2 Functions
164
7ST6 Manual
E50417-G1176-C251-A3
The parameters listed below represent important input values for a correct functioning
of the sub-functions:
The circuit breaker tripping time
T CB BREAKTIME
is a parameter supplied by the CB
manufacturer. It comprises the complete trip procedure from trip command (activation
of auxiliary power on the shunt opening release of the circuit breaker) to arc deletion.
The time is set at address
237
T CB BREAKTIME
.
The CB opening time
T CB OPENING
is also a parameter of the circuit breaker. It com-
prises the time span between trip command (activation of auxiliary power on the
trigger of the circuit breaker) and the time of separation of the main contacts. This is
configured at address
238
T CB OPENING
.
The following diagram shows the relation between these times.
Figure 2-47
Display of Circuit-breaker Times
As zero-sequence current criterion the current-flow monitoring
BkrClosed I MIN
(address
251
) is used.
The CB manufacturer defines the relation between the number of operating cycles and
trip current by means of an operating cycle diagram (see example diagram in the func-
tional description of the 2P-procedure). Both vertices of this characteristic in double-
log scale determine the parameterisation of addresses
260
to
263
:
Point P1 is determined by the number of permitted operating cycles (parameter
261
OP.CYCLES AT Ir
) during raised rated current
I
r (parameter
260
Ir-CB
).
Point P2 is determined by the maximum number of operating cycles (parameter
263
OP.CYCLES Isc
) during raised rated fault current
I
sc (parameter
262
Isc-CB
).
For the functional operation of the procedure, the time behaviour of the circuit breaker
via parameter
237
T CB BREAKTIME
and
238
T CB OPENING
must be announced.
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