ABB RED615 Technical Manual page 222

Section 4
Protection functions
216
I U
A 1
U
A
I
I
B
C
U
C
A
GUID-1937EA60-4285-44A7-8A7D-52D7B66FC5A6 V3 EN
Figure 110: Phasors in a single-phase earth 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 U
Network rotation direction
Typically, the network rotatiion direction is counterclockwise and defined as
"ABC". If the network rotation direction is reversed, meaning clockwise, that is,
"ACB", the equations for calculating the angle difference need to be changed. The
network rotation direction is defined with a system parameter Phase rotation. The
change in the network rotation direction affects the polarization method of the phase-
to-phase voltages where the calculated angle difference needs to be rotated 180
degrees. Also, when the sequence components are used, the calculation of the
components is affected but the angle difference calculation remains the same. The
sequence components are the positive-sequence voltage or negative-sequence
voltage components. When the phase-to-ground voltages are used as the polarizing
method, the network rotation direction change has no effect on the direction
calculation.
The network rotation direction is set in the IED using the parameter
in the HMI menu: Configuration/System/Phase rotation. The
default parameter value is "ABC".
I
C
U
C
U
B
1YHT530004D05 D
U
A
U
1
-90°
I
A
I - I
B c
-I
C
I
B
U
B
B
1
Technical Manual
615 series