Littelfuse 021806.3H Glass Cartridge Fuse 6.3A 250VAC 5x20mm Equivalent & Substitute Parts

Part Overview

The Littelfuse 021806.3H is a 6.3 A, 250 V AC/DC glass cartridge fuse with slow-blow response characteristics, housed in a 5mm x 20mm form factor. This component requires a dedicated fuse holder for installation and is classified as obsolete. Due to its obsolete status, direct replacement with active production equivalents is necessary for new designs and ongoing system maintenance. Substitute parts maintain identical electrical ratings and mechanical dimensions while offering improved compliance certifications and active product support.

Key Parameters

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

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Current Rating: 6.3 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Breaking Capacity @ Rated Voltage: 63 A (exact match required)
Operating Temperature Range: -55°C to 125°C (exact match required)

All substitute parts listed below meet these criteria and are classified as active production components. Substitutes differ in series designation, packaging format, approval agency certifications, and RoHS compliance status, but maintain full electrical and mechanical compatibility with the original 021806.3H specification.

Parameter Comparison

Part Number	Series	Current Rating (A)	Voltage (V AC)	Response Time	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ω)	Product Status	RoHS Status
021806.3H	218	6.3	250	Slow Blow	5x20mm	63	204	0.0075	Obsolete	Non-compliant
021306.3MXBP	213	6.3	250	Slow Blow	5x20mm	63	600	0.0095	Active	ROHS3 Compliant
021306.3MXP	213	6.3	250	Slow Blow	5x20mm	63	600	0.0095	Active	ROHS3 Compliant
021306.3TXP	213	6.3	250	Slow Blow	5x20mm	63	600	0.0095	Active	ROHS3 Compliant
021806.3HXP	218	6.3	250	Slow Blow	5x20mm	63	198.5	0.0076	Active	ROHS3 Compliant
021806.3MXBP	218	6.3	250	Slow Blow	5x20mm	63	198.5	0.0076	Active	ROHS3 Compliant
021806.3MXF11P	218	6.3	250	Slow Blow	5x20mm	63	198.5	0.0076	Active	ROHS3 Compliant
021806.3MXF34P	218	6.3	250	Slow Blow	5x20mm	63	198.5	0.0076	Active	ROHS3 Compliant
021806.3MXP	218	6.3	250	Slow Blow	5x20mm	63	198.5	0.0076	Active	ROHS3 Compliant
021806.3TXP	218	6.3	250	Slow Blow	5x20mm	63	198.5	0.0076	Active	ROHS3 Compliant
021806.3VXP	218	6.3	250	Slow Blow	5x20mm	63	198.5	0.0076	Active	ROHS3 Compliant

Engineering Selection Recommendations

Series 218 Variants (Direct Mechanical Equivalents): The 021806.3HXP, 021806.3MXBP, 021806.3MXF11P, 021806.3MXF34P, 021806.3MXP, 021806.3TXP, and 021806.3VXP maintain the same series designation as the original 021806.3H. These parts offer active product status with ROHS3 compliance and expanded certification coverage including CCC, CE, CSA, K-MARK, PSE, SEMKO, UL, and VDE. The melting I²t value of 198.5 closely aligns with the original specification of 204, ensuring comparable thermal response characteristics. These variants are suitable for direct replacement in existing designs.

Series 213 Variants (Alternative Active Equivalents): The 021306.3MXBP, 021306.3MXP, and 021306.3TXP represent an alternative series with identical electrical ratings and mechanical dimensions. These parts feature a higher melting I²t value of 600 and slightly elevated DC cold resistance of 0.0095 Ohms compared to the original 0.0075 Ohms. Series 213 components carry ROHS3 compliance and certifications including BSI, CCC, CE, CSA, PSE, SEMKO, UR, and VDE. Selection between Series 218 and Series 213 depends on application-specific thermal response requirements and certification needs.

Compliance Considerations: All substitute parts are ROHS3 compliant, addressing regulatory requirements absent in the obsolete original component. Certification coverage varies by variant; applications requiring specific approval agencies should reference the certification list for each part number.

Frequently Asked Questions (FAQ)

Q: Can Series 213 parts replace Series 218 parts directly? A: Yes. Both series maintain identical current rating (6.3 A), voltage rating (250 V), response time (Slow Blow), package dimensions (5x20mm), and breaking capacity (63 A). The primary difference is melting I²t value: Series 213 at 600 versus Series 218 at approximately 198.5. This affects thermal response speed but does not prevent mechanical or electrical substitution. Application requirements determine which series is appropriate.

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 expressed as amperes squared times seconds. Higher I²t values indicate slower thermal response. The original 021806.3H has an I²t of 204. Series 218 substitutes maintain comparable values (198.5), while Series 213 substitutes have significantly higher values (600). Applications sensitive to response time should maintain consistency within the same series.

Q: Are all substitute parts available in bulk packaging? A: Yes. All listed substitute parts are supplied in bulk packaging format, distinguishing them from the original 021806.3H which was supplied with standard packaging designation. Bulk packaging does not affect electrical or mechanical performance.

Q: What certifications are critical for my application? A: Certification requirements depend on end-use application and regional regulations. The original 021806.3H carried BSI, CSA, SEMKO, UL, and VDE approvals. Series 218 substitutes expand this to include CCC, CE, K-MARK, and PSE. Series 213 substitutes include UR in place of K-MARK. Verify that selected substitute part certifications align with application requirements.

Q: Does RoHS compliance affect electrical performance? A: No. ROHS3 compliance addresses material composition restrictions but does not alter electrical characteristics, current rating, voltage rating, or response time. All substitute parts maintain full electrical equivalence to the original component.

Q: Can I mix Series 218 and Series 213 parts in the same circuit? A: Mechanically and electrically, yes. However, mixing series with different melting I²t values in the same circuit may result in inconsistent thermal response characteristics. For circuits requiring multiple fuses, maintaining consistency within a single series is recommended.

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