Siemens siprotec 7SD5 User Manual page 305

The dead times are determined by the reclosure command of the device at the line
end with the defined dead times. In cases where this reclosure command does not
appear, e.g. because the reclosure was in the meantime blocked at this end, the readi-
ness of the local device must return to the quiescent state at some time. This takes
place after the maximum wait time T-MAX ADT (address 3434). This must be long
enough to include the last reclosure of the remote end. In the case of single cycle re-
closure, the sum total of maximum dead time plus reclaim time of the other device is
sufficient. In the case of multiple reclosure the worst case is that all reclosures of the
other end except the last one are unsuccessful. The time of all these cycles must be
taken into account. To save having to make exact calculations, it is possible to use the
sum of all dead times and all protection operating times plus one reclaim time.
Under address 3435 ADT 1p allowed it can be determined whether single-pole trip-
ping is allowed (on condition that single-pole tripping is possible). If NO, the protection
trips three-pole for all fault types. If YES, the possible tripping situations of the starting
protective functions are decisive.
Under address 3436 ADT CB? CLOSE it can be determined whether circuit breaker
ready is interrogated before reclosure after an adaptive dead time. With the setting
YES, the dead time may be extended if the circuit breaker is not ready for a CLOSE–
OPEN–cycle when the dead time expires. The maximum extension that is possible is
the circuit breaker monitoring time; this was set for all reclosure cycles under address
3409 (see above). Details about the circuit breaker monitoring can be found in the
function description, Section 2.15, at margin heading „Interrogation of the Circuit
Breaker Ready State".
If there is a danger of stability problems in the network during a three-pole reclosure
cycle, you should set address 3437 ADT SynRequest to YES. In this case, the volt-
ages from line and busbar are checked after a three-pole trip and before reclosure to
determine if sufficient synchronism exists. This is only done on condition that either the
internal synchronism and voltage check functions are available, or that an external
device is available for synchronism check. If only single-pole reclose cycles are exe-
cuted or no stability problems are expected during three-pole dead times (e.g. due to
closely meshed networks or in radial networks), set address 3437 to NO.
Addresses 3438 and 3440 are only significant if the voltage-controlled adaptive dead
time is used. 3440 U-live> is the phase-earth voltage limit above which the line is
considered to be fault-free. The setting must be smaller than the lowest expected op-
erating voltage. The setting is applied in Volts secondary. This value can be entered
as a primary value when parameterizing with a PC and DIGSI
stable establishes the measuring time used to determine that the line is fault-free
with this returning voltage. It should be longer than any transient oscillations resulting
from line energization.
1st Reclosure If working on a line with adaptive dead time, no further parameters are needed for the
Cycle individual reclose cycles in this case. All the following parameters assigned to the in-
dividual cycles are then superfluous and inaccessible.
Address 3450 1.AR:
ured with action time in the operating mode, i. e. if during configuration of the protec-
tion functions (see Section 2.1.1.3) address 134 AR control mode = Pickup w/
Tact or Trip w/ Tact was set (the first setting only applies to three-pole tripping).
It determines whether automatic reclosure should be started at all with the first cycle.
This address is included mainly for the sake of uniformity of the parameters for every
reclosure attempt and is set to YES for the first cycle. If several cycles are performed,
you can (at AR control mode = Pickup ...) set this parameter and different
action times to control the effectiveness of the individual cycles. Notes and examples
can be found in Section 2.15 at margin heading „Action Times".
7SD5 Manual
C53000-G1176-C169-1
2.15 Automatic Reclosure Function (optional)
START is only available if the automatic reclosure is config-
®
. Address 3438 T U-
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