Alternating Current Power Factor Monitoring and Correction Bryan

Alternating Current Power Factor Monitoring and Correction Bryan Underwood Advisor: Prof. Gutschlag

Power Factor is the ratio of the active power to the apparent power P. F. = Complex Power Diagram =

Power Factor (cont. ) Poor power factor is due to inductive loads such as induction motors in air conditioners and refrigerators A very low power factor usually results in the power company charging more on a utility bill

Standards Ameren Illinois requires Residential customers (rate DS-1) and Light Industrial Non-Residential customers (rate DS-2, DS-3) to maintain a power factor of 0. 90 while Heavy Industrial Non-Residential customers (rate DS-4) must maintain a power factor of 0. 951

Power Company Charges If the power factor falls below the minimum specified by Ameren and Com. Ed, they require corrective devices to be installed Pacific Gas and Electric (PG&E) charges 0. 6% more on a utility bill for each percentage point below a power factor of 0. 852

Industry Averages About 60% of the electrical load in the United States is due to AC electric motors 3 According to the U. S. Energy Information Administration (EIA), only about 25, 000 out of 200, 000 manufacturing companies participate in power factor correction (PFC)4

Reasons for Power Company Surcharges or Requirements for Power Factor Improvement Increased I 2 R losses in transmission lines due to the additional current requirements needed to provide excess reactive power reduces efficiency, capacity, and profit margins Increased current requirements result in higher transmission line, transformer, and switch gear current ratings

Power Factor Correction (PFC) Usually done by capacitor banks ◦ Generate “negative” reactive power http: //accessscience. com/content/Reactive-power/802370

Equipment Hampden Type WRM-100 3 -Phase Motor 220 V 1. 4 A 1725 RPM 1/3 HP

Motor Efficiency and Power Factor & Efficiency vs. Output Power (W) 0. 9 Power Factor & Efficiency 0. 8 0. 7 0. 6 0. 5 Power Factor Efficiency 0. 4 0. 3 0. 2 0. 1 0 0 50 100 Output Power (W) 150 200 250

Equipment (cont. ) SATEC PM 172 E-N 3 -Phase Programmable Power Meter

Software SATEC Power Analysis Software V 1. 4 Build 5 Configure basic setup of meter, set trigger points, and view event logs and waveforms

Alternative Meters Larger meters have more relay inputs and outputs to permit more incremental values of capacitors to be switched as needed for more precise control of the power factor More programming options provide more robust control for better power factor correction news. thomasnet. com directindustry. com

Relays Potter & Brunfield KRPA-11 AG-120 Power Relays

Capacitor Banks Capacitance is added to each line and can be varied from 1. 6 u. F to 50 u. F

Damping Resistors are placed in series with the capacitor banks to reduce inrush currents

Damping Resistors Loses Current through resistor with 10 u. F Capacitor Power losses Current w/ 20 u. F Power losses Current w/ 30 u. F Power losses

System Diagram

System

Capacitor Bank Switching Relay coils are energized from SATEC meter when the power factor drops below a certain point ◦ Line current is also monitored to ensure no switching occurs when no load is present Capacitors are added to the circuit in parallel with the motor ◦ Placed in parallel to maintain the same line voltages into the motor Power factor can be varied over any desired range to avoid electric utility company charges Project system maintains a power factor of above 0. 98

Flow Chart

Experimental Results -0. 9

What’s Next? Complete theoretical circuit model and compare with experimental results ◦ Research how the meter calculates its values Write tutorial on how to use power meter ◦ Will use as an appendix for final paper Write final paper

Questions?

References 1 http: //www. ameren. com/sites/aiu/Rates/Documents/AIel 14 rtds 4. pdf http: //www. ameren. com/sites/aiu/Rates/Documents/AIel 48 rdimf. pdf 2 http: //www. pge. com/includes/docs/pdfs/mybusiness/customerservice/energystatus/powerquality/power%20 factor--revised-8 -907. pdf 3 http: //www. pge. com/includes/docs/pdfs/mybusiness/customerservice/energystatus/powerquality/power%20 fa ctor--revised-8 -9 -07. pdf 4 http: //www. eia. gov/emeu/mecs 2002/data 02/excel/table 8. 1_02. xls

System Values at Various Loads Motor Load Apparent Power (VA) Power Factor Active Power (W) Motor Speed (RPM) 345 0. 312 ¼ Load 354 0. 435 156 1705 ½ Load 394 0. 554 216 1683 ¾ Load 419 0. 658 276 1677 Full Load 520 0. 776 405 1585 No Load 107 1777