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POWER MONITOR Group 11 T.A.: Brian Raczkowski

POWER MONITOR Group 11 T.A.: Brian Raczkowski . Presenting: Amitvikram Das Sairaj Dhople Srivatsan Jayaraman. Introduction. Power Monitor to characterize loads Measure power consumption with sensors Display essential information at load with LCD

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POWER MONITOR Group 11 T.A.: Brian Raczkowski

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  1. POWER MONITORGroup 11T.A.: Brian Raczkowski Presenting: Amitvikram Das Sairaj Dhople Srivatsan Jayaraman

  2. Introduction • Power Monitor to characterize loads • Measure power consumption with sensors • Display essential information at load with LCD • Wirelessly transmit data to remote computer • Analyze data with LabView interface • Save data for extended periods of time • Reload saved data for analysis in future • Marketed towards Commercial / Hobbyist use

  3. Purpose (comparison with existing) • Kill A Watt meter (Existing device) • Measurements: Volts, Amps, Watts, Frequency, kWhrs. • Limitations: • Measurements have to be taken at load. Non-Flexible • 2” Non-Graphical Display Cannot display Power waveforms • Instantaneous Power readings • Inability to extract data for further analysis • High cost for limited features ($40)

  4. Power Monitor Features • Non-invasive Current and Voltage sensors • On board power supply • LCD display for on the fly information • Easy to use Graphical User Interface • Store Data for as long as required • Export Data for advanced analysis • Easily expandable

  5. Pictures (Transmitter) LCD Device Status info and Transmitting Frequency Antenna Switch

  6. Pictures (Receiver) Antenna Switch Serial Header

  7. Block Diagram of complete system Power Supply Non-Invasive sensing LOAD SENSORS Scaling LCD UART dsPIC A/D Amplifier Wireless TX MAX 232 LabVIEW Wireless RX TTL Serial

  8. HARDWARE OVERVIEW • POWER SUPPLY • Input from AC line • Output voltage: +5 Volts, -5 Volts (OpAmp) • Current: 300mA (Typical); 500mA (Max) • 1A fuse protection • Powers - LCD, PIC, Wireless TX, Amplifier TRANSMITTER

  9. Power Supply (schematic) TRANSMITTER

  10. Hardware Overview (continued) 2.Sensors: • VOLTAGE SENSORS: • 115 V – 25 V Voltage Transformer • Voltage Divider circuit to obtain -2v to +2v swing • Vp-p= 25√8 = 70; Vin= Rin/(Rin+ Rout); Rin=4k, Rout=66k • CURRENT SENSORS: • Talema, AC1010 Current Transformer, 1000:1, 10A • Used 1k Burden resistor (Linear from data sheet) TRANSMITTER

  11. Hardware Overview 3.AMPLIFIER CIRCUIT • Differential summer OPAMP circuit • Vout= -(RF/ Rin)*(V+ - V-) + VOFF • RF = Rin (no gain); VOFF = 2.25v • Output Voltage Swing between 0 – 5 volts • Can be provided to ADC input • Easily mapped to voltage and current sensed TRANSMITTER

  12. CIRCUIT (schematics) Current Senor Voltage Sensor Amplifier Circuit TRANSMITTER

  13. Hardware Overview 4. dsPIC • 12 Bit A/D • Sampling rate : 4 MHz • UART interface for LCD and WIRELESS TX 5. LCD • 4 X 20 Black on Green LCD • Display: device status, time since device was active/ inactive and transmitting frequency • Interfaced with dsPIC 6. WIRELESS TX • LINX HP3 series • Interfaced with dsPIC TRANSMITTER

  14. LCD / WIRELESS/ PIC schematic TRANSMITTER

  15. HARDWARE OVERVIEW • Serial Interface • UART to Serial (RS 232) • MAX 232 interface with COM1 • WIRELESS RX • LINX HP3 Series • Interface with MAX 232 • Power Supply 9 Volt Battery • Voltage Regulator Circuit • Output: +5 Volts, GND RECEIVER

  16. Receiver – Schematic for LINX, MAX232 RECEIVER

  17. Schematic for Power Supply RECEIVER

  18. SOFTWARE OVERVIEW • dsPIC • Circular Buffer (FIFO) – UART • 12-bit ADC • UART protocol • Timer • Interrupt Driven vs. Multithreads • Synchronization • Interspersed Data • Independent LCD & ADC controller

  19. GRAPHICAL USER INTERFACE • LabVIEW • Display real-time data (Voltage & Current) • Average Power, Power Factor, Crest Factor • FFT Spectrum • Measurements (Voltage and Current): • THD • Frequency • RMS • Average • Peak RECEIVER

  20. Software Overview • Store Data for further use • Data format : .xls or .txt • Tab separated values • Computer hard-drive  ONLY limitation on duration over which data is stored • Append data with relevant time-stamps RECEIVER

  21. Software Interface • System Time • Basic Options • LabView Front Panel • Tabbed displays • Instantaneous voltage and current • Measurements • FFT amplitude spectrum • Power Specs • Graph palette • Zoom, cursors etc.

  22. LabView (Measurements TAB, one half displayed) • Digital Displays • THD • Average • Frequency • RMS • Peak • Crest Factor • Easy to read Graphical displays for each measurement • Time history evident

  23. LabView (FFT tab, one half displayed) • FFT amplitude spectrum • Higher harmonics revealed (if any) • Can be scaled to dB with one button press Cursors and graph palette for detailed analysis

  24. LabView (Power Tab) • Average Power history • Power Factor history • Digital display for accurate values

  25. Software Interface (Data Recall) • ‘RECALLED’ data displayed • Current and Voltage waveforms displayed as before

  26. STORED DATA FORMAT LabVIEW Measurement Writer_Version 0.92 Reader_Version 1 Separator Tab Multi_Headings Yes X_Columns One Time_Pref Absolute Operator sdhople2 Date 2007/04/23 Time 15:27:25.742003 ***End_of_Header*** Channels 2 Samples 32022 32022 Date 2007/04/23 2007/04/23 Time 15:27:25.757628 15:27:25.757628 X_Dimension Time Time X0 0.0000000000000000E+0 0.0000000000000000E+0 Delta_X 0.000200 0.000200 ***End_of_Header*** X_Value Untitled Untitled 1 Comment 0.000000 2.754902 143.487647 0.000200 2.558824 -2.907647 0.000400 2.833333 4.599804 0.000600 2.990196 0.846078 0.000800 3.147059 4.599804 0.001000 3.303922 4.599804 0.001200 3.421569 -2.907647 0.001400 3.500000 10.230392 0.001600 3.539216 36.506471 0.001800 3.578431 45.890784 0.002000 3.617647 49.644510 • Relevant time stamp • Headers separate appended data • Tab de-limited values • <TIME> <CURRENT> <VOLTAGE>

  27. Future Expansion for GUI • Handle Multiple loads, Add and delete loads at will • Display present day cost, total cost since system active and other useful cost analysis • Switch to Individual load details as before

  28. TESTING • Current Sensors: • Verified with Current Probes • Scope Captures attached • High fidelity noted • Voltage Sensors: • Verified with Oscilloscope • Scope Captures Attached • Power Supply: • Verify output voltage and ripple

  29. TESTING (MONITOR) • Current Probe • Current Transformer Max = 1.44A Max = 1.47A

  30. TESTING (MONITOR) • LabView snapshots Max_Vol ~ 180v Max_Curr ~ 1.5A

  31. TESTING (MONITOR) • Power Meter readings: • I (RMS) = 380mA • V (RMS) = 127 Volts • Power = 25 Watts • Power factor = 0.53 • LabView measurements: • I (RMS) ~ 355mA • V (RMS) ~ 126 Volts • Power ~ 23 Watts • Power factor ~ 0.5 • Current Measurement Accuracy • Quantization Error (Larger fractional error as compared to voltage)

  32. TESTING (MONITOR) • LabView Measurements:

  33. TESTING (MONITOR) • LabView FFT Spectrum • LabView Power Readings • Current Waveform displays higher harmonics • Voltage waveform and Current waveform displays peak at 60 Hz. • Avg Power = 25 Watts • Power Factor = 0.53 • Power seen to drop to zero when monitor turned off

  34. TESTING (SOLDER TOOL) • Current Probe Current (High) Current (Low)

  35. TESTING (SOLDER TOOL) • LabView snapshots HIGH STATE LOW STATE

  36. TESTING (SOLDER TOOL) • Power Meter readings: • I (RMS) = 489mA • V (RMS) = 126.88 Volts • Power = 57.7 Watts • Power factor = 0.956 • LabView measurements: • I (RMS) ~ 450mA • V (RMS) ~ 126 Volts • Power ~ 57 Watts • Power factor ~ 0.9 • Current Measurement Accuracy • Quantization Error (Larger fractional error as compared to voltage)

  37. TESTING (SOLDER TOOL) • LabView measurements:

  38. TESTING (SOLDER TOOL) • LabView FFT Spectrum • LabView Power Details • Avg Power = 58 Watts (ON) • Power Factor = 0.9 • Power seen to drop to zero when monitor turned off • Current Waveform displays higher harmonics • Voltage waveform and Current waveform displays peak at 60 Hz.

  39. TESTING (Power Supply) • Output Waveform of Power Supply +5 volts -5 volts • Max current verification using resistor load (500mA)

  40. TESTING • Wireless TX, RX • TX interfaced with Hyper-terminal via MAX232 • RX connected to Hyper-terminal via MAX 232 • Transmitted data verified with received data • Range: Too much interference with other Linx chips within lab. Unable to verify • Better range and fidelity with Loop antenna. • Determined Linx chip is not the best choice for wireless communications – due to amount of data transmitted wirelessly.

  41. TESTING • PIC + A/D , LCD • LCD: RS 232 protocol used to connect the HyperTerminal to the dsPIC. RX – TX loop back. • A/D: RS 232 protocol, this time more of a receiver. Sine wave sampled. Data acquired was reconstructed by exporting to Excel and then later by using our own LabView software.

  42. S.W.O.T. Analysis

  43. Future Hardware Options • Power supply • More Flexible power supply - +5V, -5V, +12V, -12V. Increase our load range – Opamp • Accuracy – Com protocol • USB – instead of UART/Serial. Can use the entire 12 bits of ADC instead of just 8 bits. • Wireless scheme • More reliable and robust wireless system, which can handle high data transmission rates with greater range.

  44. Future Software Options • LabView • Access information via Ethernet • Handle multiple loads • Interact with Transmitter • Advanced measurements • Power Triangle • Detect capacitive and inductive loads

  45. Green Applications & Ethics • Solar Decathlon • Desire to donate our unit for Solar Decathlon for load planning purposes. • Expense Analysis for each load • Monetary • Environmentally – Carbon Footprints • Goal – Educate People, make them realize their responsibilities to the environment • Acknowledge efforts of Kevin J. Repple - Spring ‘06, who tried to implement a similar system.

  46. Credits • Brian Raczkowski • Prof. Swenson • Prof. P. T. Krein for the idea • Parts shop • Machine Shop – Scott McDonald

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