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Measurement Computing WavePort 312P rev.1.0 User Manual

Page 48

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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