Introduction
1-37SA522 Manual
C53000-G1176-C119-2
The input amplifier group IA ensures that there is high impedance termination for the
measured signals and contains filters which are optimized in terms of band-width and
speed with regard to the signal processing.
The analogue/digital converter group AD has a multiplexor, analogue/digital convert-
ers and memory modules for the data transfer to the microcomputer.
Microcomputer
System
Apart from processing the measured values, the microcomputer system also executes
the actual protection and control functions. In particular, the following are included:
− Filtering and conditioning of the measured signals,
− continuous supervision of the measured signals,
− monitoring of the individual protection function pick-up conditions,
− Interrogation of threshold values and time sequences,
− Processing of signals for the logic functions,
− Reaching trip and close command decisions,
− Storage of fault annunciations, fault annunciations as well as fault recording data,
for system fault analysis,
− Operating system and related function management such as e.g. data storage, real
time clock, communication, interfaces etc.
Binary Inputs and
Outputs
The microcomputer system obtains external information through the binary inputs
such as remote resetting or blocking commands for protective elements. The µC is-
sues information to external equipment via the output contacts. These outputs include,
in particular, trip commands to the circuit breakers and signals for remote annunciation
of important event and conditions.
Front Elements Light-emitting diodes (LEDs) and a display screen (LCD) on the front panel provide
information such as targets, measured values, messages related to events or faults,
status, and functional status of the 7SA522.
Integrated control and numeric keys in conjunction with the LCD facilitate local inter-
action with the 7SA522. All information of the device can be accessed using the inte-
grated control and numeric keys. The information includes protective and control set-
tings, operating and fault messages, and measured values (see also Chapter 7). The
settings can be modified as are discussed in Chapter 6.
Serial Interfaces A serial operating interface on the front panel is provided for local communications
with the 7SA522 through a personal computer. Convenient operation of all functions
of the device is possible using the SIPROTEC
®
4 operating program DIGSI
®
4.
A separate serial service interface is provided for remote communications via a mo-
dem, or local communications via a substation master computer that is permanently
connected to the 7SA522. DIGSI
®
4 is required.
All 7SA522 data can be transferred to a central master or main control system through
the serial system interface. Various protocols and physical arrangements are availa-
ble for this interface to suit the particular application.
Power Supply The 7SA522 can be supplied with any of the common power supply voltages. Tran-
sient dips of the supply voltage which may occur during short-circuit in the power sup-
ply system, are bridged by a capacitor (see Technical Data, Subsection 10.1.2).
Time Synchroniza-
tion
A battery backed clock is always provided and can be synchronized via a synchroni-
zation signal with IRIG-B (GPS via satellite receiver) or DCF 77.
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