Alstom iSTAT M355, Manual

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User Manual M3x5/EN M/B
iSTAT M3x5
Page 97
FIGURE 12-11: GRAPHICAL PRESENTATION OF 10 PHASE VOLTAGE INTERHARMONIC
COMPONENTS
12.4.5 Power Quality Analysis
Main menu Measurements
Measurements Present values
Settings Min/Max values
Resets  Alarms
SD card Graphs time
Info Graphs FFT
Installation Power supply quality
14.11.2012 16:53:36 Demo cycling
 Main menu
PQ (Power Quality) analysis is the core functionality of the M3x5 Quality Analyser. PQ is a
very common and well understood expression; however it is not exactly in accordance with
its actual meaning.
PQ analysis actually deals with the quality of the Supply Voltage which is the responsibility of
the utility companies. It influences the behaviour of connected apparatus and devices.
Fluctuations in current and power on the other hand are the consequence of varying loads
and hence the responsibility of consumers. With proper filtering the load influence can be
restricted to the consumer internal network or at most within the single feeder, while poor
supply voltage quality influences much wider areas.
Therefore indications of the quality of the supply voltage (alias PQ) are limited to anomalies
connected only to supply voltage.