Cornell Dubilier Electronics 21FD3735-F Film Capacitor

Part Overview

The 21FD3735-F is a 35 µF film capacitor rated for 370V AC operation, manufactured by Cornell Dubilier Electronics (CDE). This polypropylene metallized radial capacitor is designed for motor run and power factor correction applications. The main part is classified as obsolete, making identification of suitable substitute components essential for system maintenance and replacement scenarios.

Key Parameters

Parameter	Specification
Capacitance	35 µF
Tolerance	±10%
Voltage Rating (AC)	370V
Dielectric Material	Polypropylene (PP), Metallized
Operating Temperature Range	-40°C to 70°C
Package Type	Radial, Can
Mounting Type	Chassis Mount, Requires Holder/Bracket
Lead Spacing	0.813" (20.64mm)
Size Diameter	1.875" (47.63mm)
Termination Type	Quick Connect, Disconnect

Substitute Part Grouping Explanation

Substitution for the 21FD3735-F is based on equivalence across the following critical parameters:

Capacitance Value: 35 µF (exact match required)
Voltage Rating: 370V AC (minimum acceptable rating)
Tolerance: ±10% (electrical accuracy)
Dielectric Material: Polypropylene (PP), Metallized (functional requirement)
Package Type: Radial, Can (mechanical and mounting compatibility)
Lead Spacing: 0.813" (20.64mm) (PCB layout compatibility)
Diameter: 1.875" (47.63mm) (chassis clearance)
Mounting Configuration: Chassis Mount, Requires Holder/Bracket (installation method)

Substitute parts are categorized as either direct manufacturer replacements or parametric equivalents, depending on product availability and compliance status.

Parameter Comparison

Parameter	21FD3735-F (Main)	21FD3735A-F (Direct Substitute)	21FD3735 (Parametric Equivalent)
Capacitance	35 µF	35 µF	35 µF
Tolerance	±10%	±10%	±10%
Voltage Rating (AC)	370V	370V	370V
Dielectric Material	Polypropylene (PP), Metallized	Polypropylene (PP), Metallized	Polypropylene (PP), Metallized
Operating Temperature	-40°C to 70°C	-40°C to 70°C	-40°C to 70°C
Package Type	Radial, Can	Radial, Can	Radial, Can
Lead Spacing	0.813" (20.64mm)	0.813" (20.64mm)	0.813" (20.64mm)
Diameter	1.875" (47.63mm)	1.875" (47.63mm)	1.875" (47.63mm)
Height	4.000" (101.60mm)	4.090" (103.88mm)	4.000" (101.60mm)
Termination	Quick Connect, Disconnect	Quick Connect, Disconnect	Quick Connect, Disconnect
Mounting Type	Chassis Mount, Requires Holder/Bracket	Chassis Mount, Requires Holder/Bracket	Chassis Mount, Requires Holder/Bracket
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	RoHS non-compliant
Inventory Status	1006 Pcs New Original In Stock	810 Pcs New Original In Stock	773 Pcs New Original In Stock

Engineering Selection Recommendations

21FD3735A-F (Recommended Direct Substitute)

The 21FD3735A-F is the primary replacement for the obsolete 21FD3735-F. All critical electrical and mechanical parameters are identical. This part is active in production status and carries ROHS3 compliance certification. The height dimension differs by 0.090" (2.28mm), which requires clearance verification in the target application but does not affect electrical compatibility. REACH unaffected status confirms regulatory compliance for electronics applications.

21FD3735 (Secondary Parametric Equivalent)

The 21FD3735 provides functional equivalence across all electrical parameters and mechanical dimensions except height. This part is active in production but is not RoHS compliant, making it suitable only for applications where RoHS compliance is not a requirement. It is functionally equivalent for motor run and power factor correction circuits.

Frequently Asked Questions (FAQ)

Q: Can 21FD3735A-F directly replace 21FD3735-F?

A: Yes. All electrical parameters (capacitance, voltage rating, tolerance, dielectric material) and critical mechanical dimensions (lead spacing, diameter, package type) are identical between the two parts. The height difference of 0.090" (2.28mm) requires verification that clearance exists in the target application, but does not affect electrical operation.

Q: What is the significance of the product status change from Obsolete to Active?

A: The main part 21FD3735-F is marked as obsolete, meaning it is no longer manufactured by CDE. The direct substitute 21FD3735A-F is actively manufactured and stocked, ensuring reliable long-term availability for system replacements and maintenance.

Q: Does the height difference between 21FD3735A-F and 21FD3735-F affect compatibility?

A: The 21FD3735A-F is 0.090" (2.28mm) taller than the original part. Physical clearance in the target application must be confirmed. If vertical space is limited, the 21FD3735 (identical height to the original) may be considered, provided RoHS compliance is not required.

Q: What is the difference between a direct substitute and a parametric equivalent?

A: A direct substitute (21FD3735A-F) is offered by the same manufacturer as a production replacement with identical functional specifications. A parametric equivalent (21FD3735) matches all electrical and primary mechanical parameters but may differ in secondary specifications such as compliance status.

Q: Are both substitute parts RoHS compliant?

A: The 21FD3735A-F is ROHS3 compliant. The 21FD3735 is not RoHS compliant. Selection must reflect regulatory requirements of the target application.

Q: What applications are supported by these capacitors?

A: All three parts (main and substitutes) are rated for motor run and power factor correction (PFC) applications, with operating temperatures from -40°C to 70°C.

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