Instruction manual
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AQ G3x7 Generator protection IED
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The inputs are
•
The RMS value of the third harmonic Fourier component of the generator neutral voltage,
•
Parameters,
•
Status signals.
The outputs are
•
The binary output status signals.
The software modules of the third harmonic undervoltage protection function:
Fourier3 calculation
This module calculates the third harmonic Fourier component of the generator neutral point
voltage (not part of the HIZ64 function). This is not part of the HIZ64 function; it belongs to
the preparatory phase.
Figure 3-54: Fourier calculation.
Characteristics
This module decides the stating of the function based on the third harmonic Fourier component
of the generator neutral point voltage and it counts the time delay. The time delay is defined
by the parameter setting, if the voltage is below the setting value.
The inputs are the third harmonic Fourier component of the phase voltages (N3Four) and
parameters.
The outputs are the internal status signals. These indicate the started state and the
generated trip command if the time delay determined by the setting is expired.
Decision logic
The decision logic module combines the status signals to generate the trip command of the
function.
