breakers that interrupt fault currents. All these actions result in a sudden reduction
of voltages on all voltage phases.
Due to the nature of voltage variations, the power quality standards do not specify
any acceptance limits. There are only indicative values for, for example, voltage
dips in the European standard EN 50160. However, the power quality standards
like the international standard IEC 61000-4-30 specify that the voltage variation
event is characterized by its duration and magnitude. Furthermore, IEEE Std
1159-1995 gives the recommended practice for monitoring the electric power quality.
Voltage variation measurement can be done to the phase-to-earth and phase-to-
phase voltages. The power quality standards do not specify whether the
measurement should be done to phase or phase-to-phase voltages. However, in
some cases it is preferable to use phase-to-earth voltages for measurement. The
measurement mode is always TRMS.
10.3.7 Signals
Table 653: PHQVVR Input signals
Name Type Default Description
I_A SIGNAL 0 Phase A current magnitude
I_B SIGNAL 0 Phase B current magnitude
I_C SIGNAL 0 Phase C current magnitude
U_A SIGNAL 0 Phase-to-earth voltage A
U_B SIGNAL 0 Phase-to-earth voltage B
U_C SIGNAL 0 Phase-to-earth voltage C
BLOCK BOOLEAN 0=False Block signal for activating the blocking mode
Table 654: PHQVVR Output signals
Name
Type Description
OPERATE BOOLEAN Voltage variation detected
START BOOLEAN Voltage variation present
SWELLST BOOLEAN Voltage swell active
DIPST BOOLEAN Voltage dip active
INTST BOOLEAN Voltage interruption active
1YHT530004D05 D Section 10
Power quality measurement functions
615 series 785
Technical Manual
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