1MAC050144-MB C
Section 8
Measurement functions
615 series ANSI
575
Technical Manual
8.12
Power Quality, PQSS
8.12.1
Identification
8.12.2
Function block
Figure 308:
Function block
8.12.3
Functionality
The voltage variation measurement function PQSS is used for measuring the shortduration
voltage variations in distribution networks.
Power quality in the voltage waveform is evaluated by measuring voltage swells, dips and
interruptions. PQSS 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.
PQSS contains a blocking functionality. It is possible to block a set of function outputs or
the function itself, if desired.
8.12.4
Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are Enable and Disable.
The operation of the voltage variation detection function can be described with a module
diagram. All the modules in the diagram are explained in the next sections
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Voltage variation detection function
PHQVVR
PQ 3U<>
PQSS
PQSS
I_A
I_B
I_C
V_A
V_B
V_C
BLOCK
TRIP
PICKUP
SWELLST
DIPST
INTST
Summary of Contents for 615 Series ANSI
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Page 711: ...Section 16 1MAC050144 MB C Glossary 704 615 series ANSI Technical Manual ...
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