Areva MiCOM P441, Техническое руководство

Страница: 172 / 636

P44x/EN HW/E33 Relay Description
Page 44/44 MiCOM P441/P442 & P444
5.1.3 Platform software initialisation & monitoring
In starting the platform software, the relay checks the integrity of the data held in E2PROM
with a checksum, the operation of the real-time clock, and the IRIG-B board if fitted. The final
test that is made concerns the input and output of data; the presence and healthy condition
of the input board is checked and the analogue data acquisition system is checked through
sampling the reference voltage.
At the successful conclusion of all of these tests the relay is entered into service and the
protection started-up.
5.2 Continuous self-testing
When the relay is in service, it continually checks the operation of the critical parts of its
hardware and software. The checking is carried out by the system services software (see
section on relay software earlier in this chapter) and the results reported to the platform
software. The functions that are checked are as follows:
•
the flash EPROM containing all program code and language text is verified by a
checksum.
•
the code and constant data held in SRAM is checked against the corresponding data
in flash EPROM to check for data corruption.
•
the SRAM containing all data other than the code and constant data is verified with a
checksum.
•
the E2PROM containing setting values is verified by a checksum.
•
the battery status.
•
the level of the field voltage.
•
the integrity of the digital signal I/O data from the opto-isolated inputs and the relay
contacts is checked by the data acquisition function every time it is executed. The
operation of the analogue data acquisition system is continuously checked by the
acquisition function every time it is executed, by means of sampling the reference
voltages.
•
the operation of the IRIG-B board is checked, where it is fitted, by the software that
reads the time and date from the board.
In the unlikely event that one of the checks detects an error within the relay’s subsystems,
the platform software is notified and it will attempt to log a maintenance record in battery
backed-up SRAM. If the problem is with the battery status or the IRIG-B board, the relay will
continue in operation. However, for problems detected in any other area the relay will initiate
a shutdown and re-boot. This will result in a period of up to 5 seconds when the protection is
unavailable, but the complete restart of the relay including all initialisations should clear most
problems that could occur. As described above, an integral part of the start-up procedure is a
thorough diagnostic self-check. If this detects the same problem that caused the relay to
restart, i.e. the restart has not cleared the problem, then the relay will take itself permanently
out of service. This is indicated by the ‘Healthy’ LED on the front of the relay, which will
extinguish, and the watchdog contact which will operate.