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KEB S6 Servo Drive and Allen-Bradley PowerFlex 753 AC Drive Comparison

Wyatt Blomquist | April 4th, 2023
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Variable Frequency Drives (VFDs) are essential components in industrial automation systems. They control the speed and torque of electric motors, providing precise control and energy efficiency.

Machine builders look for VFDs that communicate with other devices in the automation network. One example is EtherNet/IP. This communication protocol has quickly become popular in industrial automation, offering a reliable and standardized way to connect VFDs to other devices in a system.

Two drives that feature EtherNet/IP communication are KEB’s S6 Servo Drive and Allen-Bradley’s PowerFlex 753 AC Drive. These motor control devices have many similarities but also differ in several ways.

This article compares the two drives, distinguishing their similarities and differences in communication types, input and output power options, motion control, functional safety, etc.


Compare KEB S6 drive with AB powerflex 753 drives


Target Applications 

The S6 and PowerFlex AC drives are both suitable for lower-power applications. The S6 offers a wide range of motor and motion control options in a compact footprint, making it ideal for diverse applications. Some of which include:


Communication Options

The PowerFlex 753 operates off EtherNet/IP industrial protocol. The reach of EtherNet/IP is very strong in North America, with Allen-Bradley being one of the largest proliferators of it. This dominance in the North American market makes EtherNet/IP a prevalent choice for many customers.


2022 Global Network Market Share according to HMS
Global Network Market Share according to HMS – 2022


In contrast, the S6 supports many of the leading industrial communication protocols. It operates on EtherNet/IP, EtherCAT, Profinet, Powerlink, Modbus TCP/IP, and CAN. This flexibility gives the S6 a leg up on suitable applications, making it an appealing option to many businesses.


A chart comparing Allen Bradley Powerflex 753 AC drives with KEB S6 VFDs
A chart comparing communication protocols available Allen Bradley Powerflex 753 AC drives with KEB S6 VFDs


Power Options

KEB’s S6 is available in single-phase and three-phase 230V, and three-phase 400/480V power. The single-phase 230V power option operates motors up to 2 HP. The S6’s three-phase 400/480V power option operates motors from 2-10 HP. Above 10 HP, it becomes necessary to use KEB’s F6 VFD.


KEB S6 Drive power options for comparison to AB PowerFlex drives
KEB S6 Drive power options for comparison to AB PowerFlex drives


Allen-Bradley’s PowerFlex 753 has a broader range of voltage and power options than the S6. All voltage options are three-phase power, in 230V, 380/480V, and 600/690V. The 230V PowerFlex 753 can run motors from 1-200 HP. The 380-480V and 600-690V can operate motors between 1-300 HP.


AB Rockwell PowerFlex 753 Drive power options for comparison to S6 drives
Allen-Bradley Rockwell PowerFlex 753 Drive power options for comparison to S6 drives


Motion Control

The S6 has a variety of control options. It uses standard CiA 402 Drive profiles such as velocity, profile position, cyclic synchronous torque, cyclic synchronous position, and homing as the basis for its motion control. These drive profiles allow for a diverse manner of control over the motor. Whereas the PowerFlex 753 uses various Add on Profiles.

Velocity and profile positioning modes can be beneficial in reducing the load on the PLC by having the drive internally generate the speed or position curve.

In addition to the CiA 402 motion profiles, KEB offers a wide range of functions to improve shaft performance. Brake control, advanced gain settings, and customizable warning and error functionality come standard with all versions of the S6.



Safety is paramount when selecting a drive for a specific application. The determining factor between KEB’s S6 Servo Drives and Allen-Bradley’s PowerFlex 753 AC Drives depends on application requirements and safety needs. Both drives have Safe Torque Off (STO), Safe Stop 1, and Safe Stop 2.

Allen-Bradley’s PowerFlex has two safety profile options. First is the basic Safe Torque-Off. STO prevents the drive from generating torque on the motor and prevents unintentional starting while the function is enabled. The other safety option is Safe Speed Monitor (SSM). SSM sends a signal when the motor speed goes below a certain threshold. It prevents the motor from exceeding a certain speed limit, which could cause a safety hazard.

KEB’s S6 has a comprehensive range of safety options, as shown in the table below. There are three package options for safety available for the S6. The S6-K only has the basic STO option available to the user. The S6-A Module 1 has basic STO and Safe Break Control (SBC), which sends a safe output signal to an external mechanical brake. SBC ensures the motor stops quickly and safely during a power outage or other emergency. The S6-A Module 3 has 13 safety options (shown below) that cover many possible applications.


safe motion profiles in VFD
Safe motion functions inside the S6 Drive.


Ingress Protection Rating

The Ingress Protection (IP), defined by the International Electrotechnical Commission, provides a rating guideline for protecting or sealing enclosures against intrusion, dust, contact, and water. The protection code is listed under IPXX with the first X referring to the solid particle protection on a scale from zero to six. The second X refers to the liquid protection of the unit on a scale from zero to nine.

The S6 has a protection rating of IP20, which is meant to prevent fingers or other similarly-sized objects from entering. In turn, the PowerFlex 753 has three protection rating options. The lowest protection is the IP00, with no special protections. The next level up is the IP20. The highest level of protection is IP54. This rating protects the unit from dust and any splashing water.


Reference guide to show how the IP rating is used for categorizing ingress protection against solids and liquids
Reference guide to show how the IP rating is used for categorizing ingress protection against solids and liquids


What Drive is Best for your Application?

The choice between the KEB S6 Servo Drives and Allen-Bradley PowerFlex 753 AC Drive depends on the application’s specific needs. The S6 Servo Drives may be better if precise motion control and advanced features are required. If liquid protection and simple speed control are the main priorities, the PowerFlex 753 AC Drive may be a better fit.

Contact KEB to discuss your project with an application engineer. We can quickly determine if the S6 meets your unique requirements.

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