Hardware Comparison: Allen Bradley VFD Selection Guide

As factories and warehouses have become more connected to platforms for control and analysis of operating and production environments, equipment manufacturers have created OEM equipment to operate with more precision.  This means that more than ever, reliable and efficient control of motor speed and performance is critical.

When control systems require more than just stop and start or on and off applications, variable frequency drives (VFD) can be used to deliver the right amount of voltage and frequency to a motor so that it not only does what it is required to do, it also does so with precision and safety for both operators and equipment.  Because using VFDs allows full control of operating motors, companies can reduce both cost and energy consumption while achieving very tight process control for their operation.

Allen Bradley Low Voltage VFDs

Allen Bradley’s VFD solutions cover a wide range of sizes and applications for any control and automation needs through its PowerFlex® VFD family.  The PowerFlex® family of drives is divided into low voltage and medium voltage solutions depending on size, scale and complexity of system requirements.  Low voltage VFDs are divided into two categories, compact and architecture class.

Compact Low Voltage VFDs

For control systems that require control at the machine level for standalone applications, or for less complex, and simple control system deployment, Allen Bradley’s compact line is easy and intuitive to use and provides a reliable platform that takes up less space.  Compact low voltage PowerFlex VFD options include:

PowerFlex 4M – The PowerFlex 4M is the smallest and most compact unit available.  It is also the most cost effective and is best suited for small, standalone applications.  The PowerFlex 4M uses closed loop speed regulation.  Closed loop speed regulation is common to the PowerFlex 4M, 4, 40, 40P, and 400 as well.  Motor horsepower ranges for the 40M depend on power ratings.  These include:

  • 110-115V – 0.25-1.5 HP
  • 200-240V – 0.25-10 HP
  • 400-480V 0.5-15 HP
  • 500-600V and 690V cannot be serviced with the 4M

The 4M can handle overloads of 150% for 60 seconds and 200% for 3 seconds.  It does not have integrated safety features, but it does offer internal IGBT dynamic breaking for all versions except those with a “3” suffix in the part number.

The 4M uses RS485 for communication but when combined with a DSI external communication kit it can also support DeviceNet, EtherNet/IP, Profibus DP, ControlNet, LonWorks and Bluetooth.

The 4M has a singular analog input but no analog outputs.  It also has 5 digital inputs and a single relay output.

PowerFlex 4 – The PowerFlex 4 is similar in features to the 40M. One difference is the HP ratings depending on voltage.  The PowerFlex 4 HP ranges include:

  •  110-115V – 0.25-1.5 HP
  • 200-240V – 0.25-5 HP
  • 400-480V 0.5-5 HP
  • Like the 4M500-600V and 690V cannot be serviced with the 4

The PowerFlex 4 also has a lower output frequency range of up to 240 Hz while the 4M can range as high as 400 Hz.  The two also differ in onboard EMC filters with the 4 offering a single internal and external filter for one and three phases while the 4M offers an external for both one and three phase and internal filters for single phase up to 240V and 3 phases at 480V.

All other features on the 4 and 4M are the same.

PowerFlex 40 – For applications requiring low speed torque control, the PowerFlex 40 VFD’s strength is in its ability to supply sensorless vector control.  Motor horsepower ranges for the 40 depend on power ratings.  These include:

  • 110-115V – 0.25-1.5 HP
  • 200-240V – 0.25-10 HP
  • 400-480V 0.5-15 HP
  • 500-600V – 1.0-15 HP
  • 690V – Not available for this voltage

The PowerFlex 40 is like the 4M in its EMC filters and overload capability.  It also has the same output frequency range (400 Hz) and communication capabilities (RS485 with others optional). 

The biggest difference between the 40 and 4M are in the number of outputs.  The 40 offers 2 analog inputs and no analog outputs like the 4M. However, the 40 has 7 digital outputs with 4 programmable (compared to 5 inputs and 2 programmable for the 4M).  The 40 also has 2 transistor outputs.

PowerFlex 40P – The next step up in the compact class is the 40P.  This unit allows for basic position control across a wide range of applications while saving space and lowering cost.  Motor horsepower ranges for the 40P depend on power ratings.  These include:

  • 110-115V – Not available for this voltage
  • 200-240V – 0.25-10 HP
  • 400-480V 0.5-15 HP
  • 500-600V – 1.0-15 HP
  • 690V – Not available for this voltage

The PowerFlex 40P is identical in features to the PowerFlex 40, including inputs and outputs but with the following differences.

  1. All EMC filters on the 40P are external.
  2. Output ranges is up to 500 Hz compared to 400 Hz for the 40.
  3. The 4M, 4, 40, 40P and 400 all offer a remote keypad, RSLogix 5000, DriveExplorer and DriveTools SP.  However, the 40P offers a 4-digit LED display and fault reset instead of a local keypad. 
  4. The 40P offers integrated safety including safe torque-off, SIL 2, PLd and Cat3 while the 4M, 4, 40 and 400 have no integrated safety.

PowerFlex 400 – The PowerFlex 400’s larger feature set makes the 400 a good choice for mechanical fans, pumps and other applications related to HVAC.  The PowerFlex 400 has the most limited voltage to horsepower ratings of any of the above.  However, it does allow for larger HP motors which are generally powered by 200-240V and 400-480V in most applications.  HP ranges for the 400 include:

  • 110-115V – Not available for this voltage
  • 200-240V – 3-50 HP
  • 400-480V 3-350 HP
  • 500-600V – Not available for this voltage
  • 690V – Not available for this voltage

PowerFlex® 523 – While still part of the compact PowerFlex line, the intro level member of the 520 series is designed for simple, standalone, cost-effective motor control.  The 520 series also mark the point in the compact line where features allow for tighter positioning of motor and higher control of torque.  The 520 series offers either sensorless vector control or sensorless vector control with economizer for motor control.  Motor HP ratings are higher as well depending on voltage.  These include:

  • 100-120V – 0.25-1.5 HP
  • 200-240V – .25-20 HP
  • 380-480V – .5-30 HP
  • 535-600V 0.5-30 HP

The 523 only allows open loop speed regulation and output frequency is up to 500 Hz.  However, the frequency can vary by 47 to 63 Hz.  On all 520 family members, output voltage is adjustable all the way up to the rated motor voltage.

The 523 offers advanced control features compared to the 4M, 4, 40, 40P and 400.  These control features include:

  • Flying start
  • V/F ratio
  • Bus regulator
  • Process PID
  • Common DC Bus
  • PTC input compatible
  • ½ DC bus operation
  • 8 datalinks
  • 8 preset speeds
  • Multi-drive connectivity with communication card

The 523 offers communication options that include RS485 used with a ModBus RTU/DSI.  It also has a dual port EtherNet/IP card and a DeviceNet option card as well as Profibus DP.  In line with its deeper integration in more complex control systems, the 523 has numerous control I/O options.  These include 5 digital inputs, one analog input and one relay input.

The 523 offers a greater number of configurable options compared to the smaller units in the compact line.  These include:

  • Integral HIM
  • Remote Keypad
  • Connected Components Workbench
  • USB programming using MainsFree
  • AppView
  • CustomView and Studio 500 Logix Designer

PowerFlex® 525 – The 525 increases features over the 523 for simple integration and advanced safety features. Motor HP ratings include:

  • 100-120V – 0.5-1.5 HP
  • 200-240V – 0.5-20 HP
  • 380-480V – 0.5-30 HP
  • 525-600V 0.5-30 HP

Many of the features of the 523 are shared by the 525.  Differences include:

  1. Control I/O – The 525 has several more I/O options.  These include 7 digital and 2 analog inputs.  The 525 also has 2 digital outputs and 1 analog output as well as 1 relay.
  2. Safety – The 525 has an embedded ISO 13849-1 SIL2/PLd Cat3safe torque-off whereas the 523 has no embedded safety features.
  3. Feedback Types: The 523 has no feedback options.  On the PowerFlex 525, these options are a dual channel line driver encoder, a pulse train input, an allowance pulse frequency and frequency controlled PMW.

The 525 has the same control features as the 523 but adds the following capabilities:

  • StepLogic functions
  • Position control
  • Regulation with encoder feedback or analog input
  • Embedded multi-drive connectivity (which is optional for the 523)
  • 16 preset speeds (compared to 8)
  • PointStop functionality

PowerFlex 527 – The 527 is designed for more advanced control systems with a common design, configuration and programming environment and can only be used within the Logix control group. This means that unlike the 523 and 525, the 527 can only use the Studio 5000 Logix Designer application.  This provides a common environment for system designers building more complex control systems with more precise motor and motion control.

Motor HP ranges for the 527 include:

  • 100-120V – 0.5-1.5 HP
  • 200-240V – 0.5-20 HP
  • 380-480V – 0.5-30 HP
  • 525-600V 0.5-30 HP

There are many differences between the 527 and 525.  Differences include:

  1. Higher output frequency of up to 590 Hz.
  2. For communication, the 527 only offers a dual port EtherNet/IP that is built in.
  3. Fewer Control features:
    1. Flying start
    1. V/F ratio
    1. Bus regulator
    1. Process PID
    1. Common DC bus
    1. Position Control
    1. Regulation with encoder feedback
    1. ½ DC bus operation

Architecture Low Voltage VFDs

For more complex control system deployments, the PowerFlex architecture class offers communication and I/O solutions that are designed to integrate and work within a system to high performance control needs such as fully connected manufacturing environments and complex warehousing and packaging operations.  These drives have enhanced user interface features that allow active control and machine condition monitoring and adjustment at the floor level.  Architecture class PowerFlex VFDs include:

PowerFlex 70 – The PowerFlex 70 combines operator interface and flexible features that fit most applications.  Motor HP ranges for the PowerFlex 70 include:

  • 110-115V – Not available for this voltage
  • 200-240V – 0.5-25 HP
  • 400-480V 0.5-50 HP
  • 500-600V – 0.5-50 HP
  • 690V – Not available for this voltage

The PowerFlex 70 has a larger range of control capability that includes Vector Control, sensorless vector co0ntrol, encoder speed control as well as encoderless speed control.  It also has torque regulation and operates on volts per Hz. 

The 70 also has advanced control features compared the PowerFlex 4-400 series and these features fit into the architecture framework of advanced system designs.  Many of these features empower operators through HMIs at the shop floor level.  Control features on the 70 include:

  • User sets
  • Advanced overload control
  • Advanced bus regulation
  • Advanced PID control for both speed and torque Advanced flying start
  • Motor overload protection
  • DriveGuard safe-off
  • Flux Breaking

The PowerFlex 70 can accept a wide variety of user interfaces such as local PowerFlex HIMs as well as remote PowerFlex HIMs.  They can also use RSLogix 50000, DriveExplorer and DriveTools SP.

Because 70 is in a class of architecture class low voltage drives, it must be ready to accept communication from many sources to integrate into networks that may already be in place.  For communication, the 70 supports:

  • Internal DPI
  • DeviceNet
  • ControlNet (both coax and fiber)
  • EtheNet/IP
  • Remote I/O
  • RS485 DF1
  • BACNet
  • RS485 HVAC
  • Profibus DP
  • Interbus
  • Bluetooth
  • Modbus/TCP
  • CANopen
  • LanWorks
  • PowerFlex 700

For inputs and outputs, the 70 has 2 analog inputs and 1 analog output.  It also supports 6 digital inputs and has 2 relay outputs.  The PowerFlex 70 also has integrated safety with Safe Torque-Off SIL2, PLd, Cat 3.

PowerFlex 700 – The PowerFlex 700 is used for applications where motor control requires precise speed and torque.  This VFD is designed to allow tightly regulated torque and speed to guarantee optimum machine performance through precise motor control.  As architecture class machines, many motors in complex control systems are larger, powering larger equipment over an extended network of connected production.

Motor HP ratings include:

  • 110-115V – Not available for this voltage
  • 200-240V – 2.2-260 HP
  • 400-480V – 1.1-875 HP
  • 500-600V – 1.7-144 HP
  • 690V – 52-142 HP

Control capabilities for the 700 include vector control with FORCE technology and adjustable voltage control.  It also has encoder and encoderless speed control, slip compensation, torque regulation and sensorless vector control, like the PowerFlex 70 comparatively.

Control features include a much deeper list than the 70 or the 700H such as:

  • User sets
  • Advanced overload control
  • Advanced bus regulation
  • Advanced PID control for both speed and torque Advanced flying start
  • Motor overload protection
  • DriveGuard safe-off
  • Flux Breaking
  • Fast stop
  • Scale blocks
  • Droop
  • Common bus capability
  • Parameter linking
  • Open motor lead detection

The 700 accepts the same range of user interfaces as the 70 and the 700H.  It also utilizes the same communication protocols as the PowerFlex 70 to allow wide communication options over established networks and in complex control systems spanning multiple devices.

Compared to the 70, the 700 has the same number of inputs and outputs except that it has one more analog output and one more relay output than the 70 for a total of two each.

PowerFlex 700H – The 700H has the power to support much larger motors like the and is designed for more general-purpose applications and general-purpose speed variations. 

Motor HP ratings for the 700H are:

  • 110-115V – Not available for this voltage
  • 200-240V – Not available for this voltage
  • 400-480V – 200-900 HP
  • 500-600V – 0.5-50 HP
  • 690V – 160-800 HP

Control capabilities for the PowerFlex 700H only cover sensorless vector and slip compensation compared to the 70.  The control feature list is also smaller consisting of:

  • User sets
  • Drive overload protection
  • Bus regulation
  • PI speed control
  • Droop
  • Analog trim
  • Flying start and motor overload protection

The 700H has the accepts the same range of user interfaces as the 70.  It also uses the same communication protocols as the 70 as well.  Also compared to the 70, the 700H has the same number of inputs and outputs except that it has one more analog output and one more relay output than the 70 for a total of two each.

PowerFlex 700S – The 700S VFD is used in heavy duty and high-performance environments.  It can drive higher HP motors with accuracy and dependability.

Motor HP ranges include:

The 700S VFD has the same control capabilities as the 700 except that it also includes permanent magnet control as well.  However, given its high-performance heavy load capability, it has a deeper control feature set than does the 700 and 700H.  These include:

  • Advanced overload protection
  • Advanced bus regulation
  • Advanced PI control for both torque and speed
  • Droop
  • Analog trim
  • Feedback loss switchover
  • Integral position loop
  • SynchLink
  • DriveLogix option
  • Inertia application
  • User function blocks
  • Motor overload common bus

The 700S VFD uses the same range of user interfaces as the 700 and 700H.  It also has the same number of inputs and outputs except for an additional analog input and two less relay outputs compared to the 700.

PowerFlex 753 – The 753 VFD is another general-purpose drive by Allen Bradley.  Designed for a wide range of applications and speed control needs, the 753 is also comes with advanced safety features such as Safe Torque-Off and Safe Speed Monitor.

Motor HP ranges include:

  • 110-115V – Not available for this voltage
  • 200-240V – 2.2-477 HP
  • 400-480V – 1.0-350 HP
  • 500-600V – 1.7-289 HP
  • 690V – 12-263 HP

Control capabilities include both sensorless vector control and vector control with FORCE technology with an encoder or encoderless.

Communication protocols for the 753 include:

  • EtherNet/IP
  • ControlNet
  • DeviceNet
  • Remote I/O
  • RS485 DFI
  • Profibus DP
  • Modbus/TCP
  • HVAC
  • Bluetooth

The 753 uses many HIMs designed specifically for the 750 series.  This includes both local and remote PowerFlex 750 HIMs.  In addition, the 753 uses RSLogix 5000, DriveExplorer and DriveTools SP.

The PowerFlex 753 also has a larger number of input outputs compared to other VFDs in the architecture class.  This includes 7 analog inputs and 7 analog outputs.  It also has 21 digital inputs and 7 relay outputs.

PowerFlex 755 – For high-performance and precise motor control as well as safety, the PowerFlex 755 allows both PowerFlex and Kinetix drives to be used on the same network with common instruction sets used to program motion.  It allows for precise motor speed and torque control and precise positioning.

Motor HP range includes:

  • 110-115V – Not available for this voltage
  • 200-240V – 0.5-200 HP
  • 400-480V – 1.0-2000 HP
  • 500-600V – 1.7-1530 HP
  • 690V – 12-1485 HP

Control capabilities include Adjustable voltage, sensorless vector control, vector control with FORCE technology, permanent magnet control and multi-axis support.  The 755 uses open and closed loop speed regulation. 

For user interfaces, the 755 uses the same available HIMs compared to the 753 except the 755 also uses RSLogix 5000 v19 motion instructions.

Allen Bradley Medium Voltage VFDs

While there are many models and series within the low voltage compact and architecture class VFDs by Allen Bradley, in the medium voltage category there are only two series, the PowerFlex 6000 and the PowerFlex 7000.  The biggest distinction in the two series is that while both are designed for enterprise use across a large production, conveying, HVAC or warehousing environment, the 6000 represents large applications that require simple and predictable loads and speed requirements. 

Conversely, the 7000 series is more feature rich and used in high speed, high precision, and high-volume production environments where torque loads vary, and positioning is an important aspect of production and operation.

Both the 6000 and 7000 medium voltage VFDs offer benefits such as reduced energy consumption and advanced line harmonics.  They can handle both constant and variable torque, and as part of an integrated control system, offers advanced support for troubleshooting and problem solving within the system.

The 6000 and 7000 series also lend itself to today’s trend toward IoT enable devices that drive advanced analytics engines to optimize performance.  As a result, the benefits of the Allen Bradley medium voltage VFDs allow not only integration into complex control systems.  They also allow integration in these cloud-based platforms and work seamlessly to further improve operations and processes.

PowerFlex 6000– The PowerFlex 6000 comes only as an air-cooled unit.  It’s motor HP range includes:

  • @2.4 kV – 183-941 HP
  • @3 kV – 214-2211 HP
  • @3.3kV – 235-2432 HP
  • @4.16 kV – 294-3150 HP
  • @6 kV – 268-4490 HP
  • @6.3kV – 384-2482
  • @6.6kV – 294-4939 HP
  • @10 kV – 268-7506 HP

The 6000 series VFDs allow use of only induction motors and have an overload capacity of 120% for 1 minute every 10 minutes.  The 6000 series uses only volts per Hertz as its motor control method.  The 6000 has flying start capability but does not offer regenerative braking.

For inputs and outputs, the 6000 has 4 non-isolated inputs and 4 isolated outputs.  Communication protocols include EtherNet/IP, RS232/422/485, ModBus, ModBus Plus and Profibus DP.  The network cabling can run up to 300 meters although it may be possible to increase the run with approved cabling.

The 6000 series uses a keyed interlock system for safety and does not utilize Safe-Torque Off.

PowerFlex 7000 – As the series designed for precise large footprint control systems with tighter control and accuracy requirements, the 7000 series is more feature rich.  This gives it more flexibility and the capability to perform more complex motion control such as controlled ramp up and down, precise positioning and others.

The 7000 series comes in both an air-cooled and liquid-cooled version.  Its motor HP range depends upon whether the unit is air-cooled or liquid-cooled and includes:


  • @2.4 kV – 200-2000 HP
  • @3.3kV – 250-4750 HP
  • @4.16 kV – 350-5750 HP
  • @6.6kV – 500-8000 HP


  • @4.16 kV – 3000-5000 HP
  • @6.6kV – 4000-7500 HP

The 7000 series VFDs allows use of both induction and synchronous motors. Overload capacity on the 7000 is determined by whether the normal duty with variable torque or heavy duty with constant torque.  For normal duty, the overload is 110% for 1 minute every 10 minutes.  And for heavy duty it is 150% for 1 minute every 10 minutes.

The 7000 series uses both digital sensorless direct vector and full vector control with encoder feedback.  However, the latter is an optional selection. as its motor control method.  The 7000 has flying start capability and does offer regenerative braking.

The PowerFlex 7000 uses Active Front End (AFE) technology.  This means that the AC current is correctly phased with the system voltage.  AFE also improves harmonic distortion significantly from 25% to 3%.  By comparison, the 6000 uses pulses to rectify current.  While more expensive in outlay, the energy savings and removal of harmonics buffers means an overall cost saving.

The 7000 has 13 isolated analog inputs and a single isolated analog output along with 8 non-isolated outputs.  Because it is the series used for more high volume, precision, high torque applications, the PowerFlex 7000 is uses several more communication protocols compared to the 6000.  These include:

  • EtherNet/IP
  • RI/O
  • LonWorks
  • CANopen
  • Profibus DP
  • RS485S for HVAC
  • ModBus
  • RS485 DF1
  • InterBus
  • RS232 DF1
  • ControlNet
  • USB

The PowerFlex 7000 can operate over an enormous footprint and cabling can run up to 9.3 miles.  It is also safety enabled with both keyed mechanical interlocks and Safe Torque-Off.  And due to the larger HP motors driven by the 7000, acceleration and deceleration time can reach 4800 seconds, compared to 3276 seconds for the 6000’s smaller HP motors.  Finally, for sensitive and explosive prone environments, Allen Bradley makes an arc safe model using ArcShield technology.

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