HT instruments PQA824 - Manual (Page 133)

PQA400 - PQA823 - PQA824
EN - 132
 Detectable modes :
The below modes are available and selectable:
FIX: The meter detect and recording a event each time the TRMS value of current,
calculated on each half period (10ms @ 50Hz, 8.3ms @ 60Hz), it’s over the
limit threshold defined by user. A new event is detected by meter always if
the current value decrease under the set limit threshold.
VAR: The meter detect and recording a event each time the TRMS value of current,
calculated on each half period (10ms @ 50Hz, 8.3ms @ 60Hz), it’s over of the
previous TRMS value (calculated in previous half period) of a difference
defined by the limit threshold defined by user.
 Detectable time interval: As soon as the meter detect a event, it’s recording 100
TRMS value of current and 100 TRMS value of the
correspondent voltage within the detectable time interval
set by user. The available values are 1s, 2s, 3s, 4s.
The PQA82x meter shows at display the number of detectable events during the
recording. The analysis of results is only possible downloading the saved data to PC and
using the standard TopView software. In particular the below parameters are shown:
 Table of recorded events (phase where the event is occurred, date/time when the
event is occurred, maximum value between TRMS values calculated in a half period
during the detectable time interval, value of last sample at the end of the detectable
time interval).
 Graphical window of recorded events (graphic of saved 100 TRMS values of current
and correspondent voltage during the detectable time interval for each row of the table
of recorded events).
For any detail about saved data please refer to TopView HELP ON LINE feature.
10.4. FLICKER
Considering the theoretical definition, Flicker is due to an abnormal variations of voltage
supply, in particular relative to its RMS value as the luminescence of a traditional light is a
direct consequence. This effect should be monitoring in compliance with IEC/EN61000-4-
15 guideline.
Main causes of this disturbance are typically due to discontinuous switching of big loads
which are connected to electrical network (e.g. furnaces, foundries, arc welders for
industrial use).
Electrical suppliers should satisfy severe regulations regarding this kind of disturbance.
With suitable meters, called flicker meters, it’s possible to get a ratio between a distort
signal and an ideal signal and perform a statistics analysis relative to calculation of the
following parameters whose values must be always <1:
Pst = Short term severity of Flicker calculated in an interval of 10 minutes.
Plt = Long term severity of Flicker calculated considering a sequence of 12 values of Pst
in an interval of two hours according to the following formula:
3
12
1
3
12
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