Siemens siprotec 7SD5 User Manual page 21

and other ancillary functions. A further voltage input (U
measure either the displacement voltage, for a busbar voltage (for synchronism and
voltage check) or any other voltage U
are then routed to the input amplifier group "IA".
The input amplification IA stage provides high-resistance terminations for the analog
input quantities. It contains filters that are optimized with regard to bandwidth and pro-
cessing speed.
The AD analog digital converter group contains analog/digital converters and memory
chips for data transfer to the microcomputer system.
Microcomputer Apart from processing the measured values, the microcomputer system also executes
System the actual protection and control functions. In particular, the following are included:
• Decisions for trip and close commands,
• Continuous supervision of measured signals.
• Monitoring of the pickup conditions of the individual protection functions.
• Formation of the local differential protection values (phasor analysis and charge
• Decoding of the received transmission protocol, synchronization of differential pro-
• Monitoring of the communication with the other devices part of the line protection
• Interrogation of threshold values and time sequences.
• Processing of signals for the logic functions.
• Decisions for trip and close commands
• Storage of messages, fault annunciations as well as fault records for system fault
• Operating system and related function management such as, e.g., data recording,
The information is provided via output amplifier OA.
Binary Inputs and The microcomputer system obtains external information through binary inputs such as
Outputs remote resetting or blocking commands for protection functions. The computer system
obtains the information from the system (e.g remote resetting) or the external equip-
ment (e.g. blocking commands). These outputs include, in particular, trip commands
to circuit breakers and signals for remote annunciation of important events and condi-
tions.
Front Elements Light emitting diodes (LEDs) and a display screen (LCD) on the front panel provide
information such as measured values, messages related to events or faults, status,
and functional status of the device.
Integrated control and numeric keys in conjunction with the LCD facilitate local inter-
action with the device. 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 2 and
SIPROTEC
Using integrated switchgear control functions, the control of circuit breakers and other
equipment is possible from the device front panel.
7SD5 Manual
C53000-G1176-C169-1
current computation) and creation of the transmission protocol.
tection values and summing up of the differential currents and charge currents,
system
analysis
real-time clock, communication, interfaces, etc.
®
4 System Description /1/).
) may optionally be used to
4
(for overvoltage protection). The analog signals
X
1.1 Overall Operation
21