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2.5
Supervision Functions
The device is equipped with extensive monitoring capabilities - both for hardware and software. In addition,
the measured values are also constantly monitored for plausibility, therefore, the voltage transformer circuits
are largely integrated into the monitoring.
Measurement Supervision
2.5.1
2.5.1.1
General
The device monitoring extends from the measuring inputs to the binary outputs. Monitoring checks the hard-
ware for malfunctions and abnormal conditions.
Hardware and software monitoring described in the following are enabled continuously. Settings (including
the possibility to activate and deactivate the monitoring function) refer to the monitoring of external trans-
former circuits.
2.5.1.2
Hardware Monitoring
Auxiliary and Reference Voltages
Failure of or switching off the supply voltage removes the device from operation and a message is immedi-
ately generated by a normally closed contact. Brief auxiliary voltage interruptions of less than 50 ms do not
disturb the readiness of the device (for nominal auxiliary voltage > 110 VDC).
Buffer Battery
The buffer battery, which ensures operation of the internal clock and storage of counters and messages if the
auxiliary voltage fails, is periodically checked for charge status. If it is less than an allowed minimum voltage,
then the
Fail Battery message is issued.
Memory Components
All working memories (RAMs) are checked during startup. If a malfunction occurs then, the starting sequence
is interrupted and an LED blinks. During operation the memories are checked with the help of their checksum.
For the program memory, the cross sum is formed cyclically and compared to the stored program cross sum.
For the settings memory, the cross sum is formed cyclically and compared to the cross sum that is freshly
generated each time a setting process takes place.
If a fault occurs the processor system is restarted.
Scanning
Scanning and the synchronization between the internal buffer components are constantly monitored. If any
deviations cannot be removed by renewed synchronization, then the processor system is restarted.
AD Transformer Monitoring
The digitized sampled values are being monitored in respect of their plausibility. If the result is not plausible,
message 181
Error A/D-conv. is issued. The protection is blocked, thus preventing unwanted operation.
Furthermore, a fault record is generated for recording of the internal fault.
2.5.1.3
Software Monitoring
Watchdog
For continuous monitoring of the program sequences, a time monitor is provided in the hardware (hardware
watchdog) that expires upon failure of the processor or an internal program, and causes a complete restart of
the processor system.
An additional software watchdog ensures that malfunctions during the processing of programs are discov-
ered. This also initiates a restart of the processor system.
SIPROTEC 4, 7RW80, Manual
C53000-G1140-C233-4, Edition 07.2018
Functions
2.5 Supervision Functions
61
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