2 Functions
132
7ST6 Manual
E50417-G1176-C251-A3
The blocking duration following Manual-Close detection
T-BLOCK MC
(address
3423
)
must guarantee the circuit breaker to open and close reliably (0.5 s to 1 s). If a fault is
detected by a protection function within this time after closing of the circuit breaker was
detected, no reclosure takes place and a final trip command is issued. If this is not de-
sired, address
3423
is set to 0.
Address
3416
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 disappear-
ance 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.
Configuration of
Auto-Reclosure
This configuration concerns the interaction between the protection and supplementary
functions of the device and the auto reclose function. Here you can select which func-
tions of the device are to start the auto reclose function, and which not (see Table 2-4).
Table 2-4
Settings for configuring the auto reclose function
For the functions which are to start the auto-reclosure function, the corresponding
address is set to
YES
, for the others to
NO
. The other functions, e.g. overvoltage pro-
tection, circuit breaker failure protection, overcurrent protection, defrosting protection
cannot start the automatic reclosure because reclosure is of little use here.
The thermal overload protection is a special case in this context. It is provided with a
separate auto reclose function, the thermal auto reclosure. This auto reclose function
can be switched
ON
or
OFF
with the parameter
3450
AUTO-TH-AR
.
1st Reclosure
Cycle
In address
3430
1.AR: START
you set whether this cycle is permitted to start the
auto reclose function (=
YES
) or not.
The action time
1.AR: T-ACTION
(address
3431
) is the interval from the pickup of
a protection function within which the trip command must appear in order to start the
automatic reclosure. If the command does not appear until after the action time has
expired, there is no reclosure.
The dead time after tripping
1st Recl: Tdead
(address
3432
) 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. The stability of the
power system must also be kept in mind. Since the de-energized line cannot transfer
synchronizing energy, only short dead times are allowed. Usual values are 0.3 s to 0.6
s.
If the device is equipped with a synchronism check (see Section 2.13), a longer time
may be tolerated under certain circumstances. Longer times are also permitted for
lines on which only vehicles with converters are used.
If there is a risk of stability problems in the network during a reclosure cycle, set
address
3434
SYN-CHECK
to
YES
. In this case a check is made before every reclo-
sure following tripping whether the voltages of the feeder and the reference are suffi-
ciently synchronized. This is applicable on condition that either the internal synchro-
Address
Parameter
3405
AR w/ DIST., i.e. with distance protection
3406
AR w/ HS O/C, i.e. with high-speed overcurrent protection
3407
AR w/ DTT, i.e. with externally coupled trip command
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