PowerFlex 525 vs PowerFlex 40: replacing a 22B drive with a 25B (or not)

The Allen-Bradley PowerFlex 40 – catalog numbers beginning 22B – is a compact AC drive found in a great many machines and panels. When one fails, the obvious question is whether to put in another PowerFlex 40 or move to the PowerFlex 525 (25B), which Rockwell Automation offers as its successor. The right answer depends on how fast the machine must run again, what else would have to change around the drive, and whether you want the newer drive's features.

First, identify exactly what you have

Read the nameplate of the failed drive and record the full catalog number, the series letter and, if shown, the firmware revision. A number such as 22B-D010N104 breaks down the same way as a PowerFlex 525 number: 22B is the family, the D is the voltage class (480 V) and 010 relates to the output-current rating, with the remaining characters describing enclosure and options. Our guide to reading Allen-Bradley catalog numbers covers the pattern.

Two look-alikes are worth ruling out: a label starting 22A is a PowerFlex 4, and 22D is a PowerFlex 40P, a related but different drive. This guide is about the 22B PowerFlex 40. While you are at the panel, also note:

• how the drive is started and given its speed – keypad, control terminals, or a network;
• whether a communication adapter is fitted (for example a 22-COMM-E for EtherNet/IP);
• every wire on the control terminal block, with a photo;
• the parameter settings, uploaded with software or written down – at least every value changed from default.

What is different on the PowerFlex 525

Modular control and power

On the PowerFlex 525 the control module – keypad, control terminals and communications – clips onto a separate power module. The control module can be set up on a bench from a PC over USB before the power module is even installed, which Rockwell calls MainsFree programming. In a replacement, that means the settings can be loaded while the old drive comes out.

Embedded EtherNet/IP

The PowerFlex 40 talks to a PLC over a network only through an add-on communication adapter. The 525 has an EtherNet/IP port built in. If the old drive was hard-wired to the PLC, you can keep it that way; if it used a 22-COMM adapter, the controller program will see a different device, so the drive's configuration in the PLC project and any tags or messages that read and write it have to change.

Safe Torque Off

The 525 includes a hard-wired Safe Torque Off (STO) function. It ships with a jumper on the safety terminals so the drive can run without a safety circuit. If your application uses STO, wire it into the safety circuit as the manual and your risk assessment require; if not, make sure the jumper is in place. A missing jumper is a common reason a freshly installed 525 will not run.

Parameters and control wiring

Parameter numbers do not carry over. Start source, speed reference, acceleration and deceleration, motor nameplate data and digital-input functions all exist on both drives, but under different numbers and sometimes with different options. The control terminals also have to be checked one by one against both user manuals. The 525 offers more motor-control options than the 40; check the manual for the firmware revision you have.

Footprint and mounting

The drives are not the same size, and the mounting holes do not line up. Check the dimension drawings against the space in the panel, including clearance above and below for cooling. Plan on drilling new holes or fitting an adapter plate, and check that the power cables reach the new terminal positions.

How to migrate from a PowerFlex 40 to a 525

1. Record everything from the old drive: nameplate, parameters, wiring photos and network settings.
2. Choose the 525 by voltage class and motor full-load current, not horsepower alone – the same rule as any VFD sizing.
3. Check the space against the dimension drawings and plan the mounting.
4. Map the control wiring terminal by terminal, including the Safe Torque Off terminals.
5. Map the parameters by function. Rockwell's Connected Components Workbench software configures both drives, and Rockwell publishes migration guidance for the 520 series; use it rather than working from memory.
6. Update the controller if the drive is networked: add the new drive to the PLC project and update the logic that talks to it.
7. Commission and document: check rotation, acceleration, stopping, fault responses and the safety circuit, then save the new parameter file.

When a like-for-like PowerFlex 40 makes more sense

An identical 22B drive keeps the mounting, wiring and parameters the same, and a saved parameter set can go straight back in. A surplus PowerFlex 40 is often the better choice when:

• The machine is down now and the only fault is the drive.
• The drive is networked and changing it means PLC programming, software and testing time you don't have today.
• The equipment is validated and changing a component triggers a requalification process.
• You run several identical drives and want to keep them the same until you migrate all of them together.

Many plants do both: keep a PowerFlex 40 on the shelf to cover a failure, and move to the 525 at a planned shutdown – especially when the application needs Safe Torque Off or you want the drives on EtherNet/IP.

When buying a surplus unit, match the full catalog number, check the series and firmware in the photos, confirm whether a communication adapter is included, and remember that drives stored for a long time may need their capacitors reformed. Every item we stock is photographed, so you can read the nameplate before you buy. Search PowerFlex 40 or PowerFlex 525 drives, or send us the catalog number for an official written quote in under 24 hours on business days.