Siemens SIPROTEC 7ST6, Руководство пользователя, Страница: 126 / 356

2 Functions
126
7ST6 Manual
E50417-G1176-C251-A3
An exception to this is the last reclosure cycle. If all reclosure attempts were unsuc-
cessful, zone Z1 is enabled prior to the last configured reclosure cycle.
Initiation Initiation of the auto reclose function means storing the first trip signal during a network
fault that was generated by a protection function which operates with the auto reclose
function. In case of multiple reclosure, initiation therefore only takes place once with
the first trip command. The detection of the actual circuit breaker position is necessary
for the correct functionality of the auto reclose function.
The initiation is important when the first trip command has not appeared before expiry
of an action time (see margin heading „Action Times, Operating Mode“).
The auto reclose function can be set in such a way that it is only started if the circuit
breaker is ready for at least one TRIP-CLOSE-TRIP cycle when the first trip command
is issued (see also margin heading “Interrogation of Circuit Breaker Ready State“).
For the distance protection and the high-speed overcurrent protection, the user can
configure by parameter settings whether they will cooperate with the auto reclose
function or not, i.e. if they will be able to start the automatic reclosure or not. Starting
of the auto reclose function by the thermal overload protection can also be switched
on and off by parameter settings.
The same applies to the trip commands coupled in externally via binary input and/or
the trip commands generated by the teleprotection via permissive or intertrip signals.
Action Times It is often desirable to neutralize the ready–for–reclosure–state if the short-circuit con-
dition was sustained for a certain time, e.g. because it is assumed that the arc has
burned in to such an extent that there is no longer any chance of automatic arc extinc-
tion during the reclose dead time. For reasons of selectivity also (see above), fre-
quently faults with delayed trip should not lead to reclosure.
For the auto reclose function of the 7ST6, one action time can be set for the 1st cycle
and one for the 2nd to 8th cycle.
The action times are always started by the general starting signal (with logic OR com-
bination of all internal and external protection functions which can start the auto
reclose function). If no trip command is present before the action time expires, the cor-
responding reclosure cycle is not carried out.
The user can set separately for the 1st reclosure cycle and the 2nd to 8th cycle
whether they are allowed to be the first cycle. Following the first general pickup, only
the action times of those cycles that are set such that they may start off the recloser
are considered since the other cycles are not allowed to be the first cycle under any
circumstances. Using the action times and the start permission you can control which
cycles can be run under different command time conditions.
Example 1: 3 cycles are set. Starting of the auto-reclosure is allowed for at least the
first cycle. The action times are set as follows:
• 1st reclosure: T Action = 0.2 s
• From the 2nd reclosure: T Action = 1 s
Since reclosure is ready before the fault occurs, the first trip of a time overcurrent pro-
tection following a fault is fast, i.e. before the end of any action time. The auto reclose
function is started as a result. After unsuccessful reclosure the 2nd cycle would then
become active; but the time overcurrent protection will not trip in this example until
after 0.6 s according to its grading time. The 3rd cycle with its parameters is therefore
now executed. If the trip command appeared more than 1.2 s after the 1st reclosure,
there would be no further reclosure.
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