ABB RELION 620 Series Technical Manual page 481

1MRS757644 F
620 series
Technical Manual
GUID-8E589324-78E1-4E05-8FD9-49607B977DA2 V1 EN
Figure 239: Directional characteristic of MFADPSDE
The residual current is recommended to be measured with accurate
core balance current transformer to minimize the measurement errors,
especially phase displacement. This is especially important, when
high sensitivity of protection is targeted.
The characteristic Tilt angle should reflect the measurement errors,
that is, the larger the measurement errors, the larger the Tilt angle
setting should be. Typical setting value of 5 degrees is recommended.
The detected fault direction is available in the Monitored data view as parameter
DIRECTION.
To adapt the fault direction determination to possible fault direction change during the
fault, for example, during manual fault location process, a cyclic accumulation of sum
admittance phasors is conducted. The duration of this directional evaluation cycle is
Section 4
Protection functions
475