ABB RED615 Technical Manual page 755

1YHT530004D05 D
615 series
Technical Manual
measured (Table 629). This operation can be adjusted with the setting parameter
Cir current limit.
The blocking status can be read from the monitored data BLKD_I_CIR.
LTC_BLOCK – external block input
With the PCM600 tool configuration possibilities, a desired blocking condition can
be built by connecting an outcome to this input. The blocking status can be read
from the monitored data BLKD_LTCBLK. When activated, this input blocks only
the automatic operation of the regulator by default
automatic modes, the signal activation resets the timer, and the monitored data
BLKD_LTCBLK is not activated.
Extreme positions
This blocking function supervises the extreme positions of the tap changer. These
extreme positions can be adjusted with the setting parameters Raise block tap and
Lower block tap. When the tap changer reaches one of these two positions, the
commands in the corresponding direction are blocked
on the comparison between the Raise block tap and Lower block tap settings,
which direction is blocked
section). This blocking affects both the automatic and manual operation modes.
However, as shown in Table
fully automatic modes. Here "Auto follower" is not a fully automatic mode. The
unconnected position information does not cause the total block of OLATCC, only
the extreme position blocking is not working.
The blocking status can be seen in the generated events.
Fast lowering control
OLATCC provides the fast lowering control in the automatic operation modes.
When the set Runback raise V is exceeded, the regulator gives fast lowering control
pulses until the voltage drops below the specified limit. This fast lowering control
can be seen with the monitoring data TIMER_STS, where the value "Fast lower T
on" indicates this functionality to be active.
To allow the fast lowering operation, Runback raise V has to be set
always to a value higher than the control voltage (U_CTL) plus half
of Band width voltage.
Typically, the blockings are reset when the corresponding limit with the hysteresis
is undershoot or exceeded. Although blocking is reset after undershooting the above-
mentioned limit, the fast lowering control operation continues until the measured
voltage signal difference undershoots half the Band width voltage hysteresis limit
(Figure 397). As a result, normal automatic mode operation is not possible before
this happens.
(Voltage control vs. tap changer moving direction
629, no blocking indication is to be generated in the
Section 9
Control functions
(Table 629). For the fully
(Table 629). Here it depends
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