Alstom MiCOM P846, Technical Manual

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Firmware Design P846/EN FD/D
MiCOM P846
(FD) 9-19
FD
•
The SRAM containing all data other than the code and constant data is verified with a
checksum
1.6.1 Start-up self-testing
The self-testing which is carried out when the relay is started takes a few seconds to
complete, during which time the relay’s protection is unavailable. This is signaled by the
‘Healthy’ LED on the front of the relay which will illuminate when the relay has passed all of
the tests and entered operation. If the testing detects a problem, the relay will remain out of
service until it is manually restored to working order.
The operations that are performed at start-up are as follows:
1.6.1.1 System boot
The integrity of the flash memory is verified using a checksum before the program code and
data stored in it is copied into SRAM to be used for execution by the processor. When the
copy has been completed the data then held in SRAM is compared to that in the flash to
ensure that the two are the same and that no errors have occurred in the transfer of data
from flash to SRAM. The entry point of the software code in SRAM is then called which is
the relay initialization code.
1.6.1.2 Initialization software
The initialization process includes the operations of initializing the processor registers and
interrupts, starting the watchdog timers (used by the hardware to determine whether the
software is still running), starting the real-time operating system and creating and starting the
supervisor task. In the course of the initialization process the relay checks:
•
The status of the battery
•
The integrity of the battery backed-up SRAM that is used to store event, fault and
disturbance records
•
The voltage level of the field voltage supply which is used to drive the opto-isolated
inputs
•
The operation of the LCD controller
•
The watchdog operation
At the conclusion of the initialization software the supervisor task begins the process of
starting the platform software.
1.6.1.3 Platform software initialization & monitoring
In starting the platform software, the relay checks the integrity of the data held in non-volatile
memory 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 analog 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.
1.6.2 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 document (P846/EN FD)) and the results reported to
the platform software. The functions that are checked are as follows:
•
The flash containing all program code setting values and language text is verified by a
checksum
•
The code and constant data held in SRAM is checked against the corresponding data in
flash to check for data corruption