ABB RELION 620 Series Technical Manual page 351

1MAC504801-IB E
620 series ANSI
Technical Manual
V2
VG
VN
Directional
detector
I2
IG
IN
RCA_ CTL
Low level
blocking
BLOCK
GUID-C8755615-9FDA-41DD-9245-DBA7EC6A77CB-ANSI V1 EN
Figure 155: Functional module diagram
Directional detector
When "Neg. seq. volt." selection is made using Pol signal Sel, the Directional detector
module compares the angle of the negative-sequence current (I2) to the negative-sequence
voltage (-V2). Using the negative-sequence voltage angle as the reference, the negative-
sequence current angle is compared to the Characteristic angle setting. If the angle
difference is within the operating sector selected by Direction mode setting, the Enable
signal is sent to Timer.
The value of Characteristic angle should be chosen in such way that all
the faults in the operating direction are seen in the operating zone and all
the faults in the opposite direction are seen in the backward zone.
The operating sector is defined by the settings Max forward angle, Max reverse angle, Min
forward angle and Min reverse angle. The options that can be selected for Directional
mode settings are "Forward" and "Reverse".
Characteristic angle is also known as Relay Characteristic Angle RCA, Relay Base Angle
or Maximum Torque Line.
Timer
t
Blocking
logic
Protection functions
DIRECTION
RELEASE
Section 4
345