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Allen-Bradley 20P21AE067RA0NNN PowerFlex DC Drive

1. Product Overview

The Allen-Bradley 20P21AE067RA0NNN is a PowerFlex Digital DC Drive designed for industrial DC motor control applications where stable speed regulation, controlled acceleration and deceleration, and reliable DC motor operation are required.

This model belongs to the PowerFlex DC Drive family and is configured as a non-regenerative, two-quadrant DC drive for a three-phase AC input system in the 575 VAC class. It provides a 67.5 A DC armature current rating and is associated with a 50 HP motor power rating.

The catalog number identifies a specific factory configuration rather than simply a generic drive size. The complete catalog number includes the electrical rating, enclosure arrangement, coating, operator-interface configuration, and communication configuration.

The 20P21AE067RA0NNN is particularly suited to industrial machinery that uses separately excited DC motors and requires controlled motor speed rather than simple direct-on-line motor operation.

It is also useful in applications where an existing DC motor installation needs a modern digital drive while retaining the original DC motor technology.

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2. Brand and Product Series

Item	Description
Brand	Allen-Bradley
Product family	PowerFlex
Product series	PowerFlex DC Drive
Drive type	Digital DC Drive
Catalog number	20P21AE067RA0NNN
Drive configuration	Non-regenerative
Operating mode	Two-quadrant operation
Input system	Three-phase AC
AC voltage class	575 VAC class
DC armature current	67.5 A
Motor rating	50 HP
Approximate motor power	37 kW
Frame size	B
Enclosure style	IP20 / NEMA/UL Type Open
Cooling	Forced-air cooling
Communication configuration	No communication module in the specified configuration
Operator interface	No HIM / blank plate configuration
Conformal coating	Included in the specified catalog configuration

The PowerFlex DC family is intended for applications where DC motors remain technically or economically appropriate. It provides digital control functionality while retaining the basic electrical characteristics required by traditional DC drive systems.

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3. Main Technical Parameters

Parameter	Specification
Model	20P21AE067RA0NNN
Brand	Allen-Bradley
Series	PowerFlex DC Drive
Drive type	Digital DC Drive
Input voltage	575 VAC class
Input phase	Three-phase
Input type	6-pulse
Output type	DC armature output
DC armature current	67.5 A
Motor power	50 HP
Motor power, approximate metric equivalent	37 kW
Operating mode	Two-quadrant
Regenerative function	Non-regenerative
Frame	B
Enclosure	IP20 / NEMA/UL Type Open
Field supply	Single-phase regulated
HIM	No HIM / blank plate
Communication module	None in specified configuration
Conformal coating	Yes
Typical motor application	Separately excited DC motor
Cooling method	Forced-air
Mounting	Panel / cabinet mounting
Height	311 mm
Width	388 mm
Depth	350 mm
Approximate drive weight	25.5 kg
Approximate packaged weight	27.5 kg
Application class	Industrial motor control
Control category	DC motor speed and torque control

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4. Dimensions and Weight

The 20P21AE067RA0NNN uses the PowerFlex DC Frame B mechanical platform.

The standard Frame B dimensions are approximately 311 mm in the A dimension, 388 mm in the B dimension, and 350 mm in the C dimension.

For practical equipment planning, these dimensions can be treated as approximately 311 mm high × 388 mm wide × 350 mm deep, while the detailed mounting drawing should be used when designing a cabinet or replacement installation.

Mechanical Parameter	Value
Model	20P21AE067RA0NNN
Frame	B
Overall dimension A	311 mm
Overall dimension A1	275 mm
Bottom offset A2	16.5 mm
Bottom offset A3	7 mm
Overall dimension B	388 mm
Dimension B1	375 mm
Overall depth C	350 mm
Approximate width	388 mm
Approximate height	311 mm
Approximate depth	350 mm
Drive weight	25.5 kg
Packaged weight	27.5 kg

The dimensions above refer to the Frame B drive mechanical arrangement. Terminal clearances, cable bending space, ventilation clearance, and cabinet service space must be considered separately.

The actual installation footprint can therefore be larger than the basic product dimensions, particularly where large DC armature cables, field wiring, grounding conductors, disconnect devices, or line reactors are installed.

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5. Electrical Rating

The 20P21AE067RA0NNN is designed for a 575 VAC-class, three-phase input and has a nominal DC armature current rating of 67.5 A.

Its corresponding normal-duty motor rating is 50 HP, equivalent to approximately 37 kW.

This combination makes the drive suitable for medium-power industrial DC motors rather than small machine motors or low-power laboratory applications.

Electrical Parameter	Specification
Model	20P21AE067RA0NNN
AC input	575 VAC class
Number of phases	3
Input topology	6-pulse
DC armature current	67.5 A
Normal-duty motor rating	50 HP
Normal-duty motor rating	Approximately 37 kW
AC line current reference	Approximately 55.1 A
Drive architecture	Digital DC drive
Regeneration	Not included
Quadrant operation	Two-quadrant
Field supply	Single-phase regulated

The 6-pulse input arrangement is a conventional industrial architecture for converting three-phase AC power into the DC bus and armature supply required by a DC motor.

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6. What the 20P21AE067RA0NNN Does

A conventional DC motor requires controlled DC voltage and current in order to achieve controlled speed and torque.

The PowerFlex DC drive performs this function electronically. Instead of simply connecting the motor to a fixed DC source, the drive regulates the electrical quantities delivered to the motor.

This allows the motor speed to be controlled according to the machine’s process requirements.

For example, a conveyor can be commanded to operate at a low speed during loading, accelerate smoothly to production speed, and decelerate in a controlled manner when the production sequence changes.

The same principle can be used in winding machinery, material-handling equipment, printing systems, machine tools, hoists, and other industrial equipment.

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7. Two-Quadrant Operation

The 20P21AE067RA0NNN is a non-regenerative, two-quadrant DC drive.

Two-quadrant operation is particularly useful when the motor needs to operate in forward and controlled braking regions without requiring full regenerative operation back into the AC supply.

This is different from a four-quadrant regenerative DC drive.

A non-regenerative configuration is often selected where the machine normally operates in one direction and braking energy does not need to be returned to the incoming AC electrical system.

For applications involving frequent powered reversal or substantial regenerative braking, a regenerative PowerFlex DC model may be more appropriate.

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8. Non-Regenerative Configuration

The “21” portion of the catalog structure identifies the non-regenerative drive family.

The absence of regenerative operation simplifies the system compared with a regenerative configuration.

For applications where the motor generally runs in one direction and stopping is controlled by the drive and mechanical system, a non-regenerative drive can provide a practical solution.

Typical examples include many conveyors, fans, pumps, process machines, and older DC production machines that do not require energy regeneration.

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9. 575 VAC Input Class

The 20P21AE067RA0NNN is part of the 575 VAC three-phase input group.

This voltage class is particularly relevant in industrial facilities where higher-voltage motor distribution is used.

The higher input voltage allows industrial equipment to transmit a given amount of power with lower current than would be required at a substantially lower voltage.

The selection of a 575 VAC-class DC drive must always be coordinated with the actual plant supply voltage, transformer arrangement, motor nameplate data, field supply requirements, and applicable electrical protection.

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10. Digital DC Motor Control

One of the main characteristics of the PowerFlex DC series is digital control.

Compared with older analog DC drive systems, digital control provides a more flexible platform for configuring operating parameters and coordinating the drive with an industrial control system.

The drive can be configured for different operating requirements involving speed, current, acceleration, deceleration, field control, and feedback.

This makes the platform suitable not only for new DC motor installations but also for modernization projects in which an existing DC motor is still mechanically suitable.

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11. Field Supply

The specified configuration uses a regulated single-phase field supply arrangement.

The field circuit is important because a separately excited DC motor normally uses a separate field winding.

The field establishes the magnetic field required for normal motor operation.

Correct field configuration is therefore an important part of commissioning a DC motor drive.

Field wiring, field current, motor nameplate information, and field loss protection should be checked carefully when replacing an older DC drive with the 20P21AE067RA0NNN.

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12. No HIM Configuration

The catalog configuration specifies a no-HIM / blank-plate arrangement.

HIM refers to the Human Interface Module normally used for local drive configuration and operator interaction.

With a blank-plate configuration, the drive is intended to be integrated into a larger control system or configured through the appropriate engineering and control interface rather than relying on a permanently installed local keypad.

This can be useful in centralized control architectures where operators interact with the machine through a PLC, HMI, or supervisory control system.

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13. No Standard Communication Module

The specified catalog number does not include a communication module.

This does not mean that the drive cannot be incorporated into an automation system.

Instead, it indicates that the particular catalog configuration does not include an additional communication option.

For a replacement project, the communication architecture should therefore be checked separately.

If the existing machine communicates with a PLC or supervisory system, the engineering team should verify how the original drive exchanged commands, references, status information, alarms, and feedback.

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14. Conformal Coating

The 20P21AE067RA0NNN configuration includes conformal coating.

Conformal coating is useful in industrial environments because electronic control boards can be exposed to humidity, airborne contaminants, dust, and other environmental influences.

The coating provides an additional level of protection to electronic assemblies.

It does not mean that the drive can be installed in any environment without considering temperature, humidity, corrosive chemicals, dust, condensation, ventilation, and enclosure requirements.

Proper cabinet design remains important.

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15. Main Product Applications

The 20P21AE067RA0NNN is primarily intended for industrial DC motor control.

Its 50 HP / 67.5 A rating makes it appropriate for medium-power industrial machinery where a DC motor remains in service.

Typical application areas include:

• Conveyor systems
• Material handling equipment
• Industrial winding equipment
• Web-processing machinery
• Printing machinery
• Machine tools
• Paper-processing equipment
• Textile machinery
• Metal-processing equipment
• Industrial fans
• Industrial pumps
• Process machinery
• Production lines
• Legacy DC motor installations

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16. Conveyor Applications

DC motors have historically been widely used on industrial conveyors because their speed and torque can be controlled over a broad operating range.

The 20P21AE067RA0NNN can be used where an existing 50 HP-class DC motor is responsible for conveyor movement.

The drive can provide controlled acceleration rather than applying full motor voltage immediately.

This helps reduce mechanical shock on belts, couplings, gearboxes, shafts, and transported products.

Controlled deceleration can also improve the behavior of a conveyor when stopping at a defined position.

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17. Winding and Unwinding Machinery

Winding machinery places special requirements on motor control because speed and torque often need to change according to the diameter and tension of the material being processed.

DC motor technology has traditionally been used in these applications because of its controllability.

A PowerFlex DC drive can regulate motor operation according to the process control requirements.

Typical applications include:

• Cable winding
• Wire processing
• Film winding
• Paper winding
• Textile machinery
• Roll-to-roll processing
• Material tension systems

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18. Printing Machinery

Older printing machinery often uses DC motors because of the need for precise speed control.

A PowerFlex DC drive can serve as the replacement control platform while the existing DC motor remains in operation.

This can be particularly useful during machine modernization projects where replacing the complete motor and mechanical transmission would be expensive.

The drive can become part of a larger automation system involving PLC control, speed references, feedback devices, and machine interlocks.

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19. Machine Tools

Some machine tools and industrial production machines use DC motors because they require controllable speed and torque.

The 20P21AE067RA0NNN can be considered for such applications when the motor rating, voltage, feedback configuration, braking requirements, and mechanical characteristics are compatible.

The drive is especially relevant where the existing machine already has a suitable DC motor and the main objective is to replace an obsolete or difficult-to-maintain drive.

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20. Pump Applications

The drive can also be used with DC motor-driven pumps where variable-speed operation is required.

Changing motor speed can change the operating point of the pump.

For industrial process systems, controlled speed operation can be useful when the process requires different flow rates at different times.

The suitability of a DC drive for a pump should be determined from the pump curve, motor data, required speed range, starting torque, load characteristics, and control philosophy.

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21. Fan Applications

Fans can benefit from variable-speed operation because the required airflow is often not constant.

A DC drive can adjust motor speed according to process requirements.

For example, a ventilation system may operate at reduced speed during low-load periods and increase speed when additional airflow is required.

The motor’s field and armature characteristics must be considered when establishing the required operating range.

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22. Advantages of the 20P21AE067RA0NNN

Advantage	Description
Digital control	Provides flexible electronic control of a DC motor
50 HP capacity	Suitable for medium-power industrial DC motor applications
67.5 A armature rating	Supports substantial DC motor current
575 VAC input class	Suitable for higher-voltage industrial power systems
Two-quadrant operation	Appropriate for applications that do not require full regeneration
Non-regenerative design	Straightforward solution for many conventional DC motor applications
Frame B construction	Compact industrial form factor for its power class
Conformal coating	Adds protection for electronic assemblies in industrial environments
Blank HIM configuration	Convenient for centralized automation architectures
Field regulation	Supports separately excited DC motor control
Digital configuration	Allows detailed adjustment of drive operating characteristics
Legacy-machine suitability	Useful for modernizing existing DC motor machinery
Industrial construction	Designed for integration into industrial control cabinets
Wide application range	Can be used across many process and material-handling applications

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23. Why This Drive Is Useful for DC Motor Modernization

One of the most practical uses of the PowerFlex DC family is modernization.

Many industrial plants still have machines that were originally designed around DC motors.

Replacing the entire motor, gearbox, mechanical transmission, encoder system, and drive can be a major engineering project.

If the existing motor is mechanically sound, replacing only the drive can be considerably simpler.

The 20P21AE067RA0NNN provides a modern digital drive platform for a 50 HP-class DC motor.

This approach can reduce the amount of mechanical modification required during a retrofit.

It also allows the machine to be incorporated into a more modern automation architecture.

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24. Installation Considerations

The drive should be installed inside an appropriate industrial electrical enclosure or control cabinet.

The IP20 / NEMA/UL Type Open configuration means that the drive itself should not be treated as a completely sealed standalone outdoor enclosure.

The cabinet should provide suitable protection from dust, water, conductive contamination, excessive humidity, and mechanical damage.

Adequate ventilation is also required.

The heat generated by the drive must be removed from the cabinet so that the internal temperature remains within the permissible operating range.

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25. Cable and Wiring Considerations

DC armature current can be substantial even at a 50 HP motor rating.

The 67.5 A rating therefore requires appropriate conductor sizing and suitable termination hardware.

The actual cable size should be determined according to the applicable electrical code, installation method, ambient temperature, conductor material, permissible voltage drop, grouping, and duty cycle.

The armature conductors, field conductors, AC input conductors, grounding system, and control wiring should be physically and electrically arranged according to the installation requirements.

Special attention should be given to grounding and control wiring because industrial DC drives can be sensitive to electrical noise when installation practices are poor.

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26. Maintenance Considerations

Routine maintenance should include inspection of:

• Cooling airflow
• Ventilation openings
• Electrical connections
• Power terminals
• Control wiring
• Grounding connections
• Motor brushes
• DC motor commutator condition
• Field wiring
• Cabinet cleanliness
• Cooling fans
• Alarm history
• Feedback devices

A DC drive system should not be evaluated independently from the motor.

A drive can be operating correctly while the motor itself has brush wear, commutator problems, field problems, insulation deterioration, or mechanical bearing issues.

For this reason, preventive maintenance should cover the complete motor-drive system.

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27. DC Motor Feedback

Depending on the application, DC motor control can use feedback to improve speed regulation.

Feedback devices can provide the drive with information about actual motor speed.

The drive can then compare actual speed with the commanded speed and adjust the motor control accordingly.

This is especially useful for machinery where constant speed is important despite changing mechanical load.

For high-precision applications, the complete feedback chain should be evaluated, including encoder or tachometer characteristics, wiring, shielding, grounding, and signal conditioning.

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28. Selection Considerations

Before selecting the 20P21AE067RA0NNN as a replacement, several points should be checked.

The first is the motor nameplate.

The motor should be checked for:

• Armature voltage
• Armature current
• Horsepower
• Base speed
• Maximum speed
• Field voltage
• Field current
• Feedback type
• Motor insulation condition
• Mechanical load characteristics

The incoming electrical system should also be checked for the required 575 VAC-class, three-phase supply.

The drive’s two-quadrant, non-regenerative configuration should be compared with the actual braking requirements of the machine.

If the application requires frequent regeneration or powered reversal, a regenerative model may need to be considered instead.

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29. Five Related Models from the Same PowerFlex DC Family

The following models are closely related to the 20P21AE067RA0NNN and are useful for comparing power levels within the same 575 VAC non-regenerative family.

Model	Input	DC Current	Motor Rating	Frame	Type	Typical Position
20P21AE067RA0NNN	575 VAC, 3-phase	67.5 A	50 HP / 37 kW	B	Non-regenerative, 2Q	Reference model
20P21AE101RA0NNN	575 VAC, 3-phase	101.25 A	75 HP / 56 kW	B	Non-regenerative, 2Q	Higher-power B-frame option
20P21AE135RA0NNN	575 VAC, 3-phase	135 A	100 HP / 75 kW	B	Non-regenerative, 2Q	100 HP-class option
20P21AE270RA0NNN	575 VAC, 3-phase	270 A	200 HP / 149 kW	B	Non-regenerative, 2Q	Large B-frame option
20P21AE405RA0NNN	575 VAC, 3-phase	405 A	300 HP / 224 kW	B	Non-regenerative, 2Q	High-power B-frame option

These models share the same general PowerFlex DC architecture but differ substantially in current and motor capacity.

The 20P21AE067RA0NNN is the smaller 575 VAC model in this particular group, making it appropriate when the DC motor is approximately 50 HP.

The 20P21AE101RA0NNN moves the application into the 75 HP range, while the 20P21AE135RA0NNN is suitable for approximately 100 HP.

The 20P21AE270RA0NNN and 20P21AE405RA0NNN are substantially larger and are intended for much higher-power machinery.

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30. Comparison of Related 575 VAC PowerFlex DC Models

Parameter	20P21AE067RA0NNN	20P21AE101RA0NNN	20P21AE135RA0NNN	20P21AE270RA0NNN	20P21AE405RA0NNN
AC input	575 VAC	575 VAC	575 VAC	575 VAC	575 VAC
Phase	3	3	3	3	3
DC current	67.5 A	101.25 A	135 A	270 A	405 A
Motor HP	50 HP	75 HP	100 HP	200 HP	300 HP
Motor kW	37 kW	56 kW	75 kW	149 kW	224 kW
Frame	B	B	B	B	B
Regeneration	No	No	No	No	No
Operating quadrant	Two-quadrant	Two-quadrant	Two-quadrant	Two-quadrant	Two-quadrant
Basic enclosure class	IP20 / Open	IP20 / Open	IP20 / Open	IP20 / Open	IP20 / Open
Height	311 mm	311 mm	311 mm	311 mm	311 mm
Width	388 mm	388 mm	388 mm	388 mm	388 mm
Depth	350 mm	350 mm	350 mm	350 mm	350 mm
Approx. drive weight	25.5 kg	25.5 kg	25.5 kg	29.5 kg	32 kg

The dimensions remain within the Frame B platform for these models, although terminal arrangements and installation requirements should be checked for the exact catalog number.

The power rating increases primarily through the electrical current capacity.

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31. Five Related Models Worth Considering for Regenerative Applications

Where the machine requires regenerative braking or more advanced bidirectional energy handling, related regenerative PowerFlex DC models can be considered.

Model	Input Class	DC Current	Motor Rating	Configuration	Frame
20P41AE067RA0NNN	575 VAC, 3-phase	67.5 A	50 HP / 37 kW	Regenerative	B
20P41AE101RA0NNN	575 VAC, 3-phase	101.25 A	75 HP / 56 kW	Regenerative	B
20P41AE135RA0NNN	575 VAC, 3-phase	135 A	100 HP / 75 kW	Regenerative	B
20P41AE270RA0NNN	575 VAC, 3-phase	270 A	200 HP / 149 kW	Regenerative	B
20P41AE405RA0NNN	575 VAC, 3-phase	405 A	300 HP / 224 kW	Regenerative	B

The major difference between the 20P21 and 20P41 families is the regeneration architecture.

A regenerative drive becomes particularly relevant when the machine frequently decelerates a high-inertia load, operates with an overhauling load, or requires controlled motoring and braking in multiple operating conditions.

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32. Five Same-Brand Representative Models

The following are representative Allen-Bradley PowerFlex models from different product families and power classes.

They are useful when comparing a DC drive installation with modern AC variable-frequency-drive alternatives.

Model	Product Family	Approximate Voltage Class	Drive Type	Typical Application
25B-D017N114	PowerFlex 525	380–480 VAC class	Compact AC drive	Machinery, conveyors, pumps, fans
20F11NC022JA0NNNNN	PowerFlex 753	380–480 VAC class	AC variable-frequency drive	Industrial machinery and process control
20F11NC034JA0NNNNN	PowerFlex 753	380–480 VAC class	AC variable-frequency drive	Medium-power industrial equipment
20G1ANB140JA0NNNNN	PowerFlex 755	380–480 VAC class	High-performance AC drive	Large industrial machinery
20G1ANC350JA0NNNNN	PowerFlex 755	380–480 VAC class	High-power AC drive	Heavy industrial applications

These models are not direct electrical replacements for the 20P21AE067RA0NNN.

The PowerFlex 525, 753, and 755 families are AC variable-frequency drives, while the 20P21AE067RA0NNN is specifically a DC drive.

Therefore, migrating from the 20P21AE067RA0NNN to an AC drive normally requires an engineering review of the motor itself.

If the original DC motor is retained, the PowerFlex DC family is generally the more direct drive technology.

If the machine is being comprehensively modernized, an AC motor and AC drive combination may become an alternative.

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33. Comparison Between DC and AC Drive Modernization

Item	20P21AE067RA0NNN	Modern AC Drive System
Motor technology	DC motor	AC induction or permanent-magnet motor
Drive type	DC drive	Variable-frequency AC drive
Existing DC motor retention	Yes	Usually no
Retrofit complexity	Potentially lower when retaining existing motor	Potentially higher
Mechanical modification	Can be limited	May require motor replacement
Brush maintenance	Required on DC motor	Generally eliminated with brushless AC motor
Existing DC motor investment	Preserved	Motor may need replacement
Speed control	Digital DC control	Variable-frequency control
Regenerative options	Available in regenerative family	Available depending on drive architecture
Best fit	Existing DC motor machinery	New or fully modernized machinery

This comparison illustrates why the 20P21AE067RA0NNN remains relevant in industrial retrofit projects.

A drive replacement does not necessarily mean that the entire motor system has to be redesigned.

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34. Product Selection for a 50 HP DC Motor

For a motor around 50 HP with a 575 VAC-class industrial power supply, the 20P21AE067RA0NNN provides a closely matched PowerFlex DC solution.

The 67.5 A armature rating corresponds to the 50 HP normal-duty rating in this product group.

However, the motor nameplate should always be checked rather than selecting the drive from horsepower alone.

Two motors with the same horsepower can have different armature voltages, armature currents, field requirements, base speeds, and feedback configurations.

The actual motor electrical data therefore determines whether this particular drive is appropriate.

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35. Application Advantages

For an existing production machine, one of the strongest advantages of this type of drive is the ability to maintain the existing DC motor architecture.

This can be important in plants where the mechanical system has been operating reliably for many years.

Replacing only the drive can reduce mechanical engineering work.

It can also reduce downtime compared with a complete motor and drive conversion.

Another advantage is that the drive can be integrated into a modern digital control strategy.

This allows an older DC motor system to participate in a more contemporary automation environment.

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36. Advantages for Retrofit Projects

The 20P21AE067RA0NNN is particularly interesting for retrofit projects because its application is not limited to newly designed machinery.

Many older machines were designed around DC motors because of the speed-control characteristics available at the time.

If those motors are still mechanically sound, replacing the drive may be more practical than replacing the entire powertrain.

A properly engineered retrofit can preserve:

• Motor
• Gearbox
• Coupling
• Machine frame
• Mechanical transmission
• Existing process equipment

while updating the electronic motor controller.

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37. Industrial Reliability Considerations

Reliability depends on the complete installation rather than the drive alone.

The drive should be operated within its specified electrical and environmental conditions.

Cabinet temperature should be controlled.

Airflow should remain unobstructed.

Power terminals should be correctly tightened.

Control cables should be routed properly.

The motor should be inspected regularly.

Grounding should be correctly implemented.

These basic practices have a significant impact on the operating life of a DC drive installation.

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38. Environmental Considerations

The conformal-coated configuration provides additional protection for the electronics, which can be valuable in industrial environments.

Nevertheless, conformal coating should not be interpreted as a substitute for a properly designed enclosure.

Special environments require additional consideration.

These include:

• High humidity
• Condensation
• Conductive dust
• Salt-laden air
• Chemical vapors
• Corrosive atmospheres
• Excessive ambient temperature
• Excessive vibration
• High-altitude installations

The enclosure and ventilation arrangement should be designed around the actual plant environment.

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39. Maintenance of the DC Motor System

A DC drive system has a different maintenance profile from a typical modern AC motor system.

The DC motor contains brushes and a commutator.

These components require periodic inspection.

Brush wear should be monitored.

The commutator should be inspected for abnormal wear, arcing, contamination, or surface damage.

The field winding should also be checked.

This is particularly important in high-duty-cycle applications where the motor operates continuously.

The drive itself should also be inspected for dust accumulation, fan operation, terminal condition, and signs of overheating.

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40. Typical Industrial Control Architecture

A typical installation may include:

AC Supply → Protection → Line Reactor / Input Equipment → PowerFlex DC Drive → DC Motor

The control side can include:

PLC → Drive Command / Reference → PowerFlex DC Drive

and, where applicable:

Motor Feedback → Drive → Speed Regulation

The exact architecture depends on the machine design.

The 20P21AE067RA0NNN can therefore be treated as one component within a complete industrial motor-control system rather than as an isolated device.

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41. Recommended Application Scenarios

The 20P21AE067RA0NNN is particularly suitable for applications with the following characteristics:

Application Characteristic	Suitability
Existing 50 HP DC motor	Very relevant
575 VAC-class three-phase supply	Relevant
Need for adjustable DC motor speed	Relevant
Conventional forward operation	Relevant
Two-quadrant operation	Relevant
No requirement for regenerative braking	Relevant
Industrial cabinet installation	Relevant
Retrofit of an older DC machine	Very relevant
Centralized PLC control	Relevant
Need for conformal-coated electronics	Relevant
Frequent regenerative braking	Consider regenerative alternative
New machine using an AC motor	Consider an AC drive instead

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42. Product Advantages in Practical Terms

The technical advantages of the 20P21AE067RA0NNN become clearer when viewed from a plant-maintenance perspective.

It is not simply a 50 HP DC power converter.

It is a complete digital motor-control platform intended to regulate the behavior of a DC motor in an industrial production environment.

For a machine that already has a suitable DC motor, this can make the drive a practical replacement or modernization component.

Its Frame B construction also provides a relatively compact mechanical package for the 50 HP class.

The conformal-coated configuration adds another layer of protection for the electronics.

The blank-HIM configuration is also useful where the machine’s main operator interface is located elsewhere.

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43. Five Recommended Same-Series Models

Recommended Model	DC Current	Motor Rating	Input	Frame	Regenerative	Approx. Dimensions	Approx. Drive Weight
20P21AE067RA0NNN	67.5 A	50 HP / 37 kW	575 VAC, 3-phase	B	No	311 × 388 × 350 mm	25.5 kg
20P21AE101RA0NNN	101.25 A	75 HP / 56 kW	575 VAC, 3-phase	B	No	311 × 388 × 350 mm	Approx. 25.5 kg
20P21AE135RA0NNN	135 A	100 HP / 75 kW	575 VAC, 3-phase	B	No	311 × 388 × 350 mm	Approx. 25.5 kg
20P21AE270RA0NNN	270 A	200 HP / 149 kW	575 VAC, 3-phase	B	No	311 × 388 × 350 mm	Approx. 29.5 kg
20P21AE405RA0NNN	405 A	300 HP / 224 kW	575 VAC, 3-phase	B	No	311 × 388 × 350 mm	Approx. 32 kg

The dimensional and weight values for the related models are based on the applicable Frame B mechanical grouping and should be confirmed against the exact catalog number before cabinet fabrication.

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44. Five Recommended Regenerative Alternatives

Model	DC Current	Motor Rating	Input	Frame	Drive Type	Approx. Drive Weight
20P41AE067RA0NNN	67.5 A	50 HP / 37 kW	575 VAC, 3-phase	B	Regenerative	Approx. 25.5 kg
20P41AE101RA0NNN	101.25 A	75 HP / 56 kW	575 VAC, 3-phase	B	Regenerative	Approx. 25.5 kg
20P41AE135RA0NNN	135 A	100 HP / 75 kW	575 VAC, 3-phase	B	Regenerative	Approx. 25.5 kg
20P41AE270RA0NNN	270 A	200 HP / 149 kW	575 VAC, 3-phase	B	Regenerative	Approx. 29.5 kg
20P41AE405RA0NNN	405 A	300 HP / 224 kW	575 VAC, 3-phase	B	Regenerative	Approx. 32 kg

These models are particularly relevant when braking energy and four-quadrant-type operating requirements need to be considered.

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45. Five Same-Brand Representative Models

Model	Series	Drive Technology	Voltage Class	Approximate Power Class	Typical Use
25B-D017N114	PowerFlex 525	AC variable-frequency drive	380–480 VAC class	7.5 kW class	Compact machines, conveyors, pumps
20F11NC022JA0NNNNN	PowerFlex 753	AC variable-frequency drive	380–480 VAC class	Medium-power	Industrial machinery
20F11NC034JA0NNNNN	PowerFlex 753	AC variable-frequency drive	380–480 VAC class	Medium/high-power	Process and machine applications
20G1ANB140JA0NNNNN	PowerFlex 755	High-performance AC drive	380–480 VAC class	High-power	Large industrial equipment
20G1ANC350JA0NNNNN	PowerFlex 755	High-performance AC drive	380–480 VAC class	High-power	Heavy industrial machinery

These products belong to different PowerFlex families, so they should not be treated as direct drop-in replacements.

Their suitability depends heavily on motor technology, voltage, power, control method, feedback, braking, enclosure, and the existing automation system.

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46. Detailed Catalog Number Interpretation

The catalog number 20P21AE067RA0NNN contains several pieces of product-selection information.

The 20P prefix identifies the PowerFlex DC drive product family.

The 21 identifies the non-regenerative configuration.

The AE portion identifies the 575 VAC-class three-phase input group.

The 067 corresponds to the 67.5 A rating class.

The remaining characters define additional configuration details, including the enclosure arrangement, coating, HIM arrangement, and communication configuration.

This is why it is important to specify the complete catalog number when ordering or replacing the drive.

Ordering only a partial model number can result in a drive with different options or installation characteristics.

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47. Final Technical Specification Table

Category	Detailed Specification
Model	20P21AE067RA0NNN
Brand	Allen-Bradley
Product family	PowerFlex
Series	PowerFlex DC Drive
Product type	Digital DC Drive
Application	Industrial DC motor control
Input voltage	575 VAC class
Input phase	Three-phase
Input topology	6-pulse
AC line current	Approximately 55.1 A
DC armature current	67.5 A
Motor power	50 HP
Motor power	Approximately 37 kW
Operating mode	Two-quadrant
Regenerative	No
Field supply	Single-phase regulated
Frame size	B
Enclosure	IP20 / NEMA/UL Type Open
HIM	No HIM / blank plate
Communication module	None in specified configuration
Conformal coating	Yes
Cooling	Forced-air
Height	311 mm
Width	388 mm
Depth	350 mm
Drive weight	25.5 kg
Packaged weight	27.5 kg
Mounting	Industrial cabinet/panel
Motor type	DC motor
Typical motor application	Separately excited DC motor
Primary application	Variable-speed DC motor control
Typical industry	Manufacturing and process industries

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48. Overall Product Assessment

The Allen-Bradley 20P21AE067RA0NNN is a 50 HP-class PowerFlex DC drive designed for industrial applications using 575 VAC three-phase power and a 67.5 A DC armature output.

Its main purpose is to provide controlled operation of a DC motor, allowing the motor’s speed and operating behavior to be managed digitally rather than relying on a fixed DC supply.

The model is particularly relevant to industrial modernization projects where an existing DC motor remains mechanically suitable.

Its two-quadrant, non-regenerative architecture makes it appropriate for conventional applications where full regenerative operation is not required.

The Frame B mechanical package measures approximately 311 mm high, 388 mm wide, and 350 mm deep, with an approximate drive weight of 25.5 kg.

The conformal-coated configuration is useful in industrial environments, while the blank-HIM arrangement is appropriate for installations where drive control is handled through a centralized automation system.

For a 50 HP DC motor operating from a 575 VAC-class industrial supply, this model represents a well-defined DC drive configuration within the PowerFlex family.

When selecting it for an actual replacement project, however, the motor nameplate, armature voltage, armature current, field voltage, field current, motor speed, feedback method, braking requirements, cabinet conditions, and existing control architecture should all be checked before final selection.

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49. Short Product Description for Industrial Catalog Use

The Allen-Bradley 20P21AE067RA0NNN is a PowerFlex Digital DC Drive rated for 67.5 A DC armature current and 50 HP motor operation. It is designed for 575 VAC three-phase input power and provides non-regenerative, two-quadrant DC motor control. The drive uses a compact Frame B mechanical platform with approximate dimensions of 311 × 388 × 350 mm and a drive weight of approximately 25.5 kg. The specified configuration includes IP20/NEMA Type Open construction, conformal coating, a blank-plate/no-HIM arrangement, and no standard communication module. It is suitable for industrial conveyors, winding systems, printing machinery, machine tools, material-handling equipment, pumps, fans, process machinery, and DC motor modernization projects.

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50. Final Summary

The Allen-Bradley 20P21AE067RA0NNN belongs to the PowerFlex DC Drive series and is designed for medium-power industrial DC motor applications.

Its principal electrical characteristics are a 575 VAC three-phase input, 67.5 A DC armature rating, and 50 HP / approximately 37 kW motor rating.

The drive uses a non-regenerative, two-quadrant architecture, making it suitable for many conventional DC motor applications where full regenerative braking is not required.

Its Frame B construction provides approximately 311 mm × 388 mm × 350 mm overall mechanical dimensions, with an approximate drive weight of 25.5 kg.

The specified configuration includes conformal coating, IP20/NEMA/UL Type Open construction, no HIM/blank plate, and no communication module.

Its strongest practical application is the modernization or replacement of existing industrial DC motor systems where maintaining the existing motor and mechanical equipment is desirable.

For applications requiring higher current, the same PowerFlex DC family provides models such as the 75 HP, 100 HP, 200 HP, and 300 HP versions.

For applications requiring regenerative operation, the corresponding PowerFlex regenerative DC models can be considered.

Overall, the 20P21AE067RA0NNN is best understood as a 50 HP-class industrial digital DC motor controller intended for 575 VAC three-phase systems, with a strong fit for retrofit, process-control, material-handling, and other industrial machinery applications.