BK/AGC-4 Equivalent & Substitute Parts Reference

Part Overview

The BK/AGC-4 is a 4 A 250 V AC/DC fast-blow glass cartridge fuse manufactured by Eaton - Electronics Division. This fuse is designed for 3AB and 3AG holder applications with dimensions of 0.250" diameter × 1.250" length (6.35 mm × 31.75 mm). The part carries obsolete product status, necessitating identification of active equivalent and substitute components to maintain circuit protection functionality in existing and new designs. Equivalent parts maintain identical electrical and mechanical parameters, ensuring direct functional replacement without circuit redesign.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating (AC)	250 V
Response Time	Fast Blow
Fuse Type	Cartridge, Glass
Package / Case	3AB, 3AG, 1/4" × 1-1/4"
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	200 A
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.250" Dia × 1.250" L (6.35 mm × 31.75 mm)
Approval Agencies	CSA, UL

Substitute Part Grouping Explanation

Substitute parts for BK/AGC-4 are classified into three categories based on substitution relationship and product status:

Direct Manufacturer Equivalents (Eaton - Electronics Division): Parts AGC-4-R, BK/AGC-4-R, BK/AGC-4AX, and BK/AGC-4BB-R maintain identical electrical specifications (4 A, 250 V AC, fast-blow response, 200 A breaking capacity) and mechanical compatibility (3AB/3AG holders, 0.250" × 1.250" dimensions). These parts differ only in packaging designation or RoHS compliance status. All are active products suitable for direct replacement.

Parametric Equivalents (Littelfuse Inc.): Parts 0312004.VXP, 0312004.HXP, and 0312004.MXP from the 312 series match all critical electrical parameters (4 A, 250 V AC, fast-blow, 200 A breaking capacity) and mechanical dimensions. These Littelfuse components are active products with expanded approval certifications (CE, CSA, KC, PSE, UL) and RoHS3 compliance.

Similar Parts (SCHURTER Inc.): Parts 0001.1030 and 0034.5138 maintain electrical ratings and mechanical compatibility but carry obsolete product status. Part 0001.1030 features reduced breaking capacity (1.5 kA) and lower melting I²t (15 vs. 86.56), while 0034.5138 matches breaking capacity specifications. Both are obsolete and not recommended for new designs.

Key Parameters Determining Substitution:

Current Rating: 4 A (mandatory match)
Voltage Rating: 250 V AC (mandatory match)
Response Time: Fast Blow (mandatory match)
Package / Case: 3AB, 3AG, 1/4" × 1-1/4" (mandatory match)
Breaking Capacity: 200 A (preferred match for Eaton and Littelfuse parts)

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage (V AC)	Response	Breaking Capacity (A)	Melting I²t	Product Status	RoHS Status
BK/AGC-4	Eaton	4	250	Fast Blow	200	86.56	Obsolete	Non-compliant
AGC-4-R	Eaton	4	250	Fast Blow	200	86.56	Active	Compliant
BK/AGC-4-R	Eaton	4	250	Fast Blow	200	86.56	Active	ROHS3 Compliant
BK/AGC-4AX	Eaton	4	250	Fast Blow	200	86.56	Active	Not specified
BK/AGC-4BB-R	Eaton	4	250	Fast Blow	200	86.56	Active	Not specified
0312004.VXP	Littelfuse	4	250	Fast Blow	200	28.5	Active	ROHS3 Compliant
0312004.HXP	Littelfuse	4	250	Fast Blow	200	28.5	Active	ROHS3 Compliant
0312004.MXP	Littelfuse	4	250	Fast Blow	200	28.5	Active	ROHS3 Compliant
0001.1030	SCHURTER	4	250	Fast Blow	1500	15	Obsolete	ROHS3 Compliant
0034.5138	SCHURTER	4	250	Fast Blow	200	Not specified	Obsolete	ROHS3 Compliant

Engineering Selection Recommendations

Primary Selection (Direct Replacement): BK/AGC-4-R is the recommended substitute for BK/AGC-4. Both are manufactured by Eaton - Electronics Division with identical electrical and mechanical specifications. BK/AGC-4-R carries active product status and ROHS3 compliance, addressing the obsolescence of the original part. Inventory availability (2321 pcs) supports production requirements.

Alternative Selection (Eaton Series): AGC-4-R and BK/AGC-4AX provide equivalent functionality with active product status. AGC-4-R offers RoHS compliance, while BK/AGC-4AX maintains the BK designation series. Both support direct circuit substitution without modification.

Cross-Manufacturer Selection (Littelfuse 312 Series): Parts 0312004.HXP, 0312004.MXP, and 0312004.VXP are parametric equivalents from Littelfuse Inc. These components match all critical electrical parameters and mechanical dimensions. Littelfuse parts carry expanded approval certifications (CE, CSA, KC, PSE, UL) and RoHS3 compliance. Melting I²t differs (28.5 vs. 86.56), reflecting different thermal response characteristics within the fast-blow classification. Selection between Littelfuse variants depends on application-specific thermal requirements and certification needs. Inventory availability ranges from 1093 to 3741 pcs.

Not Recommended: SCHURTER parts 0001.1030 and 0034.5138 carry obsolete product status. Part 0001.1030 exhibits significantly reduced breaking capacity (1.5 kA vs. 200 A) and melting I²t (15 vs. 86.56), indicating incompatible thermal characteristics. These parts are unsuitable for new designs or long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can BK/AGC-4-R directly replace BK/AGC-4 without circuit modification?

A: Yes. BK/AGC-4-R maintains identical electrical ratings (4 A, 250 V AC), response time (fast-blow), breaking capacity (200 A), and mechanical dimensions (0.250" × 1.250"). Both require 3AB or 3AG holders. No circuit redesign is necessary.

Q: What is the difference between Eaton AGC-4-R and Littelfuse 0312004.HXP?

A: Both parts match electrical ratings and mechanical compatibility. The primary difference is melting I²t: Eaton AGC-4-R specifies 86.56, while Littelfuse 0312004.HXP specifies 28.5. This reflects different thermal response profiles within the fast-blow classification. Littelfuse parts carry additional certifications (CE, KC, PSE) beyond CSA and UL.

Q: Why do SCHURTER parts 0001.1030 and 0034.5138 show different breaking capacities?

A: Part 0001.1030 (SP 6.3×32 series) specifies 1.5 kA breaking capacity with melting I²t of 15, indicating different internal construction and thermal characteristics. Part 0034.5138 (FST 6.3×32 series) matches the 200 A breaking capacity. Both are obsolete and not recommended for new applications.

Q: Are Littelfuse 312 series parts (0312004.VXP, 0312004.HXP, 0312004.MXP) interchangeable?

A: Yes, within the context of this application. All three Littelfuse parts maintain identical electrical ratings (4 A, 250 V AC), response time (fast-blow), breaking capacity (200 A), and mechanical dimensions. Melting I²t is identical (28.5) across all three variants. Selection may depend on packaging designation or regional certification requirements.

Q: What holder types are compatible with these fuses?

A: All listed parts require 3AB or 3AG holder types. The mechanical dimensions (0.250" diameter × 1.250" length or 6.35 mm × 31.75 mm) are standardized across all substitutes. Verify holder compatibility before installation.

Q: Do all substitute parts meet RoHS requirements?

A: Eaton AGC-4-R, BK/AGC-4-R, and all Littelfuse 312 series parts (0312004.VXP, 0312004.HXP, 0312004.MXP) are RoHS3 compliant. The original BK/AGC-4 is RoHS non-compliant. SCHURTER parts are RoHS3 compliant but obsolete.

Q: What is the operating temperature range for these fuses?

A: Eaton parts (BK/AGC-4, AGC-4-R, BK/AGC-4-R, BK/AGC-4AX, BK/AGC-4BB-R) and Littelfuse 312 series parts operate across -55°C to 125°C. SCHURTER part 0001.1030 operates -40°C to 85°C (narrower range). SCHURTER part 0034.5138 operates -55°C to 125°C.

Q: Which substitute offers the highest inventory availability?

A: Littelfuse 0312004.HXP provides the highest inventory (3741 pcs), followed by BK/AGC-4-R (2321 pcs) and 0312004.MXP (2097 pcs). All three support immediate procurement for production requirements.

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