| 摘要 |
PURPOSE:To restore pumps to the state just before momentary power failure quickly while preventing increase of the start current at a restart time and to bring pumps to the normal operation state, by using auxiliary capaity of variable voltage and variable frequency to start simultaneously pumps which are operated just before momentary power failure. CONSTITUTION:The number of operated pumps is increased while synchronizing a variable voltage and variable frequency device (VVVF) 7 and a commercial power source with each other; and if all pumps are stopped by momentary power failure in the state where motors 3a and 3b are operated in a certain speed and a motor 3c is subjected to rotation number control, secondary-side contactors 6a and 6b of the VVVF are closed simultaneously by the output signal from an operation controller 10 when a power failure restoring and restart command is given from the external, and commercial-side contactors 5a and 5b are closed after restart with reduced power to 100% speed by the VVVF7, and the commercial power source is synchronized by the VVVF7, and contactors 6a and 6b are closed when acquisition of synchronism is completed. Thereafter, a contactor 6c is closed simlarly to subject the motor 3c to rotation number control. |
