| 摘要 |
PROBLEM TO BE SOLVED: To reduce secondary output burden onto a transformer for detecting quantity of electricity, by reducing induction against a detected signal in an electrical enclosure and the influence of noise surge, and simplifying the circuit structure of a protection controller. SOLUTION: The current and voltage of a power system are detected as optical analog signals by an optical CT 21 and an optical PD 22, and are sent to O/E converters 23a, 23b by optical cables 28a, 28b respectively. After they are converted into electric signals by the O/E converters 23a, 23b, they are converted into digital signals by A/D transducers 24 in signal processing circuits 18a, 18b. After voltage and current data expressed with the digital signals are converted into a prescribed format by digital operation parts 25, the presence of abnormality such as an accident in the power system is discriminated by a digital processing part 26 based on its magnitude, time-sequencial situation mutual phase relation and so on. The digital processing part 26 sends commands for protection and control to a circuit breaker (CB) 5 for the power system. |
