Siemens siprotec 7SA6, Manual

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Introduction
1-6
7SA6 Manual
C53000-G1176-C156-2
In the event of a communication failure, if there is no possible reserve, the devices can
automatically be switched to emergency operation using an integrated overcurrent
time protection until communication is healthy again. This overcurrent time protection
has three definite-time overcurrent stages and one inverse-time (IDMT) stage; a
series of characteristics according to various standards is available for the inverse-
time stage. Alternatively, the overcurrent time protection can be used as a back-up
overcurrent time protection, i.e. it operates independent of and parallel to the Distance
Protection at either end.
Apart from the short-circuit protection functions mentioned, further protection
functions are possible such as earth fault detection (for isolated or resonant-earthed
systems), multi-stage overvoltage and undervoltage protection, circuit breaker failure
protection and protection against the effects of power swings (for impedance starting,
simultaneously active as power swing blocking for the distance protection), as well as
thermal overload protection for protecting the operational equipment (especially
cables) against too much heating due to overloading.
For the rapid location of the damage to the line after a short-circuit, a fault locator is
integrated which also may compensate for the influence of a parallel line and load.
Digital
Transmission of
Protection Data
(optional) If the distance protection is to be complemented by digital teleprotection schemes, the
data required for this purpose can be transmitted via the protection data interface by
employing a digital communication link. Communication via the protection data
interface can be used for transmitting further information. Besides measured variables
also binary commands or other information (ordered variant) can be transmitted.
The devices will automatically find the remaining healthy communication lines. But
even with two ends, communication lines can be doubled to create redundancies.
Messages and
Measured Values;
Storage of Data for
Fault Recordings A series of operating messages provides information about conditions in the power
system and the 7SA6 itself. Measurement quantities and values that are calculated
can be displayed locally and communicated via the serial interfaces.
Messages of the 7SA6 can be indicated by a number of programmable LEDs on the
front panel, externally processed through programmable output contacts, and
communicated via the serial interfaces (see “Communication” below). With the help of
the CFC graphic tool (Continous Function Chart), user-defined annunciations and
logical combinations of internal or external signals can also be generated.
Important events and changes in conditions are saved under Annunciation in the
Event Log or the Trip Log, the latter being used for faults. The instantaneous
measured values during the fault are also stored in the device and are subsequently
available for fault analysis.
Communication Serial interfaces are available for communications with PCs, RTUs and SCADA
systems.
A 9-pin D-subminiature female connector on the front cover is used for local
communication with a personal computer. DIGSI
® 4 software is required to
communicate via this port. Using the SIPROTEC
®
DIGSI
®
4 operator software, all
operating and evalution procedures may be implemented via this operating interface,
such as setting and modification of configuration and parameter settings, configuration
of user-specific logic functions, reading out and display of operating and fault event
messages as well as measured values, reading out and display of fault records,
queries of device states as well as queries of measured values, and issuing of control
commands.