Measurement mode Phase Sel for Z Clc Voltages and currents
3Phase-phase N/A U_AB, U_BC, U_CA, I_A, I_B, I_C
Pos seqn N/A { U_A,U_B,U_C } or { U_AB,U_BC,U_CA } and
I_A, I_B, I_C
If all three phase voltages and phase currents are fed to the protection
relay, the positive-sequence alternative is recommended.
If the polarity of the voltage signals is opposite to the normal polarity, the
correction can be done by setting
Voltage reversal
to "Yes", which rotates the
impedance vector by 180 degrees.
If the magnitude of the voltage is less than 0.05 · U
N
, the calculated impedance
is not reliable and the impedance calculation is disabled. U
N
is the rated phase-to-
phase voltage.
The calculated impedance magnitudes and angles are available in the Monitored
data view. The impedance angles are provided between -180...180 degrees.
The calculated apparent impedance is converted to pu impedance as the
operating characteristics are defined with the pu settings.
Impedance reach check
The operating characteristic is a circular offset mho on the impedance plane. The
operating characteristics are defined with the
Offset
,
Diameter
and
Displacement
settings. If the calculated impedance value enters the circle in the impedance plane,
the module sends an enabling signal to start the Timer.
Protection functions
1MRS759142 F
1018 REX640
Technical Manual
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