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Allen-Bradley 20P21AE135RA0NNN PowerFlex DC Drive

1. Product Overview

The Allen-Bradley 20P21AE135RA0NNN is a PowerFlex DC Drive designed for industrial applications requiring controlled operation of medium-power DC motors.

This model has a 135 A armature current rating and a 100 HP normal-duty motor rating, equivalent to approximately 75 kW. It is designed for a 575 VAC-class, three-phase input and uses a non-regenerative, two-quadrant operating configuration.

The 20P21AE135RA0NNN is especially relevant to industrial machines that already use DC motors and require a modern digital drive for speed regulation, controlled acceleration, controlled stopping, and integration into an automated production system.

For retrofit work, this type of drive can be particularly useful because the existing DC motor, gearbox, coupling, mechanical transmission, and other machine components may be retained when their condition and electrical characteristics are suitable.

The complete catalog number identifies a specific configuration rather than simply indicating the current rating. The specified configuration includes the 135 A electrical rating, 575 VAC-class input, IP20/NEMA/UL Type Open construction, conformal-coated electronics, blank-plate/no-HIM configuration, and no standard communication module.

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2. Brand and Product Series

Item	Specification
Model	20P21AE135RA0NNN
Brand	Allen-Bradley
Product family	PowerFlex
Product series	PowerFlex DC Drive
Product type	Digital DC Drive
Drive configuration	Non-regenerative
Motor operation	Two-quadrant
Input system	Three-phase AC
Input voltage class	575 VAC
Input frequency	60 Hz class
Input type	6-pulse
DC armature current	135 A
Normal-duty motor rating	100 HP
Approximate motor power	75 kW
Frame size	B
Enclosure	IP20 / NEMA/UL Type Open
Cooling	Forced-air
Field supply	Single-phase regulated
HIM configuration	No HIM / blank plate
Communication module	None in specified configuration
Conformal coating	Yes
Main application	Industrial DC motor control

The PowerFlex DC series is designed specifically for industrial DC motor applications.

Its digital control architecture allows the drive to manage motor speed, armature current, field operation, acceleration, deceleration, protection functions, and other operating parameters according to the requirements of the machine.

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3. Main Technical Parameters

Parameter	Specification
Model	20P21AE135RA0NNN
Brand	Allen-Bradley
Series	PowerFlex DC Drive
Drive type	Digital DC Drive
Input voltage	575 VAC class
Input phase	Three-phase
Input frequency	60 Hz class
Input topology	6-pulse
DC armature current	135 A
Normal-duty motor rating	100 HP
Normal-duty motor rating	Approximately 75 kW
Approximate AC line current	110.3 A
Operating mode	Two-quadrant
Regenerative operation	No
Field supply	Single-phase regulated
Frame	B
Enclosure	IP20 / NEMA/UL Type Open
Cooling	Forced-air
HIM	No HIM / blank plate
Communication module	None in specified configuration
Conformal coating	Yes
Mounting	Panel / industrial cabinet
Approximate height	311 mm
Approximate width	388 mm
Approximate depth	350 mm
Approximate drive weight	25.5 kg
Approximate packaged weight	27.5 kg
Typical motor	Separately excited DC motor
Main application	Variable-speed industrial DC motor control

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4. Electrical Rating

The 20P21AE135RA0NNN is a 100 HP-class DC drive with a 135 A DC armature current rating.

The corresponding normal-duty motor rating is approximately 75 kW.

The model is designed for a 575 VAC-class, three-phase AC supply.

Electrical Parameter	Specification
Model	20P21AE135RA0NNN
AC input voltage	575 VAC class
AC input phase	3-phase
Input frequency	60 Hz class
Input type	6-pulse
DC armature current	135 A
AC line current	Approximately 110.3 A
Motor rating	100 HP
Motor power	Approximately 75 kW
Motor operation	Two-quadrant
Regeneration	No
Field supply	Single-phase regulated

The 135 A armature rating is the key electrical value when matching the drive to an existing DC motor.

Horsepower is important, but DC motor selection should not be based on horsepower alone.

The motor nameplate should also be checked for armature voltage, armature current, field voltage, field current, base speed, maximum speed, and feedback requirements.

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5. 100 HP Motor Capacity

The 20P21AE135RA0NNN is rated for a 100 HP normal-duty motor, corresponding to approximately 75 kW.

This places it between the 75 HP and 200 HP models in the same general 575 VAC PowerFlex DC range.

Motor Rating	DC Armature Current	Approximate kW
50 HP	67.5 A	37 kW
75 HP	101.25 A	56 kW
100 HP	135 A	75 kW
200 HP	270 A	149 kW
300 HP	405 A	224 kW

The 100 HP rating makes this model suitable for larger conveyors, industrial roll drives, process machinery, winders, printing equipment, material-handling systems, and other medium-to-heavy industrial applications.

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6. Dimensions and Weight

The 20P21AE135RA0NNN uses the Frame B mechanical platform.

The basic drive dimensions are approximately:

311 mm high × 388 mm wide × 350 mm deep

The approximate drive weight is 25.5 kg.

Mechanical Parameter	Specification
Model	20P21AE135RA0NNN
Frame	B
Height	311 mm
Width	388 mm
Depth	350 mm
Mounting dimension A1	275 mm
Bottom offset A2	16.5 mm
Bottom offset A3	7 mm
Mounting dimension B1	375 mm
Main depth	350 mm
Approximate overall envelope	311 × 388 × 350 mm
Drive weight	25.5 kg
Approximate packaged weight	27.5 kg
Mounting method	Panel / cabinet

These dimensions describe the drive itself.

The complete electrical cabinet normally requires additional space for cable bending, terminals, grounding conductors, ventilation, upstream protection, service access, and heat dissipation.

For a replacement installation, the available cabinet space should therefore be evaluated using the complete mechanical installation requirements rather than only the basic product dimensions.

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7. Product Introduction

The Allen-Bradley 20P21AE135RA0NNN is a digital DC motor drive intended for industrial production equipment.

A DC motor requires controlled armature power to regulate its speed and torque.

The drive converts the incoming three-phase AC supply into controlled DC output power and regulates the motor according to the requested operating conditions.

Instead of simply applying a fixed voltage to the motor, the drive continuously manages the electrical operating point.

This allows the machine to start smoothly, accelerate in a controlled manner, operate at an adjustable speed, and stop according to the programmed requirements.

For industrial equipment, this type of control can make a significant difference to mechanical stress and process consistency.

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8. What the Drive Controls

The drive is intended primarily for separately excited DC motors.

A typical separately excited DC motor contains:

• An armature circuit
• A field circuit
• Mechanical rotating components
• Brushes and a commutator

The armature circuit is directly associated with torque-producing motor current.

The field circuit establishes the magnetic field required by the motor.

The PowerFlex DC drive provides the electronic control necessary to operate these circuits as part of a complete motor-control system.

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9. Two-Quadrant Operation

The 20P21AE135RA0NNN is configured for two-quadrant motor operation.

This configuration is suitable for many industrial machines where controlled motoring and controlled braking are required but full regenerative operation is not necessary.

Two-quadrant operation should be distinguished from four-quadrant regenerative operation.

A conventional conveyor, pump, or fan may not require the same braking architecture as a high-inertia winder, hoist, or overhauling load.

For applications where substantial energy needs to be returned to the AC supply during braking, a regenerative PowerFlex DC model should be considered instead.

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10. Non-Regenerative Design

The 20P21AE135RA0NNN belongs to the non-regenerative PowerFlex DC family.

This means that it is designed for applications where regenerative power return is not required.

This can make the drive suitable for conventional motor-control applications in which the machine normally operates in one direction and stopping does not require continuous energy regeneration back into the AC system.

The actual braking requirements should always be evaluated before selecting a non-regenerative drive.

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11. 575 VAC-Class Three-Phase Input

The model is designed for the 575 VAC-class three-phase industrial power system.

This voltage class is commonly associated with larger industrial equipment.

The actual plant voltage should be checked before installation.

The complete electrical system should also be reviewed for:

• Incoming voltage
• Frequency
• Grounding
• Available fault current
• Input protection
• Line impedance
• Harmonics
• Transformer arrangement
• Disconnect equipment

These factors influence the overall drive installation.

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12. 6-Pulse Input Architecture

The 20P21AE135RA0NNN uses a 6-pulse input.

This is a conventional industrial power-conversion topology.

Three-phase AC power is converted into the DC power required by the motor-drive system.

The architecture is well established in industrial DC drive installations.

For facilities with strict power-quality requirements, the overall electrical installation should be evaluated for harmonic effects and the suitability of the input power arrangement.

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13. 135 A Armature Current

The 135 A armature current rating is one of the most important specifications of this drive.

When replacing an existing DC drive, the motor’s armature current should be compared directly with the drive rating.

The following motor information should be checked:

Motor Parameter	Required Check
Drive model	20P21AE135RA0NNN
Armature current	Compatible with 135 A rating
Armature voltage	Must match application requirements
Motor horsepower	Approximately 100 HP class
Motor power	Approximately 75 kW
Field current	Must match field supply capability
Field voltage	Must match field supply
Base speed	Verify against drive setup
Maximum speed	Verify motor mechanical limit
Feedback	Verify tachometer/encoder arrangement
Duty cycle	Verify continuous and peak load

A correct drive selection requires the complete motor nameplate rather than horsepower alone.

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14. Regulated Field Supply

The specified configuration includes a single-phase regulated field supply.

The field supply is important for separately excited DC motors.

The field winding creates the magnetic field used by the motor.

Field voltage and field current therefore have a direct effect on motor operation.

During commissioning, the motor field data should be checked carefully.

Field loss protection and correct field wiring are also important considerations.

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15. No HIM / Blank Plate Configuration

The catalog configuration specifies No HIM / Blank Plate.

HIM stands for Human Interface Module.

A HIM normally provides local access to parameters, status information, and operator functions.

The blank-plate configuration is useful when the drive is intended to operate under centralized machine control.

For example, an operator may control the machine through a separate HMI while a PLC handles drive commands and machine sequencing.

This arrangement can also reduce the number of operator devices mounted directly on the drive.

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16. No Standard Communication Module

The specified configuration does not include a standard communication module.

This should be considered during a replacement project.

If the original drive communicates with a PLC or supervisory controller, the existing communication architecture should be documented before the replacement is installed.

The new system may require an appropriate communication option or a different control interface.

The absence of a communication module in this particular catalog configuration does not mean that the drive cannot be used in an automated production system.

It simply identifies the configuration supplied under this catalog number.

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17. Conformal-Coated Electronics

The 20P21AE135RA0NNN includes a conformal-coated configuration.

Conformal coating provides additional protection for electronic assemblies against environmental influences such as humidity and certain airborne contaminants.

This is useful for industrial applications.

However, conformal coating does not eliminate the need for an appropriate electrical enclosure.

The drive should still be protected against direct water exposure, condensation, conductive contamination, excessive dust, corrosive gases, and other unsuitable environmental conditions.

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18. Main Product Applications

The 20P21AE135RA0NNN can be used in many industrial DC motor applications.

Typical applications include:

• Large industrial conveyors
• Paper-processing machinery
• Printing machines
• Winding and unwinding systems
• Textile machinery
• Material-handling equipment
• Industrial roll drives
• Machine tools
• Process machinery
• Fans
• Pumps
• Production lines
• Metal-processing machinery
• Legacy DC motor systems
• Industrial modernization projects

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19. Conveyor Applications

A 100 HP motor can provide substantial mechanical torque.

On a large conveyor, sudden application of this torque can create mechanical shock.

Controlled acceleration can allow the motor to reach operating speed gradually.

This can reduce stress on:

• Belts
• Gearboxes
• Shafts
• Couplings
• Bearings
• Conveyor structures

Controlled deceleration can also make machine stopping smoother.

For large production conveyors, this can be useful for both mechanical protection and process control.

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20. Winding and Unwinding Machinery

Winding equipment can have continuously changing mechanical requirements.

As the roll diameter changes, the relationship between motor speed and material speed can also change.

The motor may need to provide controlled torque while maintaining a defined process speed.

DC motors have historically been used in these applications because of their controllability.

The 20P21AE135RA0NNN can provide a digital control platform for a suitable 100 HP-class DC motor.

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21. Paper Processing Machinery

Paper-processing equipment often depends on stable material speed.

Large rolls, feeders, conveyors, winders, and processing sections can require controlled motor operation.

A DC drive can provide adjustable speed control for existing DC motors.

This makes the 20P21AE135RA0NNN useful for modernization projects where the mechanical equipment is still suitable but the original drive needs replacement.

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22. Printing Machinery

Printing machines can require precise coordination between different mechanical sections.

Speed variation between rollers can influence the quality of the finished product.

A controlled DC motor system can provide adjustable speed and controlled acceleration.

For older printing equipment with a 100 HP-class DC motor, the PowerFlex DC drive can be considered as a replacement or modernization platform when the motor’s electrical characteristics match the drive.

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23. Textile Applications

Textile equipment often requires controlled motor speed.

Machines such as:

• Winders
• Roll drives
• Drawing equipment
• Material feeders
• Spinning machinery

may use DC motors in older installations.

The 20P21AE135RA0NNN can be suitable where the motor and machine requirements correspond to the 135 A / 100 HP drive rating.

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24. Pump Applications

Industrial pumps may require variable-speed operation.

Changing motor speed changes the pump operating point.

This can allow process flow to be adjusted without relying solely on mechanical throttling.

When applying a DC drive to a pump, the complete pump curve and motor operating range should be evaluated.

Starting torque, continuous load, operating speed, and process requirements should all be considered.

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25. Fan Applications

Industrial fans can also use variable-speed DC motors.

The required airflow may change depending on the production process.

A drive allows the motor to operate at different speeds according to demand.

This can make the process more flexible than a fixed-speed motor arrangement.

The motor’s field and armature characteristics should be checked before establishing the allowable speed range.

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26. Material Handling

Material-handling systems can benefit from controlled acceleration and deceleration.

The 20P21AE135RA0NNN can be used in suitable 100 HP-class DC motor applications such as:

• Large conveyors
• Transfer equipment
• Rollers
• Feed systems
• Industrial transport machinery
• Production-line material handling

The actual motor and load characteristics determine whether the drive is appropriate.

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27. Machine Tool Applications

Some older industrial machine tools use DC motors for their speed-control characteristics.

A digital DC drive can modernize the electrical control system while retaining the original motor.

The motor’s maximum allowable speed is especially important.

The drive should not be configured to operate the motor beyond its mechanical limits.

Feedback characteristics should also be checked where closed-loop speed regulation is required.

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28. Main Product Advantages

Advantage	Description
100 HP rating	Suitable for substantial industrial DC motor loads
135 A armature current	Provides significant DC motor current capacity
575 VAC-class input	Suitable for higher-voltage industrial power systems
Digital control	Provides flexible motor regulation
Two-quadrant operation	Suitable for conventional motoring and controlled stopping
Non-regenerative architecture	Practical where regenerative power return is not required
Frame B	Compact industrial mechanical platform for the rating
Conformal coating	Additional protection for electronic assemblies
Regulated field supply	Supports separately excited DC motors
Blank-plate configuration	Suitable for centralized machine control
Retrofit capability	Useful for modernizing existing DC equipment
Wide application range	Suitable for conveyors, winders, process equipment and more

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29. Main Advantage for Retrofit Projects

One of the biggest practical advantages of the 20P21AE135RA0NNN is its suitability for existing DC motor installations.

An industrial machine is normally a combination of electrical and mechanical systems.

Replacing a drive does not necessarily require replacing:

• The motor
• Gearbox
• Couplings
• Shafts
• Rollers
• Conveyor structures
• Mechanical transmission
• Existing machine frame

When the original DC motor remains in good condition, a PowerFlex DC drive can provide a modern control platform while preserving much of the existing machine.

This can reduce engineering work and minimize mechanical modification.

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30. Digital Control Benefits

Digital control provides a flexible platform for configuring the drive.

Depending on the machine architecture, the control system can be adjusted for:

• Speed reference
• Current limits
• Acceleration
• Deceleration
• Field control
• Feedback
• Protection
• Fault response
• Operating limits

This makes the drive suitable for machines with different operating requirements.

It can also simplify the transition from an older analog DC drive to a newer digital platform.

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31. Speed Regulation

The PowerFlex DC architecture is designed to provide controlled motor speed.

For production equipment, maintaining a stable speed can be important for product quality.

A speed-regulated DC motor can compensate for changes in mechanical load.

This is particularly useful for:

• Roll drives
• Conveyors
• Winders
• Printing equipment
• Process machinery
• Material handling

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32. Controlled Acceleration

Controlled acceleration is important when a 100 HP motor is connected to a substantial mechanical load.

Applying torque too rapidly can produce mechanical shock.

A controlled acceleration profile allows the motor to build speed progressively.

This can reduce stress on the mechanical transmission and provide smoother machine startup.

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33. Controlled Deceleration

Controlled deceleration is equally important.

A large rotating load has stored mechanical energy.

When the motor is commanded to stop, that energy must be managed appropriately.

The 20P21AE135RA0NNN is non-regenerative, so the application’s braking arrangement must be compatible with this configuration.

Applications requiring substantial continuous regeneration should be evaluated against regenerative models.

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34. Cabinet Installation

The IP20 / NEMA/UL Type Open configuration means that the drive is intended to be integrated into a suitable electrical cabinet or enclosure.

It should not be treated as a fully sealed outdoor drive.

The cabinet should provide:

• Physical protection
• Adequate ventilation
• Correct electrical clearances
• Grounding
• Cable routing
• Service access
• Environmental protection

The cabinet’s thermal design should also account for the heat generated by the drive and other installed equipment.

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35. Cooling and Thermal Management

The drive uses forced-air cooling.

Airflow is therefore an important part of the installation.

Ventilation openings should remain clear.

Cooling fans should be inspected periodically.

Dust accumulation should be controlled.

Cabinet temperature should be monitored in demanding applications.

High internal temperature can reduce the available thermal margin and can shorten the service life of electronic components.

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36. Maintenance

Maintenance should cover both the drive and the motor.

Typical drive maintenance includes:

• Checking cooling fans
• Inspecting ventilation paths
• Checking power terminals
• Checking control wiring
• Inspecting grounding
• Reviewing alarms
• Checking cabinet temperature
• Removing excessive dust
• Looking for signs of overheating

Motor maintenance should include:

• Brush inspection
• Commutator inspection
• Field circuit inspection
• Bearing inspection
• Insulation checks
• Mechanical alignment
• Feedback-device inspection

The condition of the DC motor has a direct impact on the reliability of the complete drive system.

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37. DC Motor Brush Maintenance

Traditional DC motors use brushes and a commutator.

These components are wear items.

The condition of the brushes should be checked periodically.

Poor brush condition can lead to:

• Increased electrical noise
• Commutation problems
• Arcing
• Increased motor temperature
• Reduced motor reliability

A drive replacement project is therefore a good opportunity to inspect the motor before putting the new drive into service.

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38. Feedback and Closed-Loop Control

Where precise speed regulation is required, feedback can be used.

A tachometer or encoder provides actual motor-speed information.

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

This is useful where the load changes during production.

Feedback wiring should be installed carefully because noise and grounding problems can affect signal quality.

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39. Typical System Architecture

A typical system can be represented as:

Three-Phase AC Supply → Electrical Protection → PowerFlex DC Drive → DC Motor

The control architecture may be:

PLC / Controller → Speed Reference → DC Drive

and, where feedback is required:

Motor Feedback → DC Drive → Closed-Loop Speed Regulation

The actual architecture depends on the machine.

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40. Electrical Protection

The drive should be installed as part of a complete electrical protection system.

Depending on the installation, this may include:

• Disconnect devices
• Input fuses
• Circuit protection
• Line reactor
• Contactors
• Grounding
• Surge protection
• Motor protection

The 135 A DC drive rating means that upstream electrical components should be selected with appropriate current capacity.

The complete electrical design should be based on the actual installation requirements.

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41. Input Line Reactor

For the 575 VAC input range, a suitable line reactor can be part of the input power arrangement.

For the 100 HP / 135 A model, the associated line-reactor selection is in the approximately 75 kW / 100 HP class.

A line reactor can add impedance between the drive and the incoming AC supply.

Its selection should be coordinated with the drive rating and the electrical characteristics of the installation.

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42. Motor Selection Considerations

The drive should be selected against the actual motor nameplate.

Important information includes:

Parameter	Importance
Drive model	20P21AE135RA0NNN
Motor HP	100 HP class
Armature current	Must be compatible with 135 A
Armature voltage	Must match
Field voltage	Must match
Field current	Must match
Base speed	Must be suitable
Maximum speed	Must not exceed motor limit
Feedback	Must be compatible
Load type	Must be evaluated
Braking requirement	Must suit two-quadrant operation
Duty cycle	Must be evaluated

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43. Five Related Models from the Same PowerFlex DC Series

The following models are closely related within the 575 VAC-class PowerFlex DC family.

Model	DC Current	Motor Rating	Motor Power	Input	Frame	Operation
20P21AE067RA0NNN	67.5 A	50 HP	37 kW	575 VAC, 3-phase	B	Non-regenerative, 2Q
20P21AE101RA0NNN	101.25 A	75 HP	56 kW	575 VAC, 3-phase	B	Non-regenerative, 2Q
20P21AE135RA0NNN	135 A	100 HP	75 kW	575 VAC, 3-phase	B	Non-regenerative, 2Q
20P21AE270RA0NNN	270 A	200 HP	149 kW	575 VAC, 3-phase	B	Non-regenerative, 2Q
20P21AE405RA0NNN	405 A	300 HP	224 kW	575 VAC, 3-phase	B	Non-regenerative, 2Q

The 20P21AE135RA0NNN occupies the 100 HP / 135 A position in this range.

The 75 HP version is suitable for a smaller motor, while the 200 HP and 300 HP versions are intended for considerably larger industrial loads.

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44. Same-Series Model Comparison

Parameter	20P21AE067RA0NNN	20P21AE101RA0NNN	20P21AE135RA0NNN	20P21AE270RA0NNN	20P21AE405RA0NNN
Input voltage	575 VAC	575 VAC	575 VAC	575 VAC	575 VAC
Phase	3	3	3	3	3
DC armature current	67.5 A	101.25 A	135 A	270 A	405 A
Motor rating	50 HP	75 HP	100 HP	200 HP	300 HP
Motor power	37 kW	56 kW	75 kW	149 kW	224 kW
Frame	B	B	B	B	B
Operation	2Q	2Q	2Q	2Q	2Q
Regenerative	No	No	No	No	No
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
Approx. packaged weight	27.5 kg	27.5 kg	27.5 kg	31.5 kg	34 kg

The dimensions and weights of related configurations should be confirmed against the exact catalog number before cabinet fabrication.

The main selection difference between these models is the electrical current and corresponding motor power rating.

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45. Five Related Regenerative Models

For applications that require regenerative operation, the following related PowerFlex DC models provide comparable power classes.

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

The closest regenerative counterpart to the 20P21AE135RA0NNN is the 20P41AE135RA0NNN, because it has the same basic 100 HP / 135 A power class while providing a regenerative configuration.

This distinction becomes important for machines with frequent braking, overhauling loads, or significant kinetic energy.

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46. Five Same-Brand Popular Models

The following models represent other widely used products within the same overall brand portfolio.

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

These models are not direct drop-in replacements for the 20P21AE135RA0NNN.

The 20P21AE135RA0NNN is a DC drive, while the PowerFlex 525, 753, and 755 families are AC variable-frequency-drive products.

If the existing DC motor is to be retained, the PowerFlex DC family is the more directly relevant product group.

If the machine is undergoing a complete modernization, an AC motor and AC drive system can be considered, but this normally requires additional mechanical and electrical engineering.

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47. Same-Brand Model Comparison

Parameter	25B-D017N114	20F11NC022JA0NNNNN	20F11NC034JA0NNNNN	20G1ANB140JA0NNNNN	20G1ANC350JA0NNNNN
Product family	PowerFlex 525	PowerFlex 753	PowerFlex 753	PowerFlex 755	PowerFlex 755
Drive technology	AC VFD	AC VFD	AC VFD	AC VFD	AC VFD
Voltage class	380–480 VAC	380–480 VAC	380–480 VAC	380–480 VAC	380–480 VAC
Typical size	Compact	Medium	Medium/high	High power	High power
Motor technology	AC motor	AC motor	AC motor	AC motor	AC motor
Typical application	Machine control	Industrial machinery	Process equipment	Large machinery	Heavy industrial equipment
DC motor compatibility	No	No	No	No	No
Main characteristic	Compact installation	Flexible industrial control	Higher power	High-performance control	Heavy-duty AC control

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48. DC Drive Versus AC Drive Modernization

When upgrading an existing machine, the choice between continuing with DC technology and converting to AC technology should be based on the complete system.

Consideration	20P21AE135RA0NNN	Modern AC Drive System
Motor technology	DC motor	AC motor
Drive technology	DC drive	Variable-frequency AC drive
Existing motor retained	Yes	Usually no
Existing mechanical system retained	Often possible	May require modifications
Brush maintenance	Required	Usually eliminated
Retrofit scope	Potentially smaller	Potentially larger
Motor replacement	Not necessarily required	Usually required
Speed control	Digital DC control	Variable-frequency control
Regenerative option	Separate regenerative model	Available on selected AC platforms
Main use	Existing DC machinery	New or fully modernized machinery

For a machine where the DC motor is mechanically healthy and well matched to the process, replacing the drive can be a practical modernization strategy.

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49. Cabinet Planning

The basic product envelope is approximately:

311 mm × 388 mm × 350 mm

The drive weight is approximately:

25.5 kg

Cabinet design should include additional space beyond this basic envelope.

Additional space may be required for:

• Incoming AC cables
• DC armature cables
• Field wiring
• Grounding
• Control wiring
• Feedback cables
• Ventilation
• Service access
• Electrical protection
• Cable bending radius

The total cabinet heat load should also be considered.

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50. Cooling Requirements

The drive uses forced-air cooling.

This makes airflow an important installation consideration.

Cooling openings should remain clear.

Fans should be inspected during maintenance.

Dust should be prevented from accumulating around the cooling system.

Cabinet temperature should be monitored, especially when the drive operates continuously at high load.

A well-designed thermal environment can contribute significantly to drive reliability.

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51. Environmental Considerations

The conformal-coated configuration provides additional protection for electronic components.

Even so, the drive should be installed in a suitable environment.

Potential environmental concerns include:

• High humidity
• Condensation
• Conductive dust
• Metal particles
• Chemical vapors
• Corrosive gases
• Salt contamination
• Excessive temperature
• Excessive vibration
• Poor ventilation

The cabinet and surrounding installation should be designed according to the actual operating environment.

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52. Maintenance Advantages

The drive provides a modern digital control platform, which can make troubleshooting more structured than with some older analog systems.

Maintenance personnel can review drive status, operating parameters, alarms, and fault conditions as part of the troubleshooting process.

However, the DC motor itself remains an important maintenance item.

A complete preventive-maintenance program should therefore cover both electrical and mechanical components.

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53. Recommended Maintenance Schedule

A practical maintenance program can include:

Daily or Routine Inspection

Check for abnormal noise, overheating, unusual motor behavior, and visible alarms.

Periodic Inspection

Inspect cooling fans, ventilation openings, cabinet cleanliness, and electrical connections.

Motor Inspection

Check brushes, commutator condition, bearings, field wiring, and insulation.

Annual or Planned Shutdown

Perform a more detailed electrical and mechanical inspection according to the plant’s maintenance procedures.

The actual maintenance interval depends on operating hours, environmental conditions, motor duty, load, and plant maintenance policy.

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54. Product Selection for a 100 HP Motor

The 20P21AE135RA0NNN is a natural candidate when the existing motor is approximately 100 HP and the electrical requirements are compatible.

The 135 A rating provides the required current capacity for the corresponding normal-duty rating.

However, a 100 HP motor should not automatically be paired with this drive without checking its complete nameplate.

The following information should be verified:

• Armature voltage
• Armature current
• Field voltage
• Field current
• Base speed
• Maximum speed
• Motor feedback
• Duty cycle
• Load inertia
• Braking requirements
• Incoming supply voltage

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55. Five Recommended Same-Series Models

Recommended Model	DC Current	Motor Rating	Motor Power	Input	Frame	Dimensions	Weight
20P21AE067RA0NNN	67.5 A	50 HP	37 kW	575 VAC, 3-phase	B	311 × 388 × 350 mm	25.5 kg
20P21AE101RA0NNN	101.25 A	75 HP	56 kW	575 VAC, 3-phase	B	311 × 388 × 350 mm	25.5 kg
20P21AE135RA0NNN	135 A	100 HP	75 kW	575 VAC, 3-phase	B	311 × 388 × 350 mm	25.5 kg
20P21AE270RA0NNN	270 A	200 HP	149 kW	575 VAC, 3-phase	B	311 × 388 × 350 mm	29.5 kg
20P21AE405RA0NNN	405 A	300 HP	224 kW	575 VAC, 3-phase	B	311 × 388 × 350 mm	32 kg

The 20P21AE135RA0NNN is the 100 HP / 135 A model in this group.

The 50 HP and 75 HP versions are useful when the motor requirement is lower, while the 200 HP and 300 HP versions provide considerably greater current capacity.

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56. Five Same-Brand Recommended Models

Model	Series	Drive Technology	Voltage Class	Approximate Power Class	Typical Application	Physical Data
25B-D017N114	PowerFlex 525	AC VFD	380–480 VAC	7.5 kW class	Compact machinery	Configuration dependent
20F11NC022JA0NNNNN	PowerFlex 753	AC VFD	380–480 VAC	Medium power	Industrial machinery	Configuration dependent
20F11NC034JA0NNNNN	PowerFlex 753	AC VFD	380–480 VAC	Medium/high power	Process machinery	Configuration dependent
20G1ANB140JA0NNNNN	PowerFlex 755	High-performance AC drive	380–480 VAC	High power	Large industrial equipment	Configuration dependent
20G1ANC350JA0NNNNN	PowerFlex 755	High-performance AC drive	380–480 VAC	High power	Heavy industrial equipment	Configuration dependent

The dimensions and weights of these AC drive models vary according to frame and configuration, so they should not be assumed to have the same mechanical dimensions as the 20P21AE135RA0NNN.

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57. Detailed Final Parameter Table

Category	Detailed Specification
Model	20P21AE135RA0NNN
Brand	Allen-Bradley
Product family	PowerFlex
Series	PowerFlex DC Drive
Product type	Digital DC Drive
Input voltage	575 VAC class
Input phase	Three-phase
Input frequency	60 Hz class
Input topology	6-pulse
AC line current	Approximately 110.3 A
DC armature current	135 A
Normal-duty motor rating	100 HP
Motor power	Approximately 75 kW
Motor operation	Two-quadrant
Regenerative	No
Field supply	Single-phase regulated
Frame size	B
Enclosure	IP20 / NEMA/UL Type Open
Cooling	Forced-air
HIM	No HIM / blank plate
Communication module	None in specified configuration
Conformal coating	Yes
Height	311 mm
Width	388 mm
Depth	350 mm
Approximate drive weight	25.5 kg
Approximate packaged weight	27.5 kg
Mounting	Panel / industrial cabinet
Typical motor	Separately excited DC motor
Typical applications	Conveyors, winders, printing, paper, textile, pumps, fans, process machinery
Primary use	Industrial DC motor speed control and modernization

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58. Catalog Number Interpretation

The complete catalog number 20P21AE135RA0NNN contains information describing the drive configuration.

The 20P designation identifies the PowerFlex DC product family.

The 21 portion identifies the non-regenerative, two-quadrant configuration.

The AE portion corresponds to the 575 VAC-class input group.

The 135 portion identifies the 135 A armature-current rating.

The remaining catalog positions identify additional configuration characteristics, including the motor-operation arrangement, enclosure-related configuration, conformal coating, HIM arrangement, and communication configuration.

This is why the complete catalog number should be used when purchasing or replacing the drive.

A partial model number may not identify the exact same configuration.

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59. Why the 20P21AE135RA0NNN Is Suitable for Industrial Modernization

The 20P21AE135RA0NNN is particularly relevant when an industrial machine still has a functional 100 HP-class DC motor.

A modern digital drive can replace an older controller without necessarily changing the entire mechanical system.

This can be valuable for large machines where mechanical modification would be costly.

The drive can provide a modern control interface while the original motor, gearbox, and mechanical transmission remain in place.

The result can be a more controlled and maintainable electrical system without requiring a complete machine rebuild.

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60. Overall Product Advantages

Area	Advantage of 20P21AE135RA0NNN
Motor capacity	100 HP / 75 kW class
Current capacity	135 A
Input voltage	Suitable for 575 VAC-class systems
Control	Digital DC motor control
Speed regulation	Adjustable and controllable
Acceleration	Controlled acceleration capability
Deceleration	Controlled stopping within application limits
Regeneration	Non-regenerative configuration
Field control	Regulated field supply
Environment	Conformal-coated configuration
Installation	Frame B industrial construction
Operator interface	Blank plate / no HIM
Automation	Suitable for integration into centralized control architectures
Retrofit	Strong fit for existing DC motor systems
Applications	Broad industrial application range

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61. Final Product Description

The Allen-Bradley 20P21AE135RA0NNN is a 100 HP, 135 A PowerFlex Digital DC Drive designed for industrial motor-control applications using a 575 VAC-class three-phase input.

The drive uses a 6-pulse input architecture, two-quadrant motor operation, and a non-regenerative configuration.

Its rated DC armature current is 135 A, while the corresponding normal-duty motor rating is 100 HP, or approximately 75 kW.

The drive uses a Frame B mechanical platform with approximate dimensions of 311 mm × 388 mm × 350 mm and an approximate drive weight of 25.5 kg.

The specified configuration includes IP20 / NEMA/UL Type Open construction, forced-air cooling, conformal-coated electronics, a regulated single-phase field supply, no HIM/blank plate, and no standard communication module.

The model is well suited to industrial conveyors, paper-processing machines, printing equipment, textile machinery, winding systems, material-handling equipment, machine tools, pumps, fans, roll drives, and other industrial machines that use an appropriately rated DC motor.

Its main practical value is its ability to provide a modern digital control platform for an existing DC motor installation.

For a retrofit, the motor nameplate should be checked carefully, especially the armature voltage, armature current, field voltage, field current, base speed, maximum speed, feedback arrangement, and braking requirements.

The 20P21AE135RA0NNN is therefore best viewed as a 100 HP-class industrial digital DC motor controller for 575 VAC-class three-phase systems, with a particularly strong application in existing production equipment and DC motor modernization projects.

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62. Final Summary

The Allen-Bradley 20P21AE135RA0NNN belongs to the PowerFlex DC Drive series.

Its primary specifications are:

• 575 VAC-class three-phase input
• 6-pulse input
• 135 A DC armature current
• 100 HP motor rating
• Approximately 75 kW motor power
• Two-quadrant operation
• Non-regenerative configuration
• Single-phase regulated field supply
• Frame B construction
• IP20 / NEMA/UL Type Open enclosure
• Conformal-coated electronics
• No HIM / blank plate
• No standard communication module
• Forced-air cooling

The approximate mechanical specifications are:

• Height: 311 mm
• Width: 388 mm
• Depth: 350 mm
• Drive weight: 25.5 kg
• Approximate packaged weight: 27.5 kg

The product is suitable for medium-to-heavy industrial DC motor applications, particularly conveyors, winders, printing machinery, paper machinery, textile equipment, roll drives, pumps, fans, material-handling equipment, and industrial production lines.

For modernization projects, it can be particularly useful where an existing 100 HP-class DC motor remains mechanically sound.

The same PowerFlex DC family includes smaller models such as the 20P21AE067RA0NNN and 20P21AE101RA0NNN, as well as larger models such as the 20P21AE270RA0NNN and 20P21AE405RA0NNN.

For applications requiring regenerative operation, the corresponding 20P41 models provide related regenerative configurations.

For a complete machine conversion from DC to AC motor technology, other PowerFlex AC drive families such as PowerFlex 525, PowerFlex 753, and PowerFlex 755 can be evaluated, but those are not direct drop-in replacements for this DC drive.

In practical terms, the 20P21AE135RA0NNN is a 100 HP / 135 A digital DC drive designed to provide controlled and adjustable operation of an industrial DC motor, combining a relatively compact Frame B package with a 575 VAC-class three-phase input and a configuration aimed at conventional, non-regenerative industrial motor-control applications.