| 摘要 |
<p>A system for rapidly substituting one source of AC power for another is disclosed. A solid-state gated electronic valve is coupled in circuit with a principal power source or "line" and the current through the valve is monitored. Line voltage is also monitored and a timing signal produced to keep the system in synchronism with the principal power source. When the source voltage decreases or changes abruptly, or if its phase drifts unacceptably, the difference detected between the source and a reference effects the termination of valve gating signals, and allows the application of synchronous enabling signals to a standby power source. If the solid-state valve is non-conducting the standby source starts immediately in synchronism with the previously-supplied load voltage. If current is flowing in the valve, however, a commutating signal is produced which overrides the synchronous standby enabling signal to energize the standby power source with the proper polarity to extinguish current through the valve. When the current decreases below the holding current value the standby source is caused to enter the synchronous mode.</p> |
