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Bryan Underwood

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Alternating Current Power Factor Monitoring and Correction ... of the electrical load in the United States is due to AC electric motors3 According to the U.S ... – PowerPoint PPT presentation

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Title: Bryan Underwood


1
Alternating Current Power Factor Monitoring and
Correction
  • Bryan Underwood
  • Advisor Prof. Gutschlag

2
Power Factor
Power Factor is the ratio of the active power to
the apparent power P.F.
Complex Power Diagram
3
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

4
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

5
Power Company Charges
  • If the power factor falls below the minimum
    specified by Ameren and ComEd, they require
    corrective devices to be installed
  • Pacific Gas and Electric (PGE) charges 0.6 more
    on a utility bill for each percentage point below
    a power factor of 0.852

6
Industry Averages
  • About 60 of the electrical load in the United
    States is due to AC electric motors3
  • 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

7
Reasons for Power Company Surcharges or
Requirements for Power Factor Improvement
  • Increased I2R 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

8
Power Factor Correction (PFC)
  • Usually done by capacitor banks
  • Generate negative reactive power

http//accessscience.com/content/Reactive-power/80
2370
9
Equipment
  • Hampden Type WRM-100 3-Phase Motor
  • 220 V
  • 1.4 A
  • 1725 RPM
  • 1/3 HP

10
Motor Efficiency and Power Factor
11
Equipment (cont.)
SATEC PM172E-N 3-Phase Programmable Power Meter
12
Software
  • SATEC Power Analysis Software V1.4 Build 5
  • Configure basic setup of meter, set trigger
    points, and view event logs and waveforms

13
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

directindustry.com
news.thomasnet.com
14
Relays
Potter Brunfield KRPA-11AG-120 Power Relays
15
Capacitor Banks
  • Capacitance is added to each line and can be
    varied from 1.6uF to 50uF

16
Damping Resistors
  • Resistors are placed in series with the capacitor
    banks to reduce inrush currents

17
Damping Resistors Loses
  • Current through resistor
  • with 10uF Capacitor
  • Power losses
  • Current w/ 20uF
  • Power losses
  • Current w/ 30uF
  • Power losses

18
System Diagram
19
System
20
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

21
Flow Chart
22
Experimental Results
-0.9
23
Whats Next?
  • Complete the 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

24
Questions?
25
References
  • 1 http//www.ameren.com/sites/aiu/Rates/Documents
    /AIel14rtds4.pdf
  • http//www.ameren.com/sites/aiu/Rates/Documents/A
    Iel48rdimf.pdf
  • 2 http//www.pge.com/includes/docs/pdfs/mybu
    siness/customerservice/energystatus/powerquality/p
    ower20factor--revised-8-9-07.pdf
  • 3 http//www.pge.com/includes/docs/pdfs/mybusiness
    /customerservice/energystatus/powerquality/power2
    0factor--revised-8-9-07.pdf
  • 4 http//www.eia.gov/emeu/mecs/mecs2002/dat
    a02/excel/table8.1_02.xls

26
System Values at Various Loads
Motor Load Apparent Power (VA) Power Factor Active Power (W) Motor Speed (RPM)
No Load 345 0.312 107 1777
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
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