ABB RER670 Applications Manual page 297

1MRK 506 375-UEN A
Railway application RER670 2.2 IEC
Application manual
High Voltage Side
(Load Current) I
L
Low Voltage Side
IEC10000044 V2 EN-US
Figure 123: Signal flow for a single transformer with voltage control
On the HV side, the three-phase current is normally required in order to feed the
three-phase over current protection that blocks the load tap changer in case of over-
current above harmful levels.
The voltage measurement on the LV-side can be made single phase-earth.
However, it shall be remembered that this can only be used in solidly earthed
systems, as the measured phase-earth voltage can increase with as much as a factor
√3 in case of earth faults in a non-solidly earthed system.
The analog input signals are normally common with other functions in the IED for
example, protection functions.
The LV-busbar voltage is designated U
load point voltage U
Automatic voltage control for a single transformer
Automatic voltage control for tap changer, single control TR1ATCC measures the
magnitude of the busbar voltage U
(line voltage drop compensation), this voltage is further used for voltage
regulation.
I ,I ,I
L1 L2 L3
p r
a e
g
T
signals/alarms
n
d
a
a
h
o
position
C
L
3ph or ph-ph or 1ph Current
3ph or ph-ph or 1ph Voltage
Line Impedance R+jX
Load Center
.
L
. If no other additional features are enabled
B
Section 12
IED
raise,lower
BOM
BIM
MIM
TRM
U (Busbar Voltage)
B
UL (Load Point Voltage)
IEC10000044-2-en.vsd
, the load current I
B
Control
and
L
SEMOD159053-73 v6
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