21FD3705-F Film Capacitor Equivalent & Substitute Parts

Part Overview

The 21FD3705-F is a 5 µF film capacitor rated at 370V AC with polypropylene dielectric material, designed for motor run and power factor correction applications. This part is classified as obsolete, necessitating identification of active equivalent and substitute alternatives that meet the same electrical and mechanical specifications for seamless integration in existing designs and procurement workflows.

Substiute Parts

21FD3705-F

Cornell Dubilier Electronics (CDE)In Stock: 87321FD3705-F Datasheet

Current PartRFQ

21FD3705A-F

Cornell Dubilier Electronics (CDE)In Stock: 114921FD3705A-F Datasheet

DirectRFQ

SFP37T5K238B-F

Cornell Dubilier Electronics (CDE)In Stock: 1161SFP37T5K238B-F Datasheet

DirectRFQ

SFP44T5K238B-F

Cornell Dubilier Electronics (CDE)In Stock: 1060SFP44T5K238B-F Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 21FD3705-F is determined by the following critical parameters: capacitance value (5 µF), voltage rating (AC), dielectric material (polypropylene, metallized), tolerance (±10%), operating temperature range (-40°C to 70°C), mounting type (chassis mount with holder/bracket requirement), package configuration (radial, can), and termination style (quick connect/disconnect).

Substitute parts are grouped into two categories:

Category 1: Direct Equivalents (Voltage-Matched) Parts maintaining the identical 370V AC rating with active product status, ensuring direct drop-in replacement capability.

Category 2: Higher Voltage Substitutes Parts rated at higher voltage (440V AC) that function as backwards-compatible substitutes, as components rated for higher voltage operate safely at lower voltage applications.

Parameter Comparison

Engineering Selection Recommendations

For Direct Replacement (Preferred): The 21FD3705A-F serves as the primary substitute for the obsolete 21FD3705-F. Both parts are from the same manufacturer (Cornell Dubilier Electronics), share identical electrical specifications (5 µF, 370V AC, ±10% tolerance), and maintain the same dielectric material and mounting configuration. The 21FD3705A-F carries active product status with ROHS3 compliance and REACH unaffected designation, ensuring continuity in supply chain and regulatory compliance.

For Enhanced Voltage Margin: The SFP37T5K238B-F provides equivalent electrical performance at the same 370V rating within the active SF series. The SFP44T5K238B-F extends voltage capability to 440V AC, functioning as a substitute when higher voltage margin is acceptable within the circuit design parameters. Both SF series parts maintain ROHS3 compliance and REACH unaffected status.

All substitute candidates maintain compatibility with the original chassis mount configuration and quick connect/disconnect termination system.

Frequently Asked Questions (FAQ)

Q: Can the SFP44T5K238B-F (440V) directly replace the 21FD3705-F (370V)? A: Yes. The SFP44T5K238B-F operates at 440V AC but functions safely in 370V AC circuits. Higher voltage-rated capacitors are backwards-compatible for lower voltage applications, provided all other parameters (capacitance, tolerance, dielectric, mounting, termination) remain compatible.

Q: What are the dimensional differences between substitute parts? A: The 21FD3705-F has a seated height of 2.880" (73.15mm) with 1.875" diameter. The 21FD3705A-F reduces height to 2.630" (66.80mm) while maintaining the same diameter. The SF series parts (SFP37T5K238B-F and SFP44T5K238B-F) have a seated height of 2.500" (63.50mm) and slightly smaller diameter of 1.870". Lead spacing remains consistent across all parts at 0.813" to 0.810". Physical footprint differences do not impact electrical compatibility but require verification of mechanical fit within the chassis mount bracket assembly.

Q: Are all substitutes ROHS3 compliant? A: Yes. The 21FD3705A-F, SFP37T5K238B-F, and SFP44T5K238B-F are all ROHS3 compliant. The 21FD3705-F (obsolete) is also ROHS3 compliant.

Q: What is the difference between the MPF and SF series? A: The 21FD3705-F and 21FD3705A-F belong to the MPF series, while SFP37T5K238B-F and SFP44T5K238B-F belong to the SF series. Both series share identical electrical specifications and package configurations for the 5 µF 370V application. Series designation reflects different manufacturing production lines within Cornell Dubilier Electronics.

Q: Which substitute has the best inventory availability? A: The 21FD3705A-F has the highest inventory at 1099 pieces, followed by SFP37T5K238B-F at 1077 pieces and SFP44T5K238B-F at 995 pieces.