Siemens siprotec 7SA6 User Manual page 371

2nd to 4th
Reclosure Cycle
7SA6 Manual
C53000-G1176-C133-1
If only single-pole reclose cycle are to be allowed, the dead time for three-pole tripping
must be set to ∞. If only three-pole reclose cycle are to be allowed, the dead time for
single-pole tripping must be set to ∞; the protection then trips three-pole for all fault
types.
The dead time after single-pole tripping (if set) $5 7GHDG7ULS (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 is, the longer this time should be due to the recharging of the conductor
capacitances. The typical values are 0.9 s to 1.5 s.
For three-pole tripping (address  $5 7GHDG7ULS) the stability of the network
is the main concern. Since the disconnected line cannot transfer any synchronizing
forces, only a short dead time is often permitted. The usual values are 0.3 s to 0.6 s.
If the device is operating with a synchronism check (refer also to section 6.13), a
longer time may be tolerated under certain circumstances. Longer three-pole dead
times are also possible in radial networks.
In the control mode with PICKUP it is possible to make the dead times dependent on
the type of fault detected by the initiating protection function(s):
address  $5 7GHDG )OW is the dead time after 1-phase starting,
address  $5 7GHDG )OW is the dead time after 2-phase starting,
address  $5 7GHDG )OW is the dead time after 3-phase starting.
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 starting
(fault detection) conditions. The tripping can only be three-pole.
With the setting VWDUWV S $5 applied in address  (9 )/7 02'( when
setting the response to evolving faults (see above under "General", page 6-184), it is
possible to apply a separate dead time $5 7GHDG (9 (address ) for the
three-pole dead time after clearance of the evolving fault. Stability aspects are also
decisive here. Normally the setting constraints are similar to address  $5
7GHDG7ULS.
Under address  $5 &%" &/26( it can be determined whether circuit-breaker
ready must be interrogated before this first reclosure. With the setting <HV, the dead
time may be extended if the circuit-breaker is not ready for a CLOSE–TRIP–cycle
when the dead time expires. At most the dead time can be extended by the &% 7,0(
287; this was set for all reclosure cycles together under address  (see above).
Details about the circuit-breaker monitoring can be found in the function description,
section 6.12.1, under subtitle "Interrogation of Circuit-Breaker Ready", page 6-171.
If there is a danger of stability problems in the network during a three-pole dead time,
you should set address  $5 6\Q5HTXHVW to <HV. 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 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 1R.
If several cycles were selected during the configuration of the scope of functions
(section 5.1), it is possible to set individual reclosure parameters for the 2nd to 4th
cycles. The options are the same as for the 1st cycle. Again only some of the
parameters shown below will be available depending on the selections made during
configuration of the scope of protection function (section 5.1).
Functions
6-189