Siemens siprotec 7SD5 User Manual

2.23 Function Control and Circuit Breaker Test
403
7SD5 Manual
C53000-G1176-C169-1
Single-pole Dead
Time
During a single-pole dead time, the load current flowing in the two healthy phases
forces a current flow via earth which may cause undesired pickup. The temporarily ap-
plying zero-sequence voltage may also prompt undesired responses of the protection
functions.
The alarms „1pole open L1“ (No. 591), „1pole open L2“ (No. 592) and „1pole
open L3“ (No. 593)are generated in addition if the „Open Pole Detector“ recognizes
that current and voltage are absent in one phase – but neither in the other phases
current is flowing. In this case, the message will be held up only for as long as the con-
dition is fulfilled. This enables a single-pole automatic reclosure to be detected on an
unloaded line.
2.23.1.4 Pickup Logic for 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 alarms can be allocated to LEDs or output relays. For the local display of
fault annunciations and for the transmission of event messages to a personal comput-
er or a centralized control system, several protection functions provide the possibility
to display the faulted phase information in a single annunciation, e.g. „Diff Flt.
L12E“ or „Dis.Pickup L12E“ for fault detection in L1-L2-E. Only one such annun-
ciation appears, which represents 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 the alarm „Relay PICKUP“. If no protection function of the device
has 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 fault case: from general device pickup to general device dropout, all
fault indications are entered in the trip log.
• Initialization of fault storage: 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
so-called spontaneous indications (see „Spontaneous Indications“ below). This in-
dication can also be made dependent on the general device trip.
• Start action time of automatic reclosure (if available and used).
External functions may be controlled by this indication via an output contact. Examples
are:
• Automatic reclose devices,
• Channel boost in conjunction with signal transmission by PLC,
• Further additional devices or similar.
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Siemens siprotec 7SD5 Specifications

General

Brand	Siemens
Model	siprotec 7SD5
Category	Relays
Language	English