ABB Relion REC670, Applications Manual

Page: 456 / 658

A combination of line voltage drop compensation and parallel control with the negative
reactance method is possible to do simply by adding the required
Rline values and the
required Xline values separately to get the combined impedance. However, the line
drop impedance has a tendency to drive the tap changers apart, which means that the
reverse reactance impedance normally needs to be increased.
Load voltage adjustment (LVA)
LVAConst1 : Setting of the first load voltage adjustment value. This adjustment of the
target value VSet is given in percent of VBase .
LVAConst2 : Setting of the second load voltage adjustment value. This adjustment of
the target value VSet is given in percent of VBase .
LVAConst3 : Setting of the third load voltage adjustment value. This adjustment of the
target value VSet is given in percent of VBase .
LVAConst4 : Setting of the fourth load voltage adjustment value. This adjustment of the
target value VSet is given in percent of VBase .
VRAuto : Setting of the automatic load voltage adjustment. This adjustment of the target
value VSet is given in percent of VBase , and it is proportional to the load current with
the set value reached at the nominal current I2Base .
RevAct
OperationRA : This setting enables/disables the reverse action partial blocking function.
tRevAct : After the reverse action has picked up, this time setting gives the time during
which the partial blocking is active.
RevActLim : Current threshold for the reverse action activation. This is just one of two
criteria for activation of the reverse action partial blocking.
Tap changer control (TCCtrl)
Iblock : Current setting of the over current blocking function. In case, the transformer is
carrying a current exceeding the rated current of the tap changer for example, because
of an external fault. The tap changer operations shall be temporarily blocked. This
function typically monitors the three phase currents on the HV side of the transformer.
DayHuntDetect : Setting of the number of tap changer operations required during the
last 24 hours (sliding window) to activate the signal DAYHUNT
HourHuntDetect : Setting of the number of tap changer operations required during the
last hour (sliding window) to activate the signal HOURHUNT
Section 14
1MRK 511 401-UUS A
Control
450 Bay control REC670 2.2 ANSI
Application manual