ABB RER620 Technical Manual page 119

1MAC309294-MB F
RER620
Technical Manual
Figure 50: Phasors in a single-phase ground fault, phase A to ground, and a
two-phase short circuit, phases B-C, are short-circuited when the
polarizing quantity is the positive-sequence voltage V1
Network rotating direction
Typically, the network rotating direction is counterclockwise and defined as "ABC". If the
network rotating direction is reversed, meaning clockwise, that is, "ACB", the equations
for calculating the angle difference need to be changed. The network rotating direction is
defined with a system parameter Phase rotation. The change in the network rotating
direction affects the phase-to-phase voltages polarization method where the calculated
angle difference needs to be rotated 180 degrees. Also, when the sequence components are
used, which are the positive-sequence voltage or negative-sequence voltage components,
the calculation of the components is affected but the angle difference calculation remains
the same. When the phase-to-ground voltages are used as the polarizing method, the
network rotating direction change has no effect on the direction calculation.
The network rotating direction is set in the relay using the parameter in the
HMI menu: Configuration > System > Phase rotation. The default
parameter value is "ABC".
Section 4
Protection functions
113