Equivalent & Substitute Parts for Cornell Dubilier Electronics 21FB4420

Part Overview

The Cornell Dubilier Electronics 21FB4420 is a 20 µF film capacitor rated for 440V AC operation with polypropylene metallized dielectric construction. This radial, can-style component is designed for motor run and power factor correction applications in industrial equipment. The part is currently active in production with 791 units in stock. Substitute parts are identified to address inventory availability, compliance requirements, or specific application constraints while maintaining functional equivalence within defined electrical and mechanical parameters.

Key Parameters

Parameter	Value	Significance for Substitution
Capacitance	20 µF	Must match exactly for circuit function
Voltage Rating (AC)	440V	Minimum acceptable rating; higher ratings permitted
Tolerance	±10%	Acceptable tolerance range for application
Dielectric Material	Polypropylene (PP), Metallized	Determines electrical characteristics and reliability
Package Type	Radial, Can	Physical form factor and mounting interface
Mounting Type	Chassis Mount	Installation method and mechanical compatibility
Operating Temperature Range	-40°C to 70°C	Environmental operating limits
Termination Style	Quick Connect, Disconnect	Electrical connection interface

Substitute Part Grouping Explanation

Substitute parts for the 21FB4420 are classified into two categories based on electrical and mechanical compatibility:

Direct Substitute (Same Series Family): The part SFP44T20K284B-F from Cornell Dubilier Electronics (SF series) maintains identical electrical specifications: 20 µF capacitance, ±10% tolerance, and 440V AC rating. Both parts use polypropylene metallized dielectric construction and operate across the same temperature range (-40°C to 70°C). Physical dimensions are comparable (1.870" diameter vs. 1.875" for the main part), with minor height variation (2.960" vs. 3.250"). Lead spacing remains functionally equivalent (0.810" vs. 0.813"). This part qualifies as a direct substitute with ROHS3 compliance advantage.

Similar Substitute (Higher Voltage Rating, Different Manufacturer): The part C878BF35200SA0J from KEMET (C87 series) provides functional substitution with key differences: 470V AC rating (exceeds 440V requirement), ±5% tolerance (tighter than ±10%), and extended operating temperature range (-25°C to 85°C). Capacitance remains 20 µF. Physical dimensions differ: 1.772" diameter and 3.150" height. Termination uses 0.250" quick connect (vs. standard quick connect/disconnect). Lead spacing is 0.528" (significantly different from 0.813"). This part is suitable only where mechanical envelope and termination compatibility are verified.

Parameter Comparison

Parameter	21FB4420 (Main)	SFP44T20K284B-F (Direct)	C878BF35200SA0J (Similar)
Manufacturer	Cornell Dubilier Electronics	Cornell Dubilier Electronics	KEMET
Series	MPF	SF	C87
Capacitance	20 µF	20 µF	20 µF
Tolerance	±10%	±10%	±5%
Voltage Rating (AC)	440V	440V	470V
Dielectric Material	Polypropylene (PP), Metallized	Polypropylene (PP), Metallized	Polypropylene (PP), Metallized
Package Type	Radial, Can	Radial, Can	Radial, Can
Operating Temperature	-40°C to 70°C	-40°C to 70°C	-25°C to 85°C
Diameter	1.875" (47.63mm)	1.870" (47.50mm)	1.772" (45.00mm)
Height (Max)	3.250" (82.55mm)	2.960" (75.18mm)	3.150" (80.00mm)
Lead Spacing	0.813" (20.64mm)	0.810" (20.57mm)	0.528" (13.40mm)
Termination	Quick Connect, Disconnect	Quick Connect, Disconnect	Quick Connect - 0.250" (6.3mm)
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant
Inventory	791 Pcs	719 Pcs	1322 Pcs

Engineering Selection Recommendations

For Direct Substitution (SFP44T20K284B-F): This part is the primary substitute option. It maintains identical electrical specifications (20 µF, ±10%, 440V AC) and operates within the same temperature range. Physical dimensions are nearly identical, with lead spacing variation of 0.003" (0.076mm), which is within typical manufacturing tolerance. The SFP44T20K284B-F offers ROHS3 compliance, addressing regulatory requirements where the main part does not. Selection of this substitute requires no circuit redesign or mechanical re-evaluation.

For Similar Substitution (C878BF35200SA0J): This KEMET part is suitable only when the following conditions are met: (1) the equipment design accommodates the smaller diameter (1.772" vs. 1.875"), (2) the reduced lead spacing (0.528" vs. 0.813") is compatible with the PCB or terminal layout, (3) the 0.250" quick connect termination matches the equipment interface, and (4) the higher voltage rating (470V) and tighter tolerance (±5%) provide operational advantage. The extended temperature range (-25°C to 85°C) may benefit applications in extreme environments. This substitution requires mechanical verification before implementation.

Frequently Asked Questions (FAQ)

Q: Can SFP44T20K284B-F be used as a direct replacement for 21FB4420?

A: Yes. Both parts have identical capacitance (20 µF), tolerance (±10%), and voltage rating (440V AC). Operating temperature ranges match (-40°C to 70°C). Physical dimensions are nearly equivalent with lead spacing within 0.003". No circuit modification is required.

Q: What are the limitations of using C878BF35200SA0J as a substitute?

A: The KEMET part has significantly different physical dimensions: 1.772" diameter (vs. 1.875"), 3.150" height (vs. 3.250"), and 0.528" lead spacing (vs. 0.813"). The termination style is 0.250" quick connect, which may not match the equipment interface. Mechanical compatibility must be verified before use. The higher voltage rating (470V) and tighter tolerance (±5%) are technical advantages but do not address the dimensional constraints.

Q: Is the higher voltage rating of C878BF35200SA0J beneficial?

A: A 470V rating exceeds the 440V requirement, providing additional safety margin. However, this does not justify substitution if mechanical constraints exist. The primary selection criterion remains functional equivalence within the defined electrical and mechanical parameters.

Q: What is the impact of lead spacing differences?

A: The 21FB4420 has 0.813" lead spacing, SFP44T20K284B-F has 0.810" (0.003" difference, negligible), and C878BF35200SA0J has 0.528" (0.285" difference, significant). Lead spacing determines compatibility with terminal blocks, PCB holes, or quick-disconnect interfaces. The KEMET part requires mechanical re-evaluation if the equipment is designed for 0.813" spacing.

Q: Does RoHS compliance affect substitution decisions?

A: The 21FB4420 is RoHS non-compliant, while both SFP44T20K284B-F and C878BF35200SA0J are ROHS3 compliant. For applications subject to RoHS regulations, the compliant substitutes are required. For legacy equipment without regulatory constraints, compliance status does not affect electrical performance.

Q: Can these parts be used interchangeably in motor run applications?

A: SFP44T20K284B-F is fully interchangeable for motor run applications. C878BF35200SA0J is electrically suitable but requires mechanical verification due to dimensional differences. Both maintain the polypropylene metallized dielectric construction required for motor run duty.

Q: What inventory considerations apply to these substitutes?

A: The main part (21FB4420) has 791 units in stock. SFP44T20K284B-F has 719 units available. C878BF35200SA0J has the highest inventory at 1322 units. Availability may influence substitution decisions in time-sensitive procurement scenarios.

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