ABB REC670 Applications Manual page 388

Section 14
Control
382
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:
• 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.
High Voltage Side
(Load Current) I
L
Low Voltage Side
IEC10000044 V2 EN-US
Figure 169: 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
I ,I ,I
L1 L2 L3
p r
e
a
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
1MRK 511 401-UEN A
IED
raise,lower
BOM
BIM
MIM
TRM
U (Busbar Voltage)
B
UL (Load Point Voltage)
IEC10000044-2-en.vsd
Bay control REC670 2.2 IEC
Application manual
SEMOD159053-65 v6