Siemens siprotec 7SA522 - Page 251

2.13 Automatic reclosure function (optional)
251
7SA522 Manual
C53000-G1176-C155-3
The dead time after single-pole tripping (if set) $57GHDG7ULS (address )
should be long enough for the short-circuit arc to be extinguished and the surrounding
air to be de-ionized so that the reclosure promises to be successful. The longer the
line, the longer is this time due to the charging of the conductor capacitances. Con-
ventional values are 0.9 s to 1.5 s.
For three-pole tripping (address  $57GHDG7ULS) the stability of the network
is the main concern. Since the de-energized line cannot develop synchronizing forces,
only short dead times are allowed. The usual values are 0.3 s to 0.6 s. If the device is
operating with a synchronism check (see Section 2.14), a longer time may be tolerated
under certain circumstances. Longer three-pole dead times are also possible in radial
networks.
For $5FRQWUROPRGH = ZLWK3,&.83 it is possible to make the dead times
dependent on the type of fault detected by the initiating protection function(s).
Table 2-9 AR control mode = with PICKUP ...
If the dead time is to be the same for all types of faults, set all three parameters the
same. Note that these settings only cause different dead times for different pickups.
The tripping can only be three-pole.
With the setting in address  (9)/702'( VWDUWVS$5, it is possible to
apply a separate dead time $57GHDG(9 (address ) for the three-pole
dead time after clearance of the sequential fault (see above at heading “General”).
Stability aspects are also decisive here. Normally the setting constraints are similar to
address  $57GHDG7ULS.
Under address  $5&%"&/26( it can be determined whether the readiness
of the circuit-breaker ("circuit breaker ready”)is interrogated before this first reclosure.
With the setting <(6, the dead time may be extended if the circuit-breaker is not ready
for a CLOSE–TRIP–cycle when the dead time expires. The maximum extension that
is possible is the circuit-breaker monitoring time; this time was set for all reclosure
cycles together under address  &%7,0(287 (see above). Details about the
circuit-breaker monitoring can be found in the function description, section 2.13, at
margin heading “Interrogation of 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  $56\Q5HTXHVW to <(6. In this case a check
is made before every reclosure following three-pole tripping whether the voltages of
the feeder and busbar are sufficiently synchronized. This is applicable on condition
that either the internal synchronism and voltage check function is available or that an
external device is available for synchronism check. If only single-pole reclose cycles
are executed or no stability problems are expected during three-pole dead times (e.g.
due to closely meshed networks or in radial networks), set address  to 12.
2nd to 4th Reclo-
sure Cycle
If several cycles have been set in the configuration of the function scope, you can set
individual reclosure parameters for the 2nd to 4th cycles. The same options are avail-
able as for the first cycle. Again only some of the parameters shown below will be
available depending on the selections made during configuration of the scope of pro-
tection function.
3453 1.AR Tdead 1Flt is the dead time after 1-phase pickup,
3454 1.AR Tdead 2Flt is the dead time after 2-phase pickup,
3455 1.AR Tdead 3Flt is the dead time after 3-phase pickup,