Siemens siprotec 7SD5 User Manual page 42

2 Functions
reclose cycles are provided for and possible. In this case different dead times after
single-pole tripping on the one hand and after three-pole tripping on the other hand are
possible (for every reclose cycle). The protective function that issues the trip
command determines the type of trip: single-pole or three-pole. Depending on the
latter the dead time is selected.
The setting Pickup with T-action / Pickup without T-action ...
(Pickup with T-action ...) is only possible and visible if only three-pole tripping is de-
sired. This is the case when either the ordering number of the device model indicates
that it is only suited for three-pole tripping, or when three-pole tripping is solely config-
ured (address 110 Trip mode = 3pole only, see above). In this case you can set
different dead times for the auto-reclose cycles following single-pole, two-pole and
three-pole faults. Decisive here is the pickup situation of the protective functions at
the instant the trip command disappears. This control mode enables also the dead
times to be made dependent on the type of fault in the case of three-pole reclosure
cycles. Tripping is always three-pole.
The setting Trip with T-action provides an action time for each reclose cycle.
The action time is started by a general pickup of all protection functions. If no trip
command is present before the action time expires, the corresponding reclose cycle
is not carried out. Section 2.15 provides detailed information on this topic. This setting
is recommended for time-graded protection. If the protection function which is to
operate with automatic reclosure, does not have a general pickup signal for starting
the action times, select ... Trip without T-action.
Address 137 U/O VOLTAGE allows to activate the voltage protection function with a
variety of undervoltage and overvoltage protection stages. In particular, the overvolt-
age protection with the positive sequence system of the measuring voltages provides
the option to calculate the voltage at the other, remote line end via integrated com-
pounding. This is particularly useful for long transmission lines where no-load or low-
load conditions prevail and an overvoltage at the other line end (Ferranti effect) is to
cause tripping of the local circuit breaker. In this case set address 137 U/O VOLTAGE
to Enabl. w. comp. (available with compounding). Do not use compounding in lines
with series capacitors!
For the fault location you can determine in address 138 Fault Locator, Enabled
and Disabled that the fault distance is output in BCD code (4-bit units, 4-bit tens and
1-bit hundreds and 1-bit„data valid") via binary outputs (with BCD-output). A cor-
responding number of output relays (No. 1143 to 1152) must be made available and
allocated for this purpose. For double-ended fault location, address 3807 two ended
must be set to ON. Please note that address 160 L-sections FL is used to state the
number of sections of which your line length consists (e.g. cable-overhead line).
For the trip circuit supervision set at address 140 Trip Cir. Sup. the number of
trip circuits to be monitored: 1 trip circuit, 2 trip circuits or 3 trip
circuits, unless you omit it (Disabled).
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7SD5 Manual
C53000-G1176-C169-1