570 D90
PLUS
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
METERED VALUES CHAPTER 11: METERING
Positive varhour, Negative varhour
Range: 0.000 to 1000000000000.000 varh in steps of 0.001
These actual values display the metered reactive energy for each applicable source.
Frequency metering
Select the Actual Values > Metering > Frequency menu to open the metered frequency
window. Source frequency is measured via software-implemented zero-crossing detection
of an AC signal. The signal is either a Clarke transformation of three-phase voltages or
currents, auxiliary voltage, or ground current as per the source configuration. The signal
used for frequency estimation is low-pass filtered. The final frequency measurement is
passed through a validation filter that eliminates false readings due to signal distortions
and transients.
Figure 500: Frequency metering window
The following actual values display for each applicable source.
Name
Range: up to 20 alphanumeric characters
This value displays the user-programmed name for each source.
Frequency
Range: 0.000 to 90.000 Hz in steps of 0.001
These actual values display the metered frequency for each applicable source.
Tracking frequency
Select the Actual Values > Metering > Tracking Frequency menu to open the tracking
frequency window.
Figure 501: Tracking frequency window
The following actual value displays.
Tracking Frequency
Range: 0.00 to 90.00 Hz in steps of 0.01
This actual value displays the tracking frequency. The frequency is tracked based on the
selection of the reference source with the
Frequency And Phase Reference setting in the
Settings > Protection > Power System > Frequency menu.
For additional information, refer to:
Power system frequency
on page 179
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