The Ultimate Guide to PowerFlex DC Drives for Industrial Solutions

Allen-BradleyPowerFlex digital DC drives (Bulletin 20P) from Rockwell Automation are designed to provide flexible (stand-alone or coordinated) digital control for precise motor speed and current regulation in high-performance DC motor applications. They are a perfect choice for existing DC machinery and upgrades rated up to 4000 kW/6000 Hp.

These drives combine flexible control and powerful performance to deliver a highly functional, cost-effective motion control solution. They can effectively control demanding motion systems that exhibit shock loads, rapid deceleration and acceleration rates, high inertia, or continuous regeneration. Common industrial applications of PowerFlex  DC drives include cranes and hoists, turntables, elevators, conveyors, extruders, spindle drives, crushers, paper-making machines, winders, finishing and coating operations, etc.

Hardware Description

PowerFlex digital DC drives feature an innovative, modular design with an independent power unit and a common control framework for the full range of available power ratings. The power module comprises a field and armature supply. The field supply comprises a single-phase, full-wave bridge rectifier that delivers a regulated amount of voltage to the field windings of the DC motor controlled by the PowerFlex DC drive.

The armature supply comprises a three-phase, full-wave dual bridge rectifier capable of four or two quadrant output for high-power DC motor control applications. Basically, the main function of PowerFlex DC drives is to convert incoming constant-voltage AC input into a regulated, variable-voltage DC output that is then applied to the armature of the connected DC motor. This is accomplished by the armature supply’s three-phase, full-wave bridge rectifier, which often incorporates six thyristors that convert the supplied AC input voltage into an appropriate DC output voltage for the motor’s armature.

The operating speed of the DC motor connected to the PowerFlex DC drive can then be controlled by regulating the amount of DC voltage being applied across its armature. This is possible because the operating speed of any DC motor is directly proportional to the applied armature voltage (input voltage) but inversely proportional to the supplied field current.

Note: The voltage applied to the field windings of a DC motor is substantially lower than the applied armature voltage. That explains why the field supply element of the PowerFlex DC drives’ power module includes a single-phase bridge rectifier while the armature supply element has a three-phase bridge rectifier.

Other hardware components of a standard PowerFlex DC drive include:

• Armature Converter: The armature converter’s firing angle (α) is adjusted to regulate the voltage applied across the armature of the DC motor being controlled by the PowerFlex DC drive. By doing so, the motor’s operating speed can be varied below its base speed.
• Advanced Regulator with fully integrated Drive Peripheral Interface (DPI) functionality.TheDPI ability allows the PowerFlex digital DC drives and PowerFlex DC Field Controller (Bulletin 23PFC) to be perfectly compatible with Allen-Bradley’s PowerFlex Architecture-class AC drive software tools, Human Interface Modules, and communication cards.
• Regulated Field Converter: This converter is incorporated in PowerFlex DC drives to support flux-weakening or economy applications that require extended motor speeds above the rated RPM (base speed).
• Conformal coated IP20, NEMA/UL/ Open Type Enclosure: This enclosure is intended for indoor use and allows conventional mounting of a PowerFlex DC drive either within or outside a control cabinet. It offers protection against physical contact with the enclosed drive, but it does not safeguard against airborne contaminants. As such, contaminants such as abrasive debris, oils, and corrosives should be prevented from entering the enclosure.

Key Drive Features

PowerFlex DC drives are a versatile and powerful solution for industrial automation, offering an array of embedded standard I/O modules designed to meet diverse application needs. With 3 analog inputs, 2 analog outputs, 8 digital inputs, 4 digital outputs, and 2 relay outputs, these modules provide user-selectable output types and universal inputs, enhancing adaptability. The inclusion of high-speed analog inputs improves response times to speed and torque commands, ensuring precise motor control. For even greater flexibility, optional I/O modules expand the capacity to up to 5 analog inputs, 2 analog outputs, 12 digital inputs, 8 digital outputs, and 2 relay outputs, accommodating a wide range of industrial requirements.

One of the standout features of PowerFlex DC drives is their flexible internal feedback and communication options. These enable coordinated drive control in integrated motion control applications, with visible status indicators for all internal communication options that make drive configuration straightforward and monitoring seamless. This integration facilitates a cohesive operation with other Allen-Bradley industrial automation solutions. The drives also include standard encoder feedback and DC tachometer capabilities, which not only enhance functionality but also save valuable control cabinet space.

The multifunctional LCD Human Interface Module (HIM) further simplifies the user experience with its multi-lingual, multi-line display, making drive programming and configuration more intuitive. Fast-acting voltage regulation and current limiting capabilities ensure the maximum possible motor deceleration and acceleration without tripping, while enhanced global voltage settings allow for quick setup of PowerFlex DC drives anywhere in the world. Field-flashable firmware adds another layer of convenience, enabling updates on-site through DPI communication tools.

PowerFlex DC drives are available in both non-regenerative and regenerative motor control configurations, integrating seamlessly with other PowerFlex drives. This compatibility is supported by Studio 5000 Logix Designer software, which simplifies tag and parameter programming, reduces configuration time, and streamlines diagnostics and commissioning processes. Additionally, the drives support advanced features such as Flying Start mode, which synchronizes with a rotating DC motor for smooth operation, and TorqProvetechnology, ideal for applications requiring coordinated control of a mechanical brake and motor load, making these drives suitable for lifting and hoisting applications.

The drives offer robust speed regulation capabilities under both open-loop and closed-loop control. With encoder feedback, they achieve up to 0.1% speed regulation, while armature feedback provides a 2000:1 RPM speed range. DC tachometer feedback also supports up to 0.1% speed regulation. Torque regulation is equally impressive, with open-loop control offering ±5% torque regulation and closed-loop control (using encoder feedback) achieving ±1% torque regulation, capable of supporting the full motor load at zero speed.

Additional features include Feedback Loss, Adaptive Gain, Switchover, and Droop control functions, which enhance the reliability and precision of the drives. Advanced overload protection and voltage noise suppression attributes minimize installation concerns for noise-sensitive systems. The pull-apart type of control terminal blocks allows for quick disconnects and easy wiring, further streamlining the installation process.

In summary, PowerFlex DC drives offer a comprehensive and adaptable solution for a wide range of industrial applications. Their extensive I/O capabilities, advanced feedback and communication options, user-friendly interface, and seamless integration with other systems make them an ideal choice for optimizing performance and efficiency in complex automation environments.

Drive Specifications

Power Ratings

The Allen-BradleyPowerFlex DC drives are available in an extensive range of voltage and power ratings to meet the demanding needs of various motion control industrial applications. They offer the following voltage and power ratings:

• 200…240V AC input voltage: 1.5…300 Hp/1.2…224 kW/7…1050 A output power rating.
• 380…480V AC input voltage: 2…900 Hp/1.5…671 kW/4.1…1494 A output power rating.
• 500…600V AC input voltage: 50…1250 Hp/37…932 kW/67.5…1688 A output power rating.
• 690V AC input voltage: 400…1400 Hp/298…1044 kW/452…1582 A output power rating
• Engineered DC motor control solutions are available up to 6000 Hp /4000 kW.

Field Controller

PowerFlex digital DC drives can be combined with the PowerFlex DC Field Controller (Bulletin 23PFC) to provide precise and reliable DC motor control. This field controller is designed to deliver three-phase, reversing (four-quadrant) field control for DC motors or generators in the following ranges:

• 60…200V three-phase AC input: 17…570 Amps output.
• 230…500V three-phase AC input: 17…570 Amps output.

Note: You can use an optional digital and analog I/O module or fiber-optic card for transmission of reference, status, and feedback signals between the PowerFlex DC Field Controller and a PowerFlex digital DC drive.

The PowerFlex DC Field Controller offers a cost-effective solution for upgrading DC motor controls that require motor reversing while using an external power bridge or re-purposing existing DC equipment. The controller is available with the following features:

• Two frame sizes: Frame A and B.
• Reversing field supply available as a standard feature on all frame sizes.
• Fully Integrated Drive Peripheral Interface (DPI) functionality.
• Flexible inbuilt communication options.
• Field-upgradable controller firmware through a DPI communication interface.
• IP20, Open-type, NEMA/UL-rated enclosure.
• Programming and configuring via a built-in LCD keypad.
• Supports a wide variety of standard input and output modules: eight digital inputs, three analog inputs, four digital outputs, two relay outputs, and two analog outputs.

In addition, the PowerFlex DC Field Controller can be employed in standalone DC motor control systems to provide field control. In such applications, the controller:

• Uses fixed I/O to deliver power to the field windings of a DC motor featuring a fixed voltage reference.
• Provides control to non-motor DC loads or highly inductive DC loads, like electromagnets, excitation circuits for synchronous motors, and galvanic systems.

Network Communication Adapters

The PowerFlex DC Field Controller (Bulletin 23PFC) and PowerFlex digital DC drives (Bulletin 20P) are entirely compatible with a diverse range of Allen-Bradley DPI (Drive Peripheral Interface) communication adapters, including the following:

• BACnet communication adapter
• ControlNet
• EtherNet/IP
• DeviceNet
• PROFIBUS
• Modbus RTU
• RS-485 DF1

The above-mentioned DPI communication adapters offer these benefits:

• Flexible Fault Configuration: You can program the adapters to carry out fault-based actions, like ramp to stop, and send speed reference values and user-configurable control logic. This enables the fault-configured PowerFlex DC to drive to execute various actions depending on the type of network problem experienced, from major network problems (e.g., broken network cables) to minor issues like network “idle” condition due to a connected PLC being set to “Program.”
• Adapter Routing: With the RS-485 DF1, ControlNet, EtherNet/IP, and DeviceNet communication adapters, you can plug a PC into one PowerFlex DC drive and communicate with all other Allen-Bradley PowerFlex drives on the same industrial network without having to be routed via a network scanner.

• Peer Control: With EtherNet/IP and DeviceNet adapters, peer control is possible. It provides a Master-Slave control architecture between connected PowerFlex DC drives. In doing so, it allows one or more PowerFlex DC drives to run as slave drives (consumers) as per the status of the master PowerFlex DC drive (producer), which results in reduced network traffic.
• Automatic Device Replacement: You can configurean Allen-Bradley DeviceNet communication scanner to detect a new PowerFlex DC digital drive and download the needed parameter settings. This helps save considerable time and effort when replacing a faulty or outdated PowerFlex DC digital drive.
• Autobaud Capability: DPI communication adapters with this capability make initial drive connections to industrial networks less problematic.
• Change of State: The DeviceNet adapter allows the PowerFlex DC drives configured as slaves to send control messages only upon request by the master drive; this aids in reducing network traffic significantly.It also supports flexible configuration of all network nodes, including the PowerFlex DC digital drives. For example, a drive’s reference parameter can be set to change by more than 5%.
• All of the aforestated DPI communication adapters allow 100% access to all drive parameters over a given industrial network.

Drive Firmware Version

You can view the original firmware version of your PowerFlex DC drive on its data nameplate label, just above the list of certifications. If the firmware version has been updated since the drive was shipped from the factory, you can check the latest firmware version on the drive’s Human Interface Module to see if it’s installed.

Frame Sizes

The PowerFlexDC drives power ratings are classified into four distinct frame sizes (Frame A, B, C, and D) to make drive dimensioning, selection, and ordering of spare parts much easier. The frame size of each and every PowerFlexDC drive is listed just above its serial number on the provided data nameplate label.

Environmental  Specifications

PowerFlex digital DC drives are designed to work efficiently at 32 to 122 °F (0 to 50 °C) ambient temperature without power derating. The drives should also be installed in clean locations that are not usually subject to wetness or dampness.

Other environmental specifications for the PowerFlex digital DC drives include:

• Permissible Vibration Level: 152 mm (0.006 inches) displacement, 1G peak.
• Relative Humidity: Operating: 5 to 85% non-condensing. Storage: 5 up to 95% non-condensing.
• Tolerable Mechanical Shock: 15G peak for a duration of 11 milliseconds (±1.0 ms).
• Altitude: A maximum of 3,300 ft (1,000 meters) without derating. The power output was reduced by 1.2% for every 328 ft (100 meters) above 3,300 ft. (1,000 m).
• Storage Temperature: -13…131 °F (-25…55 °C).

Certifications

The Allen-Bradley PowerFlex digital DC drives are compliant with various international product-safety standards, and as such, the selected PowerFlex digital DC drive should include the following certifications:

• c-UL-us Certification: Listed to CAN/CSA C22.2 No. 14-05 and UL508C
• Korean KC Registration (or KCC): MSIP-REM-RAA-20P
• CE Marking: To indicate compliance with these European product-safety directives:
  • Electromagnetic Compatibility Directive: No. 2014/35/EU
  • Low-Voltage Directive: No. 2006/95/EC