ABB 615 series Technical Manual page 252

Section 4
Protection functions
246
Faulted Used fault Used
phases current polarizing
voltage
A - B I - I V1
A B
B - C I - I V1
B C
C - A I - I V1
C A
I V
A 1
V
A
I
I
B
C
V
C
A
GUID-75629DC6-2382-4B00-AB14-1A37836DE736-ANSI V2 EN
Figure 121: 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 V
Network rotation direction
Typically, the network rotating direction is counter-clockwise and defined as "ABC". If
the network rotating direction is reversed, meaning clockwise, that is, "ACB", the
equations for calculating the angle difference needs 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 are 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.
Angle difference
ANGLE A _ ( ) V 1
= ϕ −
GUID-D510F5F5-D43B-4D35-8963-CDFA325D8036-ANSI V1 EN
ANGLE B _ ( ) V 1
= ϕ −
GUID-59B67A43-4CE8-45F6-9D2F-F7177CDC7605-ANSI V1 EN
ANGLE C _ ( ) V 1
= ϕ −
GUID-FD2EB060-2CB9-49FE-96A8-4E10384AFF95-ANSI V1 EN
I
A
I
C
V
C
V
B
1MAC059074-MB A
o
( I I ) 30
ϕ − − ϕ +
A B RCA
o
( I I ) 90
ϕ − − ϕ −
RCA
B C
o
( I I ) 150
ϕ − − ϕ +
C A RCA
V
A
V
1
-90°
I - I
B c
-I
C
I
B
V
B
B
1
615 series ANSI
Technical Manual