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Users Manual

Formula for Plt Function

12Pst 3

Plt = 3 12i=1

Flicker [%]

Time

12 x interval length => 1 flicker value Plt

Interval length => 1 Pst

egb020.eps

Figure 17. Measuring Flicker Values

Unbalance

The ratio of negative-to-positive sequence harmonics is calculated, with the angles and magnitudes of the phase voltages taken into account. These values are averaged over the interval length defined in PQ Log.

Frequency

The line power frequency is measured and averaged over 10 seconds, and the resulting values are divided into 42 classes for establishing statistics. Values are also averaged over the interval length defined in PQ Log.

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