Siemens SIPROTEC 7SD610 Manual page 46

Functions
2.1 General
For commands via the integrated control (on site, DIGSI, serial interface) address 1152 Man.Clos. Imp.
determines whether a close command via the integrated control regarding the MANUAL CLOSE handling for
the protection functions (like instantaneous re-opening when switching onto a fault) is to act like a MANUAL
CLOSE command via binary input. This address also informs the device to which switchgear this applies. You
can select from the switching devices which are available to the integrated control. Select the circuit breaker
which operates for manual closure and, if required, for automatic reclosure (usually Q0). If none is set here, a
CLOSE command via the control will not generate a MANUAL CLOSE impulse for the protection function.
Three-pole Coupling
Three-pole coupling is only relevant if single-pole auto-reclosures are carried out. If not, tripping is always
three-pole. The remainder of this margin heading is then irrelevant.
Address 1155 3pole coupling determines whether any multi-phase pickup leads to a three-pole tripping
command, or whether only multi-pole tripping decisions result in a three-pole tripping command. This setting is
only relevant with one- and three-pole tripping and therefore only available in this version. It does not have an
impact on the differential protection since pickup and tripping are equivalent. The time overcurrent protection
function, however, can also pick up in the event of a fault occurred outside the protected object, without tripping.
More information on the functions is also contained in Section 2.16.1 Pickup Logic for the Entire Device.
With the setting with PICKUP every fault detection in more than one phase leads to three-pole coupling of
the trip outputs, even if only a single-phase earth fault is situated within the tripping region, and a further fault,
for example by overcurrent, is recognized. Even if a single-phase trip command has already been issued, each
further fault detection will lead to three-pole coupling of the trip outputs.
If, on the other hand, this address is set to with TRIP, three-pole coupling of the trip output (three-pole trip-
ping) only occurs when more than one pole is tripped. Therefore, if a single-phase fault occurs within the trip
zone and a further fault outside of it, single-pole tripping is possible. A further fault during the single-pole trip-
ping will only lead to a three-pole coupling, if it occurs within the trip zone.
This parameter is valid for all protection functions of 7SD610 which are capable of single-pole tripping.
The difference made by this parameter becomes apparent when multiple faults are cleared, i.e. faults occurring
almost simultaneously at different locations in the network.
If, for example, two single-phase earth faults occur on different lines — these may also be parallel lines —
(Figure 2-2), the protection relays detect the fault type on all four line ends L1-L2-E, i.e. the pickup image cor-
responds to a two-phase earth fault. If single pole tripping and reclosure is employed, it is therefore desirable
that each line only trips and recloses single pole. This is possible with setting 1155 3pole coupling = with
TRIP. Each of the four devices detects a single-pole internal fault and can thus trip single-pole.
Figure 2-2
In some cases, however, three-pole tripping would be preferable for this fault scenario, for example in the event
that the double-circuit line is located in the vicinity of a large generator unit (Figure 2-3). This is because the
generator considers the two single-phase ground faults as one double-phase ground fault, with corresponding-
ly high dynamic load on the turbine shaft. With the setting 1155 3pole coupling = with PICKUP, the two
lines are switched off three-pole, since each device picks up as with L1-L2-E, i.e. as with a multi-phase fault.
46
Multiple fault on a double-circuit line
SIPROTEC, 7SD610, Manual
C53000-G1176-C145-6, Release date 02.2011