Mega MEg 30, Руководство пользователя

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the telereprogramming of their structure according to user’s requirements and/or
the teleprogramming of newly developed functions.
2. Principle of measurement and of data processing, organization
of the data memory
The measurement of four voltages and of four currents is based on sampling them
with frequency 5120 Hz. The total number of 1024 values with resolution of 14 bits
are always sampled in 200 ms long intervals, following one after another without
timeouts. After transformation into the frequency area, 512 complex harmonic com-
ponents with step 5 Hz (i. e. 51 harmonic components regarding the multiple 50 Hz)
and 461 interharmonic components are then calculated from these values. The mag-
nitudes of voltages U1 to U4, currents I1 to I4 and “control signals” (ripple control)
are calculated from the absolute values of the complete spectrum. Active and reac-
tive power of individual components as well as the unbalance are calculated from
complex components.
The data from channels U1, U2 and U3 for evaluating the events and flicker on
voltages are processed in the time area. The square of the TRMS value for the
elapsed period (20 ms) is calculated after every 10 ms. Frequency is calculated from
the data of channel U1.
Corrections of DC components, corrections of strengthening the current sensors,
of voltage and current measuring channels and frequency characteristics including
corrections of a possible phase shift between individual measuring channels are
made during the calculations. The tables of calibration constants are a part of the
configuration. None up to 100 various tables of calibration constants can be stored in
the memory of the firmware depending on the set of the whole measuring string
(measuring con measuring channels).
The non-destructive data memory, type FLASH with capacity of 2 MB (4 MB as
option) is divided into five circularly organized areas. The first area shall be used for
recording the development in time of RMS values of measured voltages, currents
and power in a complex form. Detailed data on voltage quality in the elapsed week
shall be stored in the second area. The third data area includes unified data with a
list of events according to methodology of ČSN EN 50160 and the fourth data area
includes a detailed record of the development of RMS values of the half-periods of
voltages U1, U2, U3, U4 and currents I1, I2, I3, I4. The fifth data area includes com-
pressed weekly data on quality. The ratios of ranges of individual areas of the data
memories can be mutually changed respecting the user’s requirements.
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MEgA Měřicí Energetické Aparáty