Equivalent & Substitute Parts for 21FD3720-F Film Capacitor

Part Overview

The Cornell Dubilier Electronics (CDE) 21FD3720-F is a 20 µF film capacitor rated for 370V AC operation with polypropylene metallized dielectric construction. This component is classified as obsolete, necessitating identification of active equivalent alternatives for ongoing procurement and system maintenance. The part is designed for motor run and power factor correction (PFC) applications requiring radial chassis mount configuration with quick connect termination.

Substiute Parts

21FD3720-F

Cornell Dubilier Electronics (CDE)In Stock: 75321FD3720-F Datasheet

Current PartRFQ

21FD3720A-F

Cornell Dubilier Electronics (CDE)In Stock: 78521FD3720A-F Datasheet

DirectRFQ

SFP37T20K238B-F

Cornell Dubilier Electronics (CDE)In Stock: 1332SFP37T20K238B-F Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 21FD3720-F is determined by strict equivalence across the following critical parameters:

Electrical Parameters:

• Capacitance value: 20 µF (exact match required)
• Tolerance: ±10% (exact match required)
• Voltage rating (AC): 370V (exact match required)
• Dielectric material: Polypropylene (PP), Metallized (exact match required)

Mechanical Parameters:

• Package type: Radial, Can (exact match required)
• Mounting configuration: Chassis Mount, Requires Holder/Bracket (exact match required)
• Termination style: Quick Connect, Disconnect (exact match required)
• Operating temperature range: -40°C ~ 70°C (exact match required)

Compliance Parameters:

• RoHS3 Compliance (required for substitution)

The identified substitute parts 21FD3720A-F and SFP37T20K238B-F satisfy all critical electrical, mechanical, and compliance requirements. Dimensional variations in height and diameter remain within acceptable tolerances for chassis mount applications using standard holder/bracket configurations.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: 21FD3720A-F

The 21FD3720A-F represents the direct active equivalent within the same MPF series. This part maintains identical electrical specifications, mechanical mounting configuration, and termination style. The product status transition from obsolete to active ensures long-term procurement availability. The reduced seated height (2.630" versus 2.880") accommodates standard chassis mount holder/bracket assemblies without functional impact. This part is recommended as the first-choice replacement for direct substitution in existing designs.

Secondary Substitute: SFP37T20K238B-F

The SFP37T20K238B-F from the SF series provides full electrical and mechanical equivalence with identical capacitance, voltage rating, tolerance, and dielectric material. The active product status and REACH compliance certification support regulatory requirements. The reduced seated height (2.500") and marginally smaller diameter (1.870") remain compatible with standard chassis mount configurations. This part is suitable for applications where SF series components are already qualified or where the reduced physical footprint provides design advantages.

Both substitute parts satisfy all critical electrical and mechanical parameters required for motor run and power factor correction applications. Selection between 21FD3720A-F and SFP37T20K238B-F depends on existing design qualifications, procurement channel availability, and physical space constraints within the chassis mount assembly.

Frequently Asked Questions (FAQ)

Q: Can 21FD3720A-F be used as a direct replacement for 21FD3720-F?

A: Yes. The 21FD3720A-F provides complete electrical and mechanical equivalence. Both parts share identical capacitance (20 µF), voltage rating (370V AC), tolerance (±10%), dielectric material (polypropylene metallized), mounting type (chassis mount with holder/bracket), and termination style (quick connect/disconnect). The primary difference is product status: 21FD3720-F is obsolete while 21FD3720A-F is active, ensuring continued availability.

Q: What are the dimensional differences between the three parts?

A: The 21FD3720-F has a maximum seated height of 2.880" (73.15mm). The 21FD3720A-F reduces this to 2.630" (66.80mm), and the SFP37T20K238B-F further reduces it to 2.500" (63.50mm). Diameter specifications are 1.875" (47.63mm) for both 21FD3720-F and 21FD3720A-F, and 1.870" (47.50mm) for SFP37T20K238B-F. Lead spacing remains consistent at approximately 0.813" across all parts. These dimensional variations are compatible with standard chassis mount holder/bracket configurations.

Q: Are there any compliance or certification differences?

A: All three parts are ROHS3 compliant. The 21FD3720A-F and SFP37T20K238B-F both carry REACH Unaffected certification. The 21FD3720-F does not specify REACH status. Both substitute parts meet current regulatory requirements for electronic component procurement.

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

A: For new designs, either 21FD3720A-F or SFP37T20K238B-F is appropriate. The 21FD3720A-F maintains the same series designation (MPF) as the original part, providing continuity with existing design documentation. The SFP37T20K238B-F offers the advantage of reduced physical height if space constraints exist. Both parts are active products with confirmed inventory availability.

Q: Are the quick connect/disconnect terminations identical across all three parts?

A: Yes. All three parts utilize quick connect/disconnect termination, ensuring compatibility with existing connector assemblies and holder/bracket configurations designed for the 21FD3720-F.

Q: What applications are these capacitors suitable for?

A: These 20 µF 370V AC film capacitors are designed for motor run and power factor correction (PFC) applications. The polypropylene metallized dielectric provides stable performance across the -40°C to 70°C operating temperature range required for industrial motor control and power conditioning systems.