Directional Residual Current Protection Measuring 3I ·Cos - ABB REC650 Technical Manual

Section 6
Current protection
6.5.7.2
114
Directional residual current protection measuring 3I
φ is defined as the angle between the residual current 3I
jRCADir
Uref = -3U e , that is -3U
0
(φ=ang(3I )-ang(U ) ). RCADir is normally set equal to 0 in a high impedance
0 ref
earthed network with 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
gets larger than the set value.
IEC06000648 V3 EN
Figure 44: RCADir set to 0°
U
ref
3 ⋅ I cos ϕ
0
IEC06000649 V3 EN
Figure 45: RCADir set to -90°
rotated by the set characteristic angle RCADir
0

RCADir = 0 , ROADir
3I
0
ϕ = ang(3I ) ang(3U − )
0 ref
− 3U
3I cos ⋅ ϕ
0
IEC06000648-3-en.vsd

RCADir = − 90 , ROADir = 90
3I
0
ϕ = ang I (3 ) − ang U ( )
0 ref
− 3U
0
IEC06000649_3_en.vsd
1MRK 511 287-UEN A
·cos φ
0
and the reference voltage.
0

= 0
= U
0 ref

Technical manual
·cos φ
0