half of the nominal frequency period and less than one minute (European Standard EN
50160 and IEEE Std 1159-1995).
These short-duration voltage variations are almost always caused by a fault condition.
Depending on where the fault is located, it can cause either a temporary voltage rise
(swell) or voltage drop (dip). A special case of voltage drop is the complete loss of
voltage (interruption).
PHQVVR is used for measuring short-duration voltage variations in distribution
networks. The power quality is evaluated in the voltage waveform by measuring the
voltage swells, dips and interruptions.
U_B
interruption
dip
swell
duration
max duration
magnitude
Voltage Int set
Voltage dip set
Voltage swell set
V Var Dur point 1 V Var Dur point 2
min duration
GUID-EF7957CE-E6EF-483E-A879-ABD003AC1AF9 V1 EN
Figure 370: Duration and voltage magnitude limits for swell, dip and interruption
measurement
Voltage dips disturb the sensitive equipment such as computers connected to the
power system and may result in the failure of the equipment. Voltage dips are typically
caused by faults occurring in the power distribution system. Typical reasons for the
faults are lightning strikes and tree contacts. In addition to fault situations, the
switching of heavy loads and starting of large motors also cause dips.
Voltage swells cause extra stress for the network components and the devices
connected to the power system. Voltage swells are typically caused by the earth faults
that occur in the power distribution system.
Voltage interruptions are typically associated with the switchgear operation related to
the occurrence and termination of short circuits. The operation of a circuit breaker
disconnects a part of the system from the source of energy. In the case of overhead
networks, automatic reclosing sequences are often applied to the circuit breakers that
Section 10 1MRS758755 A
Power quality measurement functions
692 REC615 and RER615
Technical Manual
To Next Page
Loading...
