| 摘要 |
PURPOSE:To change over stably a switching selection discriminating circuit by providing the circuit not requiring a power supply of a common section to the active/spare side respectively and using a fail safe interface to monitor the mutual state thereby switching the circuit automatically when the other circuit is normal. CONSTITUTION:An active side (a) series and a spare side (b) series consist respectively of power supplies 11a, 11b, master sets 12a, 12b and changeover selection discriminating circuits 13a, 13b. The changeover selection discriminating circuits 13a, 13b supervise the master sets 12a, 12b by using state signals STATUS 1, 2 and supervise the mutual state with each other via the fail safe interface 14. Outputs 11a', 11b' from power supplies 11a, 11b, outputs 12a', 12b' from the master sets 12a, 12b and switching instruction signals 5, 5' from the changeover selection discriminating circuits 13a, 13b are inputted to a switch 15. The discriminating circuit in the normal state is selected automatically and when both is normal or faulty, the changeover is not conducted. Thus, stable changeover is attained by eliminating the unnecessary changeover and the common power supply is not required to miniaturized the device. |
