PowerFlex 700 to PowerFlex 755 Upgrade Guide

Overview

The Allen-Bradley PowerFlex 700 AC drive series has been a reliable workhorse in industrial automation for decades, driving standard induction motors in applications ranging from simple fan and pump controls to highly engineered systems requiring vector control or encoder feedback. However, with the PowerFlex 700 marked as legacy and nearing complete obsolescence, facilities face escalating risks of unplanned downtime and high spare parts costs.

Migrating to the Allen-Bradley PowerFlex 755 AC drive series is the recommended engineering path. The PowerFlex 755 provides improved control accuracy, embedded industrial communications, modern safety features, and a scalable, modular architecture. This technical guide outlines the exact hardware, software, and configuration steps required to execute a seamless migration from the PowerFlex 700 (both Standard and Vector Control variants) to the PowerFlex 755.

Legacy Product Information

The legacy PowerFlex 700 series is categorized primarily by catalog numbers beginning with 20B (Standard Control) and 20D (Vector Control/High Power). These drives span Frame Sizes 0 through 10, covering voltage ranges of 240V, 480V, 600V, and 690V AC.

Key characteristics of the legacy hardware include:

• Control Interfaces: DPI (Drive Peripheral Interface) used for communication adapters, HMI modules (such as the 20-HIM-A3), and handheld tools.
• Communication Adapters: Built using the 20-COMM series of cards, including 20-COMM-E (EtherNet/IP), 20-COMM-C (ControlNet), and 20-COMM-D (DeviceNet), mounted in a dedicated internal bay.
• I/O Configuration: Usually equipped with integrated main control cassettes providing 24V DC or 115V AC inputs, dry contact outputs, and analog inputs/outputs.
• Programming Tools: Programmed and maintained via legacy software suites such as DriveExecutive, DriveExplorer, or legacy RSLogix 5000 Drive Add-On Profiles (AOPs).

Recommended Replacements

The direct upgrade path for the PowerFlex 700 is the PowerFlex 755 (catalog prefix 20G1). While both drives offer excellent motor speed and torque regulation, the PowerFlex 755 utilizes a highly modular structure where communication cards, option modules, and auxiliary power supplies fit into physical slots (Slots 4 through 8) on the main control unit.

When mapping old catalog configurations to the new series, note the following standard baseline replacements:

• PowerFlex 700 480V, 100 HP, Normal Duty: Catalog code 20D11ND125... matches the PowerFlex 755 Catalog code 20G11ND125AA0NNNNN.
• PowerFlex 700 Vector Control High HP: Replaced by high-horsepower PowerFlex 755 configurations (Frames 8 through 10), which can be ordered with matching floor-mount systems and integrated incoming bypass or line reactor cabinets.

Because the physical footprints do not match exactly, Rockwell provides mechanical migration retrofit kits (the *20-750-MNT-F series) that allow you to mount the slightly narrower and deeper PowerFlex 755 chassis into the exact mounting drill holes of the legacy PowerFlex 700.

Compatibility Considerations

A direct replacement requires careful assessment of form-factors, control architecture, electrical ratings, and existing networks.

Form Factor and Mounting Adapters

PowerFlex 700 and PowerFlex 755 frame sizes scale differently. For example, a legacy Frame 4 drive cannot physically be swapped with a PowerFlex 755 Frame 4 without modifications. Retrofit mounting plates (e.g., 20-750-MNT-F2 through 20-750-MNT-F5) must be sourced to adapt the backplate mounting holes in your enclosure.

I/O and Control Cassettes

The PowerFlex 700 featured built-in terminal blocks on the main control board for digital and analog integration. The PowerFlex 755 control pod has minimal built-in I/O. To replicate legacy I/O circuits, you must purchase option cards such as:

• 20-750-2262C-2R: 24V DC I/O Option Module (6 inputs, 2 opto-outputs, 2 relay outputs, 2 analog inputs, 2 analog outputs).
• 20-750-2263C-1R2T: 115V AC I/O Option Module with relay and triac outputs.

Networking and Communications

The PowerFlex 755 comes standard with an embedded EtherNet/IP port on the main control board. If your legacy drive operated on ControlNet, DeviceNet, or PROFINET, you will need corresponding option modules:

• 20-750-CNETC (ControlNet Coaxial Module)
• 20-750-DNET (DeviceNet Module)
• 20-750-PNET (PROFINET Module) Alternatively, you can utilize the 20-750-20COMM adapter module, allowing you to reuse your legacy 20-COMM-E or other 20-COMM cards during transitional migration phases, though native 750-series modules are highly recommended.

Controller Software Integration

If the drive integrates with a Logix5000 controller, the migration involves moving from older Add-On Profiles (AOP) in RSLogix 5000 (v16-v20) to the latest AOPs in Studio 5000 Logix Designer. If upgrading to Studio 5000, you can leverage Automatic Device Configuration (ADC), which allows a Logix controller to push drive parameters and firmware directly to a newly swapped PowerFlex 755 over EtherNet/IP.

Upgrade Benefits

Migrating to the PowerFlex 755 platform introduces several distinct plant-floor advantages:

• Embedded EtherNet/IP Port: Simplifies network daisy-chaining and integration without purchasing external communication cards.
• Enhanced Diagnostic Tools: Built-in predictive maintenance tracks the remaining operating life of cooling fans, relay contacts, and motor running hours.
• Superior Closed-Loop Control: Embedded support for permanent magnet motor control, linear actuators, and indexing applications.
• Modern Safety Protocols: Support for dual-port Safe Torque Off (STO) and Safe Speed Monitor options (SIL3, Category 4, PLe certified), which reduce cabling and safety relay requirements in high-hazard environments.

Common Migration Challenges

Be prepared for these three primary friction points during standard conversions:

1. User Parameter Mapping: Parameter numbering is completely different. A register block parameter in the legacy drive (e.g., Parameter 140 for Motor NP Volts) will have a completely different index in the PowerFlex 755. Use the Connected Components Workbench (CCW) conversion utility to translate old .dnl (DriveExecutive) files to modern .pf5 configurations.
2. Dynamic Braking Resistor Sizing: While legacy dynamic braking resistors can generally be reused, you must verify that the resistance value (Ohms) is above the minimum resistance rating of the new PowerFlex 755 internal brake transistor database to prevent damage to the drive.
3. HMI Compatibility: Legacy 20-HIM-A3/A5 HIM modules are mechanically incompatible with the bezel or cradle of the PowerFlex 755. You must purchase the 20-HIM-A6 high-resolution LCD HIM for local configuration and diagnostic purposes.

FAQ

Q: Can I reuse the existing PowerFlex 700 wiring connections with the PowerFlex 755?

No. The wire terminal layouts and connector blocks are completely different. You must un-wire the legacy terminal blocks and re-wire them to the newly selected PowerFlex 750 series I/O option module (installed in one of the drive's option slots).

Q: Do I need a computer to clone the drive parameters during a replacement?

No. If you purchase the 20-HIM-A6 keypad, you can copy the entire parameter set from the legacy drive (using a DPI connection if an adapter is available) or manually input parameters. However, downloading the configuration using Connected Components Workbench (CCW) and a 1203-USB cable is highly recommended for safety and parameter validation.

Q: What is the footprint difference, and will I need to drill new holes in the panel sub-plate?

Yes, the mounting hole dimensions differ. Rockwell provides dedicated migration retro-fit plates that bolt directly into the legacy PowerFlex 700 drill patterns, allowing the new PowerFlex 755 drive to hook and lock onto the plate with no additional drilling required.

Q: Can the PowerFlex 755 operate with third-party PLC systems over Modbus or PROFINET?

Yes. By installing a 20-750-BNET (BACnet) or 20-750-PNET (PROFINET) option card in Option Slot 4, 5, or 6, the PowerFlex 755 can communicate standard I/O assemblies and configuration data directly to non-Rockwell PLCs.