ABB RELION REX640 Technical Manual page 504

Section 4
Protection functions
498
Io
IRES
Directional
calculation
Uo
URES
RCA_CTL
Residual
calculation
BLOCK
GUID-1FBCBB74-8683-4E03-BE20-F61A65A590E7 V2 EN
Figure 272: Function module diagram
Directional calculation
The Directional calculation module monitors the angle between the operating quantity
(residual current Io) and polarizing quantity (residual voltage Uo). When the angle
between operating quantity and polarizing quantity after considering the
Characteristic angle setting is in the operation sector, the module sends an enabling
signal to Level detector. The directional operation is selected with the Directional
mode setting. Either the "Forward" or "Reverse" operation mode can be selected. The
direction of fault is calculated based on the phase angle difference between the
operating quantity Io and polarizing quantity Uo, and the value (ANGLE) is available
in the monitored data view.
In the phasor diagrams representing the operation of WPWDE, the polarity of the
polarizing quantity (residual voltage Uo) is reversed. Reversing is done by switching
the polarity of the residual current measuring channel (see the connection in the
Protection relay's physical connections section).
If the angle difference lies between -90° to 0° or 0° to +90°, a forward-direction fault
is considered. If the phase angle difference lies within -90° to -180° or +90° to +180°,
a reverse-direction fault is detected. Thus, the normal width of a sector is 180°.
Level
detector
power
Blocking
logic
1MRS759142 C
Timer
OPERATE
t
t
START
Technical Manual
REX640