| 摘要 |
PROBLEM TO BE SOLVED: To prevent erroneous action of a relay by mixing a diagnostic input date with an actual input data and subtracting the diagnostic input date subjected to A/D conversion digitally from the mixed data subjected to A/D conversion. SOLUTION: A data corresponding to diagnostic input is stored in a buffer 14 and an actual input date of other channels is stored in a butter 13. The actual input date stored in the butter 13 is subtracted, at a digital adder, by an amount corresponding to the diagnostic input date. More specifically, output from the digital adder is determined by subtracting the diagnostic input date from the actual input date. It is passed through a digital filter DF1 to a relay processing section. The actual input date is passed, as it is, through a digital filter DF2 to the relay processing section 15 where relay processing for system protection is effected. When a decision is made that a diagnostic input is not present, a diagnostic processing section 16 delivers an alarm signal notifying abnormality at the analog part of a relay. |
