| 摘要 |
An emergency standby power system for automatic transfer from utility power to a battery powered inverter when a normal source of utility power is interrupted to a given load, and for automatic re-transfer to utility power when it is restored. The inverter includes SCR circuitry whereby commutation failure during start-up and shut-down is prevented by applying power to the inverter prior to the application of the gate drive during start-up, and removing power from the inverter prior to the removal of the gate drive during shut-down. Further, the control circuitry ensures that the first SCR gated on will operate for a complete one-half cycle, thereby fully charging the commutating capacitor for reliable commutation off of the first SCR before turning on the second SCR. The control circuitry also permits the inverter to start up even if it is presented with a short circuit and operate without damage.
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