Equivalent & Substitute Parts for BK/S504-630MA

Part Overview

The BK/S504-630MA is a 630 mA, 250 V AC/DC glass cartridge fuse with a 5mm x 20mm form factor manufactured by Eaton - Electronics Division. This component is classified as obsolete and requires a holder for installation. Due to its obsolete product status, equivalent and substitute parts from active product lines are necessary for ongoing system maintenance and new designs. The fuse operates with slow-blow response characteristics and is approved by multiple international standards bodies including BSI, IMQ, SEMKO, UL, and VDE.

Key Parameters

Parameter	Value
Current Rating	630 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	5mm x 20mm
Response Time	Slow Blow
Breaking Capacity @ Rated Voltage	35A
Mounting Type	Requires Holder
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution eligibility for the BK/S504-630MA is determined by strict equivalence across the following critical parameters:

Primary Equivalence Criteria:

Current Rating: 630 mA (exact match required)
Voltage Rating: 250 V AC (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Breaking Capacity: 35A (exact match required)
Mounting Type: Requires Holder (exact match required)

All substitute parts listed meet these primary criteria. Secondary parameters such as melting I²t, DC cold resistance, and approval agencies may vary within acceptable ranges for the same functional classification. Parts are grouped into two categories: direct Eaton equivalents (same manufacturer, active product status) and similar alternatives from other manufacturers (Littelfuse) that meet identical electrical and mechanical specifications.

Parameter Comparison

Part Number	Manufacturer	Current Rating	Voltage (AC)	Package	Response Time	Breaking Capacity	Melting I²t	DC Cold Resistance (Ohms)	Product Status	RoHS Status
BK/S504-630MA	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	1.3	0.19	Obsolete	Non-compliant
BK/S506-630-R	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	1.33	0.186	Active	ROHS3 Compliant
BK/GDC-630MA	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	1.33	0.186	Active	RoHS Compliant
BK/GMD-630-R	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	3.1	0.629	Active	ROHS3 Compliant
BK1/GMD-630-R	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	3.1	0.629	Active	ROHS3 Compliant
BK1/S506-630-R	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	1.33	0.186	Active	ROHS3 Compliant
GDC-630MA	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	1.33	0.186	Active	Not specified
GMD-630-R	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	3.1	0.629	Active	ROHS3 Compliant
S506-630-R	Eaton	630 mA	250 V	5x20mm	Slow Blow	35A	1.33	0.186	Active	ROHS3 Compliant
0218.630HXP	Littelfuse	630 mA	250 V	5x20mm	Slow Blow	35A	4.675	0.275	Active	ROHS3 Compliant
0218.630MXP	Littelfuse	630 mA	250 V	5x20mm	Slow Blow	35A	4.675	0.275	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation - Eaton S506 Series:

The BK/S506-630-R, BK1/S506-630-R, and S506-630-R represent the most direct active-product substitutes for the obsolete BK/S504-630MA. These parts maintain identical electrical specifications (630 mA, 250 V, 35A breaking capacity, 1.33 melting I²t) and mechanical form factor (5x20mm). All S506 variants carry ROHS3 compliance and are approved by BSI, CCC, CSA, cULus, IMQ, SEMKO, and VDE. The BK1/S506-630-R variant offers the highest inventory availability (10,840 pieces).

Secondary Recommendation - Eaton GDC Series:

The BK/GDC-630MA and GDC-630MA are active Eaton products with identical electrical and mechanical specifications to the main part. These parts carry RoHS compliance and are approved by cULus and IMQ. The GDC series maintains the same 630 mA rating and 5x20mm package. The melting I²t of 1.33 matches the S506 series.

Alternative Recommendation - Eaton GMD Series:

The BK/GMD-630-R, BK1/GMD-630-R, and GMD-630-R are active Eaton products that meet all primary equivalence criteria. These parts differ in melting I²t (3.1 versus 1.3-1.33) and DC cold resistance (0.629 Ohms versus 0.186-0.19 Ohms), indicating different thermal response characteristics within the slow-blow classification. GMD variants are approved by CSA and UL. Selection of GMD series should be based on specific thermal response requirements of the application.

Cross-Manufacturer Alternative - Littelfuse 218 Series:

The 0218.630HXP and 0218.630MXP from Littelfuse meet all primary electrical and mechanical equivalence criteria. These parts carry ROHS3 compliance and are approved by CCC, CE, CSA, K-MARK, SEMKO, UL, and VDE. Operating temperature range is specified as -55°C to 125°C. Melting I²t is 4.675, indicating slower thermal response compared to Eaton S506 and GDC series. DC cold resistance is 0.275 Ohms.

Frequently Asked Questions (FAQ)

Q: Can BK/S504-630MA be directly replaced with any of the listed substitutes?

A: Yes. All listed substitute parts meet the critical equivalence parameters: 630 mA current rating, 250 V AC voltage rating, 5x20mm package, cartridge glass fuse type, slow-blow response, 35A breaking capacity, and holder-mount requirement. Physical and electrical compatibility is confirmed.

Q: What is the difference between Eaton S506, GDC, and GMD series fuses?

A: All three series meet the primary electrical and mechanical specifications. The primary difference is melting I²t: S506 and GDC series have 1.33 I²t, while GMD series has 3.1 I²t. This indicates GMD series has slower thermal response. DC cold resistance also differs: S506/GDC at 0.186 Ohms versus GMD at 0.629 Ohms. Selection depends on specific thermal response requirements of the application circuit.

Q: Why is the original BK/S504-630MA listed as obsolete?

A: The BK/S504-630MA is classified as obsolete by Eaton - Electronics Division. Active product lines (S506, GDC, GMD series) provide equivalent functionality with current manufacturing support and improved compliance certifications (ROHS3).

Q: Are Littelfuse 0218 series fuses compatible with Eaton fuse holders?

A: Littelfuse 0218.630HXP and 0218.630MXP share identical 5x20mm package dimensions and cartridge glass construction with Eaton parts. Physical compatibility with standard 5x20mm fuse holders is confirmed. Electrical specifications (630 mA, 250 V, 35A breaking capacity) are equivalent.

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

A: Melting I²t defines the thermal energy required to melt the fuse element and is a measure of fuse response speed within the slow-blow classification. Lower I²t values (1.3-1.33) indicate faster response; higher values (3.1-4.675) indicate slower response. Application circuit design determines the appropriate I²t value.

Q: Which substitute offers the best RoHS compliance?

A: All active substitute parts carry either RoHS Compliant or ROHS3 Compliant status. ROHS3 Compliant parts (S506 series, GMD series, Littelfuse 218 series) represent the current regulatory standard. The original BK/S504-630MA is RoHS non-compliant.

Q: What approval agencies are common across all substitutes?

A: CSA and UL approvals are present across multiple substitute options. For comprehensive international approval coverage, the S506 series (BSI, CCC, CSA, cULus, IMQ, SEMKO, VDE) offers the broadest certification scope.

Q: Is inventory availability a factor in substitute selection?

A: Inventory levels vary significantly. BK1/S506-630-R has the highest availability (10,840 pieces), followed by BK/GDC-630MA (2,020 pieces). Availability should be evaluated against project timeline requirements and supply chain strategy.

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