Monitoring Functions; Description Of Measured Values Monitoring; Hardware Monitoring - Siemens SIPROTEC 7SJ62 Instruction Manual

Functions
6.17

Monitoring Functions

6.17.1 Description of Measured Values Monitoring

6.17.1.1 Hardware Monitoring

Auxiliary and
Reference Voltages
Buffer Battery
Memory
Components
Probing
Measurement Value
Collection – Cur-
rents
6-148
The device is equipped with extensive monitoring capabilities - both for hardware and
software. In addition, the measured values are also constantly monitored for plausibil-
ity, therefore, the current transformer and voltage transformer circuits are largely inte-
grated into the monitoring. It is also possible to implement trip and closing circuit mon-
itoring, using appropriate binary inputs as available.
The device is monitored from the measurement inputs to the binary outputs. Monitor-
ing checks the hardware for malfunctions and disallowed conditions.
The processor voltage of 5 V DC is monitored, and if the voltage decreases below the
minimum value, the device is removed from operation. When the normal voltage re-
turns, the processor system is restarted.
Removal of or switching off the supply voltage removes the device from operation and
a message is immediately generated by a dead contact. Brief voltage interruptions of
less than 50 ms do not disturb the readiness of the device (for nominal auxiliary volt-
age ≥ 110 V DC).
The processor monitors the offset and reference voltage of the AD (analog-digital)
converter. The protection is suspended if the voltages deviate outside an allowable
range, and lengthy deviations are reported.
The buffer battery, which ensures the operation of the internal clock and the 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 "EDWWHU\ HPS
W\" message is issued.
The working memory (RAM) is tested when the system is started up. If a malfunction
occurs then, the starting sequence is interrupted and an LED blinks. During operation,
the memory is checked using its checksum.
For the program memory, the cross sum is formed periodically and compared to the
stored program cross sum.
For the settings memory, the cross sum is formed periodically and compared to the
cross sum that is freshly generated each time the setting process takes place.
If a malfunction occurs, the processor system is restarted.
Probing and the synchronization between the internal buffer components are con-
stantly monitored. If any deviations cannot be removed by renewed synchronization,
then the processor system is restarted.
Up to four input currents are measured by the device. Three of the currents corre-
spond to phase currents and the fourth current corresponds to the neutral or ground
7SJ62 Manual
C53000-G1140-C121-1