AC drives expand diagnostics, voltage range, DC bus option to save energy

Rockwell Automation extends power range of its Allen-Bradley PowerFlex 755 AC Drives. New high-power drives provide users with expanded application flexibility, additional voltages and common DC bus option for energy savings.


Rockwell Automation Power Flex 755 AC DrivesBuilding on the foundation of the Allen-Bradley PowerFlex 755 high-power models, Rockwell Automation Inc. (NYSE: ROK) extended the power range of its PowerFlex 755 AC drives to 900 kW / 1,350 hp and added 600 / 690 V ratings. The new drives, said to be well-suited for a variety of heavy industrial applications, provide users with increased application flexibility, advanced diagnostics and a common dc bus option.

“We’ve expanded the horsepower range and added new features to bring the benefits of the PowerFlex 755 family – advanced diagnostics, a convenient roll-out design and control options – to a broader range of motor control applications,” said John Cherney, global product manager, Rockwell Automation. “This helps heavy industrial users reduce costs through enhanced flexibility, reduced downtime and low meantime to repair.”

The common dc bus option allows users to connect the PowerFlex 755 AC drive to a common dc-bus configuration, which takes advantage of different drive cycles to share energy. In this configuration, a dc bus acts as a common energy source that feeds energy from a generating load to a motoring load. Managing energy from a shared source increases overall system performance and reduces losses – ultimately improving the application’s energy efficiency, the company said.

Like all PowerFlex 755 drives, this latest frame size includes an embedded Ethernet port and five option slots, so users can tailor it to the application. Option modules include I/O, feedback, safety, additional communications and an auxiliary power supply. A convenient roll-out design allows easy access to the drive for fast installation and maintenance. The drive’s converter and control pod can remain in the unit while the inverter is rolled out, so control wiring can remain connected.

In addition to the extended power range, a firmware upgrade for all PowerFlex 755 drives will contain the following new features and benefits:

• Interior permanent magnet motor control – Delivers increased application flexibility and high energy efficiency.

•  “Stop Dwell” feature – Helps prevent a motor from coasting to a stop. Ideal for converting applications, it allows users to preconfigure the motor to perform a controlled stop to protect valuable motor investments.

The next version of Rockwell Software RSLogix 5000 software, planned for later this year, will include an automatic device configuration feature. Rather than manually configuring a replacement drive, this feature allows Logix controllers to automatically configure the drive upon installation. Users can quickly and easily replace drives without programming – ultimately improving uptime while reducing time and money spent on installation.

Rockwell Automation said it is the world’s largest company dedicated to industrial automation and information. It is headquartered in Milwaukee, Wis., and employs about 21,000 people serving customers in more than 80 countries.

The company will feature the drives at its Automation Fair.

- Edited by Mark T. Hoske, CFE Media, Control Engineering,

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