Drive Modernization Part VI: PowerFlex 40 to PowerFlex 525

7/13/21  |  Scott Savage, Rexel Technical Consultant

For migrating PowerFlex 40 to PowerFlex 525 drives, let’s start with some basics on what we need to accomplish to do a quick and easy installation. The most important task you can do is to back up the program using a program called Connected Components Workbench™ (CCW). It is a free download on the Rockwell Automation® website. A couple of methods can be used to access the drive with the software. You can go to each individual drive via “sneakernet” (plug into each drive individually with a cable) or via the network you may have in your location. 

The download for CCW can be found on the Compatibility & Downloads offering on the Rockwell Automation website. It is strongly advised to download this software and retrieve your drive parameter sets long before the existing drive fails. Before you can migrate from PowerFlex 40 to PowerFlex 525 drives, you need to know the parameters in the old PowerFlex 40 drive to correlate to the new parameter set in the PowerFlex 525 drive. You cannot retrieve them once the old drive has failed, and this makes the transition extremely arduous. The time saved will lead you on your way to a fast and professional approach when the time is at hand!

The Rockwell Automation website has the Compatibility & Downloads feature, search for CCW acronym or “Connected Components Workbench.”

This software will be used in coordination with RSLinx® Classic communication software to talk to the drive. The communication software has all the drivers in the library to talk to the drive. RSLinx software comes with the CCW download package, so if you don’t have it, you will have RSLinx software when CCW is installed.

If you choose not to use the software, it is a great tool for using offline and using the filter in the software to find parameters by name or by number instead of using the user manual and the time-consuming hunt and peck approach. If you don’t have a laptop, please load it on an engineering desktop and write down the parameters of interest as an offline tool. The software loads the parameters and default values so you can make some decisions on install. These drives do not have a copycat function in the keypad because the keypad is an integral drive. Once again, please back up your programs prior to a failure.

If you have a remote human interface module (HIM), you can back up your programs with these two devices:

• 22-HIM-A3 NEMA 1 KEYPAD (HIM)
• 22-HIM-C2S NEMA 4/12 KEYPAD (HIM)

Proper Grounding for PowerFlex 525 Drives

THREE MAJOR ELECTRICAL DISTRIBUTION SYSTEMS

SOLIDLY GROUNDED DISTRIBUTION SYSTEM

Both PE-A(MOV) and PE-B (common mode output filter) are installed.

Both PE-A(MOV) and PE-B (common mode output filter) are removed.

UNGROUNDED DELTA

BOTH PE-A(MOV) AND PE-B (COMMON MODE OUTPUT FILTER) ARE REMOVED.

Know your distribution system prior to installation of the drive. If the transformer is not solidly grounded (resistive or delta secondary), you must remove the jumper for the MOVs. Failure to remove the jumper will cause damage to the MOVs and the drive will fail. These drives are not repairable after damage. It also is mandatory to place a line reactor in front of the drive on all delta systems. Failure to install a line reactor may cause high current flow upon a distribution fault, and if the system has one ground fault, it could result in severe damage between the two ground paths in your facility. The PowerFlex 525 drive does not have PE-B only the MOV jumper. Below illustrates the location of this jumper.

Please keep in mind, a resistive grounding scheme also allows the first ground fault to occur. Though not mandatory, please keep in mind, a line reactor in front of these drives is strongly recommended. If the KVA is 10X KVA value of the HP of the drive, then a line reactor becomes mandatory (i.e., a 100KVA transformer supplying a 10 HP requires a line reactor). The PowerFlex 525 drive does not have an internal DC link inductor till frame size E. There is no DC link inductor on the DC bus till frame E.

Grounding of the Motor

The motor needs a solid bond from the drive to the motor. The ground wire or multiple ground wires needs to go directly from one of the two green ground screws on the drive chassis to the conduit box on the motor. Do not place the ground from the motor to a common ground bus in the drive cabinet or the common ground bus in a motor control center (MCC), this injects noise that seeks noise generated from the drive output to other areas in your facility. This is a physical requirement for a successful drive installation. In addition, variable frequency drive (VFD) shielded cable should be on the output side of the drive to cancel noise, which could be contained to the output wires or airborne in the output cable. 

Please avoid THHN, if possible. Thermoset insulation “cold sets” and is also susceptible to moisture. XHHN wire is preferred and shielding using VFD cable is extremely important to the successful commissioning of the drive. Inspect all wires down at the motor end of the drive for corona damage (pitting) and replace, if needed. 

To ensure a good bond at the motor, remove all paint on the motor junction box, all currents need to cancel to zero, including noise, and drives should be considered “noise generators.” The ground wire from the motor goes directly back to the green drive ground screws on the chassis of the drive. Good practices lead to fewer problems later when the drive is operating. Please do not assume that because the drive operated properly before it will continue to operate in the same manner. Once again, the grounding path is a physical practice and must be followed specifically upon installation.

How to Properly Ground the Drive and Motor

Please note, the PE connections from the motor frame to the drive PE screw are grounded at both ends. This holds true for all distribution systems unlike the jumpers discussed above.

If you are using a VFD cable with proper shielding and braiding to help capture the noise on the output of the drive, make sure all shields and braids are terminated on both ends of the cable—the drive chassis and motor chassis. All bare bonding wires, which could be multiples depending on the style of cable, must all be bonded uninterrupted to the drive, not to a common ground bus. The other end of the shielded cable must also be terminated to the frame of the motor. Please use low impedance terminals or lugs and remove any paint on the motor conduit box for a low impedance connection. Since this drive has no output filter, provide the best path to the drive from the motor. 

If you have an MCC, the drive grounds (bonds) do not terminate on the MCC ground bus. They need to go directly to the drive the noise was generated from. Keep in mind, noise can be airborne and the foil shields (usually two shields for 100% coverage need to get back to the drive to cancel out all currents from the drive itself). If you do not have VFD shielded cable, the single ground will act as the best return path to the drive. 

Noise degrades all kinds of electronic equipment. Sometimes the damage is months down the road. Improper grounding will result in premature failure of all low impedance paths where the noise will travel to go back to where it was generated from (the drive), even internal drive components. Your most important wire is your ground and how physically it is connected. A drive can be wired to code and still be bonded improperly.

Wiring the I/O on a PowerFlex 525 Drive

Wiring the I/O on a PowerFlex 40 Drive

Two-Wire Control

Quickly, let’s review two-wire control concepts, Allen-Bradley traditionally uses the term “Run” for a two-wire control term. Run Forward and Run Reverse are used for two-wire control.

Three-Wire Control

Three-wire control uses a momentary switch versus the two-wire control. Some applications and environments require three-wire control. Either method works—it becomes a matter of preference to which control method you choose to standardize on.

Please note, terminals 19 and 20 are not the correct terminal numbers for the PowerFlex 525 drive. This is for concept only, showing the electrical symbols for momentary and maintained switches. Three-wire and two-wire electrical symbols and their nomenclature of “Start Stop” and “Run” are important to observe. These terms and symbols can’t be mixed, rather you have momentary or maintained devices.

If you have three-wire control, terminal two will have a momentary pushbutton instead of a maintained switch. If you have two-wire control, the jumper should remain between terminals 1-11 on PowerFlex 525 drives. This jumper determines two-wire control or three-wire control, leaving the jumper is the proper installation for two-wire control. If you are hardwired to a PLC, and wired to a relay output, two-wire control is very common.

Note on the PowerFlex 40 drive, you have an SRC/SNK switch, observe its position, most common is SRC to supply I/O positive voltage to the terminals shown above in the PowerFlex 40 drive example. The sourcing or sinking in the PowerFlex 525 drive is determined by wiring to the example shown in the PowerFlex 525 drive I/O wiring and wiring to either negative switching (SNK) or positive switching (SRC) and setting J5 to the proper mode shown above. The default is set to SRC mode, it is a safer mode in case the supply wire goes to ground.

Example of Two-Wire Control for PowerFlex 525 Drives

Example of Three-Wire Control for PowerFlex 525 Drives

Analog Inputs PowerFlex 40 Drives

Analog Inputs PowerFlex 525 Drives

Analog Input Potentiometer PowerFlex 40 Drives

Analog Input Potentiometer PowerFlex 525 Drives

Potentiometer terminals are identical from PowerFlex 40 to PowerFlex 525 drives. A 10K potentiometer gives you a full range from 0-60Hz. Other resistance values on the potentiometer must be scaled to achieve full range of speed (i.e., in a 5K potentiometer you would have to adjust the maximum frequency on the drive to 120Hz to achieve 60 Hz. output on the drive).

4-20mA and 0-10VDC Analog Output PowerFlex 40 Drives

A 4-20mA signal is wired to terminal 16, and the common (-) jumper should be on the 4-20 setting shown below. Signal loss is programmed in the drive as an offset to achieve 4-20 mA from the default of 0-20 mA.