Jim Mimlitz, NRI<\/p><\/div>In Part 1<\/a> and Part 2<\/a> of this series,\u00a0we discussed how to measure and optimize pump station energy consumption using VFDs.\u00a0 In the case study, a water utility\u00a0was able to realize an energy consumption decrease of 67%.\u00a0 It is important to note that your savings may be more or less, as every application is unique.<\/p>\n Has your interest been piqued?\u00a0 Well, we’ve only scratched the surface.\u00a0In fact, there are even more<\/strong> <\/em>advantages to our new VFD & Energy Analytics Package.<\/p>\n Installation Complete: In the 3rd and final installment of this article, we will discuss:<\/p>\n Any of the above topics would be worthy of\u00a0an in-depth analysis, and perhaps\u00a0a few more focused\u00a0articles will be forthcoming, but for now a brief synopsis will be given.<\/p>\n <\/p>\n VFD’s have additional internal protections that go above-and-beyond those in a typical across-the-line motor starter.\u00a0 For example, when a momentary overvoltage is detected, the VFD will shut down and report a fault\u00a0code on its LCD display.\u00a0 The VFD will not allow a restart until the operator acknowledges the alarm by pressing the RESET button on the VFD keypad.<\/p>\n A common problem faced by VFD users is the occasional nuisance fault,\u00a0which requires\u00a0travel to the\u00a0remote site to press the VFD RESET button.\u00a0This can be particularly\u00a0bothersome for water utilities who suffer from poor electric power quality.\u00a0However, these problems can be alleviated \u2014 NRI’s new VFD & Energy Analytics Package provides the operator with instant alarm notifications via the SCADA system when a VFD fault is tripped.\u00a0 The operator is also notified of the nature of the fault (the actual fault code), and he is able to acknowledge and reset the fault remotely at his discretion.\u00a0 This acknowledgement\/reset may even be performed remotely using a smart phone, such as an iPhone or Android.<\/p>\n VFD Faults\u00a0May Be Remotely Viewed And Reset Using A SmartPhone.<\/p><\/div>\n Any VFD Faults That Occur are Available from the VFD via the Network.<\/p><\/div>\n <\/p>\n The featured Williamsville booster pump station\u00a0was equipped with\u00a0soft starters<\/a> before the installation of the VFD upgrade.\u00a0Their soft starters provided a 30-second ramp-up and ramp-down of the pumps, but Williamsville still saw significant water hammers right at start-up and shut-down.\u00a0 The VFD upgrade, however, was programmed to provide a 300-second ramp-up and ramp-down, which completely eliminated all pump-induced pressure spikes, as illustrated in the following\u00a0before<\/strong> and\u00a0after<\/strong> Telemetry history charts:<\/p>\n Pressure Charts Before VFDs…<\/strong><\/p>\n Discharge Pressure (PSIG)\u00a0\u2014 An Earlier History Chart when Booster Station was equipped with Soft Starts. Note the pressure spike at pump start-up at approx. 7:15am.<\/p><\/div>\n Suction Pressure (PSIG) \u2014 An Earlier History Chart when Booster Station was equipped with Soft Starts. Note the pressure spike at pump start-up at approx. 7:15am.<\/p><\/div>\n <\/p>\n Pressure Charts After VFDs…<\/strong><\/p>\n Discharge Pressure (PSIG) \u2014 A Later History Chart after the Booster Station was equipped with VFDs. Note the lack of pressure spikes at pump start-up at approx. 5:30pm.<\/p><\/div>\n Suction Pressure (PSIG) \u2014 A Later History Chart after the Booster Station was equipped with VFDs. Note the lack of pressure spikes at pump start-up at approx. 5:30pm.<\/p><\/div>\n <\/p>\n Eventually, all cooling fans fail<\/em><\/strong>.\u00a0 As a moving part subject to wear \u2014 It’s simply a fact of life \u2014 And every VFD is equipped with active cooling fans for protection\u00a0against\u00a0current-generated heat buildup.\u00a0 The VFD Analytics Module, though, is capable of monitoring and alarming the VFD Heat Sink for\u00a0extreme\u00a0temperatures,\u00a0allowing the owner to detect and repair\u00a0a broken\u00a0fan before the entire VFD fails due to overheating.<\/p>\n Also, VFD’s are occasionally installed outdoors \u2014 for example within a NEMA-3R outdoor package \u2014 and these units\u00a0can be\u00a0subject to both<\/strong><\/em> hot and cold extreme temperatures.\u00a0 To protect the\u00a0drive electronics, the enclosure is typically outfitted with additional thermostat-controlled\u00a0cooling fans and heaters.\u00a0 The fans, heaters, and thermostats, though,\u00a0are also subject to failure.\u00a0 The VFD Analytics Module can detect and alarm\u00a0any over-temperatures or under-temperatures \u2014 thereby allowing the owner to detect and repair the temperature controls before the entire VFD fails.<\/p>\n VFD Heat Sink Temperature May Be Viewed and Alarmed \u2014 Particularly Useful\u00a0for the\u00a0Detection of Enclosure Fan or Heater Failures.<\/p><\/div>\n <\/p>\n If a VFD suffers a non-resettable failure, one of the first on-site\u00a0troubleshooting steps is to verify that the drive\u00a0is holding\u00a0the correct DC bus voltage:\u00a01.41 x Station Voltage.\u00a0 The PowerFlex drive even has multimeter hookup terminals dedicated to helping the technician perform this function.\u00a0\u00a0The VFD Analytics has a built-in function to extract the DC Bus Voltage, display the value on the Telemetry screen, and generate alarms when the Bus Voltage falls outside of specifications.<\/p>\n VFD DC Bus Voltage. A Healthy VFD Has A Bus Voltage of Approximately 1.41 x Station Voltage.\u00a0 In this Instance of a 230VAC Station, the DC Bus Voltage Should Be Approximately 325VDC.<\/p><\/div>\n <\/p>\n The Analytics software can also extract and present important electric power output data \u2014namely speed<\/strong>,\u00a0voltage<\/strong>, current<\/strong>,\u00a0kilowatts<\/strong> , and kilowatt-hour<\/strong> information:<\/p>\n VFD Output Speed (%) – 24 Hour History Chart<\/p><\/div>\n Motor Voltage (VAC) – 24 Hour History Chart<\/p><\/div>\n Motor Current (Amps) – 24 Hour History Chart<\/p><\/div>\n Motor Power Consumption (KW) – 24 Hour History Chart<\/p><\/div>\n Motor Accumulated Energy Consumption (KWH) – 24 Hour History Chart<\/p><\/div>\n <\/p>\n The pump efficiency is defined as the ratio of Pump Work to Pump Electric Power Consumption.\u00a0 Using the new tools at our disposal, this performance measure may be calculated and tracked in realtime:<\/p>\n Pump Efficiency May Be Derived and Monitored Using KW (from VFD), Flow Rate (from EtherMeter), Discharge & Suction Pressures (from Transducers).<\/p><\/div>\n <\/p>\n In order to implement advanced VFD control and monitoring, it was imperative that our preferred VFD offer integral networking capability as a standard,\u00a0non-optional\u00a0feature.\u00a0 Additionally, it was imperative that the VFD\u00a0offer that networking in the form of a non-proprietary communication protocol \u2014 such as Modbus<\/a>, EtherNet\/IP<\/a>, DF1<\/a>,\u00a0and\/or BACnet<\/a>.<\/p>\n A non-proprietary protocol \u2014 such as Modbus<\/a> \u2014 is one that adheres to an international communication standard and ensures that equipment from multiple vendors can co-exist on the same network within a pump station.\u00a0 When a proprietary VFD networking protocol is introduced into a pump station control network, additional expense and risk is assumed by the customer, as he becomes locked-in to the whims of a single VFD vendor.<\/p>\n The PowerFlex 400 VFD offers non-proprietary, Modbus network communications standard on all size and voltage combinations.<\/p>\n Modbus has become a de facto standard of industrial <\/p>\n Good engineering practice demands that we provide an alternative control path in addition to the Modbus network control.\u00a0 For example, should the Modbus network fail, then we would still like to be able to run and monitor the pumps automatically using the Telemetry Controls.\u00a0 To accomplish this, we recommend an alternative backup control method\u00a0\u2014 implemented via the VFD’s terminal block.\u00a0 In case of Modbus network failure, the Operator may\u00a0toggle the VFD\u00a0Control to “Discrete Control”, which will cause the\u00a0Telemetry to run the pump(s) when required at\u00a0a preset speed with soft-starts and soft-stops.<\/p>\n As a Backup to Digital Network Control, Discrete Terminal Block Control of the VFD Should Be Implemented.<\/p><\/div>\n <\/p>\n If a pump motor has available, unused horsepower at 100% speed (60 Hz), it is possible to run the pump at speeds greater than 100%.\u00a0 For example, during a period of emergency high water demand, or perhaps as a method of increasing the flow capacity of a pump station without changing out the pump.\u00a0 When using network-based control, greater-than-100% speed is easily achieved and generally does not require additional on-site modifications.<\/p>\n <\/p>\n Due to the energy-saving\u00a0nature of\u00a0VFD’s, along with their\u00a0associated reduced motor\u00a0starting currents,\u00a0many Power Utilities\u00a0are offering monetary incentives to\u00a0Water Utilities to upgrade\u00a0across-the-line starters in pump stations and water plants\u00a0to VFD’s.\u00a0 Before embarking on a VFD project, it is certainly worth investigating whether your Power Utility offers any sort of rebate or incentive plan.\u00a0 Some useful links are provided below.<\/p>\n ILLINOIS:<\/span><\/p>\n When available, the rebates in Illinois are typically around $100 per HP per pump.\u00a0 For example, for a 2 pump station where each pump is 75HP, the rebate\u00a0might be $15,000.00.<\/p>\n MISSOURI:<\/span><\/p>\n When available, the rebates in Missouri are typically around $50\u00a0per HP per pump.\u00a0 For example, for a 2 pump station where each pump is 75HP, the rebate\u00a0might be $7,5000.00.<\/p>\n Power Factor Correction<\/strong><\/p>\n A 3-Phase Motor with an across-the-line starter presents an inductive load to the Power grid\u00a0\u2014 a less-than-unity power factor<\/a>\u00a0\u2014 which in basic terms means that the current-voltage product exceeds the stations wattage, thereby posing\u00a0challenges for the Power Utility’s generation and distribution grid.\u00a0 A VFD’s power factor, on the other hand, is very close to ideal (1.0) \u2014 and therefore corrects for the motor’s inductive load.<\/p>\n Typical Motor Power Factors (from Engineering Toolbox<\/a>)<\/p>\n![\"Installation](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/NRI_PowerFlex_001s-300x253.jpg\")
<\/a>
Circuit Breaker \/ Load Reactor Panels (Partially Shown Left).
New PowerFlex 400 Variable Frequency Drives (Right).<\/p><\/div>\n\n
VFD Fault Alarming and Remote Reset<\/strong><\/h3>\n
![\"VFD](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/Fault_Reset_001-300x112.jpg\")
<\/a>![\"Any](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/vfd_fault_h_2014_12_25_002_3_161.png\")
<\/a><\/h3>\n
Water Hammer Reduction<\/strong><\/h3>\n
![\"Discharge](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/old_discharge_h_2013_12_24_002_3_001.png\")
<\/a>![\"Suction](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/old_suction_h_2013_12_24_002_3_011.png\")
<\/a>![\"Pump](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/h_2015_01_01_002_3_00.png\")
<\/a>![\"Pump](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/h_2015_01_01_002_3_01.png\")
<\/a>VFD Temperature Monitoring and Alarming<\/strong><\/h3>\n
![\"VFD](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/vfd_temp_h_2014_12_25_002_3_121.png\")
<\/a>VFD Health Monitoring and Alarming<\/strong><\/h3>\n
![\"VFD](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/vfd_bus_dc_h_2014_12_25_002_3_141.png\")
<\/a>![\"VFD](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/speed_h_2014_12_25_002_3_041.png\")
<\/a>![\"Motor](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/motor_vac_h_2014_12_25_002_3_081.png\")
<\/a>![\"Motor](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/motor_a_h_2014_12_25_002_3_101.png\")
<\/a>![\"Motor](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/power_h_2014_12_25_002_3_061.png\")
<\/a>![\"Motor](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/vfd_energy_h_2014_12_25_002_4_051.png\")
<\/a><\/h3>\n
Pump Efficiency Monitoring<\/strong><\/h3>\n
\n
Efficiency\u00a0=\u00a0PumpWork(kw)\u00a0 \/\u00a0 VfdPowerOutput(kw)<\/strong><\/em><\/pre>\n
Efficiency\u00a0=\u00a0[FlowRate(gpm)x[Discharge(psi)-Suction(psi)]\/2302]\u00a0\/\u00a0VfdPower(kw)<\/strong><\/em><\/pre>\n
![\"Pump](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/pump_efficiency_h_2014_12_25_002_3_181.png\")
<\/a><\/h3>\n
<\/h3>\n
VFD Network Communications<\/strong><\/h3>\n
\ncommunication protocols. \u00a0Gathering 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.\u00a0 It is openly published, royalty-free, and forms a relatively easy-to-deploy industrial network.<\/p>\nVFD Terminal Block (Backup) Controls<\/strong><\/h3>\n
![\"As](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/Discrete_VFD_Ctrl_001-300x111.jpg\")
<\/a><\/h3>\n
Faster-than-100% Pump Speed<\/strong><\/h3>\n
Utility Rebates<\/strong><\/h3>\n
![\"Rebate_001\"](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/Rebate_001-300x226.jpg\")
<\/a><\/p>\n\n
\n
![\"VFD's](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/Power_Factor_002s-205x300.jpg\")
<\/a>![\"VFD's](\"https:\/\/wireless-telemetry.com\/blog\/wp-content\/uploads\/2015\/01\/RotoPhase_001-300x258.jpg\")
<\/a>