Fluke 1744 User Manual

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Users Manual 
36 
Formula for Plt Function 
3
12
1
3
12
=
=
i
Pst
Plt
 
Time
 Flicker [%]
 
Interval length  => 1 Pst
 
12 x interval length => 1 flicker value Plt
 
 
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.