ABB RELION 620 Series Technical Manual page 521

1MAC504801-IB E
620 series ANSI
Technical Manual
Measurement mode Phase Sel for Z Clc
3Phase-earth
3Phase-phase
Pos seqn
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
reliable and the impedance calculation is disabled. U
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.
Voltages and currents
N/A U_A, U_B, U_C, I_A, I_B, I_C
N/A U_AB, U_BC, U_CA, I_A, I_B, I_C
N/A { U_A,U_B,U_C } or { U_AB,U_BC,U_CA } and I_A,
I_B, I_C
Section 4
Protection functions
, the calculated impedance is not
N
is the rated phase-to-phase voltage.
N
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