ABB RELION 620 Series Technical Manual page 725

1MRS757644 F
620 series
Technical Manual
GUID-8AD2B23E-F625-4B01-BD82-EA15FF35989A V1 EN
Figure 364: Functional module diagram
Impedance calculation
This module calculates the apparent impedance based on the selected voltages and
currents. The Measurement mode and Phase Sel for Z Clc settings determine which
voltages and currents are to be used. If the Measurement mode is set to "1Phase-earth"
or "1Phase-phase", the Phase Sel for Z Clc setting is needed for determining which
phase or phase-phase voltages ("A or AB", "B or BC" and "C or CA") and currents
should be used for calculating the impedance.
Table 682: Voltages and currents used in impedance calculation
Measurement mode
1Phase-earth
1Phase-earth
1Phase-earth
1Phase-phase
1Phase-phase
1Phase-phase
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.
Phase Sel for Z Clc Voltages and currents
A or AB U_A, I_A
B or BC U_B, I_B
C or CA U_C, I_C
A or AB U_AB, I_A, I_B
B or BC U_BC, I_B, I_C
C or CA U_CA, I_C, I_A
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
719