ABB Relion 670 Series Applications Manual page 355

1MRK 511 358-UUS A
T1
V
B
V
L
ANSI06000512 V1 EN-US
Figure 171: Capacitor bank on the LV-side
From figure
completely the same regarding the currents in the primary network. However the CT measured
currents for the transformers would be different. The capacitor bank current may flow entirely to
the load on the LV side, or it may be divided between the LV and the HV side. In the latter case, the
part of I
measured with opposite direction for T2 and T1. This in turn would be misinterpreted as a
circulating current, and would upset a correct calculation of I
in the left figure the capacitive current I
conditions and in ATCC this is made numerically. The reactive power of the capacitor bank is given
as a setting Q1, which makes it possible to calculate the reactive capacitance:
V
X =
C
Q1
EQUATION1981-ANSI V1 EN-US
Thereafter the current I
Application manual
I cc....T2
T2
I
cc....T1
I
I
T2
T1
I
C
I
T1
I L
Load
171 it is obvious that the two different connections of the capacitor banks are
that goes to the HV side will divide between the two transformers and it will be
C
2
at the actual measured voltage V
C
T1
I
V
B
V
L
. Thus, if the actual connection is as
cc
needs to be compensated for regardless of the operating
C
can be calculated as:
B
I cc....T2
T2
I cc....T1
I
T2
T1
I I
T1 T2
I
C
I L
Load
en06000512_ansi.vsd
(Equation 125)
Section 13
Control
349