Allen-Bradley 20P21AD167RA0NNN Product Overview, Specifications, Applications and Model Recommendations

Note: The following content is organized around the catalog number 20P21AD167RA0NNN. I have intentionally omitted web links, source citations, and company names as requested. Where a dimension or weight is not reliably established from the available product data, it is explicitly marked as “not specified” rather than using an estimated value.

1. Product Basic Information

20P21AD167RA0NNN is an Allen-Bradley PowerFlex DC Drive designed for industrial DC motor control applications.

It belongs to the PowerFlex DC product family and is an architecture-class DC drive intended for applications that require controlled DC motor speed and torque. The unit is configured for a 480 VAC, three-phase input, with a rated output current of 167 A and a nominal power rating of 100 HP.

The drive uses a six-pulse input configuration and provides two-quadrant, non-regenerative motor operation. In practical terms, it is intended primarily for applications where controlled motoring operation is required rather than applications requiring continuous regenerative braking.

The catalog number also identifies several important configuration details. The unit uses an IP20 / NEMA/UL Type Open enclosure, has conformal coating, is supplied without a HIM display/keypad, and does not include a standard communication module.

2. Product Identification

3. Detailed Electrical Parameters

The electrical characteristics are the most important part of selecting this drive because the catalog number is closely associated with the input voltage, current rating, motor power and operating configuration.

The 167 A output-current rating is one of the defining characteristics of this model. It places the unit in a considerably higher power class than smaller DC drives and makes it suitable for substantial industrial machinery.

The 100 HP / approximately 75 kW rating provides a useful reference when matching the drive to a DC motor. Actual motor selection should still be based on the motor’s nameplate current, armature voltage, field requirements, duty cycle, acceleration requirements and application load rather than simply matching horsepower.

4. Size and Weight

The physical dimensions and shipping weight should be treated carefully because drive dimensions can vary according to enclosure configuration, accessories, installation arrangement and the exact mechanical revision.

For this particular catalog number, the available product identification establishes the Frame B mechanical classification, but does not provide sufficiently reliable dimensional and mass figures to justify presenting a fabricated number.

For engineering or cabinet-design work, the exact mechanical drawing for the specific revision should be used. This is especially important because cabinet clearance, airflow, cable routing and heat dissipation all depend on the actual installation dimensions.

I would not recommend using a guessed weight or guessed dimensions for a 167 A DC drive in a production cabinet.

5. Product Description

The 20P21AD167RA0NNN is a high-current industrial DC drive in the PowerFlex DC family.

Its basic function is to receive three-phase AC electrical power and provide controlled DC power to the armature of a DC motor. By controlling the armature power, the drive can regulate motor speed and operating torque according to the requirements of the machine.

The six-pulse input architecture is a conventional industrial rectifier arrangement. It provides a practical solution for large DC motor applications where high current capability and robust industrial control are required.

The drive’s two-quadrant configuration is particularly important. It is intended for applications where the motor operates primarily in the forward motoring region and where regenerative operation is not a fundamental requirement.

The IP20 / NEMA/UL Type Open enclosure means this is not a standalone outdoor drive with a sealed enclosure. It is normally integrated into an appropriate industrial control cabinet or electrical enclosure.

The unit is also supplied with no standard HIM, which makes sense for installations where the drive is expected to be configured or supervised through an external control system, local panel, engineering software or another interface.

6. Main Functions

6.1 DC Motor Speed Control

One of the primary purposes of the drive is controlled DC motor speed operation.

Compared with direct connection of a DC motor to a fixed DC source, the drive provides much greater control over motor acceleration, deceleration and operating speed.

This is particularly valuable in production machinery where speed consistency has a direct effect on product quality.

6.2 Motor Current Control

At 167 A, the drive is intended for relatively high-current DC motor applications.

Current regulation is important because motor torque is closely related to armature current. Proper current control allows the system to respond to changing mechanical loads while maintaining stable motor operation.

6.3 Controlled Acceleration

The drive can be incorporated into a controlled acceleration sequence rather than applying full power to the motor immediately.

This can reduce mechanical shock to:

• Gearboxes
• Couplings
• Shafts
• Rollers
• Conveyors
• Belts
• Production machinery

This is particularly useful for large machines with significant rotating inertia.

6.4 Controlled Deceleration

Controlled deceleration can also be used to reduce mechanical stress.

Because this model is a non-regenerative two-quadrant drive, applications requiring significant regenerative energy management need to be evaluated separately. If the machine routinely drives the motor into regeneration, a regenerative configuration may be more appropriate.

7. Product Advantages

7.1 High Current Capacity

The 167 A output rating is one of the major advantages of this model.

It is suitable for considerably larger DC motor systems than low-power general-purpose drives. This makes it useful for industrial machinery where the motor requires substantial armature current.

7.2 100 HP Power Class

The nominal 100 HP rating places this drive in a high-power industrial category.

This allows it to serve applications such as large material-handling machines, production lines, processing equipment and other industrial systems using DC motors.

7.3 Industrial DC Motor Control

The PowerFlex DC family is designed specifically around DC motor control rather than being a generic AC frequency converter.

This makes the architecture appropriate for industrial equipment where a DC motor is already installed and replacement with an AC motor is not economically or mechanically practical.

7.4 Two-Quadrant Operation

Two-quadrant operation provides controlled motoring operation without requiring a regenerative drive architecture.

For machinery that does not need continuous regenerative braking, this can be a simpler and more economical configuration.

7.5 Regulated Field Supply

The integrated single-phase regulated field supply is another useful feature.

The motor field is an important component of a DC motor system. A regulated field supply helps provide a controlled field excitation rather than relying entirely on an uncontrolled external field supply.

7.6 Conformal Coating

The conformal coating configuration provides an additional level of protection for electronic circuitry against environmental influences.

It can be beneficial in industrial environments where humidity, dust or other contaminants may create additional stress on electronic assemblies.

This does not mean the drive can simply be installed in any harsh environment without an appropriate enclosure. The overall cabinet and environmental design remains important.

7.7 Flexible Industrial Integration

The PowerFlex DC architecture can be integrated into larger automation systems.

Depending on the overall configuration, the drive can be used with external control equipment, feedback devices and industrial automation systems.

This makes it suitable for machines where the drive is only one component of a larger control architecture.

8. Typical Applications

8.1 Conveyor Systems

Large conveyor systems can use DC motors when high starting torque and precise speed control are required.

The 167 A rating makes this model suitable for larger industrial conveyor applications, provided the motor’s actual voltage and current ratings match the drive.

Typical uses include:

• Heavy material conveyors
• Mining conveyors
• Bulk-material handling
• Industrial transfer systems
• Long production conveyors

8.2 Rolling and Metal Processing Equipment

DC drives have historically been widely used in metal-processing machinery because of their ability to provide controlled torque and speed.

Potential applications include:

• Rolling equipment
• Strip processing
• Coil handling
• Tension control
• Material processing machinery

For applications with frequent regenerative operation, however, the braking and regeneration requirements must be examined carefully.

8.3 Printing Machinery

Large printing machines can require stable motor speed and coordinated movement.

DC drive technology can be useful in older or established printing lines where DC motors are already installed.

Typical requirements include:

• Stable speed
• Smooth acceleration
• Controlled torque
• Repeatable operation
• Coordination with other machine sections

8.4 Extrusion and Processing Machinery

Industrial processing equipment can require consistent motor speed and torque.

A DC drive can be integrated into machines where the motor and mechanical transmission were originally designed around DC technology.

8.5 Material Handling Equipment

Large material-handling systems can benefit from the high-current capability of the drive.

Examples include:

• Hoisting-related machinery
• Heavy-duty handling equipment
• Large transfer machines
• Industrial lifting mechanisms

However, lifting and lowering applications deserve particular attention because the braking and regeneration characteristics can be substantially different from ordinary motoring applications.

8.6 Existing DC Motor Retrofit Projects

One of the most practical uses for this type of product is modernization of existing equipment.

Many older industrial machines were designed around DC motors. Replacing the entire motor, gearbox, mechanical system and control architecture can be expensive.

A modern DC drive can provide a way to upgrade the electrical control section while retaining much of the existing mechanical infrastructure.

9. Important Selection Considerations

Before selecting 20P21AD167RA0NNN as a replacement or new installation, several parameters should be checked.

The most important point is that motor horsepower alone should not be used to select the drive.

The motor nameplate current is particularly important. A 100 HP motor with one set of electrical characteristics may require a different drive configuration from another 100 HP motor with a different armature voltage or field rating.

10. Series Information

The PowerFlex DC family is intended for industrial DC motor applications covering a broad range of voltage, current and power requirements.

Within this family, different catalog numbers are created by combining voltage, current, frame, operating configuration, enclosure and accessory options.

11. Five Related Models / Same-Family Selection References

Because the full catalog number contains configuration characters, it is important to distinguish between a base model/current class and a fully configured catalog number.

The following models are useful comparison points for applications in the same general PowerFlex DC family. Exact accessory and configuration suffixes should be checked against the motor and cabinet requirements before ordering.

The 20P21 configuration is particularly relevant when the application needs non-regenerative/two-quadrant operation.

The 20P41 configuration is more relevant when regeneration is an important part of the machine’s operating cycle.

For example, a machine that repeatedly accelerates and decelerates a high-inertia load may have significantly different requirements from a conveyor that mainly runs continuously in one direction.

12. Comparison of the Related Models

For a direct replacement, 20P21AD167RA0NNN should not automatically be replaced with a 250 A or 412 A model simply because the larger model has a higher current rating.

The motor armature voltage, motor current, field current, overload requirements, cabinet capacity, cooling, control architecture and machine braking requirements all need to be considered.

13. Five Popular Allen-Bradley Models from Related Drive Families

If the objective is not necessarily to retain the existing DC motor but instead to modernize the entire drive system, several other Allen-Bradley drive families are worth considering.

These models are not direct electrical replacements for the 20P21AD167RA0NNN.

They belong to AC-drive families and are more appropriate when the project is also considering replacing the existing DC motor with an AC motor.

14. Brand Model Comparison

The choice between these families depends heavily on whether the existing motor is a DC motor or AC motor.

If the machine already uses a 100 HP DC motor and the objective is to replace the drive while keeping the motor, the PowerFlex DC family is the logical starting point.

If the project is a complete machine modernization and motor replacement is acceptable, an AC drive family may provide a wider range of modernization possibilities.

15. Why 20P21AD167RA0NNN Is Attractive for Existing Machinery

The strongest argument for this model is not necessarily that it is the newest type of drive.

Its strength is that it is designed specifically for large industrial DC motor systems.

Many industrial machines have mechanical systems that were engineered around DC motors. The motor, gearbox, coupling, shaft, encoder and load may all have been working together for many years.

Replacing the entire system simply to eliminate an older drive technology can involve:

• Motor replacement
• Mechanical modifications
• New coupling
• New feedback system
• New control logic
• New cabinet
• New protection devices
• New software
• Machine downtime
• Commissioning work

A DC drive can therefore be an attractive option when the existing motor and mechanical system remain serviceable.

16. Product Advantages in Practical Industrial Use

17. Application Selection Guide

18. Recommended Selection Logic

If the existing motor is approximately 100 HP, operates from a 480 VAC industrial supply, and requires approximately 167 A armature current, then 20P21AD167RA0NNN is a highly relevant catalog configuration to investigate.

If the motor current is substantially higher, a higher-current PowerFlex DC configuration should be considered.

If the machine frequently drives energy back toward the drive during deceleration, lowering, unwinding or overhauling loads, a regenerative PowerFlex DC configuration deserves consideration rather than automatically selecting another two-quadrant unit.

If the machine is being completely modernized and the existing DC motor is approaching the end of its service life, an AC motor plus a PowerFlex AC drive may provide a more future-oriented architecture.

19. Key Specification Summary

20. Final Product Evaluation

The 20P21AD167RA0NNN is best understood as a high-current, 100 HP-class industrial DC drive intended for demanding machinery where controlled DC motor operation is still required.

Its combination of 480 VAC three-phase input, 167 A output current, 100 HP rating, six-pulse input, regulated field supply, two-quadrant operation and IP20 open construction makes it particularly relevant to large industrial machines using existing DC motors.

Its biggest practical advantage is compatibility with the established DC motor architecture. For an existing production line, retaining the motor and mechanical system can significantly reduce the scope of a modernization project.

At the same time, the two-quadrant non-regenerative configuration is an important limitation to understand. Machines with frequent regenerative braking, overhauling loads or substantial energy return should be evaluated for a regenerative configuration rather than treating this model as a universal DC-drive solution.

For replacement work, the most important parameters to verify are motor armature voltage, motor armature current, field voltage/current, overload requirement, feedback method, regeneration requirement, cabinet dimensions, cooling requirements and control-system interface.

One final point is especially important for procurement: the catalog number 20P21AD167RA0NNN contains configuration information, so two drives that appear similar by horsepower can have materially different electrical or accessory configurations. The complete catalog number should therefore be matched against the original drive nameplate and the motor nameplate before making a replacement decision.