ABB RES670 Technical Manual page 236

Section 8
Current protection
230
with large capacitive ground fault currents. In such networks, the active fault
current would be small and by using sensitive directional residual power
protection, the operating quantity is elevated. Therefore, better possibility to detect
ground faults. In addition, in low impedance grounded networks, the inverse time
characteristic gives better time-selectivity in case of high zero-resistive fault
currents.
Phase
currents
IN
Phase
ground
voltages
VN
ANSI13000013 V1 EN-US
Figure 69: Connection of SDEPSDE to analog preprocessing function block
Overcurrent functionality uses true 3I0, i.e. sum of GRPxA, GRPxB and GRPxC. For
3I0 to be calculated, connection is needed to all three phase inputs.
Directional and power functionality uses IN and VN. If a connection is made to
GRPxN this signal is used, else if connection is made to all inputs GRPxA, GRPxB
and GRPxC the internally calculated sum of these inputs (3I0 and 3V0) will be used.
1MRK 511 408-UUS A
ANSI13000013-1-en.vsd
Phasor measurement unit RES670 2.2 ANSI
Technical manual