ABB RET670 - Page 700

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
tWindowHunt: Setting of the time window for the window hunting function. This
function is activated when the number of contradictory commands to the tap changer
exceeds the specified number given by NoOpWindow within the time tWindowHunt.
NoOpWindow: Setting of the number of contradictory tap changer operations (RAISE,
LOWER, RAISE, LOWER etc.) required during the time window tWindowHunt to
activate the signal HUNTING.
Power
P>: When the active power exceeds the value given by this setting, the output
PGTFWD will be activated after the time delay tPower. It shall be noticed that the
setting is given with sign, which effectively means that a negative value of P> means
an active power greater than a value in the reverse direction. This is shown in figure
290 where a negative value of P> means pickup for all values to the right of the
setting. Reference is made to figure
285 for definition of forward and reverse direction
of power through the transformer.
en06000634_2_en.vsd
P
P>
IEC06000634 V2 EN
Figure 290: Setting of a negative value for P>
P<: When the active power falls below the value given by this setting, the output
PLTREV will be activated after the time delay tPower. It shall be noticed that the
setting is given with sign, which effectively means that, for example a positive value of
P< means an active power less than a value in the forward direction. This is shown in
figure 291 where a positive value of P< means pickup for all values to the left of the
Section 3 1MRK504116-UUS C
IED application
694
Application manual