Mega MEg40+, Manual

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9
Universal Energy Meter MEg40
+
5-minute intervals and for up to 30 events during every 6 hr 45 min, the minimum time
of measurement is 573.6 days.
Then both 10-minute voltage quality evaluations and 15-minute energy evaluations can
be made from 5-minute intervals.
The organisation of the internal data memory of MEg40
+
and the memory card can be
circular or linear. When the measured data are stored into the circular data memory,
after the memory is full, the oldest data in the range of one page are deleted and new
data are recorded on their place. When the measured data are stored into the linear
data memory, after the memory is full, the new measured data are not recorded into
the memory and the data measured after the measurement is started are stored in the
memory permanently. Cooperation of the internal data memory and the memory card is
included in the following description of the 16 MB memory card.
An event is registered when the voltage U
rms(1/2)
of any phase gets out of the preset limits;
according to ČSN EN 50160, ed. 3 it is 90 % U
nom
and 110 % U
nom
. The beginning and
ending time of an event can be recorded with the max. inaccuracy 10 msec. During
an event, minimum and maximum voltages U
rms(1/2)
are evaluated, or also currents of
all phases. The event ends when all of the voltages return in accordance with ČSN
EN 50160 into the allowable tolerance band narrowed by the hysteresis of 2 % U
nom
. E.g.
if the limits of 90 % U
nom
and 110 % U
nom
are selected, then the limits to end an event are
92 % U
nom
and 108 % U
nom
. Beside the time when an event occurred, also the duration
of the event is recorded. As an event, it is also recorded a measurement failure due to
a supply voltage loss, and it is recorded the beginning and ending time of the failure.
The universal energy meter measures for 1 sec also in case of a supply voltage failure.
Duration of longer failures is measured using the internal backup clock with the time
resolution of 1 sec. After the failure ends and the supply voltage is restored, the HW of the
instrument MEg40
+
is checked for about 1 sec and then the measurement is restored. The
duration, during which the measurement is interrupted in case of a longer power failure,
is extended by about 1 sec.
When it is required so that the instrument measures also during supply voltage failures,
see ČSN EN 61000-4-30, ed. 2, it is possible to order also the uninterruptible power
supply MEg102 together with the instrument MEg40
+
, which can supply the instrument
MEg40
+
during up to four subsequent supply voltage failures always for the required time
of 3 minutes.
In the function of measurement and registration of maximum currents, the maximum
currents are searched in the instrument MEg40
+
among values measured during the
preset measurement interval for each phase and the whole outlet from the beginning of
the measurement, which appear only on the display of the instrument together with the
time of occurrence.