Equivalent & Substitute Parts for Cornell Dubilier Electronics 21FD3706-F

Part Overview

The Cornell Dubilier Electronics 21FD3706-F is a 6 µF film capacitor rated for 370V AC operation with polypropylene metallized dielectric construction. This component is designed for motor run and power factor correction applications in radial, can-style packaging with quick connect termination. The 21FD3706-F carries an obsolete product status, necessitating identification of equivalent substitute components that maintain electrical and mechanical compatibility for continued system operation and maintenance.

Substiute Parts

21FD3706-F

Cornell Dubilier Electronics (CDE)In Stock: 120121FD3706-F Datasheet

Current PartRFQ

21FD3706A-F

Cornell Dubilier Electronics (CDE)In Stock: 93121FD3706A-F Datasheet

DirectRFQ

SFP37T6K238B-F

Cornell Dubilier Electronics (CDE)In Stock: 899SFP37T6K238B-F Datasheet

DirectRFQ

SFP44T6K238B-F

Cornell Dubilier Electronics (CDE)In Stock: 1074SFP44T6K238B-F Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute components for the 21FD3706-F are classified based on strict electrical and mechanical parameter alignment. The primary substitution criteria are:

Electrical Parameters:

• Capacitance value: 6 µF (exact match required)
• Tolerance: ±10% (exact match required)
• Voltage Rating - AC: 370V minimum (equal or higher voltage rating acceptable)
• Dielectric Material: Polypropylene (PP), Metallized (exact match required)
• Operating Temperature Range: -40°C ~ 70°C (exact match required)

Mechanical Parameters:

• Package / Case: Radial, Can (exact match required)
• Mounting Type: Chassis Mount, Requires Holder/Bracket (exact match required)
• Termination: Quick Connect, Disconnect (exact match required)
• Lead Spacing: 0.813" (20.64mm) nominal tolerance (within 0.003" acceptable)
• Physical dimensions: Compatible with standard radial can mounting

Compliance Parameters:

• RoHS Status: ROHS3 Compliant (required)

Substitutes are grouped into two categories: direct electrical equivalents (21FD3706A-F, SFP37T6K238B-F) and higher voltage-rated alternatives (SFP44T6K238B-F) suitable for applications where voltage margin is beneficial.

Parameter Comparison

Engineering Selection Recommendations

21FD3706A-F (Direct Equivalent - Recommended Primary Substitute)

The 21FD3706A-F is the direct electrical and mechanical equivalent to the obsolete 21FD3706-F. Both components share identical capacitance (6 µF), tolerance (±10%), voltage rating (370V AC), dielectric material (polypropylene metallized), operating temperature range (-40°C ~ 70°C), and termination specifications. The 21FD3706A-F carries active product status with ROHS3 compliance and REACH unaffected certification. The primary dimensional difference is a reduced seated height (2.630" versus 2.880"), which provides improved space efficiency while maintaining full electrical compatibility. This component is the preferred substitute for direct replacement applications.

SFP37T6K238B-F (Electrical Equivalent - Alternative Substitute)

The SFP37T6K238B-F maintains identical electrical specifications to the 21FD3706-F: 6 µF capacitance, ±10% tolerance, 370V AC rating, polypropylene metallized dielectric, and -40°C ~ 70°C operating temperature. This component belongs to the SF series and carries active product status with ROHS3 compliance and REACH unaffected certification. Lead spacing is 0.810" (20.57mm), which differs minimally from the 0.813" specification. Seated height is 2.500" (63.50mm), providing additional space savings. This substitute is suitable for applications where the SF series compatibility is acceptable.

SFP44T6K238B-F (Higher Voltage Rating Alternative)

The SFP44T6K238B-F provides identical capacitance (6 µF), tolerance (±10%), dielectric material (polypropylene metallized), and operating temperature range (-40°C ~ 70°C) to the 21FD3706-F. The voltage rating is elevated to 440V AC, providing increased voltage margin for applications operating at or near 370V. This component carries active product status with ROHS3 compliance and REACH unaffected certification. Lead spacing and seated height specifications match the SFP37T6K238B-F. This substitute is applicable in motor run and power factor correction circuits where higher voltage rating provides operational benefit.

Frequently Asked Questions (FAQ)

Q: Can the 21FD3706A-F directly replace the obsolete 21FD3706-F in existing equipment?

A: Yes. The 21FD3706A-F is electrically and mechanically equivalent to the 21FD3706-F. Both components have identical capacitance (6 µF), tolerance (±10%), voltage rating (370V AC), dielectric material (polypropylene metallized), operating temperature range (-40°C ~ 70°C), and termination type (quick connect/disconnect). The reduced seated height (2.630" versus 2.880") provides improved space efficiency without affecting electrical performance or circuit compatibility.

Q: What is the difference between the SFP37T6K238B-F and SFP44T6K238B-F substitutes?

A: Both components share identical electrical specifications: 6 µF capacitance, ±10% tolerance, polypropylene metallized dielectric, and -40°C ~ 70°C operating temperature. The primary difference is the voltage rating: SFP37T6K238B-F is rated for 370V AC, while SFP44T6K238B-F is rated for 440V AC. Both components have identical physical dimensions (1.870" diameter, 2.500" seated height) and lead spacing (0.810"). The higher voltage rating of the SFP44T6K238B-F provides additional voltage margin in applications operating near 370V.

Q: Are there any dimensional compatibility concerns when substituting these components?

A: Lead spacing differences are minimal and within acceptable tolerance. The 21FD3706-F and 21FD3706A-F specify 0.813" (20.64mm) lead spacing, while the SFP series components specify 0.810" (20.57mm). This 0.003" difference is within standard manufacturing tolerance for radial can capacitor mounting. Seated height varies among substitutes: 21FD3706-F (2.880"), 21FD3706A-F (2.630"), and SFP series (2.500"). Reduced height substitutes provide improved space efficiency and are compatible with standard chassis mount holders designed for radial can capacitors.

Q: Do all substitute components meet the same compliance requirements as the original part?

A: Yes. All substitute components (21FD3706A-F, SFP37T6K238B-F, and SFP44T6K238B-F) are ROHS3 compliant. The 21FD3706A-F and SFP series components carry REACH unaffected certification. All components are manufactured by Cornell Dubilier Electronics and carry active product status, ensuring continued availability and supply chain reliability.

Q: Which substitute should be selected for new equipment designs?

A: For new designs, the 21FD3706A-F is the recommended primary choice due to its direct equivalence to the original specification and active product status. The SFP37T6K238B-F provides an alternative with identical electrical performance and improved space efficiency. The SFP44T6K238B-F is suitable when higher voltage margin is beneficial for the application. All three substitutes are electrically compatible with motor run and power factor correction circuits designed for the original 21FD3706-F.

Q: Are these components suitable for motor run and power factor correction applications?

A: Yes. All substitute components are rated for motor run and power factor correction (PFC) applications. The 6 µF capacitance, ±10% tolerance, polypropylene metallized dielectric, and specified voltage ratings (370V or 440V AC) are appropriate for these applications. The quick connect/disconnect termination enables straightforward installation in standard motor run capacitor holders and PFC circuit configurations.