ABB Relion REC670 Applications Manual page 326

Section 13
Control
Table 36: Blockings without setting possibilities
Activation
Disconnected
transformer
(automatically reset)
No Master/More than
one Master
(automatically reset)
One transformer in a
parallel group switched
to manual control
(automatically reset)
Communication error
(COMMERR)
(automatic deblocking)
Circulating current method
Mutual blocking
When one parallel instance of voltage control TR8ATCC blocks its operation, all other
TR8ATCCs working in parallel with that module, shall block their operation as well. To achieve
this, the affected TR8ATCC function broadcasts a mutual block to the other group members
via the horizontal communication. When mutual block is received from any of the group
members, automatic operation is blocked in the receiving TR8ATCCs that is, all units of the
parallel group.
The following conditions in any one of TR8ATCCs in the group will cause mutual blocking when
the circulating current method is used:
• Over-Current
• Total block via settings
• Total block via configuration
• Analog input error
• Automatic block via settings
• Automatic block via configuration
320
Type of blocking Description
Auto Block Automatic control is blocked for a transformer
when parallel control with the circulating current
method is used, and that transformer is
disconnected from the LV-busbar. (This is under
the condition that the setting
selected
Otherwise the transformer will get into the state
Homing). The binary input signal DISC in TR1ATCC
or TR8ATCC function shall be used to supervise if
the transformer LV circuit breaker is closed or not.
The outputs TRFDISC and AUTOBLK will be
activated . Blocking will be removed when the
transformer is reconnected (input signal DISC set
back to zero).
Auto Block Automatic control is blocked when parallel control
with the master-follower method is used, and the
master is disconnected from the LV-busbar. Also
if there for some reason should be a situation
with more than one master in the system, the
same blocking will occur. The binary input signal
DISC in TR1ATCC or TR8ATCC function shall be
used to supervise if the transformer LV circuit
breaker is closed or not. The outputs TRFDISC,
MFERR and AUTOBLK will be activated. The
followers will also be blocked by mutual blocking
in this situation. Blocking will be removed when
the transformer is reconnected (input signal DISC
set back to zero).
Auto Block When the setting
automatic control will be blocked when parallel
control with the master-follower or the circulating
current method is used, and one of the
transformers in the group is switched from auto
to manual. The output AUTOBLK will be activated.
Auto block If the horizontal communication (GOOSE) for any
one of TR8ATCCs in the group fails it will cause
blocking of automatic control in all TR8ATCC
functions, which belong to that parallel group.
This error condition will be reset automatically
when the communication is re-established. The
outputs COMMERR and AUTOBLK will be set.
OperHoming is
Off for the disconnected transformer.
OperationAdapt is " Off ",
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Application manual