| 摘要 |
PURPOSE:To enable to continue the operation without starting an internal pump trip by lowering the AC output frequency of a power inverter when a power source voltage decreases. CONSTITUTION:When the voltage of a bus 10 decreases so that the increase of the current of a thyristor power inverter 16 is detected by a detector 26, a current-time setter 28 switches an overload operation allowable time command to a switch 25, the set frequency command lower than the normal frequency of a current/frequency setter 27 is applied to a pulse amplifier 21, the frequency of the output AC current of the inverter 16 is lowered, thereby limiting the current to an allowable value or lower of the thyristor which forms the inverter 16, and enabling to continue the operation without immediately stopping the operation of an internal pump 18. |
