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Device handbook LINAX PQ3000-PQ5000
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7.6 PQ monitoring
Power quality monitoring provides both a statistical evaluation, allowing an assessment of compliance
with standards (e.g. EN 50160) or supply contracts, as well as records of events in the grid (e.g. power
voltage dips). This facilitates the analysis of causes and effects.
7.6.1 PQ events
The device monitors the voltage events listed in the subsequent table. The default values of the trigger
thresholds and hystereses are set to the common values of the EN50160 for a public low-voltage
distribution system. These values can be changed by the user to his individual needs. Recorded PQ
events can be
visualized
either via the local display or the webpage of the device.
Monitored voltage events
Default values
Threshold
Hysteresis
Reference value
Voltage dip
90%
2%
Nominal voltage
Voltage interruption
10%
2%
Voltage swell
110%
2%
Rapid voltage changes
6%
50%
1)
1)
Related to the respective threshold
The device does not verify the user-defined values. If these values are not plausible, events
may be not recognized correctly or misclassified. In particular, the trigger threshold for RVC
events should not be greater than half of the difference of the threshold values of voltage
swell and voltage dip.
Mains signalling voltage
The device monitors mains signalling voltages, which are transmitted in the supply system for control
purposes, and records them as events. Typically these are ripple control signals. The user can define the
frequency of the signalling voltage, the threshold and hysteresis (related to the nominal voltage) as well
as the recording duration in multiples of the measurement interval of 10/12 cycles. The recording duration
must not exceed 120s. The ripple control frequency is typically below 3 kHz and can be requested from
the local energy provider.