ABB REG670 Applications Manual page 583

1MRK 502 071-UEN -
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
transformer", except that horizontal communication messages are still sent and
received, but the received messages are ignored. TR8ATCC is at the same time also
automatically excluded from the parallel group.
Disabling of blockings in special situations
When the Automatic voltage control for tap changer TR1ATCC for single control and
TR8ATCC for parallel control, function block is connected to read back information
(tap position value and tap changer in progress signal) it may sometimes be difficult
to find timing data to be set in TR1ATCC or TR8ATCC for proper operation.
Especially at commissioning of for example, older transformers the sensors can be
worn and the contacts maybe bouncing etc. Before the right timing data is set it may
then happen that TR1ATCC or TR8ATCC becomes totally blocked or blocked in auto
mode because of incorrect settings. In this situation, it is recommended to temporarily
set these types of blockings to alarm instead until the commissioning of all main items
are working as expected.
Tap Changer position measurement and monitoring
Tap changer extreme positions
This feature supervises the extreme positions of the tap changer according to the
settings LowVoltTap and HighVoltTap. When the tap changer reaches its lowest/
highest position, the corresponding ULOWER/URAISE command is prevented in
both automatic and manual mode.
Monitoring of tap changer operation
The Tap changer control and supervision, 6 binary inputs TCMYLTC or 32 binary
inputs TCLYLTC output signal URAISE or ULOWER is set high when TR1ATCC or
TR8ATCC function has reached a decision to operate the tap changer. These outputs
from TCMYLTC and TCLYLTC function blocks shall be connected to a binary
output module, BOM in order to give the commands to the tap changer mechanism.
The length of the output pulse can be set via TCMYLTC or TCLYLTC setting
parameter tPulseDur. When an URAISE/ULOWER command is given, a timer ( set
by setting tTCTimeout ) (settable in PST/local HMI) is also started, and the idea is then
that this timer shall have a setting that covers, with some margin, a normal tap changer
operation.
Usually the tap changer mechanism can give a signal, "Tap change in progress",
during the time that it is carrying through an operation. This signal from the tap
changer mechanism can be connected via a BIM module to TCMYLTC or TCLYLTC
input TCINPROG, and it can then be used by TCMYLTC or TCLYLTC function in
three ways, which is explained below with the help of figure 292.
Section 15
Control
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