Alstom iSTAT M355, Manual

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User Manual M3x5/EN M/B
iSTAT M3x5
Page 79
12. MEASUREMENTS
The M3x5 performs measurements with a constant sampling frequency of 31 kHz.
Measurement methods differ for normal operation quantities, where values are averaged and
aggregated according to the aggregation requirements of IEC 61000-4-30 standard (Class
A) and voltage events where half-period values are evaluated again according to IEC 61000-
4-30 (Class A).
12.1 Online Measurements
Online measurements are available on the device display or they can be monitored with the
setting and monitoring software
QDSP2 .
The readings on the display are performed continuously with a refresh time dependent on
the defined average interval whereas the rate that
QDSP2 monitors the readings is fixed at
approximately every two seconds.
For a better overview over numerous readings, the measurements are divided into several
groups, which contain basic measurements, minimum and maximum values, harmonics, PQ
parameters and alarms.
Each group can represent the data in graphical form or in detailed tabular form. When in
tabular form the readings can be frozen to allow the data to be copied into various report
generation software tools.
A record can be made on the PC of the online data in .csv format for later analysis.
FIGURE 12-1: SAMPLE OF ONLINE MEASUREMENT DISPLAYS
12.2 Selection of available measurements
The available online measuring quantities and their appearance can vary according to the
settings for the type of power network and other settings such as; average interval,
maximum demand mode, reactive power calculation method, etc.
PLEASE NOTE
The Measurements supported depends on the connection mode configured. Calculated
measurements (for example voltages
U
1
and U
2
when 3-phase, 4-wire connection with a
balanced load is used) are only informative.
PLEASE NOTE
For 3b and 3u connection modes, only the phase to phase voltages are measured. Because
of this, a factor
√ 3 is applied to the calculation of qualities requiring nominal phase voltage.
For the 4b connection mode measurements support is the same as for 1b.