Siemens Siprotec 7VK61 Manual page 57

Address 3408 T-Start MONITOR monitors the reaction of the circuit breaker after a trip command. If the CB
has not opened during this time (from the beginning of the trip command), the automatic reclosure is blocked
dynamically. The criterion for circuit breaker opening is the position of the circuit breaker auxiliary contact or
the disappearance of the trip command. If a circuit breaker failure protection (internal or external) is used on
the feeder, this time should be shorter than the delay time of the circuit breaker failure protection so that no
reclosure takes place if the circuit breaker fails.
Configuring the Automatic Reclosing Function
This configuration concerns the interaction between the protection and supplementary functions of the device
and the auto reclose function. Here you can select which device functions will start the automatic reclosing
function and which not.
Address 3425
For the functions which are to start the automatic reclosing function, the corresponding address is set to YES,
for the others to NO. The other functions cannot start the automatic reclosing function because reclosing is not
relevant here.
Forced three-pole trip
If a blocking of the auto-reclosure occurs during the dead time of a 1-pole cycle without a previous 3-pole trip
command, the breaker remains open at one pole. With address 3430 AR TRIP 3pole it is possible to deter-
mine that the tripping logic of the device issues a three-pole trip command in this case (pole discrepancy pre-
vention for the CB poles). Set this address to YES if the CB can be tripped single-pole and if it has no pole dis-
crepancy protection. Nevertheless, the device pre-empts the pole discrepancy supervision of the CB because
the forced three-pole trip of the device is immediately initiated as soon as the reclosure is blocked following a
single-pole trip or if the CB auxiliary contacts report an implausible breaker state (see also Section 2.2 at margin
heading „Processing the circuit breaker auxiliary contacts"). The forced three-pole trip is also activated when
only three-pole cycles are allowed, but a single-pole trip is signalled externally via a binary input.
The forced three-pole trip is unnecessary if only a common three-pole control of the CB is possible.
Dead line check / reduced dead time
Under address 3431 the dead line check or the reduced dead time function can be activated. Either the one or
the other can be used as the two options are contradictory. The voltage transformers must be connected to the
line side of the circuit breaker if either of these modes is to be used. If this is not the case or if neither of the
two functions is used, set DLC or RDT = WITHOUT. If the adaptive dead time is used (see below), the param-
eters mentioned here are omitted because the adaptive dead time implies the properties of the reduced dead
time.
DLC or RDT = DLC means that the dead line check of the line voltage is used. This only enables reclosure
after it becomes apparent that the line is dead. In this case, the phase-earth voltage limit is set in address 3441
U-dead< below which the line is considered voltage-free (disconnected). The setting is applied in Volts sec-
ondary. This value can be entered as a primary value when parameterising with a PC and DIGSI. Address 3438
T U-stable determines the measuring time available for determining the no-voltage condition. Address 3440
is irrelevant here.
DLC or RDT = RDT means that the reduced dead time is used. This is described in detail in Section 2.2 at
margin heading „Reduced Dead Time (RDT)". In this case the setting under address 3440 U-live> deter-
mines the limit voltage, Phase–Earth, 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. Address 3441 is irrelevant here.
SIPROTEC, 7VK61, Manual
C53000-G1176-C159-3, Release date 05.2009
AR w/ BackUpO/C, i.e. with time overcurrent protection
2.2 Automatic reclosure function (optional)
Functions
57