ABB ret650 - Page 199

Automatic voltage control for tap changer, TR1ATCC for single control and
TR8ATCC for parallel control function block has three inputs I3P1, I3P2 and U3P2
corresponding to HV-current, LV-current and LV-voltage respectively. These
analog quantities are fed to the IED via the transformer input module, the Analog
to Digital Converter and thereafter a Pre-Processing Block. In the Pre-Processing
Block, a great number of quantities for example, phase-to-phase analog values,
sequence values, max value in a three phase group etc., are derived. The different
function blocks in the IED are then “subscribing” on selected quantities from the
pre-processing blocks. In case of TR1ATCC or TR8ATCC, there are the following
possibilities:
SEMOD159053-65 v6
• I3P1 represents a three-phase group of phase current with the highest current
in any of the three phases considered. As only the highest of the phase current
is considered, it is also possible to use one single-phase current as well as two-
phase currents. In these cases, the currents that are not used will be zero.
• For I3P2 and U3P2 the setting alternatives are: any individual phase current/
voltage, as well as any combination of phase-phase current/voltage or the
positive sequence current/voltage. Thus, single-phase as well as, phase-phase
or three-phase feeding on the LV-side is possible but it is commonly selected
for current and voltage.
L
o
a
d
T
a
p
C
h
a
n
g
e
r
raise,lower
signals/alarms
position
BOM
MIM
IED
IL1,IL2,IL3
TRM
3ph or ph-ph or 1ph Current
High Voltage Side
(Load Current) IL
Low Voltage Side
Line Impedance R+jX
U
B
(Busbar Voltage)
Load Center
UL (Load Point Voltage)
IEC10000044-2-en.vsd
BIM
3ph or ph-ph or 1ph Voltage
IEC10000044 V2 EN-US
Figure 70: Signal flow for a single transformer with voltage control
1MRK 504 169-UEN A Section 11
Control
Transformer protection RET650 2.2 IEC 193
Application manual