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This is an old revision of this page, as edited by 174.118.142.187 (talk) at 13:16, 16 June 2013 (→Data Collection). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Data Collection

  • Fairchild Application Note[1] "The power factor can vary from 0 to 1 and can be either inductive..." in lede paragraph.
  • Fluke 434 Series II Energy Analyzer[2] in specifications states "Power factor (Cos j/DPF) Measurement range: 0 to 1
Fluke 434/435 manual[3] states "Interpretation of power factor readings... PF = -1, device generates power". "If you see negative power or power factor readings and you are connected to load, check to make sure the arrows on your current clamps are pointed towards the load."
Fluke 430 Series specification states the same o to 1 and Measurement method: "Calculated total watt/VA"
  • Voltech PM1000+ Precision Power Analyzer [4] states "Power Factor: Range: 0 to +/-1.000" and on same spec page "+ indicates leading PF and - indicates lagging PF". This device does not indicate negative power factor for reverse connections but to indicate lagging PF.
  • Hioki Clamp On Power HiTester 3286-20 [5] states "[Power factor] Forward 0 to 1.000 to delay 0" and "[Phase angle] Forward 90.0° to 0 to delay 90.0°" Won't measure negative PF period.

Under investigation

Metering phasors

Where:

a,b,c represent phase identifiers
Ean, Ebn, Ecn represent phase to neutral voltages (volts)
Eab, Ebc, Eca represent phase to phase voltages (volts)
Ia, Ib, Ic represent phase line currents (amperes)
In represents neutral current (amperes)
represents the phase angle each current lags the listed potential (degrees)
represents total system power (watts)

3 phase 4 wire (wye) using 3 element metering

See Measurement Canada Standard Drawing[18]

Each line current and respective voltage is metered as three single phase circuits and then totalized in the meter.

3 phase 4 wire (wye) using 2.5 element metering

See Measurement Canada Standard Drawing[19]

Ia and Ic currents are metered with their respective voltages as two single phase circuits. Ib is fed, polarity reversed, through an additional (split) winding on each element. Since the reversed Ib is 60° out of phase (at system unity PF) from each potential each element will meter cos(60°) or 50% of Ib, resulting in 100% metering for Ib. The two elements are totallized in the meter. Balanced system voltages are a requirement for technique accuracy.

3 phase 4 wire (wye) using 2.0 element metering and delta connected CTs

See Measurement Canada Standard Drawing[20]

Ia and Ic currents are metered with their respective voltages as two single phase circuits. Ib is fed, polarity reversed, via a current transformer delta connection through each element. Since the reversed Ib is 60° out of phase (at system unity PF) from each potential each element will meter cos(60°) or 50% of Ib, resulting in 100% metering for Ib. The two elements are totallized in the meter. Balanced system voltages are a requirement for technique accuracy.

3 phase 3 wire (delta) using 2 element metering

See Measurement Canada Standard Drawing[21]

Two phase line currents are metered with phase to phase voltages. The odd combination of each current and voltage results in using voltages 1.732 higher and shifted by 30° resulting in 1.732 EI * cos(30°) = 1.5EI (at system unity pf) on each element. The elements are totalized to 3EI * cos() and correct metering. Balanced system voltages are a requirement for technique accuracy.

References

  1. ^ "Power Factor Correction (PFC) Basics" (PDF). Fairchild Application Note 42047. Retrieved 16 June 2013.
  2. ^ "Fluke 434 Series II Energy Analyzer". Fluke. Retrieved 16 June 2013.
  3. ^ "Fluke 434/435 User manual" (PDF). Fluke. Retrieved 16 June 2013.
  4. ^ "Voltech PM1000+ Precision Power Analyzer" (PDF). Voltech. Retrieved 16 June 2013.
  5. ^ "CLAMP ON POWER HiTESTER 3286-20". Hioki. Retrieved 16 June 2013.
  6. ^ On the resistance and electromotive forces of the electric arc, W. Duddell, Proceedings of the Royal Society of London, pp. 512-515, 1901. “The fact that the solid arc has, at low frequencies, a negative power factor, indicates that the arc is supplying power to the alternator…”
  7. ^ Expanded scale voltmeter, N.P. Millar, U.S. Patent 2,788,491, April 1957. “…are more than 90 degrees out of phase, corresponding to a negative power factor condition…”
  8. ^ Synchrotron Power Supply Light Source Note M. Fathizadeh, U.S. Gov. Contract W•3H09-ENG-38, LS-164, March 1991. “However, during the extraction, the power supply operates as an inverter which, therefore, delivers power to the utility. This action cause the negative power factor.”
  9. ^ Power Conversion Scheme Employing Shorting Means to Control Current Magnitude L.H. Walker, U.S. Patent 5,091,840, February 1992. “Positive power factor represents power flow from the DC source to the AC source. Negative power factor represents power flow from the AC source to the DC source.”
  10. ^ Analysis of some measurement issues in bushing power factor tests in the field, S. Zhang, IEEE Trans Pwr Del, Vol 21, Issue 3, pp 1350-1356, July 2006. “…(the measurement) gives both negative power factor and negative resistive current (power loss).”
  11. ^ Performance of Grid-Connected Induction Generator under Naturally Commutated AC Voltage Controller A.F. Almarshoud et al., Electric Power Components and Systems, Vol 32, Issue 7, 2004. “Accordingly, the generator will absorb active power from the grid, which leads to negative power factor.”
  12. ^ Comparison of closed-loop speed control schemes for a doubly fed twin stator induction motor drive N. Chilakapati, Proc. of the Third International Power Electronics and Motion Control Conference, vol. 2, pp 786-791, 2000. “It is to be noted that, a positive power factor denotes positive power input to the control winding while a negative power factor denotes power regeneration from the control winding.”
  13. ^ System and Method for Controlling Power Balance in an Electrical/Mechanical System, D.G. Oteman et al., European Patent EP2345147, filed October 2009. “If COSθ is negative, power factor is negative, and there is regeneration current on the system…”
  14. ^ Analytic synthesis of a hysteresis motor, L.U. Anih et al., Energy Conversion and Management, Vol 52, Issue 1, pp 391-396, January 2011. “This means negative power factor or that electric power flows out of the machine from rotor to the stator resulting in generator operation, a reversal of power flow... “
  15. ^ Influence of control strategies on DFIG-based Wind Farms integration in the power systems R. Reginatto and C. da Rocha, Proc. XVIII Congresso Brasileiro de Automática (English), pp 2570-2576, September 2010. “In this case, a negative power factor means that the wind farm is absorbing reactive power from the grid…”
  16. ^ More Discussion of the Terminology of Alternating Current Power C.B.Campbell, Power Engineering Letters, IEEE Power Engineering Review, July 1999
  17. ^ Solid-state Electricity Meters ANSI C12.16-1991, American National Standards Institute, New York, NY, 1991.
  18. ^ "Measurement Canada Standard Dwg. No.3403" (PDF). MEASUREMENT CANADA. Retrieved 12 December 2012.
  19. ^ "Measurement Canada Standard Dwg. No.3412" (PDF). MEASUREMENT CANADA. Retrieved 12 December 2012.
  20. ^ "Measurement Canada Standard Dwg. No.3407" (PDF). MEASUREMENT CANADA. Retrieved 12 December 2012.
  21. ^ "Measurement Canada Standard Dwg. No.3312" (PDF). MEASUREMENT CANADA. Retrieved 12 December 2012.
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