Measurement Computing WavePort 312P rev.1.0 - Manual (Page 48)

4-14 Device Configuration PowerVista/312 User’s Manual
Modifications to power calculations are performed as follows:
⇒ Fundamental Phasor Power: has phasor currents modified before power calculations. Phase shift thus
automatically affects real and reactive power.
⇒ RMS Per Phase Wye Power: has no phasor currents, but calculates average real and reactive power per
phase point by point on the wave. Phase corrections are applied on a per phase bases to the real and
reactive power.
⇒ RMS Delta Power: uses the Two Wattmeter Method point by point on wave for both real and reactive
power. This generates only a total three-phase power. Phase correction is made to the total three phase
power using an average phase correction calculated from the three current phase corrections. The three
phase value of power is then divided by three to display per phase values.
Table 8. Effect of Harmonic Current Phase Error
on RMS Reactive Power.
Harmonic Q
(in percent of
total Q)
Gross Harmonic
Phase Error (deg) Error in Q(%)
10% 10 0.152
10% 15 0.341
10% 20 0.603
20% 10 0.304
20% 15 0.681
20% 20 1.206
30% 10 0.456
30% 15 1.022
30% 20 1.809