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The analog-to-digital (AD) element consists of an analog-to-digital (A/D) converter and memory components
for data transmission to the microcomputer system.
Microcomputer System
Apart from processing the measured values, the microcomputer system μC also executes the actual protection
and control functions. They especially consist of:
•
Filtering and preparation of the measured quantities
•
Continuous monitoring of the measured quantities
•
Monitoring of the pickup conditions for the individual protection functions
•
Interrogation of limit values and time sequences
•
Control of signals for the logic functions
•
Decision on trip and close commands
•
Recording of messages, fault data and fault values for analysis
•
Administration of the operating system and its functions, e.g. data storage, realtime clock, communica-
tion, interfaces, etc.
•
Formation of the local differential protection values (phase comparision for phase-to-phase faults and
phasor analysis for phase-to-ground faults) and creation of the transmission protocol
•
Decoding the received transmission protocol, synchronization of differential protection values and
totaling the differential currents and charge currents
•
Monitoring the communication with the device of the remote end
The information is provided via output amplifier OA.
Binary Inputs and Outputs
Binary inputs and outputs to and from the computer system are relayed via the input/output modules. The
computer system obtains information from the system (e.g. remote resetting) or from other devices (e.g.
blocking commands). Outputs are, in particular, commands to the switchgear units and annunciations for
remote signaling of important events and statuses.
Front Elements
Information such as messages related to events, states, measured values and the functional status of the
device are visualized by light-emitting diodes (LEDs) and a display screen (LCD) on the front panel.
Integrated control and numeric keys in conjunction with the LCD enable communication with the remote
device. These elements enable the user to retrieve all device information such as configuration and setting
parameters, operational indications and fault indications or measured values and to edit setting parameters.
In addition, control of circuit breakers and other equipment is possible from the front panel of the device.
Interfaces
Communication with a PC can be implemented via the USB DIGSI interface using the DIGSI software allowing
the user to conveniently handle all device functions.
Port A can be used as protection interface to communicate with another 7SD80 device via an optical fiber
cable.
If you are using a copper link to create a connection to the other 7SD80 device, use the voltage terminals D1
and D2 as protection interface.
The protection data interfaces are used to transfer the data of the measured quantities from each end of the
protected zone to the opposite end. Further information such as closing of the local circuit breaker or other
externally injected trip commands can be transmitted to the opposite end via the protection interface.
In addition to the device communication via DIGSI, Port B can also be used to transmit all device data to a
central evaluator or a control center. This interface may be provided with various protocols and physical trans-
mission schemes to suit the particular application.
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
Introduction
1.1 Overall Operation
21
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