Functions
6-173
7SA522 Manual
C53000-G1176-C119-2
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)
(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 capaci-
tances. The typical values are 0.9 s to 1.5 s.
For three-pole tripping (address
) 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, a longer time may
be tolerated under certain circumstances. Longer three-pole dead times are also pos-
sible in radial networks.
In the control mode
it is possible to make the dead times dependent on
the type of fault detected by the initiating protection function(s):
is the dead time after 1-phase starting,
is the dead time after 2-phase starting,
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)
. The
tripping
can only be three-pole.
applied in address
when
setting the response to sequential faults (see above under "General", page 168), it is
possible to apply a separate dead time
(address
) for the
three-pole dead time after clearance of the sequential fault. Stability aspects are also
decisive here. Normally the setting constraints are similar to address
Under address
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 MAKE–BREAK–cycle
when the dead time expires. At most the dead time can be extended by the
; 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 6.11.1, under subtitle "Interrogation of circuit-breaker ready state", page 155.
If there is a danger of stability problems in the network during a three-pole
dead time, you should set address
<HV
. In this case a
check is made before every reclosure following three-pole tripping whether the voltag-
es 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 de-
vice 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
.
2nd to 4th
reclosure cycle
If several cycles were selected during the configuration of the scope of functions (sec-
tion 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).
For the 2nd cycle:
Address
; determines if starting in 2nd cycle is allowed at all
Summary of Contents for siprotec 7SA522
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