2 Functions
230
7SA522 Manual
C53000-G1176-C155-3
Each short circuit protection function can be parameterized as to whether it should
operate with the automatic reclose function or not i.e. whether it should start the
reclose function or not. The same goes for external trip commands applied via binary
input and/or the trip commands generated by the teleprotection via permissive or in-
tertrip signals.
Those protection and monitoring functions in the device which do not respond to short-
circuits or similar conditions do not initiate the automatic reclosure function because a
reclosure will be of no use here. For 7SA522 this is e.g. the overvoltage protection.
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. Also for the sake of selectivity (see above), faults
that are usually cleared after a time delay should not lead to reclosure. It is therefore
recommended to use action times in conjunction with the distance protection.
The automatic reclosure function of the 7SA522 can be operated with or without action
times (configuration parameter $5FRQWUROPRGH, address , see section
2.1.1.2). No starting signal is necessary from the protection functions or external pro-
tection devices that operate without action time. Starting takes place as soon as the
first trip command appears.
When operation with action time, an action time is available for each reclose 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 automatic
reclosure function). If no trip command is present before the action time expires, the
corresponding reclose cycle is not carried out.
For each reclosure cycle, you may set whether or not it allows the initiation. 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. By means of the action times and the permis-
sion to start the recloser (permission to be the first cycle that is executed) it is possible
to determine which reclose cycles are executed depending on the time used by the
protection function to trip.
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;
• 2nd Reclosure: T Action = 0.8 s;
• 3rd Reclosure: T Action = 1.2 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 automatic
reclosure function is therefore started (the first cycle is initiated). After unsuccessful
reclosure the 2nd cycle would then become active; but the time overcurrent protection
would not trip in this example until after 1s according to its grading time. Since the
action time for the second cycle was exceeded here, it is blocked. The 3rd cycle with
its parameters is therefore now. If the trip command only appeared more than 1.2s
after the 1st reclosure, there would have been no further reclosure.
Example 2
: 3 cycles are set. Starting is only allowed for the first. The action times are
set as in example 1. The first protection trip takes place 0.5s after starting. Since the
action time for the 1st cycle has already expired at this time, this cannot start the au-
tomatic reclosure function. As the 2nd and 3rd cycles are not permitted to start the
reclose function they will also not be initiated. Therefore no reclosure takes place as
no starting took place.
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