ABB RER620 Technical Manual page 303

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RER620
Technical Manual
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Figure 153: Simplified CBB diagram
Each CBB has individual Init signals CBB_ and Blk signals CBB_ settings. Therefore,
each initiation line can be used for both initiating and blocking any or all autoreclose shots.
Other conditions that must be fulfilled before any CBB can be initiated are, for example,
the closed position of the circuit breaker.
The autoreclose sequence is implemented by using up to seven CBBs. For example, if the
user wants a sequence of three shots then only the first three CBBs are needed. Using
building blocks instead of fixed shots gives enhanced flexibility, allowing multiple and
adaptive sequences.
Each CBB is identical. The Shot number CBB_ setting defines at which point in the
autoreclose sequence the CBB should be performed, that is, whether the particular CBB is
going to be the first, second, third, fourth or fifth shot.
During the initiation of a CBB, the conditions of initiation and blocking are checked. This
is done for all CBBs simultaneously. Each CBB that fulfils the initiation conditions
requests an execution.
The function also keeps track of shots already performed. That is, at which point the
autoreclose sequence is from shot 1 to lockout. For example, if shots 1 and 2 have already
been performed, only shots 3 to 5 are allowed.
Additionally, the Enable shot jump setting gives two possibilities:
• Only such CBBs that are set for the next shot in the sequence can be accepted for
execution. For example, if the next shot in the sequence should be shot 2, a request
from CBB set for shot 3 is rejected.
• Any CBB that is set for the next shot or any of the following shots can be accepted
for execution. For example, if the next shot in the sequence should be shot 2, also
CBBs that are set for shots 3, 4 and 5 are accepted. In other words, shot 2 can be
ignored.
Init signals CBB_
AND
Blk signals CBB_
Section 5
Control functions
CBB/Shot
execution
297