Title: Bryan Underwood
1Alternating Current Power Factor Monitoring and
Correction
- Bryan Underwood
- Advisor Prof. Gutschlag
2Power Factor
Power Factor is the ratio of the active power to
the apparent power P.F.
Complex Power Diagram
3Power 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
4Standards
- 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 -
5Power 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
6Industry 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
7Reasons 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
8Power Factor Correction (PFC)
- Usually done by capacitor banks
- Generate negative reactive power
http//accessscience.com/content/Reactive-power/80
2370
9Equipment
- Hampden Type WRM-100 3-Phase Motor
- 220 V
- 1.4 A
- 1725 RPM
- 1/3 HP
10Motor Efficiency and Power Factor
11Equipment (cont.)
SATEC PM172E-N 3-Phase Programmable Power Meter
12Software
- SATEC Power Analysis Software V1.4 Build 5
- Configure basic setup of meter, set trigger
points, and view event logs and waveforms
13Alternative 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
14Relays
Potter Brunfield KRPA-11AG-120 Power Relays
15Capacitor Banks
- Capacitance is added to each line and can be
varied from 1.6uF to 50uF
16Damping Resistors
- Resistors are placed in series with the capacitor
banks to reduce inrush currents
17Damping Resistors Loses
- Current through resistor
- with 10uF Capacitor
- Power losses
- Current w/ 20uF
- Power losses
- Current w/ 30uF
- Power losses
18System Diagram
19System
20Capacitor 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
21Flow Chart
22Experimental Results
-0.9
23Whats 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
24Questions?
25References
- 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
26System 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