| 摘要 |
PROBLEM TO BE SOLVED: To assure a short period of time for updating a program by removing a memory in order to update the program which has been once stored in an existing digital type protection relay. SOLUTION: The digital type protection relay comprises an input circuit 2, including an analog/digital converter for converting an input current/voltage of a power system into a digital value after sampling hold of a value with the prescribed sampling frequency, an arithmetic processing circuit 3 for executing the prescribed arithmetic processings to the digital signal outputted from this input circuit 2 using an operation decision program; and a memory device 4 for storing various programs, including the operation decision program and an output circuit 5 for receiving the arithmetic processings result from the arithmetic processing circuit 3 and then outputting the result to external circuits. Therefore, the memory device 4 can store, in addition to the operation judging program, a monitor program for deciding the true or false state of the operation program, with sum check and the operation judgment is stopped, when the monitor program detects a fault in the operation decision program. |
