2A-BK Selection Criteria:

• Active product status with extended manufacturer support
• Identical current rating (2 A) and response time (slow-blow)
• Matching mechanical form factor (radial, can, vertical through-hole)
• Broader approval agency certifications (CCC, cULus, KC-MARK, PSE, SEMKO, VDE)
• RoHS3 compliance for modern supply chain requirements
• Lower operating temperature minimum (-40°C vs. -55°C) may be limiting factor in extreme cold environments
• Reduced breaking capacity (35 A vs. 100 A) acceptable for most board-level protection applications

0034.6618 Selection Criteria:

• Active product status with extended manufacturer support
• Identical current rating (2 A) and response time (slow-blow)
• Matching mechanical form factor (radial, can, vertical through-hole)
• Dual voltage rating (250 V AC / 125 V DC) provides flexibility for mixed-voltage applications
• Operating temperature range matches original specification (-55°C ~ 125°C)
• Broader approval agency certifications (CCC, cURus, KC, PSE/JET, VDE)
• RoHS3 compliance for modern supply chain requirements
• Higher melting I²t (34 vs. 23) indicates different thermal response profile

Compliance Considerations: Both substitute parts carry RoHS3 compliance and expanded international certifications (VDE, CCC, PSE/JET, KC) compared to the original BK/ETF-2 (SEMKO, UL only). This represents improved regulatory alignment for global applications.

Frequently Asked Questions (FAQ)

Q: Can SR-5-2A-BK or 0034.6618 be used as direct replacements for BK/ETF-2 in 277 V AC applications?

A: No. Both substitute parts are rated at 250 V AC maximum. The BK/ETF-2 is rated at 277 V AC. Using a 250 V AC rated fuse in a 277 V AC circuit exceeds the component's voltage specification and violates electrical safety standards. Substitution is only valid for circuits operating at 250 V AC or lower.

Q: What are the key electrical differences between the substitute parts?

A: SR-5-2A-BK is rated for 250 V AC only. The 0034.6618 provides dual voltage capability (250 V AC / 125 V DC), making it suitable for applications with both AC and DC voltage requirements. Both maintain the 2 A current rating and slow-blow response of the original part.

Q: How do the breaking capacities compare?

A: The BK/ETF-2 has a breaking capacity of 100 A at rated voltage. Both SR-5-2A-BK and 0034.6618 have breaking capacities of 35 A AC. For board-level protection in typical electronic circuits, 35 A breaking capacity is generally sufficient. Applications requiring 100 A breaking capacity cannot use these substitutes.

Q: Are there temperature range limitations with the substitute parts?

A: SR-5-2A-BK operates from -40°C to 85°C, which is narrower than the original BK/ETF-2 range of -55°C to 125°C. The 0034.6618 matches the original temperature range (-55°C to 125°C). For applications requiring operation below -40°C or above 85°C, SR-5-2A-BK is unsuitable; 0034.6618 is compatible.

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

A: Melting I²t indicates the thermal energy required to melt the fuse element. BK/ETF-2 has I²t of 23, SR-5-2A-BK has 30, and 0034.6618 has 34. Higher I²t values indicate slower thermal response. These differences affect nuisance trip behavior in circuits with inrush currents. Verify compatibility with circuit inrush characteristics before substitution.

Q: Do the substitute parts have improved certifications?

A: Yes. Both SR-5-2A-BK and 0034.6618 carry expanded international certifications (VDE, CCC, PSE/JET, KC) and RoHS3 compliance, compared to the original BK/ETF-2 (SEMKO, UL only). This represents improved regulatory alignment for global markets and modern supply chain requirements.

Q: What is the physical size difference?

A: BK/ETF-2 dimensions are 0.329" Dia × 0.303" H (8.35mm × 7.70mm). SR-5-2A-BK is 0.335" Dia × 0.319" H (8.50mm × 8.10mm). The 0034.6618 is 0.335" Dia × 0.335" H (8.50mm × 8.50mm). All three fit the radial, can, vertical through-hole package category with minor dimensional variations. Verify PCB footprint compatibility before substitution.

Q: Which substitute part should be selected for new designs?

A: For new designs operating at 250 V AC or lower with temperature requirements between -40°C and 85°C, SR-5-2A-BK is recommended due to active status and broad certifications. For applications requiring the full -55°C to 125°C temperature range or dual AC/DC voltage capability, 0034.6618 is the appropriate selection. Both parts are active products with extended manufacturer support.