Functions
2.25 Function Control and Circuit Breaker Test
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
451
1-pole Dead Time
During a 1-pole dead time, the load current flowing in the two healthy phases forces a current flow via earth
which may cause undesired pickup. The raising zero-sequence voltage can also produce undesired responses
of the functions.
The indications
„1pole open L1“
(No. 591),
„1pole open L2“
(No. 592) and
„1pole open L3“
(No.
593) are additionally generated if the „Open Pole Detector“ detects that current and voltage are absent in one
phase – while current flow is detected in both other phases. In this case, one of the indications will only be main-
tained while the condition is met. This enables a single-pole automatic reclosure to be detected on an unloaded
line.
Specially for applications with busbar side voltage transformers the indication
„1pole open Lx“
is addition-
ally transmitted if the phase-selective CB auxiliary contacts clearly show a single-pole open circuit breaker, and
the current of the affected phase falls below the parameter
1130
PoleOpenCurrent
.
Depending on the setting of parameter
1136
OpenPoleDetect.
, the Open Pole Detector evaluates all avail-
able measured values including the auxiliary contacts (default setting
w/ measurement
) or it processes only
the information from the auxiliary contacts including the phase current values (setting
Current AND CB
). To
disable the Open Pole Detector, set parameter
1136
to
OFF
.
2.25.1.4 Pickup Logic of the Entire Device
Phase Segregated Fault Detection
The fault detection logic combines the fault detection (pickup) signals of all protection functions. In the case of
those protection functions that allow for phase segregated pickup, the pickup is output in a phase segregated
manner. If a protection function detects an earth fault, this is also output as a common device alarm. Thus, the
alarms
„Relay PICKUP L1“
,
„Relay PICKUP L2“
,
„Relay PICKUP L3“
and
„Relay PICKUP E“
are
available.
The above indications can be allocated to LEDs or output relays. For the local display of fault indications and
for the transmission of the indications to a personal computer or a central control system, several protection
functions provide the option to display the faulted phase information in a single message, e.g.
„Diff Flt.
L12E“
or
„Dis.Pickup L12E“
for fault detection L1-L2-E; only one such indication appears, which repre-
sents the complete definition of the fault detection.
General Pickup
The pickup signals are combined with OR and lead to a general pickup of the device. It is signalled with
„Relay
PICKUP“
. If no function of the device is picked up any longer,
„Relay PICKUP“
disappears (indication
„OFF“).
General device pickup is a precondition for a series of internal and external functions that occur subsequently.
The following are among the internal functions controlled by general device pickup:
• Opening of a trip log: from general device pickup to general device dropout, all fault indications are entered
in the trip log.
• Initialization of fault record: the storage and maintenance of fault values can also be made dependent on the
occurrence of a trip command.
• Generation of spontaneous indications: Certain fault indications can be displayed as spontaneous indica-
tions (see margin heading „Spontaneous Indications“). In addition, this indication can be made dependent
on the general device trip.
• Start action time of automatic reclosure (if available and used).
