Instruction manual
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AQ G3x7 Generator protection IED
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Figure 3-39: Structure of the current unbalance protection algorithm.
The analogue signal processing principal scheme is presented in the figure below.
Figure 3-40: Analogue signal processing for the current unbalance function.
The signal processing compares the difference between measured current magnitudes. If the
measured relative difference between the minimum and maximum current is higher than the
setting value the function generates a trip command. For stage to be operational the measured
current level has to be in range of 10 % to 150 % of the nominal current. This precondition
prevents the stage from operating in case of very low load and during other faults like short
circuit or earth faults.