Littelfuse 021806.3MXP Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 021806.3MXP is a 6.3 A, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm package format. This component is classified as Active product status and is designed for applications requiring reliable overcurrent protection in industrial and commercial equipment. Substitute parts are identified when equivalent electrical characteristics, mechanical dimensions, and approval certifications align with the original specification, enabling seamless integration into existing designs or addressing supply chain requirements.

Key Parameters

Parameter	Value
Current Rating	6.3 A
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Package / Case	5mm x 20mm
Fuse Type	Cartridge, Glass
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	63 A
Operating Temperature Range	-55°C to 125°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict alignment of the following parameters:

Primary Criteria (Must Match):

Current Rating: 6.3 A
Voltage Rating (AC): 250 V
Package / Case: 5mm x 20mm
Fuse Type: Cartridge, Glass
Response Time: Slow Blow

Secondary Criteria (Allowable Variation):

Breaking Capacity: Parts with 63 A or higher breaking capacity are acceptable
Melting I²t: Variation permitted within application tolerance
DC Cold Resistance: Minor variation acceptable
Approval Agencies: Subset or superset of original certifications acceptable

Substitute parts are grouped into two categories: Direct Manufacturer Equivalents (identical part specifications from the same manufacturer) and Parametric Equivalents (parts meeting all primary criteria with allowable secondary parameter variations).

Parameter Comparison

Part Number	Manufacturer	Series	Current (A)	Voltage (V)	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ω)	Product Status
021806.3MXP	Littelfuse Inc.	218	6.3	250	63	198.5	0.0076	Active
021806.3HXP	Littelfuse Inc.	218	6.3	250	63	198.5	0.0076	Active
021306.3MXP	Littelfuse Inc.	213	6.3	250	63	600	0.0095	Active
021806.3MXBP	Littelfuse Inc.	218	6.3	250	63	198.5	0.0076	Active
021806.3MXF34P	Littelfuse Inc.	218	6.3	250	63	198.5	0.0076	Active
021806.3TXP	Littelfuse Inc.	218	6.3	250	63	198.5	0.0076	Active
021906.3MXABP	Littelfuse Inc.	219XA	6.3	250	150	1093.035	0.0117	Active
021906.3MXAP	Littelfuse Inc.	219XA	6.3	250	150	1093.035	0.0117	Active
061806.3MXP	Littelfuse Inc.	618	6.3	250	63	198.5	0.0076	Active
0034.3125	SCHURTER Inc.	FST 5x20	6.3	250	63	190	—	Active
BK/S506-6.3-R	Eaton - Electronics Division	S506	6.3	250	63	237.6	0.0071	Active

Engineering Selection Recommendations

Direct Manufacturer Equivalents (Littelfuse Inc.):

021806.3HXP is a direct equivalent with identical electrical and mechanical specifications. Selection is appropriate for applications where Littelfuse Series 218 continuity is required.

Parametric Equivalents within Littelfuse Series 218:

021806.3MXBP, 021806.3MXF34P, and 021806.3TXP maintain identical core parameters (current, voltage, breaking capacity, melting I²t, DC cold resistance) and differ only in packaging or certification scope. These are suitable for direct substitution.

Littelfuse Series 213 Alternative:

021306.3MXP meets all primary electrical criteria but exhibits higher melting I²t (600 vs. 198.5) and slightly elevated DC cold resistance (0.0095 vs. 0.0076 Ω). This part is suitable where the higher thermal capacity is compatible with circuit design.

Littelfuse Series 219XA High-Breaking-Capacity Alternatives:

021906.3MXABP and 021906.3MXAP provide 150 A breaking capacity (versus 63 A) and significantly higher melting I²t (1093.035). These are applicable in circuits requiring enhanced fault current handling. DC cold resistance is elevated to 0.0117 Ω.

Littelfuse Series 618 Alternative:

061806.3MXP maintains identical electrical parameters to the main part but operates under a different series designation. Approval certifications differ slightly (excludes K-MARK, includes UR).

Cross-Manufacturer Alternatives:

0034.3125 (SCHURTER Inc., FST 5x20 series) and BK/S506-6.3-R (Eaton Electronics Division, S506 series) both meet primary electrical and mechanical criteria. Melting I²t values are 190 and 237.6 respectively, within acceptable variation. Approval certifications differ by manufacturer.

All substitute parts maintain Active product status and ROHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can 021806.3HXP replace 021806.3MXP directly?

A: Yes. Both parts are Littelfuse Series 218 with identical current rating (6.3 A), voltage rating (250 V), breaking capacity (63 A), melting I²t (198.5), and DC cold resistance (0.0076 Ω). The parts are mechanically and electrically interchangeable.

Q: What is the difference between Series 218 and Series 219XA fuses?

A: Series 219XA parts (021906.3MXABP, 021906.3MXAP) provide higher breaking capacity (150 A vs. 63 A) and significantly higher melting I²t (1093.035 vs. 198.5). These characteristics allow handling of higher fault currents. Selection depends on circuit fault current requirements.

Q: Are cross-manufacturer substitutes (SCHURTER, Eaton) acceptable?

A: Cross-manufacturer parts 0034.3125 and BK/S506-6.3-R meet all primary electrical criteria (6.3 A, 250 V, 5mm x 20mm package, slow-blow response). Melting I²t values (190 and 237.6) represent minor variation from the original (198.5). Approval certifications differ by manufacturer. Substitution is permissible where certification requirements align with application standards.

Q: Does the 5mm x 20mm package dimension apply to all substitutes?

A: Yes. All listed substitute parts conform to 5mm x 20mm package dimensions and require a compatible fuse holder. Physical interchangeability is confirmed across all alternatives.

Q: What does "Requires Holder" mean for mounting type?

A: These are cartridge fuses that must be installed in a dedicated fuse holder or socket. They are not surface-mount or panel-mount components. The holder provides electrical contact and mechanical retention.

Q: Can I use 021306.3MXP (Series 213) as a substitute?

A: Yes, with circuit design consideration. Series 213 exhibits higher melting I²t (600 vs. 198.5), indicating slower thermal response. This is acceptable where the application tolerates extended response time before fuse operation. Verify compatibility with circuit protection requirements.

Q: What is the significance of DC Cold Resistance variation?

A: DC cold resistance affects voltage drop across the fuse during normal operation. Variations from 0.0071 Ω to 0.0117 Ω are minor and typically negligible in most applications. Verify if circuit design includes fuse voltage drop calculations.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance status, meeting environmental and material restriction requirements.

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