Bender B93100735, Руководство пользователя

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Power Quality
46 PEM735_D00084_02_M_XXEN/06.2020
6.3.4 Flicker severity
Supply voltage variations cause changes in the luminance of lamps which can create
the visual phenomenon called flicker. Above a certain threshold flicker becomes annoy-
ing. The annoyance grows very rapidly with the amplitude of the fluctuation. At certain
repetition rates even very small amplitudes can be annoying.
The intensity of flicker annoyance can be evaluated by the following quantities:
 
Short-term flicker severity (perceptibility unit short term P
st
), measured over a
period of 10 minutes;
 
Long-term flicker severity (perceptibility unit long term P
lt
), calculated from a
sequence of 12 P
st
values (= two-hour interval) according to the following equa-
tion
P
lt
must be ≤ 1 during each period of one week for 95 % of the time.
The reaction to flicker is subjective and can vary depending on the perceived cause of
the flicker and the period during which it persists. In some cases
P
lt
= 1 gives rise to an-
noyance, whereas in other cases higher levels of P
lt
are noticed without annoyance.
Measurement overview
U
n
Nominal system voltage
Flicker ≤ 1 for 95 % of the time
Basic value Flicker algorithm
Integration interval 2 h
Observation period 1 week
Number of measurement intervals 84