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
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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
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Capacitor Banks

• Capacitance is added to each line and can be
  varied from 1.6uF to 50uF

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Damping Resistors

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

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Damping Resistors Loses

• Current through resistor
• with 10uF Capacitor
• Power losses
• Current w/ 20uF
• Power losses
• Current w/ 30uF
• Power losses

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System Diagram
19
System
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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

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Flow Chart
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Experimental Results
-0.9
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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

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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

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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