S506-250-R Glass Cartridge Fuse 250mA 250VAC 5x20mm Equivalent & Substitute Parts

Part Overview

The S506-250-R is a 250 mA, 250 V AC/DC slow blow glass cartridge fuse manufactured by Eaton - Electronics Division. This component requires a holder for installation and is designed for circuit protection in applications requiring slow response characteristics. The part is Active status with 767 pieces in current inventory. Equivalent and substitute parts are identified based on matching electrical ratings, mechanical dimensions, response time characteristics, and regulatory approvals to ensure direct functional replacement in existing designs.

Key Parameters

Parameter	Value
Current Rating	250 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	5mm x 20mm
Breaking Capacity @ Rated Voltage	35A
Melting I²t	0.265
Mounting Type	Requires Holder
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the S506-250-R are grouped into two categories based on substitution relationship type:

Direct Manufacturer Equivalents share identical electrical specifications, mechanical dimensions, response time, and breaking capacity. These parts are manufactured by Eaton - Electronics Division and represent alternative part numbers within the same product family:

Current Rating: 250 mA
Voltage Rating: 250 V AC
Response Time: Slow Blow
Package: 5mm x 20mm
Breaking Capacity: 35A

Parametric Equivalents from alternative manufacturers (Littelfuse Inc., SCHURTER Inc.) match the core electrical and mechanical parameters but may differ in melting I²t values, DC cold resistance, operating temperature ranges, or approval agency certifications. These parts are functionally equivalent for circuit protection purposes when the specific parameter variations are acceptable for the application.

Key parameters determining substitution eligibility:

Current Rating (250 mA)
Voltage Rating (250 V AC)
Fuse Type (Cartridge, Glass)
Response Time (Slow Blow)
Package Dimensions (5mm x 20mm)
Breaking Capacity (35A minimum)

Parameter Comparison

Part Number	Manufacturer	Current Rating	Voltage (AC)	Response Time	Package	Breaking Capacity	Melting I²t	DC Cold Resistance (Ω)	Approval Agencies	Inventory
S506-250-R	Eaton	250 mA	250 V	Slow Blow	5x20mm	35A	0.265	0.64	BSI, CCC, CSA, IMQ, SEMKO, UR, VDE	767
BK/S506-250-R	Eaton	250 mA	250 V	Slow Blow	5x20mm	35A	0.265	0.64	BSI, CCC, CSA, IMQ, SEMKO, UR, VDE	1549
BK/GDC-250MA	Eaton	250 mA	250 V	Slow Blow	5x20mm	35A	0.265	0.64	cULus, IMQ	1735
BK/GMD-250-R	Eaton	250 mA	250 V	Slow Blow	5x20mm	35A	0.4	3.455	CSA, UL	1216
0218.250MXP	Littelfuse	250 mA	250 V	Slow Blow	5x20mm	35A	0.5405	1.0495	CCC, CE, CSA, K-MARK, SEMKO, UL, VDE	2100
0218.250TXP	Littelfuse	250 mA	250 V	Slow Blow	5x20mm	35A	0.5405	1.0495	CCC, CE, CSA, KC, SEMKO, UL, VDE	1226
0034.3111	SCHURTER	250 mA	250 V	Slow Blow	5x20mm	35A	0.238	—	CCC, cURus, VDE	2161
0034.5037	SCHURTER	250 mA	250 V	Slow Blow	5x20mm	35A	2.53	—	cURus	857
0034.5611.11	SCHURTER	250 mA	250 V	Slow Blow	5x20mm	35A	0.238	—	cURus, VDE	1112
0218.250HXP	Littelfuse	250 mA	250 V	Slow Blow	5x20mm	35A	0.5405	1.0495	CCC, CE, CSA, K-MARK, SEMKO, UL, VDE	1775
0219.250MXAP	Littelfuse	250 mA	250 V	Slow Blow	5x20mm	150A	0.54	1.0495	CCC, CE, CSA, SEMKO, UL, VDE	6331

Engineering Selection Recommendations

Direct Replacement (Eaton Equivalents): BK/S506-250-R and BK/GDC-250MA are direct Eaton equivalents with identical electrical ratings and mechanical dimensions. BK/S506-250-R maintains identical melting I²t and DC cold resistance specifications. BK/GDC-250MA differs in melting I²t (0.4 vs 0.265) and DC cold resistance (3.455 vs 0.64 Ω) but retains core electrical parameters. Both are ROHS3 compliant and Active status.

Littelfuse Parametric Equivalents: 0218.250MXP, 0218.250TXP, and 0218.250HXP from Littelfuse Series 218 match all core electrical and mechanical parameters with operating temperature range -55°C to 125°C. Melting I²t is 0.5405 and DC cold resistance is 1.0495 Ω. These parts carry comprehensive approval agencies including UL, CSA, VDE, and CCC. 0219.250MXAP (Series 219XA) provides higher breaking capacity (150A vs 35A) while maintaining identical current and voltage ratings.

SCHURTER Parametric Equivalents: 0034.3111 (FST 5x20 series) and 0034.5611.11 (SMD-FST series) provide melting I²t of 0.238, lower than the main part. 0034.5037 (FTT 5x20 series) has significantly higher melting I²t of 2.53 and reduced operating temperature range (-40°C to 85°C). All SCHURTER parts are ROHS3 compliant and carry cURus certification.

Selection should prioritize parts with matching melting I²t and DC cold resistance when circuit protection timing is critical. For applications where approval agency certifications are specified, verify that substitute part certifications align with design requirements.

Frequently Asked Questions (FAQ)

Q: Can BK/S506-250-R directly replace S506-250-R? A: Yes. BK/S506-250-R is a direct Eaton equivalent with identical electrical ratings (250 mA, 250 V), response time (Slow Blow), package dimensions (5x20mm), breaking capacity (35A), melting I²t (0.265), and DC cold resistance (0.64 Ω). Both require a holder for installation and are ROHS3 compliant.

Q: What is the difference between Littelfuse 0218.250MXP and 0218.250TXP? A: Both parts are functionally equivalent with identical electrical specifications, melting I²t (0.5405), and DC cold resistance (1.0495 Ω). The primary difference is approval agency certification: 0218.250MXP includes K-MARK certification while 0218.250TXP includes KC certification. Both operate across -55°C to 125°C.

Q: Why does 0219.250MXAP have a higher breaking capacity (150A vs 35A)? A: 0219.250MXAP belongs to the Littelfuse 219XA series, which is designed for higher fault current environments. Despite the higher breaking capacity, it maintains identical current rating (250 mA), voltage rating (250 V), response time (Slow Blow), and package dimensions (5x20mm), making it suitable for applications requiring enhanced fault protection capability.

Q: Are SCHURTER parts with different melting I²t values suitable substitutes? A: SCHURTER parts 0034.3111 and 0034.5611.11 have lower melting I²t (0.238 vs 0.265), while 0034.5037 has significantly higher melting I²t (2.53 vs 0.265). These differences affect fuse response timing. Substitution is acceptable only when the application circuit design accommodates the altered thermal response characteristics.

Q: What approval agencies are most commonly required? A: UL, CSA, and VDE certifications are present across most substitute parts. The main part S506-250-R includes BSI, CCC, CSA, IMQ, SEMKO, UR, and VDE. When selecting substitutes, verify that required certifications for your application region are present on the substitute part documentation.

Q: Can I use these fuses without a holder? A: No. All listed parts, including the main part S506-250-R, are cartridge-type fuses that require a holder for installation. The 5x20mm package dimensions specify the holder compatibility. Do not attempt to use these fuses in applications without proper holder installation.

Q: What is the significance of DC cold resistance values? A: DC cold resistance affects voltage drop across the fuse during normal operation. The main part has 0.64 Ω, while Littelfuse parts have 1.0495 Ω and SCHURTER parts do not specify this value. Higher resistance increases power dissipation. Select based on circuit design requirements for acceptable voltage drop and thermal performance.

Q: Are all substitute parts ROHS3 compliant? A: Yes. All listed substitute parts carry ROHS3 compliance status, matching the main part S506-250-R. This ensures compatibility with environmental and regulatory requirements across EU and equivalent markets.

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