Siemens Siprotec 7VK61 Manual page 59

pected 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 operating voltage. The setting is applied in Volts secondary. This value can
be entered as a primary value when parameterising with a PC and DIGSI. Address 3438 T U-stable estab-
lishes 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.
The adaptive dead time is only available if address 106 VT CONNECTION is set to 3phase.
1st reclosure cycle
If working on a line with adaptive dead time, no further parameters are needed for the individual reclose cycles
in this case. All the following parameters assigned to the individual cycles are then superfluous and inaccessi-
ble.
Address 3450 1.AR:
operating mode, i. e. if during configuration of the protective functions (see Section 2.1.1.2) 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 due to the 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 are listed in
Section 2.2 at margin heading „Action times".
The action time 1.AR: T-ACTION (address 3451) is the timeframe after initiation (fault detection) by any pro-
tective function which can start the automatic reclosure function within which the trip command must appear. If
no trip command is issued until the action time has expired, there is no reclosure. Depending on the configu-
ration of the protective functions, the action time may also be omitted; this applies especially when an initiating
protective function has no fault detection signal.
Depending on the configured operating mode of the automatic reclosure (address 134 AR control mode)
only address 3456 and 3457 (if AR control mode = with TRIP...) are available or address 3453 to 3455
(if AR control mode = with PICKUP ...).
In AR control mode = with TRIP ... you can set different dead times for single-pole and three-pole
reclose cycles. Whether single-pole or three-pole tripping is triggered depends solely on the initiating protective
functions. Single-pole tripping is of course only possible if the device and the corresponding protective function
are also capable of single-pole tripping:
Table 2-1
3456 1.AR Tdead1Trip
3457 1.AR Tdead3Trip
If you only want to allow a single-pole reclose cycle, set the dead time for three-pole tripping to ∞. If you only
want to allow a three-pole reclose cycle, set the dead time for single-pole tripping to ∞, the protection then trips
three-pole for each fault type.
The dead time after single-pole tripping (if set) 1.AR Tdead1Trip (address 3456) 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.
Conventional values are 0.9 s to 1.5 s.
For three-pole tripping (address 3457 1.AR Tdead3Trip) the network stability is the main concern. Since the
disconnected line cannot transfer any synchronising forces, only a short dead time is often permitted. Usual
values are 0.3 s to 0.6 s. If the device is operating with a synchronism check (compare Section 2.4), a longer
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
START is only available if the automatic reclosure is configured with action time in the
AR control mode = with TRIP...
is the dead time after single-pole tripping,
is the dead time after three-pole tripping.
2.2 Automatic reclosure function (optional)
Functions
59