SIPROTEC 4 7SA522 Distance Protection Relay for Transmission ...

SIPROTEC 4 – 7SA522
Distance Protection Relay for Transmission Lines
Description
Application
The 7SA522 relay provides
full scheme distance protection
and incorporates all functions
usually required for the
protection of a power line.
The relay is designed to provide
fast and selective fault
clearance on transmission
and subtransmission overhead
lines and cables. This
contributes towards improved
stability and availability
of your electrical power
transmission system. The power
system star point can
be solid or impedance grounded
(earthed). The 7SA522 is
suitable for single- and
three-phase tripping applications
with and without pilot-
(tele-) protection schemes.
The effect of apparent impedances
in unfaulted fault
loops is eliminated by a
sophisticated and improved
method which uses pattern
recognition with symmetrical
components and load compensation.
The correct phase
selection is essential for selective
tripping and reliable
fault location.
During network power
swings an improved power
swing blocking feature prevents
the distance protection
from unwanted tripping and
optionally provides controlled
tripping in the event of loss
of synchronism (out of step).
This function guarantees power
transmission even under
critical network operating
conditions.
Maximum Lifetime and
Reliability
The 7SA522 hardware is based
on 20 years of experience
by Siemens with numerical
protection. State-of-theart
32 bit microprocessor
technology is employed.
Naturally the device complies
with the latest standards and
techniques for electromagnetic
compatibility. The overall
number of electronic components
is substantially reduced
by using large-scale integrated
circuits.
The relay software is designed
in accordance with high
level programming language
techniques. The long experience
in manufacturing numerical
relays provide the basis
for a modern software structure.
This along with modern
manufacturing techniques
and quality controls ensure
maximum lifetime and reliability.
Cost-effective power
system management
The SIPROTEC 4 units are
numerical relays which also
provide control and monitoring
functions and therefore
support the user in view of a
cost-effective power system
management. They contribute
towards the reliable
supply of electric power to
the customers.
Local operation has been designed
according to ergonomic
criteria. Large, easy-toread
displays are a major design
aim.
The SIPROTEC 4 units have
a uniform design and a degree
of functionality which
represents a whole new
level of quality in protection
and control. If the application
requirements change the
relays may be adapted
quickly by entering new settings
without any additional
hardware costs.
The use of powerful microcontrollers
and the application
of digital measured value
conditioning and processing
largely suppresses the influence
of higher-frequency
transients, harmonics and
DC components.
Back-up protection
The unit can also be used as
backup distance and overcurrent
protection for all types
of differential protection
equipment.
Add-on protective
functions
The 7SA522 incorporates several
protective functions
usually required for transmission
line protection. These
are
− High-resistance earth fault
protection
− Phase overcurrent protection
− STUB bus overcurrent stage
− Overvoltage protection
− Automatic reclosure
− Synchrocheck
− Circuit breaker failure protection.
Programmable logic
The integrated programmable
logic functions allow the
user to implement his own
functions for the automation
of a switchgear (interlocking)
or a substation via a graphic
user interface. The user can
also generate user-defined
messages and logical combinations
of internal or external
signals.
Local and remote
communication
The SIPROTEC 4 units provide
several serial communication
interfaces for various
tasks:
− Front interface for connecting
a PC
− IEC system interface for
connecting to a control
system via
IEC 60870-5-103 or
Profibus-FMS/DP,
Modbus RTU,
DNP3.0
− Prepared for Ethernet
(UCA)
− Modem interface for connecting
a PC via modem
and/or starcoupler
− Time synchronization via
IRIG-B/SCADA (DCF 77)
The 7SA522 relay has two
additional optional interfaces
for communication with the
remote relay or process bus.
It is therefore well prepared
for future communication
standards.
Operational indications
and fault indications with
time stamp
The SIPROTEC 4 units provide
extensive data for fault
analysis as well as control.
All indications listed below
are protected against power
supply failure.
− Fault event record
The last eight fault cases
are always stored in the
unit. All fault recordings
are time stamped with a
resolution of 1 ms.
− Operational indications
All indications that are not
directly associated with
the fault (e.g. operating or
switching actions) are stored
in the status indication
buffer. The time resolution
is 1 ms.
2 Siemens SIP 4.2 · 08/99