4 Measured Quantities and Recording
4.1 Power Quality Measuring System and Recording System
36 SICAM Q100, 7KG95xx, Device Manual
E50417-H1040-C522-A6, Edition 06.2019
Analysis of Harmonic Phase Angles
For the voltage and current harmonics, the following values are given additionally:
• Prevailing phase angle (Prev°; PreAngle in user interface)
• Prevailing ratio (PR)
The prevailing phase angle represents harmonic emissions for intervals (such as 10-min aggregation
interval). The Prev° indicates the phase angle of a certain load. The prevailing phase angle is calculated via
the aggregation time from the phase angles of the 10-cycle or 12-cycle intervals. In the graphics in the following
table, the prevailing phase angle is displayed as a red line.
The prevailing ratio indicates load fluctuations during aggregation and indicates the degree of the variation of
a phase angle. For a prevailing-ratio value of 1, the phase angle of the corresponding harmonic is constant
(PR = 1: no fluctuation). The phase angles of the large variation (see following table), which have a prevailing
ratio of <0.8, are high dispersal and the prevailing phasor has no useful meaning.
The table shows 3 examples for the relation between prevailing ratio and prevailing phase angle:
However, the prevailing phasor only has sense if the harmonic phase angles have a low variation (the
measurements are not high dispersed in the complex plane). The prevailing ratio (PR) is proposed to indicate
how much the harmonic measurements vary in the complex plane.
Table 4-1 Examples for Phase-Angle Variations
Phase-angle variation Low Variation Medium Variation Large Variation
Prevailing phase angle 43° 79° 19°
Prevailing ratio 0.988 0.88 0.2
NOTE
You find further information to this feature in the application note: www.siemens.com/powerquality.
MAN_SICAM_Q100_US.book Page 36 Wednesday, June 5, 2019 9:31 AM
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