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Functions
2.10 Monitoring Functions
2.10
Monitoring Functions
The device incorporates comprehensive monitoring functions which cover both hardware and software. The
measured values too are continuously checked for plausibility so that the current and voltage transformer cir-
cuits are largely included into the monitoring system.
2.10.1
Measurement Supervision
2.10.1.1 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 transformer cir-
cuits.
2.10.1.2 Hardware Monitoring
Voltages
Failure or switch-off of the supply voltage shuts off the device; an annunciation is output via 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 V–).
Buffer Battery
The buffer battery - which ensures operation of the internal clock and storage of counters and annunciations if
the auxiliary voltage fails - is periodically checked for its charge status. If there is less than the allowed minimum
voltage, the annunciation „Fail Battery" is output.
Memory Components
All working memories (RAM) are checked during system start-up. If a malfunction occurs during that, the start-
up 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 gen-
erated each time a setting process has taken place.
If a malfunction occurs, the processor system is restarted.
Sampling
Sampling and synchronism between the internal buffer components are monitored constantly. If any occurring
deviations cannot be removed by renewed synchronization, the processor system is restarted.
164
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A5, Release date 11.2012
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