ABB Relion 670 series, Техническое руководство

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DB1, transformers with positive voltage deviation, V
di
, are disregarded. Thus in the example above,
the calculated no-load voltage for T3, although above DB1, would not be considered in this case.
Thus in the example above, the calculated no-load voltage for T3, although above DB1, would not
be considered for tapping in this case.
It is possible to avoid simultaneous tapping, and to distribute tapping actions evenly among the
parallel transformers in a busbar group. This is a selected by a setting parameter, and the
algorithm in the TR8ATCC (90) function will then select the transformer with the greatest voltage
deviation V
di
to tap first that is, after time delay t1. Thereafter, the transformer with the then
greatest value of V
di
amongst the remaining transformers in the group will tap after a further time
delay t2, and so on. This is made possible as the calculation of I
cc
is updated every time the
measured values are exchanged on the horizontal communication (every 300 ms). If two
transformers have equal magnitude of V
di
, then there is a predetermined order governing which
one is going to tap first.
Logic diagrams
SEMOD158887-166 v1
AND
AND
AND
AND
OR
OR
<
V
L
V1 INNER DB
>
<
V1 DB
V2 DB
>
V
B
OR
AUTO
a
b
a<b
a
b
a>b
a
b
a<b
a
b
a>b
>
a
b
a>b
AND
VRAISE
VLOWER
V2 INNER DB
V MAX
FSD
en06000509_ansi.vsd
ANSI06000509 V1 EN-US
Figure 465: Simplified logic for automatic control in single mode operation
Section 14 1MRK 502 066-UUS B
Control
876
Technical manual