PowerFlex 700 vs PowerFlex 755

PowerFlex 700 and Powerflex 755 are part of Allen-Bradley’s product line of powerful AC drives that provide flexible control. The Powerflex 700 consists of low-power and high-power AC drives. These AC drives offer superior performance and are easy to use in operations. The PowerFlex AC drives control three-phase induction motors for numerous industrial applications. The applications range from simple speed control to demanding ones, including high torque control. In 2017, Rockwell Automation discontinued PowerFlex 700 AC high-power drives (250-700 Hp). The low-power AC drives are still available from the manufacturer. A new range of AC drives, PowerFlex 755, was introduced to replace the discontinued high-power PowerFlex 700 AC drives. The new AC drives have many features and enhanced performance to improve operations. This guide highlights the different features of PowerFlex 700 AC drives and PowerFlex 755 AC drives and provides an in-depth comparison.

Technical Specifications of PowerFlex 700 and PowerFlex 755 AC Drives

Power Ratings

PowerFlex 700 and PowerFlex 755 are both available in four different power ratings. The PowerFlex 755 AC drives are much more powerful and can handle huge loads more efficiently than the PowerFlex 700.

• In the 200 to 240 volts range, PowerFlex 700 outputs power between 0.37 to 75 kW (0.5 to 100 Hp), whereas the PowerFlex 755 delivers power between 0.37 to 132 kW (0.5 to 200 Hp).
• In the 380 to 480 volts range, PowerFlex 700 outputs power between 0.37 to 500 kW (0.5 to 700 Hp), whereas the PowerFlex 755 delivers power between 0.75 to 1400 kW (1.0 to 2000 Hp).
• In the 500 to 600 volts range, PowerFlex 700 outputs power between 0.75 to 110 kW (1.0 to 150 Hp), whereas the PowerFlex 755 delivers power between 1.0 to 1500 Hp.
• In the 690 volts category, PowerFlex 700 outputs power between 45 to 132 kW (50 to 150 Hp), whereas the PowerFlex 755 delivers power between 7.5 to 1500 kW.

Motor Control

PowerFlex 700 and PowerFlex 755 AC drives feature various types of motor control. Three motor control techniques are present in both series of AC drives. One is volts per hertz, the second is sensorless vector control, and the third is vector control with FORCE Technology. The FORCE Technology is Allen Bradley’s patented vector control technology that works with and without an encoder. The PowerFlex 700 also provides an adjustable voltage control method for motor control. The PowerFlex 755 has a unique motor control feature named permanent magnet motor control.

Enclosure Types

Multiple types of enclosures are available for PowerFlex 700 and PowerFlex 755 AC drives.

• The PowerFlex 700 comes with IP00, NEMA Open / Flange type enclosure, NEMA Type 1 enclosure, and IP20, NEMA / UL Type open enclosure.
• The PowerFlex 755 offers IP54 NEMA / UL Type 12, IP20 NEMA / UL Type 1, IP00 NEMA / UL Type Open, IP66 NEMA / UL Type 4X, and Flange mount back enclosures.

Communications

The PowerFlex 700 AC drives provide Common Industrial Protocol (CIP) communications through a variety of option modules. The option modules are available for EtherNet/IP, DeviceNet, and ControlNet networks. Other than these, other network modules support various industrial networks that can be opted based on user requirements.

In PowerFlex 755 AC drives, the EtherNet/IP port is integrated into the drive as standard in all models of the drives. The option modules are also available for PowerFlex 755 AC drives. The modules include DeviceNet, ControlNet, and dual port EtherNet/IP networks. Other modules support additional industrial networks, which can be used to meet particular industrial networking requirements in specific applications.

Safety Options

The PowerFlex 755 features safety features such as torque off and a safe speed monitor. These drive safety options are not available in PowerFlex 700 AC drives.

• The safe torque-off feature can be enabled in two configurations, which are a hardwired configuration or a network. The feature is certified at safe motor ratings of SIL 3, PLe, Cat 3. The torque off feature cuts off the power supply to the motor without disconnecting it to the drive, which helps resume the function at a fast speed when required.
• The safe speed monitor function allows the operators to control and monitor the speed of the application during maintenance work without the need to stop the operation. The feature is certified at SIL 3, PLe, Cat 4.  
• The safety module in PowerFlex AC drives provides sophisticated safety over EtherNet/IP network. It uses the safety instruction standard of IEC 61800-5-2. The function enables the AC drive to monitor the direction, speed, and position of the motor. The safety ratings include SIL CL3 and PLe Cat 4.

I/O

The PowerFlex AC drives offer various types of onboard inputs and outputs. The PowerFlex 700 AC drives have six digital inputs which can utilize 24V DC or 115V AC power sources. Then two analog inputs have bipolar voltage or current-type input signals. There is one PTC input available too. There are two bipolar analog outputs available, which can be configured for voltage or current type as required. Then there are also three relay outputs.

PowerFlex 755 AC drives do not provide that many onboard I/O capabilities, but there are option cards available that can be used to add I/O to the AC drives if required. By default, the PowerFlex 755 works only on one digital input standard.

Motor Types

The PowerFlex 700 AC drives can run and control three-phase AC induction motors only. The PowerFlex 755 AC drives provide additional functionality by supporting permanent magnet motors. The PowerFlex 755 AC drives support the surface type and interior type, both permanent magnet motors.

Positioning

The PowerFlex 700 AC drives provide two types of positioning methods, which include Indexing and Position or Speed Profiling. In contrast, the PowerFlex 755 AC drives provide these two positioning techniques. Additionally, they also offer Electronic Gearing and PCaming positioning control. So, in total, the PowerFlex 755 AC drives offer four different positioning control methods.

Feedback

The PowerFlex 700 AC drives provide an incremental feedback method, whereas the PowerFlex 755 AC drives provide incremental, as well as EnDat, Hiperface, SSI, and BiSS feedback mechanisms for the drives.

Energy Efficiency Calculation

A useful tool is available for PowerFlex AC drives that calculates the AC drive’s power efficiencies. The power loss calculation and monitoring of your Allen Bradley drive ensure that the drive meets the industrial energy standard IEC 61800-9-2. This feature also helps a user to take precautions in unusual situations.

Application Sets

The PowerFlex AC drives are designed to provide the end customer with a seamless operation of their drives to assist a robust specialized solution for applications. The PowerFlex 700 AC and PowerFlex 755 AC drives are recommended and designed for specific applications based on their capabilities. For example, the PowerFlex 700 AC drives can be used in Lifting as TorqProve, and in Oil week as pump jack and pump off. In addition to these two applications, the PowerFlex 755 AC drives also support Fibers application in P-jump and traverse tasks.

Features of PowerFlex 700 AC Drives

• The PowerFlex 700 AC drives are reliable, flexible, and meet requirements for space for many applications.
• These AC drives provide exceptional torque ratings and regulations and feature fast update time between torque inputs.
• The AC drive can accelerate and decelerate at maximum rates due to fast-acting Bus voltage and current limit regulation.
• The flying start mechanism provides a seamless and fast connection to the application, irrespective of the command direction and speed feedback requirement.
• The AC drive has an integrated process PI control that can be used in various motor control applications. A separate controller for the process loop is not needed.
• The AC drives offer an Inertia Ride-Through function, which ensures continuous operation in case of long power failure. It utilizes the rotating energy stored in the loads that are low friction and high inertia.
• The PowerFlex 700 AC drives offer a controlled cassette that combines the encoder options, control, and I/O in one package.
• The AC drive provides point-to-point position indexing using a 16-step indexer. It also provides speed profiling by employing digital inputs, time encoder counts, and parameter levels.
• The AC drives have speed and torque regulations which can be open loop or closed loop in nature.

Features of PowerFlex 755 AC Drives

• A power option bay is available in the PowerFlex 755 AC drives, which enables a smooth and cost-efficient solution to switch or use popular power options.
• The dual EtherNet/IP network minimizes the cabling needs. It reduces the number of switches to be managed when Device Level Ring networks are used.
• The logic controllers can automatically detect and configure parameters of the installed devices through an automatic device configuration function.
• The configuration and programming of the AC drive can be performed via an integrated human interface module and more.
• The built-in predictive diagnostics analyzes the performance of cooling fans and relay outputs that helps increase the life of the components.
• The PowerFlex 755 AC drives have a slot-based design, bringing ultimate flexibility to add up to five different option cards, fulfilling the requirement of any application.
• The PowerFlex 755 AC drives are available in wall-mount and floor-mount options.
• The wall-mounted drives deliver power between 0.75 kW (1 Hp) and 270 kW (400 Hp). The wall-mount AC drive units are available in several types of enclosure options, including field and factory installable options, which helps in achieving most environmental specifications.
• The floor-mounted PowerFlex 755 AC drives feature various models with power ratings ranging from 250 Hp to 2000 Hp. These AC drives provide flexibility for many applications by offering multiple duty ratings. One AC drive provides up to three different motor current ratings.

PowerFlex 755 On-Machine Drive Features

The PowerFlex 755 on-machine drive is a unique product that lets the user combine variable-frequency drive with the PowerFlex 755, to experience the on-machine solution. It is an intelligently engineered, cost-effective product that can be mounted in two ways. Either the product can be mounted directly onto the machine or somewhere near the machine. The on-machine drive feature product offers safety options, network communication, and I/O in one package, along with IP66 environmental certification.

• Installing AC drives near your machine brings several benefits that save money and time, reduce floor space requirements, and minimize downtime.
• The IP66 enclosure ratings allow close mounting of the drive to the machine, reducing cables cost. The panels are smaller with plug’ n play-type connections. The ease of connection allows for the installation time and downtime to be minimized.
• A pre-designed product helps in fast installation with fewer chances of mistakes. The product’s safety options ensure that the equipment and the personnel are protected.
• The product features four encoders making it a flexible choice for most applications. The type of encoders includes absolute, incremental, and linear feedback.
• The additional four digital inputs can be used for different types of digital switches, such as overtravel, in-position, and auxiliary switches.
• An integrated dual Ethernet port can accommodate several network configurations, including star, linear, and device Level Ring, making a highly resilient network.
• The product provides a local disconnect which isolates the motor and helps reduce maintenance time.
• The product is easy to handle and manageable in a way that the user can easily replace major components without assistance.

Migration from PowerFlex 700 to PowerFlex 755

Rockwell Automation recommends its customers still using PowerFlex 700 AC drives migrate to the newer product line PowerFlex 755 AC drives. The demanding market brings new challenges with time. The industrial control equipment should be upgraded to keep up with the pace while leveraging your automation investment. The upgrades offer various perks, including higher performance, better network capabilities, application flexibility, energy efficiency, cost-effectiveness, ease of operation and maintenance, added safety features, and so on. The PowerFlex 755 AC drives can be used for a wide range of motor control applications.