Load
T1
I
L
T2
I
cc....T2
I
cc....T1
U
B
U
L
I
T1
I
T2
I
C
I
T
2
-
I
C
Load
T1
I
L
T2
I
cc....T2
I
cc....T1
U
B
U
L
I
T1
I
T2
I
T2
I
T1
I
T1
I
C
en06000512.vsd
IEC06000512 V1 EN
Figure 289: Capacitor bank on the LV-side
From figure 289 it is obvious that the two different connections of the capacitor banks
are 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
C
that goes to the HV side will divide
between the two transformers and it will be 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
cc
. Thus, if the actual connection is as in the left figure the
capacitive current I
C
needs to be compensated for regardless of the operating
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:
EQUATION1871 V1 EN (Equation 274)
Thereafter the current I
C
at the actual measured voltage U
B
can be calculated as:
Section 15 1MRK 502 071-UEN -
Control
566 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
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