12-4
IM WT3001E-51EN
Display Example of dc
1s
1s
1s
1s
dcA
dcB
dcC
dcD
t1
dcB
t2
t1: Observation period 01
0
dc display
Undef
t2: Observation period 02
dcA
Undef
dcC
dcC(dcC>dcD)
Relative voltage change
Steady-state condition
dcB
0
0
dcA
0
dcC
IEC 61000-4-15 Ed 1.1
IEC 61000-4-15 Ed 2.0
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
th
10 minutes
12.1 Voltage Fluctuation and Flicker Measurement Function
