| 摘要 |
The invention relates to a system for automatically switching on and off, in particular, self-priming rotary pumps in operating ranges with intermittent pump flow and its object is to provide, with simple means, a system which reliably prevents the pump running dry and always guarantees a perfect pumping operation. According to the invention, it is proposed for this purpose to fit, in the liquid pipeline of the pump, an automatic flow controller or switch which closes when liquid flows through and opens if flow ceases and to which the switching contactor of the pump drive motor is connected via two time-interval switches in such a way that, if the liquid pumping ceases or if the automatic flow controller or switch opens, the contactor drops out, the motor switches off and the first time-interval switch is started, that after the expiry of the adjustable time interval of the first time-interval switch, the contactor operates, the motor switches on and the second time-interval switch is started at the same time, and that after the expiry of the set time interval of the second interval switch, the contactor drops out if the automatic flow controller or switch is open (no flow), the motor remains switched off and the first time-interval switch is started again and, if the automatic flow controller or switch is closed the contactor remains energised (flow), i.e. the motor runs and the pump pumps ... Original abstract incomplete. <IMAGE>
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