Table of Contents
Advertisement
Functions
2.17 Automatic Reclosure Function (optional)
If the distance protection is operated with one of the signal transmission methods described in Section 2.7 the
signal transmission logic controls the overreaching zone, i.e. it determines whether a non-delayed trip (or
delayed with T1B) is permitted in the event of faults in the overreaching zone (i.e. up to the reach limit of zone
Z1B) at both line ends simultaneously. Whether the automatic reclosure device is ready for reclosure or not is
irrelevant, because the teleprotection function ensures the selectivity over 100% of the line length and fast, si-
multaneous tripping. The same applies for the earth fault-direction comparison protection (Section 2.9).
If, however, the signal transmission is switched off or the transmission path is disturbed, the internal automatic
reclosure circuit can determine whether the overreaching zone (Z1B in the distance protection) is released for
fast tripping. If no reclosure is expected (e.g. circuit breaker not ready) the normal grading of the distance pro-
tection (i.e. fast tripping only for faults in zone Z1) must apply to retain selectivity.
However, fast tripping of the protection may also be desired before reclosure after tripping by other short-circuit
protection functions. For this purpose, every short-circuit protection which can start the automatic reclosure
function has the possibility of initiating non-delayed tripping in at least one stage when the automatic reclosure
function is ready for the first reclosure cycle. Please note, however, that fast, non-selective tripping should be
avoided as long as the differential protection works properly: The distance protection should not trip instanta-
neously as second main protection function, even if reclosing is performed.
Fast tripping before reclosure is also possible with multiple reclosures. Appropriate links between the output
signals (e.g. 2nd reclosure ready: „AR 2.CycZoneRel") and the inputs for enabling/releasing non-delayed
tripping of the protection functions can be established via the binary inputs and outputs or the integrated user-
definable logic functions (CFC).
Mixed Lines Overhead Line/Cable
In the distance protection, it is possible to use the distance zone signals to distinguish between cable and over-
head line faults to a certain extent. The automatic reclosure circuit can then be blocked by appropriate signals
generated by means of the user-programmable logic functions (CFC) if there is a fault in the cable section.
Initiation
Initiation of the automatic reclosure function means storing the first trip signal of a power system fault that was
generated by a protection function which operates with the automatic reclosure function. In case of multiple
reclosure, initiation therefore only takes place once, with the first trip command. This storing of the first trip
signal is the prerequisite for all subsequent activities of the automatic reclosure function. The starting is impor-
tant when the first trip command has not appeared before expiry of an action time (see below under „Action
times").
Automatic reclosure function is not started if the circuit breaker has not been ready for at least one OPEN-
CLOSE-OPEN–cycle at the instant of the first trip command. This can be achieved by setting parameters. For
further information, please refer to „Interrogation of Circuit Breaker Ready State".
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 intertrip signals.
Those protection and monitoring functions in the device which do not respond to short-circuits or similar con-
ditions (e.g. an overload protection) do not initiate the automatic reclosure function because a reclosure will be
of no use here. The circuit breaker failure protection must not start the automatic reclosure function either.
320
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
Advertisement
Table of Contents
