ABB REG670 - Page 588

Operation
FSDMode: This setting enables/disables the fast step down function. Enabling can be
for automatic and manual control, or for only automatic control alternatively.
tFSD: Time delay to be used for the fast step down tapping.
Voltage
UseCmdUSet: This setting enabled makes it possible to set the target voltage level via
IEC 61850 set point command. This, in turn, makes the setting USet redundant.
USet: Setting value for the target voltage, to be set in percent of UBase.
UDeadband: Setting value for one half of the outer deadband, to be set in percent of
UBase. The deadband is symmetrical around USet, see section "Automatic voltage
control for a single transformer", figure 282. In that figure UDeadband is equal to DU.
The setting is normally selected to a value near the power transformer’s tap changer
voltage step (typically 75 - 125% of the tap changer step).
UDeadbandInner: Setting value for one half of the inner deadband, to be set in percent
of UBase. The inner deadband is symmetrical around USet, see section "Automatic
voltage control for a single transformer",figure 282. In that figure UDeadbandInner is
equal to DU
in
. The setting shall be smaller than UDeadband. Typically the inner
deadband can be set to 25-70% of the UDeadband value.
Umax: This setting gives the upper limit of permitted busbar voltage (see section
"Automatic voltage control for a single transformer", figure 282). It is set in percent of
UBase. If OVPartBk is set to Auto&ManBlock, then busbar voltages above Umax will
result in a partial blocking such that only lower commands are permitted.
Umin This setting gives the lower limit of permitted busbar voltage (see section
"Automatic voltage control for a single transformer", figure 282). It is set in percent of
UBase. If UVPartBk is set to Auto Block orAuto&ManBlock, then busbar voltages
below Umin will result in a partial blocking such that only raise commands are
permitted.
Ublock: Voltages below Ublock normally correspond to a disconnected transformer
and therefore it is recommended to block automatic control for this condition (setting
UVBk). Ublock is set in percent of UBase.
Time
t1Use: Selection of time characteristic (definite or inverse) for t1.
t1: Time delay for the initial (first) raise/lower command.
t2Use: Selection of time characteristic (definite or inverse) for t2.
t2: Time delay for consecutive raise/lower commands. In the circulating current
method, the second, third, etc. commands are all executed with time delay t2
independently of which transformer in the parallel group that is tapping. In the master-
Section 15 1MRK 502 071-UEN -
Control
582 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual