Jim Mimlitz, NRI

Navionics Research Inc. is pleased to introduce the PowerFlex 753-Series VFD to our Water and Wastewater Utility Clients.  This Architecture-Class, Made in the USA drive from Allen Bradley offers a modular design and can be flexibly configured for most any potable water or wastewater pumping application.

We recently had the privilege of commissioning a 150 HP PowerFlex 753 at Gateway Regional Water District as part of an emergency repair project at their critical raw water intake.  During the course of this project, NRI’s VFD & Energy Analytics Firmware Module was expanded to accommodate the nuances of the PowerFlex 753’s 32-bit Modbus control and monitoring data structures.

Additionally, in order to enhance electrical protection for both the VFD and the Pump Motor, a Line Reactor and dV/dT Load Filter (MTE Corporation) were provided to condition the incoming and outgoing power, respectively.

The project was a successful joint-venture between Navionics Research Inc. and JF Electric (Edwardsville, IL), with excellent support by NRI’s vendors French Gerleman (St. Louis, MO | Quincy, IL | Columbia, MO)Rockwell Automation/Allen Bradley (Milwaukee, WI) and Fabrication Specialists (Alton IL).

Pump Station Electrical and Chemical Feed Building.


Pump Station Motor and Pump Building.  Note the Dual 150HP/480VAC/3-φ Submersible Pumps and Above-Grade-Mounted Motors.


Damaged Legacy VFD, Before Replacement.


Installation of New VFD, Reactors, and dV/dT Filter by Trevor Kurlbaum, J. F. Electric.


Legacy Back Panel. Note that Shallow Depth and Proprietary Cutout for One Particular Make/Model VFD — Which Was No Longer Available.  A Replacement Full-Depth Back Panel Design Was Submitted to Our Local Machine Shop, Fabrication Specialists (Alton, IL), for Construction.


Replacement Back Panel: Painted and Installed.


New Allen Bradley PowerFlex 753 VFD. Note That the New Back Panel Allowed for the Full-Depth of the Bay to be Utilized.


Line Reactor Installed to Condition Incoming Utility Power, Providing a Measure of Protection to the New VFD.


DV/DT Filter Installed on the Outgoing Power Cables to the Motor, Providing a Measure of Protection to the Motor Windings and Bearings. This Was Especially Important, Due to the Long Length (~200 Ft.) of these Cables.


New #1 Pump VFD to the Left. Legacy #2 Pump VFD to the Right.


Repair/Replacement Completed.


Allen Bradley 20-COMM-H Modbus/RTU RS-485 Network Communication Module.


Allen Bradley PowerFlex 20HIM-C6 VFD User Interface. Panel-Mounted over Hole for Legacy Display. The 20HIM-C6 Is Used Extensively During Initial Setup. After Commissioning, the Customer Can Monitor and/or Manually Control the VFD Using This User-Friendly Interface.


Allen Bradley PowerFlex 753 Factory: Mequon, Wisconsin.

PowerFlex 753 Nameplate. Made in the USA in Mequon, Wisconsin.


NRI VFD & Energy Analytics: Enhanced Monitoring and Control of Variable Frequency Drives

In order to fully take advantage of the new PowerFlex 753 VFD, NRI installed its new VFD & Energy Analytics Firmware module. This new module allowed for enhanced monitoring and control of the drive using the industry-standard Modbus/RTU Protocol. The following historical trending charts illustrate a sampling of the new capability:


24-Hr History Chart: VFD Running.


24-Hr History Chart: VFD Speed (0-100%).


24-Hr History Chart: Pump Flow (Gallons per Minute).


24-Hr History Chart: VFD Output Power (KW).


24-Hr History Chart: Pump GPK Efficiency (Gallons per Kilowatt-Hr). The average GPK depicted in this chart is 1250.  If, for example, the cost of a Kilowatt-Hr is $0.10, then the Water District is able to pump 12,500 gallons of water per $1.00 of electricity. Alternatively, the ratio can be inverted to show that the Water District pays $0.08 (electricity) per 1000 gallons to pump from the Lake Intake to the Plant.


24-Hr History Chart: VFD Bus Voltage, Normalized to 480V Reference. Note that the Bus Voltage dips by approximately 5% while the Pump Running, which is Normal.


24-Hr History Chart: VFD Internal Temperature (degF). Note that the VFD Temperature Rises by Approximately 40 degF while the Pump is Running. A Cooling Fan Failure can be easily detected as an Abnormally-High increase in VFD Temperature.


24-Hr History Chart: Detected VFD Fault Codes. No Fault Codes Were Detected During this 24-Hr Period. Fault Codes are Represented as an Integer, whose Meaning can be Interpreted from a Lookup Table.


New Setpoints Were Programmed to Provide the Operators with the Ability to Reset VFD Faults Remotely using the SCADA System GUI.


NRI’s VFD & Energy Analytics Firmware provides a groundbreaking, unique ability to monitor overall pumping system efficiency in the form of Gallons-per-KilowattHr (GPK), which is analogous to MPG for a vehicle.  GPK was formulated by NRI as the ratio of Pump Flow-Rate (Gallons per Hour) divided by VFD Output Power (KW). This unique efficiency measurement represents an advance in the state-of-the-art of rural water SCADA monitoring.

Bus Voltage — an important VFD and Electric Utility health measurement — is monitored, trended, and alarmed in the system.  VFD Temperature is another valuable data tag, which helps the Water Utility to avert temperature-related failures that can occur due to fan failures. Note that there are cooling fans in the VFD, as well as in the overall Motor Control Center.

About Modbus: One of the key industrial protocols utilized within Navionics Research SCADA Systems to communicate with VFD’s and other smart devices, MODBUS has become a de facto standard of industrial communication protocols. It is an especially important protocol when connecting control equipment from an in-homogeneous set of manufacturers. Gathering momentum and support since 1979 when it was first introduced by Modicon (now a division of Schneider Electric), it is the most common means of connecting industrial electronic devices. It is openly published, royalty-free, and forms a relatively easy-to-deploy industrial network.


NRI’s first pump application using Allen Bradley’s Architecture-Class PowerFlex 753 was interesting, exciting, and — most importantly — successful!  Furthermore, the expertise that was gained during this project is ready to be applied to Water Plants and Pumping Stations throughout the Region.  Are you interested in upgrading to a PowerFlex 753 VFD?  If yes, then let me know, and we’ll get started.

And as always, if you have any questions, please don’t hesitate to reach out by phone or email.

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About Jim Mimlitz

Licensed Professional Electrical Engineer @ Navionics Research. Specialties: Radio-Telemetry / Controls / SCADA System Integration for Water Utilities, Flow Metering, Variable Frequency Drives, Motorized Valves, Electronic Circuit Design, Software Development.

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