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2 Functions
A circuit breaker position logic is incorporated in the device (Figure 2-176). Depending
on the type of auxiliary contact(s) provided by the circuit breaker and the method in
which these are connected to the device, there are several alternatives of implement-
ing this logic.
In most cases it is sufficient to furnish the status of the circuit breaker with its auxiliary
contacts via a binary input to the device. This always applies if the circuit breaker is
only switched three-pole. Then the NO auxiliary contact of the circuit breaker is con-
nected to a binary input which must be configured to the input function „>CB 3p
Closed" (No. 379). The other inputs are then not used and the logic is restricted in
principle to simply passing of this input information on.
If the circuit breaker poles can be switched individually, and only a parallel connection
of the NO individual pole auxiliary contacts is available, the relevant binary input (BI)
is allocated to the function „>CB 3p Open" (No. 380). The remaining inputs are again
not used in this case.
If the circuit breaker poles can be switched individually, and the individual auxiliary
contacts are available, an individual binary input should be used for each auxiliary
contact if this is possible and if the device can and should trip single-pole. With this
configuration, the device can process the maximum amount of information. Three
binary inputs are used for this purpose:
• „>CB Aux. L1" (No. 351) for the auxiliary contact of pole L1,
• „>CB Aux. L2" (No. 352) for the auxiliary contact of pole L2,
• „>CB Aux. L3" (No. 353) for the auxiliary contact of pole L3.
The inputs No. 379 and No. 380 are not used in this case.
If the circuit breaker can be switched individually, two binary inputs are sufficient if both
the parallel as well as series connection of the auxiliary contacts of the three poles are
available. In this case, the parallel connection of the auxiliary contacts is routed to the
input function „>CB 3p Closed" (No. 379) and the series connection is routed to the
input function „>CB 3p Open" (No. 380).
Please note that Figure 2-176 shows the complete logic for all connection alternatives.
For each particular application, only a portion of the inputs is used as described above.
The eight output signals of the circuit breaker position logic can be processed by the
individual protection and supplementary functions. The output signals are blocked if
the signals transmitted from the circuit breaker are not plausible: for example, the
circuit breaker cannot be open and closed at the same time. Furthermore, no current
can flow over an open breaker contact.
The evaluation of the measuring quantities is according to the local conditions of the
measuring points (see Section 2.1.4.1 at margin heading „Circuit Breaker Status").
The phase currents are available as measuring quantities. A flowing current excludes
that the circuit breaker is open (exception: a fault between current transformer and
circuit breaker). If the circuit breaker is closed, it may, however, still occur that no
current is flowing. The decisive setting for the evaluation of the measuring quantities
is PoleOpenCurrent (address 1130) for the presence of the currents.
In 7SD5 the position of the circuit breaker poles detected by the device is also trans-
mitted to the remote end device(s). This way the position of the circuit breaker poles
is also recognized by at all other ends. The high-current switch-on-to-fault protection
(see Section 2.13) makes use of this function.
400
7SD5 Manual
C53000-G1176-C169-1
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