| 摘要 |
PURPOSE:To prevent water hammering action from occurring inside a water pipe, by selecting the winding of a motor from delta connection to star one and stopping it at the time of pump stoppage, in case of a device which drives a pump with a three-phase induction motor. CONSTITUTION:At a time when a three-phase induction motor for pump driving is operated in rating, winding of the said motor is set down to delta connection as in (1). And, when a pump is stopped as in this state, first the delta connection is released as in (2) and, after the motor is rotated in its inertia, star connection is set up and the motor is rotted at low speed. After that, a power source is cut off, stopping rotation of the motor. With this constitution, the occurrence of water hammering action inside a water pipe at the time of pump stoppage is preventable.
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