Equivalent & Substitute Parts for BK/C515-350MA

Part Overview

The BK/C515-350MA is a 350 mA, 250 V AC/DC slow-blow glass cartridge fuse manufactured by Eaton - Electronics Division. This component is classified as obsolete, with 937 units currently in stock. The fuse is designed for through-hole mounting in 2AG form factor (5mm x 15mm axial configuration) and is approved by CSA and UL standards.

Due to the obsolete product status of BK/C515-350MA, equivalent and substitute parts are necessary to ensure continued availability for maintenance, repair, and new design implementations. The substitute parts listed below maintain electrical and mechanical compatibility within the specified parameter tolerances.

Key Parameters

Parameter	Value	Significance for Substitution
Current Rating	350 mA	Critical - must match exactly for circuit protection
Voltage Rating (AC)	250 V	Critical - determines maximum operating voltage
Fuse Type	Cartridge, Glass	Critical - physical and functional form factor
Response Time	Slow Blow	Critical - determines inrush current tolerance
Package / Case	2AG, 5mm x 15mm (Axial)	Critical - mechanical fit and mounting compatibility
Mounting Type	Through Hole	Critical - PCB assembly method
Breaking Capacity @ Rated Voltage	35A	Important - maximum fault current interruption capability
Melting I²t	1.169	Important - thermal energy dissipation characteristic
DC Cold Resistance	1.04 Ohms	Important - voltage drop and power dissipation
Approval Agency	CSA, UL	Important - regulatory compliance certification

Substitute Part Grouping Explanation

Substitute parts for BK/C515-350MA are classified into two categories based on electrical and mechanical parameter alignment:

Category 1: Direct Eaton Equivalents (Active Status) These parts maintain identical electrical specifications and are manufactured by the same supplier (Eaton - Electronics Division). They differ only in packaging configuration and product status (active vs. obsolete).

BK/C515-350-R
BK/C515S-350-R

Category 2: Littelfuse Cross-Substitutes (Parametric Equivalents) These parts share the same current rating (350 mA), AC voltage rating (250 V), fuse type (cartridge glass), response time (slow blow), and mounting type (through hole). However, they feature different physical dimensions, DC voltage ratings, melting I²t values, and DC cold resistance characteristics.

0230.350DRT1P
0230.350DRT2P
0230.350DRT3P
0230.350HXP
0230.350MXP

Substitution Logic: All listed substitutes maintain the critical parameters of 350 mA current rating, 250 V AC voltage rating, slow-blow response, and through-hole mounting. Category 1 parts are direct replacements with identical mechanical dimensions. Category 2 parts are parametric equivalents suitable for applications where the non-standard cartridge dimensions and enhanced DC voltage rating (125 V DC) are acceptable within the circuit design constraints.

Parameter Comparison

Part Number	Manufacturer	Current Rating (mA)	Voltage AC (V)	Voltage DC (V)	Response Time	Package / Case	Breaking Capacity @ Rated Voltage	Melting I²t	DC Cold Resistance (Ohms)	Product Status	RoHS Status
BK/C515-350MA	Eaton	350	250	Not specified	Slow Blow	2AG, 5mm x 15mm	35A	1.169	1.04	Obsolete	Non-compliant
BK/C515-350-R	Eaton	350	250	Not specified	Slow Blow	2AG, 5mm x 15mm	35A	1.169	1.04	Active	Compliant
BK/C515S-350-R	Eaton	350	250	Not specified	Slow Blow	2AG, 5mm x 15mm	35A	1.169	1.04	Active	Compliant
0230.350DRT1P	Littelfuse	350	250	125	Slow Blow	Cartridge, Non-Standard (Axial)	35A AC, 10kA DC	0.49	1.31	Active	ROHS3 Compliant
0230.350DRT2P	Littelfuse	350	250	125	Slow Blow	Cartridge, Non-Standard (Axial)	35A AC, 10kA DC	0.49	1.31	Active	ROHS3 Compliant
0230.350DRT3P	Littelfuse	350	250	125	Slow Blow	Cartridge, Non-Standard (Axial)	35A AC, 10kA DC	0.49	1.31	Active	ROHS3 Compliant
0230.350HXP	Littelfuse	350	250	125	Slow Blow	Cartridge, Non-Standard (Axial)	35A AC, 10kA DC	0.49	1.31	Active	ROHS3 Compliant
0230.350MXP	Littelfuse	350	250	125	Slow Blow	Cartridge, Non-Standard (Axial)	35A AC, 10kA DC	0.49	1.31	Active	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Preferred): BK/C515-350-R and BK/C515S-350-R are the primary substitutes for BK/C515-350MA. Both parts are manufactured by Eaton - Electronics Division and maintain identical electrical and mechanical specifications. Both are active products with RoHS compliance, addressing the obsolescence of the original part. These substitutes are suitable for direct PCB retrofit without design modification.

For Cross-Manufacturer Substitution: The Littelfuse 230 series parts (0230.350DRT1P, 0230.350DRT2P, 0230.350DRT3P, 0230.350HXP, 0230.350MXP) are suitable substitutes when Eaton equivalents are unavailable. These parts maintain the critical 350 mA current rating and 250 V AC voltage rating with slow-blow response. However, the following differences must be evaluated:

Physical dimensions differ (4.50mm x 14.50mm vs. 5.50mm x 15.20mm), requiring mechanical fit verification in the fuse holder
DC voltage rating is specified at 125 V (not specified for original part)
Melting I²t is lower (0.49 vs. 1.169), indicating faster thermal response
DC cold resistance is higher (1.31 vs. 1.04 Ohms), resulting in increased voltage drop
Breaking capacity includes DC rating (10kA DC vs. 35A AC only)

All substitute parts carry CSA and UL approvals, maintaining regulatory compliance. Littelfuse parts include CE certification and ROHS3 compliance, exceeding the original part's compliance profile.

Frequently Asked Questions (FAQ)

Q1: Can BK/C515-350-R be used as a direct replacement for BK/C515-350MA?

A: Yes. BK/C515-350-R is a direct equivalent manufactured by Eaton - Electronics Division with identical electrical specifications (350 mA, 250 V AC, slow-blow response) and mechanical dimensions (2AG, 5mm x 15mm). The primary difference is product status (active vs. obsolete) and RoHS compliance. No circuit modification is required.

Q2: What is the difference between BK/C515-350-R and BK/C515S-350-R?

A: Both parts are Eaton equivalents with identical electrical and mechanical specifications. The difference lies in the series designation (C515 vs. C515S) and packaging configuration. Both are active products suitable for direct replacement of BK/C515-350MA.

Q3: Can Littelfuse 0230.350DRT1P replace BK/C515-350MA in all applications?

A: Littelfuse 0230.350DRT1P shares the critical parameters of 350 mA current rating, 250 V AC voltage rating, and slow-blow response. However, physical dimensions differ (4.50mm x 14.50mm vs. 5.50mm x 15.20mm), requiring verification that the fuse holder accommodates the non-standard cartridge size. Additionally, the lower melting I²t (0.49 vs. 1.169) and higher DC cold resistance (1.31 vs. 1.04 Ohms) may affect circuit performance in applications sensitive to thermal response or voltage drop. Mechanical and electrical validation is required before substitution.

Q4: What are the packaging differences among the Littelfuse substitutes?

A: The Littelfuse 230 series substitutes differ in packaging configuration: 0230.350DRT1P, 0230.350DRT2P, and 0230.350DRT3P are supplied in Tape & Reel (TR) format, while 0230.350HXP and 0230.350MXP are supplied in Bulk packaging. All five parts maintain identical electrical specifications and physical dimensions. Selection depends on procurement volume and assembly process requirements.

Q5: Are all substitute parts RoHS compliant?

A: BK/C515-350MA is RoHS non-compliant. BK/C515-350-R and BK/C515S-350-R are RoHS compliant. All Littelfuse substitutes (0230.350DRT1P, 0230.350DRT2P, 0230.350DRT3P, 0230.350HXP, 0230.350MXP) are ROHS3 compliant. For applications requiring RoHS compliance, Eaton or Littelfuse substitutes are appropriate selections.

Q6: What is the significance of the melting I²t parameter in fuse substitution?

A: Melting I²t represents the thermal energy required to melt the fuse element. BK/C515-350MA has a melting I²t of 1.169, while Littelfuse substitutes have 0.49. A lower melting I²t indicates faster thermal response to overcurrent conditions. In applications with high inrush currents or sensitive to nuisance tripping, the difference in melting I²t must be evaluated to ensure the substitute fuse does not operate prematurely.

Q7: Why do Littelfuse parts specify a DC voltage rating when the original part does not?

A: Littelfuse 230 series parts are rated for both AC and DC operation (250 V AC, 125 V DC), providing broader application flexibility. The original BK/C515-350MA does not specify a DC rating. When substituting with Littelfuse parts in DC circuits, the 125 V DC rating applies. For AC-only applications, this additional rating does not affect performance.

Q8: How does DC cold resistance affect fuse selection?

A: DC cold resistance determines the voltage drop across the fuse during normal operation. BK/C515-350MA has 1.04 Ohms, while Littelfuse substitutes have 1.31 Ohms. At 350 mA, the voltage drop difference is approximately 0.09 V. In circuits with tight voltage budgets or high-current applications, this difference may be significant and should be verified against circuit design specifications.

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