Allen-Bradley PowerFlex VFDs: Variable Speed Drives Made Easy!

Variable frequency drives (VFDs) play an integral role in industrial automation systems by allowing precise control over the speed and torque of AC motors. This enables operators to match motor output to the varying demands of their processes to save energy, improve control, and boost productivity. 

Allen-Bradley‘s PowerFlex family of drives provides a versatile, easy-to-use VFD solution for demanding applications from fractional horsepower to tens of thousands of horsepower. PowerFlex drives are designed to deliver high-performance motor control while simplifying setup, PLC, and operation.

This article will examine PowerFlex VFDs’ operation and key benefits. We’ll also explore the drive models, features, accessories, and support that make them an excellent choice for industrial variable-speed applications. Let’s get started!

Article Outline

1. What Are Variable Frequency Drives and How Do They Work? 
2. Key Benefits of Using Allen-Bradley PowerFlex Variable Frequency Drives
3. PowerFlex Features That Simplify Setup, Programming and Use 
4. How PowerFlex VFDs Increase Energy Efficiency
5. PowerFlex Drive Models for Standard and High Power Applications
6. Typical Applications and Uses for PowerFlex VFDs
7. Selecting the Right PowerFlex VFD
8. PowerFlex Drive Options and Accessories 
9. Integrating PowerFlex VFDs into Automation Systems
10. PowerFlex Training Resources
11. Supporting Your PowerFlex Drive Investment
12. Key Takeaways

 

What Are Variable Frequency Drives and How Do They Work?

Before jumping into the PowerFlex drives themselves, let’s briefly go over what variable frequency drives are and what they do. 

A VFD is an electronic device that controls the rotational speed and torque of 3-phase AC induction motors. It works by taking fixed frequency and voltage AC power supplied by the utility and converting it into an adjustable frequency and voltage output. 

The VFD’s adjustable output allows the motor’s speed to be precisely matched to the speed required by the load. This gives an extremely flexible way to control processes compared to direct online control or mechanical throttling.

Inside the VFD, the drive’s rectifier converts the incoming AC into DC. The drive’s inverter circuit converts this DC into adjustable frequency AC power using fast-switching semiconductors. 

By varying the frequency and voltage of the inverter output, the VFD can control the speed and torque produced by the connected AC motor. The drive also continuously monitors motor current and voltage to adjust its output dynamically.

Now that we’ve covered the basics of variable-frequency drives let’s examine how Allen-Bradley PowerFlex VFDs can benefit your operations.

 

Key Benefits of Using Allen-Bradley PowerFlex Variable Frequency Drives (VFDs)

Allen-Bradley PowerFlex drives provide industrial operators with several advantages that can optimize processes, reduce energy costs, and improve productivity:

Precise Motor Control

By continuously adjusting the frequency and voltage supplied to the motor, PowerFlex drives allow very precise control over motor speed and torque output. This will enable you to fine-tune processes for maximum efficiency and flexibility.

Energy Savings 

One of the biggest benefits of PowerFlex VFDs is substantial energy savings – typically 30-50% compared to alternatives. Large savings can be achieved by matching motor speed to the load rather than running at constant full speed.

Improved Process Control

The precise speed regulation provided by PowerFlex drives enables you to control processes with a level of accuracy not possible otherwise. This can improve product quality, increase throughput, and efficiently operate processes. 

Soft Starting and Stopping

PowerFlex drives allow gradual ramp-up and ramp-down of motor speed. This soft starting/stopping significantly reduces mechanical and electrical stress on the motor and driven equipment compared to direct-on-line starting.

Reactive Power Compensation

VFDs can help stabilize the local power supply system by compensating reactive power. This reduces stress on the utility supply and improves overall system efficiency.

As you can see, PowerFlex drives offer some clear benefits for industrial operators. Let’s look at how Allen-Bradley has designed PowerFlex VFDs to simplify implementation and use.

 

PowerFlex Features That Simplify Setup, Programming and Use 

Out of the box, PowerFlex drives provide intuitive setup, programming, and control capabilities that allow fast commissioning and simple operation:

Easy Drive Commissioning

All PowerFlex drives include a built-in USB port that enables quick access to the drive’s parameters for configuration. Drives are also equipped with pre-programmed application macros to get up and running fast.

Copy/Download Parameters 

Once one PowerFlex drive is configured, its parameters can be easily copied to additional drives via USB or over the network. This allows quick commissioning of multiple drives in an application.

Auto-Tuning

PowerFlex VFDs provide auto-tuning to measure motor characteristics and optimize drive output. This ensures dynamic performance and typically takes less than a minute.

Onboard HIM (Human Interface Module)

An optional HIM module with an LCD screen can be added directly to PowerFlex drives. This allows easy local monitoring and control without needing a separate keypad.

Seamless PLC Integration

PowerFlex drives have built-in EtherNet/IP ports and add-on instructions for Allen-Bradley Logix PLCs. This enables seamless integration for drive control, configuration, and monitoring.

Customizable Default Settings 

While default settings provide solid out-of-box performance, PowerFlex drives make dialing in default parameters tailored to your specific application needs easy.

The combination of quick setup, programming simplicity, and advanced integration capabilities help make PowerFlex VFDs extremely user-friendly for both new users and VFD experts.

 

How PowerFlex VFDs Increase Energy Efficiency

With rising energy prices an ever-present concern, the energy-saving capabilities of PowerFlex drives are more valuable than ever.

Running an induction motor with a VFD can save significant energy versus direct online operation in several ways:

Lower Motor Speeds Use Less Energy

The affinity laws show that motor power requirements are proportional to the speed cube. This means even small reductions in motor speed can produce large energy savings. PowerFlex drives enable optimized speed control to minimize power consumption.

Auto Energy Optimization 

Special algorithms in PowerFlex drives actively minimize motor losses at any operating point. This tunes efficiency on the fly as conditions change to maintain the highest efficiency possible.

Sleep/Auto-Shutdown Modes

PowerFlex VFDs can be programmed to enter sleep mode or perform an automatic shutdown when the motor operation is not required. This eliminates wasted energy from an idling motor.

Smaller Motor Sizing Possible

The adjustable speed capability allows the selection of a smaller motor sized for average load rather than peak load, facilitating the use of more efficient motor sizes.

By leveraging these energy-saving capabilities, many PowerFlex drive users see electrical energy cost reductions of 30% or more compared to alternatives.

 

PowerFlex Drive Models for Standard and High Power Applications

Automation Ready Panels offers PowerFlex VFD models suitable for virtually any application from fractional up to thousands of horsepower:

Standard Power Drives

• PowerFlex 525 – The workhorse of the PowerFlex family, available from 0.34HP up to 845 HP

Low Voltage Drives

• PowerFlex 755 – Cost-effective, high-performance drives ranging from 3HP to 4,000 HP

Medium Voltage Drives

• PowerFlex 755MV – For 4160V to 13.8kV applications up to 25,000 HP

Here are a few ways Automation Ready Panels round out the PowerFlex offerings:

• Packaged Drives – Optionally packaged in enclosures or with bypass
• Regen Drives – Regenerative models to capture braking energy
• Common Bus – Combine drives on a DC bus for large installations 

This extensive portfolio offers a PowerFlex model suitable for virtually any motor control application.

 

Typical Applications and Uses for PowerFlex VFDs

PowerFlex VFDs are designed for the most demanding variable speed applications, including:

Pumps, Fans, Compressors

• Typical variable torque applications like pumps, fans, and compressors are an ideal match for PowerFlex drives due to their variable torque capability and energy savings potential.

Material Handling

• Conveyors, mixers, extruders, mills, and other material handling applications benefit from the precise speed control possible with a PowerFlex drive.

Machine Tools

• Machine tools like centrifuges, grinders, lathes, and unwind stands often require complex speed control profiles, which are made possible by the dynamic performance of PowerFlex VFDs.

High Inertia Loads

• The robust torque production enables smooth and rapid acceleration of high inertia loads – a critical capability for large fans, pumps, and compressors.

Unwinding/Rewinding Applications

• PowerFlex drives provide the necessary tension and torque control for winding/unwinding applications like web lines, laminators, roll feeds, and more.

General Purpose

• With their wide operating range, PowerFlex VFDs also work for general-purpose variable speed applications – a great one-drive solution.

If your application involves controlling the speed of three-phase AC induction motors, PowerFlex VFDs can likely provide an optimized drive solution.

 

Selecting the Right PowerFlex VFD

With the wide range of PowerFlex models and options available, here are key considerations when selecting a drive:

Motor Power

Match your motor’s nameplate rating as closely as possible for optimum performance and efficiency. Leave some margin to account for the motor service factor.

Input Voltage

Determine if a 230V, 460V, 575V, or higher input drive is required based on your supply voltage. Medium-voltage options up to 13.8 kV are available.

Environment

Select the enclosure type based on the operating environment – open chassis, NEMA 1, NEMA 3R, or NEMA 12. Harsh environment options are offered. 

Performance

Standard drives provide good performance for most applications. For demanding uses, vector control options add high torque, speed regulation, and other benefits.

By consulting the PowerFlex selection guides and working with Automation Ready Panel Engineers, you can specify the ideal drive and options to suit your particular application needs.

 

PowerFlex Drive Options and Accessories 

While Packaged drives with bypass and other options are available, here are some of the most popular drive accessories to enhance performance:

Input Line Reactors

An input line reactor smoothes the input current, increases supply capacity, and reduces harmonics.

Output Filters

Output filters help reduce peak voltage spikes and motor noise issues – which are important for many applications.

Dynamic Braking Resistors

For high inertia loads, a braking resistor allows the drive to dissipate energy during deceleration or overhauling loads.

Input Disconnect Switches

Integrating an input disconnect with the drive enclosure simplifies connecting and disconnecting supply power to the drive.

Communications

A wide range of communication modules, including EtherNet/IP, Modbus, PROFIBUS, DeviceNet, and more, are offered to add various industrial protocol connectivity to PowerFlex Drives.

Specialty Options

Options include enclosure heaters, air filters, and HVAC units for hot, cold, humid, and contaminated environments.

Leveraging accessories helps tailor your PowerFlex VFD to your specific application needs.

 

Integrating PowerFlex VFDs into Automation Systems

PowerFlex drives are designed to integrate seamlessly with Allen-Bradley industrial automation hardware and software:

PLC Integration

Control, configure, and monitor PowerFlex drives directly from Logix 5000 PLCs using EtherNet/IP and guide add-on instructions.

HMI Monitoring

Add PowerFlex drive interfaces to FactoryTalk View HMIs for at-a-glance monitoring and simple control using PowerFlex Drive XXX tags.

Multi-Axis Control

Coordinate multi-axis PowerFlex drive and motor operation using Allen-Bradley Kinetix 

integrated motion controllers.

Safety

Implement safety-related drive functions like Safe Torque Off using Allen-Bradley GuardLogix safety PLCs.

Network Architecture

EtherNet/IP, ControlNet, and DeviceNet allow combining multiple PowerFlex VFDs into unified drive systems.

The unified Rockwell architecture and Automation Ready Panel’s approach make it easy to implement PowerFlex drives across automation system functions. Get help today!

 

PowerFlex Training Resources

To help you get the most from your investment in PowerFlex VFDs, Automation Ready Panels provides extensive training options:

TechED Online Courses

Free web-based training covers everything from PowerFlex drive fundamentals to advanced operation, configuration, troubleshooting, and integration.

On-site Training

Allen-Bradley representatives provide customized PowerFlex training tailored to your drive models and applications at your facility.

Documentation

In addition to the user manual, parameter manuals, quick start guides, and other resources provide helpful information for installing and using PowerFlex drives.

By leveraging the training materials available, your team can quickly become proficient in applying PowerFlex VFD technology.

 

Supporting Your PowerFlex Drive Investment

Beyond drives and training, Automation Ready Panels also provides the services you need over the life of your system: 

Technical Support

Pre-sales sizing assistance plus global technical phone and online support is provided at no charge to assist with any drive issues.

Commissioning

Certified start-up technicians can come on-site and assist with installing and configuring your PowerFlex drives.

Repair Services

Local authorized Allen-Bradley distributors and repair centers offer quick turn-around on drive inspections, repairs, and replacements. 

Engineering Support

Automation Ready Panel Engineers can consult on system architecture, specifications, integration, and optimization for more complex projects.

Life Cycle Management

Throughout the life of your system, Automation Ready Panels can help upgrade drives, migrate programming, and ensure your PowerFlex investment continues to meet your needs.

Automation Ready Panels is committed to providing world-class support, training, service, and expertise to help you maximize the value of your PowerFlex VFD investment. Contact us today!

 

Key Takeaways

We’ve covered a lot of ground on how PowerFlex variable frequency drives can benefit your operation. Here are some key takeaways:

• PowerFlex VFDs provide precise speed control to optimize motor and process performance
• Intuitive setup, programming, and integration make PowerFlex drives easy to implement
• Energy savings of 30% or more are often achievable using PowerFlex VFDs
• Available in models from fractional HP to tens of thousands of HP
• Designed for demanding industrial applications across all industries
• Extensive accessories and options to suit your specific requirements
• Built-in Ethernet/IP allows seamless control from Allen-Bradley PLCs
• Backed by Automation Ready Panels’ unmatched level of training, service and support

PowerFlex drives are integral to many of the world’s most sophisticated and efficient manufacturing operations. By delivering exceptional performance and ease of use, Allen-Bradley PowerFlex VFDs offer an extremely flexible, cost-effective solution for industrial variable speed applications.

I hope this overview has provided insight into how Allen-Bradley PowerFlex drives can benefit your operations. Please contact us at Automation Ready Panels for further assistance in applying VFD technology to your production processes.

Check out our VFD Panels or Other control panels with integrated PowerFlex VFDs

 

SHOP NOW