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CASE STUDY 12
Inflow and Outflow of Harmonics
Environment:
Analysis:
Target: 3-phase 3-wire (3P3W2M), 6.6kV circuit
This is an example of inflow and outflow judgement taken as a result of harmonics measurement
Using a 3-phase 3-wire set up, the overall inflow and outflow of a 3-phase installation are judged
by the harmonic voltage-current phase difference (θsum). When it is between -90 to 0 to +90
degrees, it is inflow. Conversely, outflow is determined when the sum is in between -180 to -90 or
+90 to +180 degrees.
The fundamental wave (brown) is consumption (inflow) as shown below.
Most of the 5th harmonic (green) is also inflow.
Time Plot of Harmonic Voltage-Current Phase Difference (fundamental and 5th harmonic)
The 3rd harmonic (red) is outflow in the graph below. The 7th (blue) harmonic is outflow.
The data shows with the vertical lines that the phase difference exceeds 180 degrees and returns
to -180 degrees (or vice versa).
Time Plot of Harmonic Voltage-Current Phase Difference (3rd and 7th harmonics)
Outflow
Outflow
Inflow
Outflow
Outflow
Inflow
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