A Comprehensive Guide to the Allen Bradley PowerFlex 750

The Allen-Bradley PowerFlex750-Series is a comprehensive family of Variable Frequency Drives (VFDs), also known as AC drives, from Rockwell Automation. These drives provide greater application flexibility, high performance, and an exceptional user experience for a wide array of multi-drive or general-purpose motor control applications. They are appropriate for applications that require speed, torque, and/or position control.

The PowerFlex 750-Series offers PowerFlex 753 AC drives with power ratings of 0.5 to 400 Hp (0.37 to 250 kW) for general-purpose motor control applications. For advanced motor control applications, the series offers PowerFlex 755 AC drives that include multiple hardware and control options and an extensive power range of 0.37 to 1500 kW ( 0.5 to 2000 Hp).

Standard Features

PowerFlex 750-Series AC drives provide a standard set of innovative features and options aimed at assisting users in improving the productivity of their motion control systems and maximizing their investments. Those features and options include:

• DeviceLogixTechnology: This platform-independent control engine is embedded into PowerFlex 750-Series AC drives. It controls discrete outputs and manages the status information within a PowerFlex 750 drive locally, allowing users to operate the drive separately or as part of supervisory control while using the status information and discrete inputs onboard the AC drive in question. This helps improve the performance and productivity of PowerFlex 750 drive systems.
• Advanced Inbuilt Safety Features
• Option Modules: Each PowerFlex 750-Series AC drive features a slot-based mechanical architecture supporting different option modules. The modules provide additional communications, feedback, digital and analog I/O, safety options, and a backup power supply.
• Multiple Communication Option Modules are available for various industrial networks, including EtherNet/IP, DeviceNet, ControlNet(Fiber or Coax), PROFINET, LonWorks,  Modbus/TCP, RS-485 DF1, CANopen, HVAC (Metasys N2, FLN P1, Modbus RTU), PROFIBUS DP, and CIP Motion
• A High-definition LCD Human Interface Module (HIM) with an assisted start-up function and multi-language support to reduce drive start-up time and allow easy tuning and configuring of the drive. This HIM also supports six lines of text, allowing for more valuable descriptions of events and drive parameters.
• Predictive Diagnostics: Predictive algorithms in PowerFlex 750-Series VFDs track information regarding the condition of the drives’ relay outputs and cooling fans to provide real-time diagnostics.  Also, these algorithms enable PowerFlex 750 drives to be programmed to consistently monitor the runtime hours for motor bearings or connected equipment. This allows timely maintenance and repairs before breakdowns, thereby reducing unplanned equipment downtime.
• Dual-port EtherNet/IP Option Module, which supports star, linear, and ring network topologies, along with DLR (Device Level Ring) functionality for high drive availability and fault tolerant connectivity.
• Simplified Integration with Allen-Bradley Logix controller platforms using embedded instructions or Add-on Profiles. This integration helps simplify and enhance drive programming, configuration, commissioning, monitoring, diagnostics, and maintenance.
• Selectable Motor Control Methods: These includeVolts per Hertz (V/Hz), Vector Control using FORCE Technology without and with an encoder, Sensorless Vector (SV) Control, Permanent Magnet (PM) Motor Control (interior only with PowerFlex 753, interior and surface with PowerFlex 755T and PowerFlex 755), Closed-Loop Speed Regulation (with PowerFlex 755 and PowerFlex 755T), and Open-Loop Speed Regulation (with PowerFlex 755 and PowerFlex 755T). The aforementioned motor control algorithms allow the PowerFlex 750-Series AC drives to support different types of electric motors.
• Diverse Feedback Options: The following feedback option modules are available for use in PowerFlex 750-Series drive systems:
• Single Incremental Feedback Option (Cat. No. 20-750-ENC-1): This module supports just one incremental encoder.
• Dual Incremental Feedback Option (Cat. No. 20-750-DENC-1): The module can support up to two incremental encoders.
• Universal Feedback Option (Cat. No. 20-750-UFB-1): This module incorporates multiple feedback interfaces to handle a vast array of linear and rotary applications. Supported feedback interfaces are SSI and BiSS, Incremental interface, Hiperface Stegmann interface, and EnDat interface from Heidenhain for high-resolution feedback.

Note: You can install multiple feedback options in a PowerFlex 750-Series drive system. However, if you’re using Integrated Motion on an EtherNet/IP network, you can only install two feedback modules.

• A Common Power Structure: PowerFlex 750-Series AC drives share a standard power structure that allows them to provide the same power range and physical footprint irrespective of the specific drive within the series being used.
• Multiple Drive Control Modes: Adjustable voltage, position, torque, and speed control modes are included in each PowerFlex 750-Series AC drive to support multiple types of applications.
• Auxiliary Power Supply Module (Catalog No. 20-750-APS): This option module is included in a PowerFlex 750 drive system to maintain communications and control if the main power supply is unavailable.
• Easy-to-access internal cooling fans and heat sink
• A Real-time Clock that provides time-stamped events against run-time data. It can be set locally or using a remote controller.

PowerFlex 750-Series AC Drives

Specific Variable Frequency Drives/AC drives within the Allen-Bradley PowerFlex 750-Series include:

PowerFlex 753 AC Drives

PowerFlex 753 variable frequency drives are designed to control induction motors in general-purpose applications requiring simple integration and advanced safety features. They have built-in analog and digital inputs and outputs as standard, along with three option slots to accommodate additional I/O, safety, 24 VDC power supply, feedback, and communications option cards. The integrated standard I/O platform includes one (1) analog input,  three (3) digital inputs, one (1) PTC (Positive Temperature Coefficient) input, one (1) relay output, one (1) analog output, and one (1) transistor output.

The PowerFlex 753 drives cover a broad range of power ratings:

• 0.5…200 Hp / 0.37…132 kW / 2.2…477 A in 200…240 V AC input voltage class
• 1.0…400 Hp / 0.75…250 kW / 2.2…477 A in 380…480V AC input voltage class
• 1.7…289 A / 1.0…300 Hp in 600 VAC
• 12…263 A /7.5…250 kW in 690 VAC

In addition, the PowerFlex 753 AC drives are available with communication option modules for EtherNet/IP, DeviceNet, ControlNet, and a variety of other industrial networks. The integrated I/O and multiple communication options make PowerFlex 753 drives a cost-effective solution for system integrators and machine builders seeking to reduce engineering time, lower system integration costs, and meet customer demands for size-optimized drives and high-yielding machines.

PowerFlex 755 AC Drives

PowerFlex 755 variable frequency drives are well suited for applications requiring higher performance and advanced positioning, as they offer an integrated position control loop for PCamming, indexing, speed/position profiling, homing, and electronic gearing. They can control both permanent magnet (PM) and induction motors from Rockwell Automation or third-party vendors. Common applications include controlling conveyors, fans, and pumps used in material handling, oil and gas, tire and rubber processing, mining, and metal fabrication processes.

These drives offer the following power ratings:

• 0.5…200 Hp / 0.37…132 kW / 2.2…477 A in 200…240V AC input voltage class
• 1.0…2000 Hp / 0.75…1400 kW / 2.1…2330 A in 380…480V AC input voltage class
• 1.7…1530 A / 1.0…1500 Hp in 600 VAC
• 12…1485 A / 7.5…1500 Kw in 690 VAC

The PowerFlex 755 drives incorporate one digital input and an integral Ethernet port as standard. They also include five option slots to support additional I/O, auxiliary 24 VDC control power, communications, safety, and feedback options. They are available with DeviceNet and ControlNetoption modules, and additional communication modules can be included to support other industrial networks.

Using embedded drive instructions for advanced motor control, you can integrate a PowerFlex 755 drive with an Allen-Bradley CompactLogix or ControlLogix Programmable Automation Controller platform. This integration provides support for high-performance Integrated Motion on an EtherNet/IP network, allowing users to connect the PowerFlex 755 drives on a common network with Kinetix servo drives and a variety of Allen-Bradley induction and permanent motors. This eliminates the need for an exclusive motion control network, reducing system costs and increasing machine design flexibility.

PowerFlex 755T AC Drives

PowerFlex 755T variable frequency drives are customized to provide common bus, regeneration, and harmonic mitigation solutions. They are the first Allen-Bradley AC drives to incorporate TotalFORCE technology. This smart technology integrates several patented motor control features designed to deliver precise and adaptive torque, positioning, and velocity control.

PowerFlex 750-Series AC drives with TotalFORCE smart technology include:

• PowerFlex755TS Drives: These are six-pulse VFDs designed to deliver real-time operational data, energy savings, greater uptime, and increased productivity and throughput in a vast range of motor control applications, from standard to highly demanding industrial applications.
• PowerFlex755TL Drives: These AC drives use active front-end technology to provide harmonic mitigation functionality and power factor correction. This enables compliance with the IEEE 519-2014 standard that defines the recommended current and voltage harmonic limits in electrical power systems. They are available with 10…1800 Hp / 7.5…1400 kW power ratings in 400…690V AC input voltages.
• PowerFlex755TM VFDs for Common Bus Configurations: These drives make use of a shared bus drive system to reduce the required floor space, minimize installation costs, and gain design flexibility. They provide power ratings of 70…4800 kW (DC) and 250…6000 Hp /160…4500 kW (AC) in global voltages ranging from 400…690V. They also provide energy-efficient regenerative capabilities, harmonic mitigation functionality, and power factor correction. Such PowerFlex755TM drive systems can coordinate multiple motors.
• PowerFlex755TM VFDs with Non-Regenerative Bus Supplies: These AC drives provide a cost-effective non-regenerative power supply for a PowerFlex 755TM common bus when low harmonics and regenerative capabilities are not needed. They essentially convert 3-phase AC input voltage into DC and are “XT” rated with improved corrosive gas protection features.
• PowerFlex755TR AC Drives: These drives offer an energy-efficient regenerative solution using active front-end technology, thereby transmitting energy back to the main power supply. They also avail power factor correction and harmonic mitigation functionality to allow conformity with the IEEE 519-2014 standard. They are available with 10…6000 Hp / 7.5…4500 kW power ratings in 400…690V AC voltages.

PowerFlex 750-Series Safety Solutions

PowerFlex 750-Series VFDs provide a choice of the following safety options:

• Integrated Safety Functions: These functions equip the Allen-Bradley PowerFlex750 AC drives with advanced safety features over an EtherNet/IP network. They are either drive-based safety instructions that are specified by the IEC 61800-5-2 standard or controller-based safety functions.
• Hardwired Safe Torque Off (STO): The STO function is generally used to help prevent unanticipated motor rotation in the course of an emergency while the PowerFlex 750 drive remains connected to the main/auxiliary power supply. The hardwired STO safety option is designed for safety-related motor control applications that benefit when rotational power is removed from the drive. This functionality also allows quick drive start-up after the safety system is activated.
• Networked Safe Torque Off: With this safety option, a GuardLogix safety programmable controller sends out the Safe Torque Off command over an EtherNet/IP network, and the connected PowerFlex 750-Series AC drive executes the command. Essentially, the networked STO option offers the same advantages as the hardwired STO option, allowing users to simplify their drive system design and reduce engineering costs.
• Hardwired Safe Speed Monitor (SSM): This safety option delivers a hardwired solution for motion control applications that leverage safe access to a guarded zone. It enables operators to carry out maintenance work or other tasks without completely stopping the machine; instead, the machine’s motion is limited to what is considered to be the safe state.

Note: You can use the Safe Torque Off and Safe Speed Monitor safety options discussed above in the following safety applications:

• Safety Integrity Level (SIL) CL3 applications, in conformity with the EN 62061 standard
• Safety Integrity Level (SIL) 3 applications, in accordance with IEC 61508 and EN/IEC 61800-5-2 standards
• CAT (Category) 4 and Performance Level [PL e] applications, in line with the EN ISO 13849-1 standard