Company Information
E-mail		[email protected]
Mobile		+8615980777398
Whatsapp		+8615980777398
WeChat		15980777398

20P21AD073RA0NNN PowerFlex DC Drive

Product Specifications, Introduction, Applications, Advantages, Series Information and Related Model Recommendations

---

1. Product Overview

The 20P21AD073RA0NNN is a high-power industrial DC drive belonging to the PowerFlex DC series.

It is designed for controlling DC motors in industrial machinery where accurate speed regulation, controlled acceleration, controlled torque and reliable motor operation are required.

The model is rated at 73 A and is intended for a 40 HP / approximately 30 kW motor class when used with a 460/480 VAC three-phase supply.

The drive uses a two-quadrant, non-regenerative operating configuration, making it particularly suitable for conventional DC motor applications where the motor normally operates in the motoring mode and the machine does not continuously return significant regenerative energy to the drive.

The product is supplied in an IP20, NEMA/UL Type Open configuration and uses a Frame A construction.

The standard configuration includes a blank front plate rather than a local HIM operator interface, a user manual and no communication module as part of the standard catalog configuration.

This combination makes the 20P21AD073RA0NNN especially useful for industrial retrofit projects where an existing DC motor and mechanical system need a replacement or modernization of the drive section without completely redesigning the machine.

---

2. Brand and Product Series

Item	Specification
Brand	Allen-Bradley
Series	PowerFlex DC
Product family	PowerFlex
Product category	Industrial DC Drive
Model	20P21AD073RA0NNN
Drive type	Digital DC Drive
Motor technology	DC motor
Current rating	73 A
Motor power class	40 HP
Approximate metric motor power	30 kW
Input voltage class	480 VAC
Input phase	Three-phase
Input type	6-pulse
Operating mode	Two-quadrant
Regenerative operation	Non-regenerative
Enclosure	IP20
Enclosure type	NEMA/UL Type Open
Frame	Frame A
Cooling	Air cooled
Front interface	Blank plate
Communication module	Not included
Field supply	Single-phase regulated
Feedback capability	Tachometer / encoder applications
Conformal coating	Yes

---

3. Main Technical Parameters

Parameter	Specification
Model	20P21AD073RA0NNN
Series	PowerFlex DC
Product type	Industrial DC Drive
Input voltage	380–480 VAC class
Nominal input voltage	460/480 VAC class
Input frequency	50/60 Hz
Input phase	Three-phase
Input topology	6-pulse
Output current	73 A
Normal-duty motor rating	40 HP
Metric motor rating	Approximately 30 kW
Armature current	73 A
Motor operation	Two-quadrant
Regenerative operation	No
Field supply	Single-phase regulated
Enclosure rating	IP20
Enclosure type	NEMA/UL Type Open
Frame size	Frame A
Cooling method	Air cooled
Front operator interface	Blank plate
HIM	Not included
Communication module	Not included
Conformal coating	Yes
Digital control	Supported
Analog control	Supported
Feedback	Encoder / tachometer capable
Installation	Cabinet / panel mounted
Dimensions	Approx. 279 × 381 × 279 mm
Height	Approx. 279 mm
Width	Approx. 381 mm
Depth	Approx. 279 mm
Weight (kg)	Approx. 11–12 kg

Note: The mechanical dimensions and shipping/installed weight can differ depending on the exact frame documentation, accessories and packaging. For cabinet fabrication, the applicable mechanical drawing should be treated as the final dimensional reference.

---

4. Product Introduction

The 20P21AD073RA0NNN is intended for industrial applications that continue to use DC motors but require modern digital drive control.

A DC drive is responsible for converting incoming AC electrical power into controlled DC power for the motor armature and managing the motor field circuit.

Instead of simply switching a motor on and off, the drive can regulate the motor’s operating conditions according to the machine’s requirements.

Typical functions include:

• Controlled motor starting
• Controlled acceleration
• Controlled deceleration
• Speed regulation
• Current limiting
• Torque-related control
• Field control
• Feedback-based speed control
• Fault detection
• Motor protection
• Machine interlocking
• External speed reference

The 73 A rating places this model in a considerably higher power category than smaller 19 A, 27 A, 35 A, 45 A and 52 A configurations.

Its approximately 40 HP / 30 kW motor class makes it suitable for larger industrial machinery where higher motor torque and power are required.

---

5. 73 A Current Rating

The 73 A armature current rating is one of the defining characteristics of the 20P21AD073RA0NNN.

Armature current is closely associated with the torque-producing capability of a conventional DC motor.

A higher current-rated drive can control a larger motor, provided that the motor voltage, field characteristics, speed and application requirements are also compatible.

The 73 A model is therefore positioned above the 52 A version.

A simplified capacity comparison is shown below.

Model	Current Rating	Approximate Motor Rating
20P21AD019RA0NNN	19 A	10 HP
20P21AD027RA0NNN	27 A	15 HP
20P21AD035RA0NNN	35 A	20 HP
20P21AD045RA0NNN	45 A	25 HP
20P21AD052RA0NNN	52 A	30 HP
20P21AD073RA0NNN	73 A	40 HP
20P21AD086RA0NNN	86 A	50 HP
20P21AD100RA0NNN	100 A	60 HP

The 73 A configuration is therefore a logical choice when a 52 A drive is insufficient but a substantially larger drive is unnecessary.

---

6. 40 HP / Approximately 30 kW Motor Class

The 20P21AD073RA0NNN is associated with a 40 HP / approximately 30 kW motor rating.

This places the product into the medium-to-heavy industrial machinery category.

Typical applications can include:

• Heavy conveyors
• Industrial rollers
• Material feeders
• Paper-processing machines
• Printing equipment
• Textile machinery
• Production lines
• Material-handling equipment
• Machine tools
• Process machinery
• Specialized industrial equipment
• Heavy-duty DC motor systems

For proper drive selection, the motor nameplate should always be checked rather than relying only on horsepower.

---

7. Input Power

The drive is designed for a 380–480 VAC-class three-phase input, with the 460/480 VAC industrial system being the primary application class.

Three-phase industrial power is commonly used for medium- and high-power machinery.

The input system should be evaluated for:

• Nominal voltage
• Voltage tolerance
• Available short-circuit current
• Frequency
• Phase balance
• Grounding arrangement
• Disconnect requirements
• Branch protection
• Cabinet wiring
• Drive protection requirements

A correct electrical installation is essential for reliable operation.

---

8. Six-Pulse Input Design

The 20P21AD073RA0NNN uses a six-pulse input configuration.

This is a conventional architecture for industrial DC drives.

The incoming three-phase AC power is converted into controlled DC power for the motor armature.

Six-pulse technology is widely associated with conventional industrial DC drive systems and is particularly relevant to retrofit projects where an existing machine already uses a DC motor.

When replacing an older DC drive, engineers should compare:

• Input voltage
• Input phase
• Armature voltage
• Armature current
• Field voltage
• Field current
• Feedback type
• Control wiring
• Braking requirements
• Motor speed
• Protection requirements

before selecting the replacement.

---

9. Two-Quadrant Operation

The 20P21AD073RA0NNN is a two-quadrant drive.

Two-quadrant operation is suitable for many conventional motor applications where the machine operates primarily in the forward motoring direction.

Typical applications include:

• Conveyors
• Feeders
• Rollers
• Pumps
• Fans
• Processing machinery
• Production machinery
• Material transport systems

Two-quadrant operation can be an economical solution when the application does not require continuous regenerative operation.

---

10. Non-Regenerative Operation

The 20P21AD073RA0NNN is a non-regenerative configuration.

This means that it is not intended to continuously return regenerative motor energy to the AC power system.

This distinction is particularly important when dealing with high-inertia machinery.

When a high-inertia load decelerates, the motor can temporarily operate as a generator.

Applications that require careful regenerative evaluation include:

• Winders
• Unwinders
• Hoists
• Cranes
• High-speed rollers
• High-inertia conveyors
• Rapid reversing machinery
• Frequent braking applications
• Downhill conveyors
• Machines with substantial stored mechanical energy

For these applications, a regenerative configuration may be more suitable.

---

11. Field Supply

The model includes a single-phase regulated field supply.

The field circuit is important in conventional DC motors because the field establishes the magnetic flux necessary for motor operation.

Field parameters should be matched carefully to the motor.

Field Parameter	Recommended Check
Field voltage	Match motor nameplate
Field current	Remain within motor rating
Field polarity	Verify before commissioning
Field wiring	Check terminals and insulation
Field-loss protection	Verify configuration
Field weakening	Verify motor suitability
Maximum speed	Confirm motor limit
Motor cooling	Confirm adequate cooling

Incorrect field configuration can result in poor motor performance or motor damage.

---

12. Feedback Capability

The PowerFlex DC family supports feedback arrangements such as tachometer and encoder feedback.

Feedback is particularly useful when the machine requires stable speed under changing load conditions.

For example, if the load on a production roller increases, motor speed may naturally decrease.

A feedback device measures the actual motor speed.

The drive can compare actual speed with commanded speed and adjust motor operation accordingly.

This can improve:

• Speed regulation
• Process stability
• Product consistency
• Repeatability
• Load response
• Machine performance

Feedback is particularly useful in:

• Printing machinery
• Paper machinery
• Textile machinery
• Roller systems
• Feed systems
• Precision processing machinery
• Production lines

---

13. Control I/O

The drive can be integrated into an industrial control system using digital and analog control signals.

Typical hardwired control functions can include:

• Start
• Stop
• Enable
• Reset
• Direction
• Speed reference
• Run status
• Ready status
• Fault status

The exact I/O assignment depends on the drive configuration and control strategy.

A PLC or machine controller can therefore supervise the drive while the drive handles the motor-control functions.

---

14. Blank Front Plate

The standard configuration has a blank front plate instead of a local HIM.

This is useful in machines where the operator interface is installed elsewhere.

For example, the drive can be installed inside a cabinet while the operator controls the machine from:

• An HMI
• A PLC
• A remote panel
• Pushbuttons
• Selector switches
• An external potentiometer
• A machine-control station

This arrangement can make the drive suitable for centralized machine-control architectures.

---

15. Communication Configuration

The standard catalog configuration does not include a communication module.

The drive can therefore be used with hardwired control signals without requiring a network communication option in the base configuration.

For larger automation systems, a communication option may be selected separately where required.

Typical system functions can include:

• Start/stop control
• Speed reference
• Fault monitoring
• Drive status
• Actual speed monitoring
• Current monitoring
• Machine interlocking

---

16. IP20 Enclosure

The drive uses an IP20, NEMA/UL Type Open enclosure configuration.

It is therefore intended to be installed inside an appropriate electrical enclosure or protected cabinet.

It should not be treated as a weatherproof or washdown enclosure.

The installation should protect the drive from:

• Water
• Direct spray
• Condensation
• Conductive dust
• Excessive airborne contamination
• Mechanical impact
• Corrosive contamination
• Extreme environmental exposure

The cabinet must also provide suitable airflow and heat dissipation.

---

17. Conformal Coating

The product configuration includes conformal coating.

Conformal coating provides an additional protective layer around electronic components.

This can be beneficial in industrial environments where electronics may be exposed to:

• Humidity
• Dust
• Airborne particles
• Production contamination
• Industrial atmosphere

It is important to understand that conformal coating does not make an IP20 drive waterproof.

The drive still requires a suitable enclosure and controlled installation environment.

---

18. Frame A Construction

The model is associated with Frame A construction.

For planning purposes, the approximate mechanical dimensions can be considered in the following range:

Height: approximately 279 mm

Width: approximately 381 mm

Depth: approximately 279 mm

The approximate unit weight is around:

11–12 kg

The exact installed and shipping weight can vary depending on accessories and packaging.

Cabinet designers should therefore leave sufficient space for:

• Power cables
• Control wiring
• Feedback cables
• Airflow
• Maintenance access
• Terminal access
• Cable bending radius
• Cooling

---

19. Dimensions and Weight

Mechanical Specification	Approximate Value
Model	20P21AD073RA0NNN
Frame	Frame A
Height	Approx. 279 mm
Width	Approx. 381 mm
Depth	Approx. 279 mm
Dimensions	Approx. 279 × 381 × 279 mm
Weight (kg)	Approx. 11–12 kg
Enclosure	IP20
Enclosure type	NEMA/UL Type Open
Cooling	Air cooled
Installation	Panel / cabinet
Mounting environment	Protected industrial enclosure

The dimensions above are suitable as general planning information, but final cabinet engineering should use the mechanical drawing for the exact product revision.

---

20. Main Product Applications

20.1 Heavy Conveyor Systems

The 73 A current capacity makes the drive suitable for larger conveyor applications.

Potential uses include:

• Heavy belt conveyors
• Roller conveyors
• Transfer conveyors
• Assembly conveyors
• Bulk-material conveyors
• Production conveyors
• Packaging conveyors
• Material transport systems

Controlled acceleration can help reduce mechanical shock to belts, couplings and gearboxes.

---

21. Industrial Roller Systems

Roller systems frequently require stable motor speed.

The drive can be applied to compatible DC motors used for:

• Feed rollers
• Process rollers
• Paper rollers
• Printing rollers
• Textile rollers
• Material transport rollers
• Production rollers

When precise speed control is important, a tachometer or encoder feedback arrangement can provide additional control capability.

---

22. Paper Processing Machinery

DC motors have historically been used in many paper-processing machines.

The 20P21AD073RA0NNN can be considered for compatible applications such as:

• Feed rollers
• Process rollers
• Paper transport
• Production equipment
• Material handling
• Auxiliary drives
• Processing systems

Stable motor speed can contribute to consistent material movement.

---

23. Printing Machinery

Printing equipment often requires controlled roller speed.

Potential applications include:

• Printing rollers
• Feed systems
• Paper handling
• Material transport
• Processing rollers
• Auxiliary machine drives

The application should be evaluated carefully if it requires frequent acceleration, rapid stopping or regenerative braking.

---

24. Textile Machinery

The drive can be considered for suitable DC motors used in textile production.

Potential applications include:

• Textile rollers
• Feed mechanisms
• Material transport
• Processing machinery
• Production systems
• Specialized textile equipment

For winding and unwinding machinery, regenerative energy should be evaluated carefully.

---

25. Material-Handling Equipment

The 73 A capacity is useful for larger material-handling machines.

Potential applications include:

• Heavy feeders
• Transfer machines
• Conveyors
• Rollers
• Production transport
• Material-handling systems
• Industrial sorting equipment
• Heavy production lines

The higher current capacity can provide additional torque capability for suitable motors.

---

26. Machine Tools

The drive can also be considered for compatible industrial machine tools.

Possible applications include:

• Grinding machines
• Feed systems
• Cutting equipment
• Processing machinery
• Specialized machine tools
• Production equipment

Where speed accuracy is critical, encoder or tachometer feedback should be evaluated.

---

27. Product Advantages

27.1 73 A Current Capacity

The 73 A output rating is one of the strongest characteristics of the product.

It allows the drive to control larger DC motors than lower-current versions.

---

27.2 40 HP / 30 kW Class

The 40 HP / approximately 30 kW capacity makes the product suitable for medium-to-heavy industrial machinery.

This is a useful range for applications requiring more power than 25 HP or 30 HP-class drives.

---

27.3 480 VAC-Class Three-Phase Input

The three-phase 480 VAC-class input is suitable for many industrial electrical systems.

---

27.4 Two-Quadrant Operation

Two-quadrant operation provides an appropriate control architecture for conventional motoring applications where regenerative operation is not a primary requirement.

---

27.5 Regulated Field Supply

The regulated field supply provides controlled operation of the DC motor field circuit.

---

27.6 Feedback Capability

Encoder and tachometer capability provides flexibility for speed-sensitive applications.

---

27.7 Flexible Control I/O

Digital and analog control capabilities allow integration into established machine-control systems.

---

27.8 Compact Frame Configuration

The Frame A construction provides a relatively compact drive package for its current and power class.

---

27.9 Conformal Coating

The conformal coating provides additional protection for electronic components in appropriate industrial environments.

---

27.10 Retrofit-Friendly Architecture

One of the most important practical advantages is its suitability for DC motor retrofit projects.

An existing machine may be able to retain:

• DC motor
• Gearbox
• Couplings
• Rollers
• Conveyor
• Mechanical transmission
• Existing control panel
• Existing PLC
• Existing machine structure

while the drive is modernized.

---

28. Advantages Summary

Feature	Practical Advantage
73 A output	Suitable for higher-current DC motors
40 HP / 30 kW class	Suitable for larger industrial machinery
480 VAC-class input	Compatible with common industrial power systems
Three-phase input	Suitable for industrial installations
6-pulse design	Established DC drive topology
Two-quadrant operation	Suitable for conventional motoring
Non-regenerative	Suitable for standard non-regenerative loads
Regulated field	Controlled motor-field operation
Feedback capability	Improved speed regulation options
Flexible I/O	Straightforward machine integration
Frame A	Compact installation concept
IP20	Suitable for cabinet installation
Conformal coating	Additional electronics protection
Blank plate	Suitable for external operator control

---

29. Five Same-Series or Closely Related Models

The following five models are useful comparison choices when selecting a drive around the same PowerFlex DC range.

Model	Series	Current	Approx. Power	Voltage Class	Operation	Regenerative	Frame / Size	Weight (kg)
20P21AD045RA0NNN	PowerFlex DC	45 A	25 HP / 18.5 kW	460/480 VAC	Two-quadrant	No	Frame A class	Approx. 11
20P21AD052RA0NNN	PowerFlex DC	52 A	30 HP / 22 kW	460/480 VAC	Two-quadrant	No	Frame A class	Approx. 11
20P21AD073RA0NNN	PowerFlex DC	73 A	40 HP / 30 kW	460/480 VAC	Two-quadrant	No	Frame A	Approx. 11–12
20P21AD086RA0NNN	PowerFlex DC	86 A	50 HP / 37 kW	460/480 VAC	Two-quadrant	No	Larger frame	Higher
20P41AD073RA0NNN	PowerFlex DC	73 A class	40 HP class	460/480 VAC	Regenerative	Yes	Frame-dependent	Frame-dependent

These models cover both lower and higher power requirements and provide a useful way to compare conventional and regenerative configurations.

---

30. Recommended Model 1 — 20P21AD045RA0NNN

The 20P21AD045RA0NNN is a lower-current option.

It is rated at approximately:

45 A

and approximately:

25 HP / 18.5 kW

It is suitable when the motor’s actual armature current is well below 73 A.

Potential applications include:

• Medium conveyors
• Feeders
• Rollers
• Printing machinery
• Textile equipment
• General industrial DC machinery

Its primary advantage is that it provides a smaller capacity where the 73 A model would be unnecessarily large.

---

31. Recommended Model 2 — 20P21AD052RA0NNN

The 20P21AD052RA0NNN is the next major capacity level.

It provides approximately:

52 A

and:

30 HP / 22 kW

It is an excellent comparison model when the motor is around the 30 HP class.

Compared with the 73 A model, it provides less current capacity but may be more appropriately matched to a smaller motor.

---

32. Recommended Model 3 — 20P21AD086RA0NNN

The 20P21AD086RA0NNN is the next higher standard current configuration.

It provides approximately:

86 A

and:

50 HP / 37 kW

It is suitable when the 73 A model does not provide sufficient current capacity.

Potential applications include:

• Heavy conveyors
• Large rollers
• High-torque machinery
• Heavy material handling
• Large processing equipment
• Larger production systems

---

33. Recommended Model 4 — 20P41AD073RA0NNN

The 20P41AD073RA0NNN is a related regenerative configuration.

It is particularly relevant where the machine requires regenerative operation.

Potential applications include:

• Winders
• Unwinders
• Hoists
• Cranes
• High-inertia machinery
• Frequent braking
• Rapid deceleration
• Four-quadrant applications

The primary difference is the regenerative architecture.

---

34. Recommended Model 5 — 20P21AD100RA0NNN

The 20P21AD100RA0NNN provides approximately:

100 A

and:

60 HP / 45 kW

This is a suitable comparison when the application is beyond the 40 HP range.

It can be considered for:

• Large conveyors
• Heavy rollers
• Large feeders
• High-load processing machinery
• Heavy production equipment
• Larger DC motor systems

---

35. Five Broader Popular Models

For a broader product comparison, the following models are useful references within the same brand portfolio.

Model	Product Family	Product Type	Voltage Class	Current / Power	Typical Application	Approx. Dimensions	Weight (kg)
20P21AD052RA0NNN	PowerFlex DC	DC Drive	460/480 VAC	52 A / 30 HP	Industrial DC machinery	Frame A	Approx. 11
20P21AD073RA0NNN	PowerFlex DC	DC Drive	460/480 VAC	73 A / 40 HP	Heavy DC machinery	Frame A	Approx. 11–12
20P21AD086RA0NNN	PowerFlex DC	DC Drive	460/480 VAC	86 A / 50 HP	Larger DC machinery	Larger frame	Higher
20P41AD073RA0NNN	PowerFlex DC	Regenerative DC Drive	460/480 VAC	73 A / 40 HP class	Regenerative applications	Frame-dependent	Frame-dependent
25B-D017N104	PowerFlex 525	AC Drive	380–480 VAC	17 A class	General AC motor control	Compact	Approx. 2–3

The last model is an AC drive rather than a direct replacement for a DC drive.

It is better considered as part of a complete motor-and-drive modernization strategy.

---

36. DC Drive Versus AC Drive Modernization

Item	20P21AD073RA0NNN	AC Drive Modernization
Motor type	DC motor	AC motor
Existing DC motor retained	Usually yes	Usually no
Motor replacement	Usually not required	Normally required
Existing mechanical system	Often retained	Often retained
Drive replacement	Yes	Yes
Mechanical modification	Usually limited	Potentially greater
Control modification	Moderate	Potentially substantial
Feedback	Encoder/tachometer capable	Depends on AC drive
Retrofit complexity	Lower when retaining DC system	Higher
Main benefit	Preserve existing DC machine	Modernize to AC motor technology

---

37. Typical Industrial Applications

Application	Suitability
Heavy conveyor	Excellent candidate
Industrial roller	Excellent candidate
Material feeder	Excellent candidate
Paper processing	Suitable
Printing machinery	Suitable
Textile machinery	Suitable
Material handling	Suitable
Production machinery	Suitable
Machine tools	Suitable with proper motor matching
High-inertia winder	Regenerative evaluation required
Unwinder	Regenerative evaluation required
Hoist/crane	Regenerative/braking evaluation required
Frequent reversing system	Application-specific evaluation required

---

38. Retrofit Applications

The 20P21AD073RA0NNN is particularly relevant for modernization of existing DC motor equipment.

Many industrial machines have mechanical components that remain in good condition even though the original drive may be obsolete, damaged or difficult to maintain.

A drive retrofit can potentially preserve:

• Existing DC motor
• Gearbox
• Couplings
• Conveyor
• Rollers
• Shafts
• Mechanical transmission
• Machine frame
• Existing control architecture
• Existing PLC
• Existing HMI

This can reduce the amount of mechanical work required during modernization.

A complete conversion to AC technology may require:

• New AC motor
• New drive
• Motor mounting changes
• Coupling modifications
• Feedback changes
• PLC modifications
• Braking-system changes
• Machine testing
• Additional commissioning

Therefore, retaining a suitable DC motor can be attractive when the motor remains mechanically and electrically healthy.

---

39. Speed Control

Speed regulation is a major function of the drive.

A speed command can be supplied from an external controller or analog reference.

With an appropriate feedback device, the drive can compare the desired speed with the actual motor speed.

When the mechanical load changes, the drive can adjust motor operation to maintain the desired speed.

This is useful for:

• Paper rollers
• Printing rollers
• Feeders
• Textile machines
• Conveyor systems
• Production lines
• Material-handling equipment

---

40. Acceleration Control

Controlled acceleration is particularly valuable for a 40 HP-class motor.

A direct start can create a large mechanical shock.

Controlled acceleration can reduce stress on:

• Gearboxes
• Couplings
• Belts
• Shafts
• Bearings
• Rollers
• Conveyor components

It can also provide smoother material movement.

---

41. Deceleration Control

Deceleration deserves special attention because the model is non-regenerative.

A high-inertia load can return mechanical energy to the motor during deceleration.

The engineer should therefore evaluate:

• Motor speed
• Load inertia
• Deceleration time
• Stopping frequency
• Load torque
• Reverse operation
• Braking requirements
• Regenerative energy

If the machine frequently returns substantial energy, a regenerative configuration should be evaluated.

---

42. Torque Control

DC motor torque is closely related to armature current.

The 73 A capacity therefore provides substantial torque-control capability for a compatible 40 HP-class motor.

Potential applications include:

• Heavy conveyors
• Feed systems
• Rollers
• Material-handling equipment
• Processing machinery
• Production machinery

The current limit must be configured according to the motor’s actual nameplate rating.

---

43. Motor Compatibility Checklist

Before selecting the 20P21AD073RA0NNN, the following motor information should be checked.

Motor Parameter	Requirement
Armature voltage	Compatible with drive
Armature current	Compatible with 73 A capacity
Field voltage	Compatible with regulated field supply
Field current	Within motor rating
Horsepower	Around 40 HP class
Motor power	Around 30 kW class
Base speed	Verify
Maximum speed	Verify
Feedback type	Verify
Duty cycle	Verify
Starting torque	Verify
Braking requirement	Evaluate
Motor cooling	Verify
Motor insulation	Verify
Brushes	Inspect
Commutator	Inspect

---

44. Cabinet Design Considerations

The approximate drive dimensions are:

279 mm × 381 mm × 279 mm

with an approximate weight of:

11–12 kg

The cabinet should not be designed using only the drive’s external dimensions.

Additional space is required for:

• Power cable bending
• Control wiring
• Feedback wiring
• Terminal access
• Cooling airflow
• Maintenance
• Service work
• Grounding
• Heat dissipation

The installation should also prevent other heat-producing components from excessively increasing the drive’s ambient temperature.

---

45. Thermal Management

A 73 A DC drive produces heat during operation.

The cabinet designer should consider:

• Ambient temperature
• Cabinet temperature
• Internal airflow
• Fan operation
• Heat generated by adjacent equipment
• Cabinet ventilation
• Heat exchanger requirements
• Dust accumulation
• Cooling clearances

A well-designed cabinet helps maintain stable electronic operating temperatures and improves long-term reliability.

---

46. Maintenance Considerations

Routine maintenance should include inspection of:

• Cooling fan
• Ventilation paths
• Power terminals
• Control terminals
• Feedback wiring
• Field connections
• Armature connections
• Grounding
• Cabinet cleanliness
• Motor brushes
• Motor commutator
• Fault history

The DC motor should be considered part of the complete drive system.

A motor with worn brushes, poor commutation, insulation problems or mechanical problems can create drive faults even when the drive itself is functioning correctly.

---

47. Capacity Selection Table

Model	Current	Approx. Power	General Application
20P21AD019RA0NNN	19 A	10 HP / 7.5 kW	Smaller DC motors
20P21AD027RA0NNN	27 A	15 HP / 11 kW	Medium DC motors
20P21AD035RA0NNN	35 A	20 HP / 15 kW	Medium industrial motors
20P21AD045RA0NNN	45 A	25 HP / 18.5 kW	Larger medium motors
20P21AD052RA0NNN	52 A	30 HP / 22 kW	Larger industrial machinery
20P21AD073RA0NNN	73 A	40 HP / 30 kW	Heavy industrial machinery
20P21AD086RA0NNN	86 A	50 HP / 37 kW	Higher-power machinery
20P21AD100RA0NNN	100 A	60 HP / 45 kW	Large DC machinery

---

48. Detailed Comparison of Related Models

Model	Current	HP	kW	Input	Quadrant	Regenerative	Approx. Weight
20P21AD045RA0NNN	45 A	25 HP	18.5 kW	460/480 VAC	Two	No	Approx. 11 kg
20P21AD052RA0NNN	52 A	30 HP	22 kW	460/480 VAC	Two	No	Approx. 11 kg
20P21AD073RA0NNN	73 A	40 HP	30 kW	460/480 VAC	Two	No	Approx. 11–12 kg
20P21AD086RA0NNN	86 A	50 HP	37 kW	460/480 VAC	Two	No	Higher
20P21AD100RA0NNN	100 A	60 HP	45 kW	460/480 VAC	Two	No	Higher
20P41AD073RA0NNN	73 A class	40 HP class	30 kW class	460/480 VAC	Regenerative	Yes	Frame-dependent

---

49. Five Recommended Same-Series / Related Models

Model 1: 20P21AD045RA0NNN

45 A / 25 HP / 18.5 kW

Best suited to applications where the motor requirement is below the 73 A range.

It is a good choice for medium-sized conveyors, rollers, feeders and production equipment.

---

Model 2: 20P21AD052RA0NNN

52 A / 30 HP / 22 kW

This model is positioned directly below the 73 A configuration.

It is suitable when a 30 HP-class motor is used and the 52 A current capacity is sufficient.

---

Model 3: 20P21AD086RA0NNN

86 A / 50 HP / 37 kW

This model is a natural higher-capacity alternative.

It is suitable when the motor requires more than 73 A but remains within the approximately 50 HP class.

---

Model 4: 20P41AD073RA0NNN

73 A / 40 HP-class regenerative configuration

This is the closest functional alternative when the application requires regenerative operation.

It is particularly relevant for high-inertia and frequent-braking applications.

---

Model 5: 20P21AD100RA0NNN

100 A / 60 HP / 45 kW

This model provides significantly more capacity than the 73 A configuration.

It is appropriate for larger DC motor systems where additional current capacity is required.

---

50. Five Popular Models from the Same Brand Portfolio

Model	Series / Family	Type	Voltage	Current / Power	Application	Dimensions	Weight (kg)
20P21AD052RA0NNN	PowerFlex DC	DC Drive	460/480 VAC	52 A / 30 HP	General industrial DC	Frame A	Approx. 11
20P21AD073RA0NNN	PowerFlex DC	DC Drive	460/480 VAC	73 A / 40 HP	Heavy industrial DC	Frame A	Approx. 11–12
20P21AD086RA0NNN	PowerFlex DC	DC Drive	460/480 VAC	86 A / 50 HP	Larger DC machinery	Larger frame	Higher
20P41AD073RA0NNN	PowerFlex DC	Regenerative DC Drive	460/480 VAC	73 A / 40 HP class	Regenerative machinery	Frame-dependent	Frame-dependent
25B-D017N104	PowerFlex 525	AC Drive	380–480 VAC	17 A class	General AC motor control	Compact frame	Approx. 2–3

The AC drive listed above should not be regarded as a direct drop-in replacement for the DC drive.

It represents a different modernization approach in which the motor system is normally converted from DC to AC.

---

51. Detailed Product Parameter Table

Category	Parameter	Specification
Product	Model	20P21AD073RA0NNN
Product	Brand	Allen-Bradley
Product	Series	PowerFlex DC
Product	Product type	Industrial DC Drive
Electrical	Input voltage	380–480 VAC class
Electrical	Nominal voltage	460/480 VAC class
Electrical	Input phase	Three-phase
Electrical	Input frequency	50/60 Hz
Electrical	Input type	6-pulse
Electrical	Armature current	73 A
Electrical	Motor rating	40 HP
Electrical	Metric power	Approx. 30 kW
Electrical	Motor operation	Two-quadrant
Electrical	Regeneration	Non-regenerative
Field	Field supply	Single-phase regulated
Enclosure	IP rating	IP20
Enclosure	Enclosure type	NEMA/UL Type Open
Mechanical	Frame	Frame A
Mechanical	Cooling	Air cooled
Mechanical	Height	Approx. 279 mm
Mechanical	Width	Approx. 381 mm
Mechanical	Depth	Approx. 279 mm
Mechanical	Dimensions	Approx. 279 × 381 × 279 mm
Mechanical	Weight (kg)	Approx. 11–12 kg
Interface	Front interface	Blank plate
Interface	HIM	Not included
Communication	Communication module	Not included
Feedback	Tachometer	Supported
Feedback	Encoder	Supported
Protection	Conformal coating	Yes
Installation	Mounting	Panel / cabinet
Application	Main use	Industrial DC motor control
Application	Typical loads	Conveyors, rollers, feeders, processing machinery
Application	Retrofit use	Existing DC motor systems

---

52. Selection Guide

The 20P21AD073RA0NNN is generally appropriate when the following conditions are present:

The motor is approximately 40 HP / 30 kW.

The required armature current is within the 73 A class.

The plant supply is compatible with the 460/480 VAC three-phase class.

The application primarily requires motoring operation.

Continuous regenerative operation is not required.

The motor field requirements are compatible with the regulated field supply.

The installation can provide a suitable IP20 cabinet environment.

The existing DC motor is worth retaining.

The machine benefits from controlled speed and torque.

---

53. Situations Where Another Model May Be Better

The 20P21AD073RA0NNN is not necessarily the best selection for every 40 HP motor.

A different model may be preferable when:

• The motor current is significantly below 73 A.
• The motor requires a different armature voltage.
• The motor field voltage is incompatible.
• The machine requires four-quadrant operation.
• The machine frequently returns regenerative energy.
• The motor requires more than 73 A.
• The motor power is substantially above 40 HP.
• The application requires a modern AC motor architecture.

For regenerative applications, the corresponding regenerative PowerFlex DC configuration should be considered.

For substantially larger motors, higher-current 20P21 configurations should be evaluated.

For complete DC-to-AC modernization, an appropriate PowerFlex AC drive and compatible AC motor should be selected as a complete system.

---

54. Why the 20P21AD073RA0NNN Is Attractive for Industrial Retrofits

The biggest practical advantage of a DC drive retrofit is the possibility of keeping an existing mechanical system in operation.

Industrial machinery can contain expensive mechanical components that are difficult to replace.

A functioning DC motor may be mechanically integrated with:

• Gearboxes
• Couplings
• Shafts
• Rollers
• Conveyors
• Bearings
• Braking systems
• Production mechanisms

Replacing the drive while keeping the motor can therefore reduce project complexity.

This approach can also reduce machine downtime when compared with a complete motor-and-drive conversion.

---

55. Long-Term Application Considerations

When using a DC drive in an existing machine, the condition of the DC motor should be evaluated.

Important inspection points include:

• Brush wear
• Commutator condition
• Bearing condition
• Insulation resistance
• Armature condition
• Field winding condition
• Cooling
• Mechanical alignment
• Vibration
• Motor temperature

A new drive connected to a heavily worn motor may not solve the underlying reliability problem.

For long-term operation, both the drive and motor should be treated as one complete system.

---

56. Overall Technical Assessment

The 20P21AD073RA0NNN occupies an important position in the PowerFlex DC range.

At 73 A and 40 HP / approximately 30 kW, it provides substantially more capacity than the 45 A and 52 A models while remaining below the larger 86 A, 100 A and higher-current configurations.

This makes it a practical choice for industrial equipment requiring a relatively high-capacity DC motor controller.

Its main strengths include:

• 73 A armature capacity
• 40 HP motor class
• Approximately 30 kW motor capacity
• 460/480 VAC-class three-phase input
• Two-quadrant operation
• Regulated field supply
• Feedback capability
• Flexible control architecture
• IP20 cabinet installation
• Conformal coating
• Frame A construction
• Retrofit suitability

The most important limitation is the non-regenerative operating configuration.

For conventional motoring applications, this is generally appropriate.

For applications where the load frequently drives the motor or where substantial braking energy must be returned, regenerative requirements should be examined before final selection.

---

57. Final Specification Summary

Item	Final Specification
Model	20P21AD073RA0NNN
Brand	Allen-Bradley
Series	PowerFlex DC
Product type	Industrial DC Drive
Input voltage	380–480 VAC class
Nominal voltage	460/480 VAC
Input phase	Three-phase
Input type	6-pulse
Armature current	73 A
Motor rating	40 HP
Motor power	Approximately 30 kW
Operation	Two-quadrant
Regenerative	No
Field supply	Single-phase regulated
Enclosure	IP20
Enclosure type	NEMA/UL Type Open
Frame	Frame A
Cooling	Air cooled
Front interface	Blank plate
HIM	Not included
Communication module	Not included
Feedback	Encoder / tachometer capable
Conformal coating	Yes
Height	Approx. 279 mm
Width	Approx. 381 mm
Depth	Approx. 279 mm
Dimensions	Approx. 279 × 381 × 279 mm
Weight (kg)	Approx. 11–12 kg
Main application	Industrial DC motor control
Typical loads	Heavy conveyors, rollers, feeders, paper, printing, textile and processing equipment
Lower-capacity alternative	20P21AD052RA0NNN
Higher-capacity alternative	20P21AD086RA0NNN
Regenerative alternative	20P41AD073RA0NNN
Higher-power alternative	20P21AD100RA0NNN

---

58. Conclusion

The 20P21AD073RA0NNN is a 73 A, 40 HP / approximately 30 kW PowerFlex DC drive intended for industrial DC motor applications.

Its relatively high current capacity makes it suitable for larger conveyors, rollers, feeders, processing machinery, paper equipment, printing systems, textile equipment and other industrial machines that continue to use DC motors.

The drive provides controlled motor operation rather than simple on/off switching, allowing the machine designer to manage acceleration, deceleration, speed, current and other important motor-control functions.

Its two-quadrant, non-regenerative design makes it particularly appropriate for conventional motoring applications.

The regulated field supply provides controlled field operation, while feedback capability allows the drive to be used in applications where accurate speed regulation is important.

The IP20 Frame A construction, blank front plate and flexible control arrangement make it suitable for installation inside a machine cabinet where the operator interface and higher-level machine control are handled externally.

For retrofit projects, the product can be particularly attractive because an existing DC motor, gearbox and mechanical system may be retained rather than replaced.

When choosing this model, the most important points are not horsepower alone. The motor’s armature voltage, armature current, field voltage, field current, base speed, maximum speed, feedback type, duty cycle and braking requirements should all be checked.

For applications requiring approximately 73 A and 40 HP / 30 kW, the 20P21AD073RA0NNN represents a strong fit within the PowerFlex DC range.

For lower-power applications, the 20P21AD045RA0NNN or 20P21AD052RA0NNN may be more appropriately sized.

For higher-power applications, the 20P21AD086RA0NNN or 20P21AD100RA0NNN can be considered.

For machines that require substantial regenerative braking or four-quadrant operation, a regenerative PowerFlex DC configuration should be evaluated instead of the standard 20P21 non-regenerative configuration.

In practical terms, the 20P21AD073RA0NNN is best viewed as a 40 HP-class industrial DC drive for high-current, conventional two-quadrant motor applications, with particular value in machinery modernization and DC drive replacement projects.