Directional Residual Current Protection Measuring 3I - ABB Relion Technical Manual

Section 8
Current protection
8.3.7.2
226

Directional residual current protection measuring 3I

φ is defined as the angle between the residual current 3I
jRCADir
-3V e , that is -3V
0
ang(V ) ). RCADir is normally set equal to 0 in a high impedance grounded network with
ref
a neutral point resistor as the active current component is appearing out on the faulted
feeder only. RCADir is set equal to -90° in an isolated network as all currents are mainly
capacitive. The function operates when 3I
ANSI06000648 V1 EN
Figure 100: RCADir set to 0°
rotated by the set characteristic angle RCADir (φ=ang(3I
0
·cos φ gets larger than the set value.
0
V
RCA = 0°, ROA = 90°
ref
3I
0
) - ang(3V
= ang(3I
0 ref
3I cos
0
en06000648_ansi.vsd
1MRK 502 048-UUS A
·cos φ
0
and the reference voltage. Vref =
0
)
-3V =V
0 ref
Technical manual
)-
0