Instruction manual
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AQ G3x7 Generator protection IED
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The input signals are the RMS values of the fundamental Fourier components of the three
phase currents and three phase voltages.
The internal output signals are the calculated three-phase active and reactive power values.
Directional decision
This module decides if, on the power plane, the calculated complex power is closer to the
origin than the corresponding point of the characteristic line, i.e. if the point S is on the
“Operate” side of
the P-Q plane.
The internal input signals are the calculated active and reactive power values.
The internal output signal is the start signal of the function.
Decision logic
This part of the function block combines status signals to make a decision to start.
Additionally to the directional decision, the function may not be blocked by the general
“Block” signal, and may not be blocked by the signal “Block for VTS” of the voltage
transformer supervision function.
If the parameter setting requires also a trip signal (DUP32_StOnly_BPar_=0), then the
measurement of the definite time delay is started. The expiry of this timer results in a trip
command.
The symbol of the function block in the AQtivate 300 software
The function block of directional underpower protection function is shown in figure below.
All binary input and output status signals applicable in the AQtivate 300 software are
explained below.
Figure 3-58: The function block of the directional under power protection function.