ABB REX 521 Technical Reference Manual, Standard Configurations page 92

REX 521
7.3.2.
7.3.3.
92
Protection Relay
Technical Reference Manual, Standard Configurations
Three-phase current measurement, 3I
IL1
IL2
IL3
IL1
IL2
IL3
IL1 demand
IL2 demand
IL3 demand
IL1 demand
IL2 demand
IL3 demand
Io
The neutral current measurement function block Io measures the true RMS neutral
current, i.e. harmonics are not suppressed. The current values are updated once a
fundamental frequency cycle, i.e. the integration time for the true RMS calculation
is one fundamental cycle.
Io
Io
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Neutral current measurement, Io
Io (A)
Io (%)
Uo
The function block Uo measures the true RMS residual voltage, i.e. harmonics are
not suppressed. The voltage value is updated once a fundamental frequency cycle,
i.e.the integration time for the true RMS calculation, is one fundamental cycle.
Uo
Uo
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