Instruction manual
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AQ G3x7 Generator protection IED
173 (211
)
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Voltage sag, when the RMS value of the measured voltage is below a level defined by a
dedicated parameter and at the same time above a minimum level specified by another
parameter setting. For the evaluation, the duration of the voltage sag should be between a
minimum and a maximum time value defined by parameters.
Figure 3-104 Voltage sag
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Voltage swell, when the RMS value of the measured voltage is above a level defined by a
dedicated parameter. For the evaluation, the duration of the voltage swell should be
between a minimum and a maximum time value defined by parameters.
Figure 3-105 Voltage swell
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Voltage interruption, when the RMS value of the measured voltage is below a minimum
level specified by a parameter. For the evaluation, the duration of the voltage interruption
should be between a minimum and a maximum time value defined by parameters.
Figure 3-106 Voltage interruption
Sag and swell detection
Voltage sag is detected if any of the three phase-to-phase voltages falls to a value between
the “Sag limit” setting and the “Interruption Limit” setting. In
this state, the binary output
“Sag” signal is activated. The signal resets if all of the three phase
-to-phase voltages rise
above the “Sag limit”, or if the set time “Maximum duration”
elapses. If the voltage returns
to normal state after the set “Minimum
duration” and before the time “Maximum duration”
elapses, then the “Sag Counter” increments by 1, indicating a short
-time voltage variation.