10.3.3
Functionality
The voltage variation function PHQVVR is used for measuring the short-duration
voltage variations in distribution networks.
Power quality in the voltage waveform is evaluated by measuring voltage swells,
dips and interruptions. PHQVVR includes single-phase and three-phase voltage
variation modes.
Typically, short-duration voltage variations are defined to last more than half of the
nominal frequency period and less than one minute. The maximum magnitude (in
the case of a voltage swell) or depth (in the case of a voltage dip or interruption)
and the duration of the variation can be obtained by measuring the RMS value of
the voltage for each phase. International standard 61000-4-30 defines the voltage
variation to be implemented using the RMS value of the voltage. IEEE standard
1159-1995 provides recommendations for monitoring the electric power quality of
the single-phase and polyphase ac power systems.
PHQVVR contains a blocking functionality. It is possible to block a set of function
outputs or the function itself, if desired.
10.3.4
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of PHQVVR can be described with a module diagram. All the modules
in the diagram are explained in the next sections.
U_A
U_B
U_C
I_A
I_B
I_C
Figure 575: Functional module diagram
Power quality measurement functions
1MRS757644 H
1090
620 series
Technical Manual
