ABB RELION REX640 Technical Manual page 1198

Section 5
Protection related functions
1192
Characteristic angle/
Max torque line
Min forward
angle
Non-operating area
Min operate voltage
Max reverse
angle
Min operate current
GUID-8324BABA-0041-4738-B1CF-8BDC0687E475 V1 EN
Figure 645: Configurable directional setting for Zero seq. volt. (residual voltage)
using the Pol quantity setting
The Characteristic angle setting is done based on method of grounding employed in
the network. For example, in case of an isolated network, Characteristic angle is set
to -90°, and in case of a compensated network, Characteristic angle is set to 0° and 60°
for solidly grounded systems. In general Characteristic angle is selected so that it
matches close to the expected fault angle value, which results in maximum sensitivity.
Characteristic angle can be set anywhere between -179° to +180°. The figures show
examples of the operating area with RCA set to +60° and -90°, respectively.
RCA = 0 deg
-U ( polarizing quantity)
0
Forward
area
I ( operating quantity)
0
Max forward
angle
Non-operating area
Min reverse
angle
Backward
area
1MRS759142 C
Zero torque line
Technical Manual
REX640