| 摘要 |
PURPOSE:To recover immediately the fault of an analog circuit, by sampling inputted analog data, and by correcting A/D-converted digital data, and further, by performing the storage of the correcting values thereof, and moreover, by performing automatically protective operations through a computing circuit from its inputted data while using the correcting values. CONSTITUTION:An analog input circuit 1 performs the level conversions of the inputted analog data of a plurality of system electric quantities by respective transformers 11, and it removes higher harmonics from the analog data by filter circuits 12, and then, it samples and holds of the analog data at a predetermined time-interval by sampling-hold circuits 13, and further, it inputs the sampled data to a multiplexer 14. Subsequently, the analog input circuit 1 reads out in succession the analog data from the multiplexer 14, and it performs the A/D conversions of the read analog data by an A/D conversion circuit 15, and then, it corrects the errors of the read analog data by a correcting-value storage circuit 16, and further, it stores the resultant correcting values in the circuit 16. Using the outputs of the A/D conversion circuit 15 and the correcting-value storage circuit 16, a computing circuit 2 performs predetermined protective operations, and when the operational results satisfy operating conditions, it outputs a tripping command to a circuit breaker via an output circuit 4. Thereby, in case of the fault of the input circuit 1, its quick replacement-recovery work is performed. |
