Equivalent & Substitute Parts for 21FD3704-F

Part Overview

The Cornell Dubilier Electronics (CDE) 21FD3704-F is a 4 µF film capacitor rated for 370V AC operation with polypropylene metallized dielectric construction. This component is classified as obsolete and is designed for motor run and power factor correction applications in chassis-mounted configurations requiring a holder or bracket.

Due to the obsolete product status of the 21FD3704-F, equivalent substitute parts are necessary to maintain system functionality and ensure continued availability for replacement and new installations. The substitute parts listed maintain the core electrical specifications while offering active product status and improved availability.

Substiute Parts

21FD3704-F

Cornell Dubilier Electronics (CDE)In Stock: 111521FD3704-F Datasheet

Current PartRFQ

21FD3704A-F

Cornell Dubilier Electronics (CDE)In Stock: 88421FD3704A-F Datasheet

DirectRFQ

SFP37T4K238B-F

Cornell Dubilier Electronics (CDE)In Stock: 1099SFP37T4K238B-F Datasheet

DirectRFQ

SFP44T4K238B-F

Cornell Dubilier Electronics (CDE)In Stock: 840SFP44T4K238B-F Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution logic for the 21FD3704-F is based on the following critical parameters that must remain constant across all equivalent parts:

Mandatory Matching Parameters:

• Capacitance: 4 µF
• Tolerance: ±10%
• Dielectric Material: Polypropylene (PP), Metallized
• Package Type: Radial, Can
• Mounting Type: Chassis Mount, Requires Holder/Bracket
• Termination: Quick Connect, Disconnect
• Operating Temperature Range: -40°C ~ 70°C
• RoHS Compliance: ROHS3 Compliant

Voltage Rating Consideration: The 21FD3704-F operates at 370V AC. Substitute parts may operate at equal or higher voltage ratings. A higher voltage rating provides additional safety margin and is electrically compatible in 370V applications.

Physical Dimensions: Radial can dimensions vary slightly between substitute parts. All substitute parts maintain radial can configuration with quick connect termination, ensuring mechanical compatibility with standard holder/bracket assemblies.

Parameter Comparison

Engineering Selection Recommendations

21FD3704A-F (Primary Direct Substitute)

The 21FD3704A-F is the direct successor to the 21FD3704-F within the Cornell Dubilier MPF series. This part maintains identical electrical specifications (4 µF, 370V AC, ±10% tolerance) and physical mounting requirements. The primary distinction is active product status, ensuring long-term availability and supply chain continuity. The 21FD3704A-F features a reduced height of 2.630" compared to the original 2.880", which may provide improved fit in space-constrained applications while maintaining full electrical compatibility.

SFP37T4K238B-F (Series Alternative)

The SFP37T4K238B-F represents an alternative from the Cornell Dubilier SF series, maintaining all critical electrical parameters and mounting specifications. This part operates at 370V AC with 4 µF capacitance and ±10% tolerance. The SF series offers active product status and bulk packaging availability. Physical dimensions are comparable to the original part, with a height of 2.500" and diameter of 1.870".

SFP44T4K238B-F (Higher Voltage Alternative)

The SFP44T4K238B-F is rated for 440V AC operation while maintaining 4 µF capacitance and ±10% tolerance. This higher voltage rating provides additional operational margin in 370V applications. The part is suitable for installations where voltage transients or future system upgrades to 440V operation are anticipated. Physical dimensions match the SFP37T4K238B-F configuration.

All substitute parts carry ROHS3 compliance and are manufactured by Cornell Dubilier Electronics, ensuring consistency with original design specifications and regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can the 21FD3704A-F directly replace the 21FD3704-F in existing installations?

A: Yes. The 21FD3704A-F maintains identical electrical specifications (4 µF, 370V AC, ±10% tolerance), dielectric material (polypropylene metallized), mounting type (chassis mount with holder/bracket), and termination style (quick connect/disconnect). The reduced height of 2.630" versus 2.880" does not affect electrical performance and may improve mechanical fit in certain applications.

Q: What is the difference between the SFP37T4K238B-F and SFP44T4K238B-F?

A: Both parts are 4 µF film capacitors with ±10% tolerance and polypropylene metallized dielectric. The primary difference is voltage rating: SFP37T4K238B-F is rated for 370V AC, while SFP44T4K238B-F is rated for 440V AC. Both are electrically compatible with 370V applications. The 440V rating provides additional safety margin for systems with voltage transients or future upgrades.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. The 21FD3704-F, 21FD3704A-F, SFP37T4K238B-F, and SFP44T4K238B-F are all ROHS3 compliant, meeting current environmental and regulatory requirements.

Q: Do the substitute parts require the same holder/bracket assembly?

A: All substitute parts are configured as radial can capacitors with quick connect/disconnect termination and require chassis-mount holder/bracket assemblies. Physical dimensions vary slightly between parts, but all maintain compatibility with standard radial can holders designed for this form factor.

Q: What is the operating temperature range for all substitute parts?

A: All substitute parts operate across the temperature range of -40°C to 70°C, matching the original 21FD3704-F specification.

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

A: For new designs, the 21FD3704A-F or SFP37T4K238B-F are recommended due to active product status and established supply chain availability. The SFP44T4K238B-F is suitable when higher voltage margin is required or anticipated for future system modifications.