YOKOGAWA WT3002E User Manual page 205

12.1 Voltage Fluctuation and Flicker Measurement Function
Display Example of dc
Relative voltage change
dc display
IEC 61000-4-15 Ed 1.1
IEC 61000-4-15 Ed 2.0
12-4
Steady-state condition
dcA
1s
0 Undef dcA
dcA
0 0
t1
t1: Observation period 01
t2: Observation period 02
Short-Term Flicker Value Pst
The method using the flicker meter is standard in IEC 61000-3-3. For details on the
flicker meter, see IEC 61000-4-15. The normal observation period of Pst is 10 minutes.
Long-Term Flicker Value Plt
The long-term flicker value is normally determined from 12 Pst values using the equation
below. The normal observation period is 2 hours. If the number of observation periods is
less than constant N (12) in the calculating equation, the Plt values that are not observed
are computed as 0.0.
Pst of the first 10 minutes
Pst of the second 10 minutes
Pst of the 12
dcB
1s
dcB Undef
0
dcB
th 10 minutes
dcC
1s 1s
dcC
dcC
t2
dcD
dcC(dcC>dcD)
IM WT3001E-51EN