摘要 |
PURPOSE:To prevent a pump from eddy current to run the pump under the optimum conditions and improve reliability of the pump by detecting the occurrence of the eddy current in a suction water tank to control the running of the pump according to this detecting signal. CONSTITUTION:When depth Ha to which a pump 3 is immersed is reduced gradually, eddy current 8a occurs on water surface 2 and the pump 3 produces abnormal phenomena such as pressure variation, vibration and noise. These phenomena are detected by eddy current detectors 9a, 9b the detecting signals 10a, 10b of which are amplified by a amplifier 11 and then sent to the input of a computing circuit 12. Signals from the computing circuit 12 is sent to the input of a decision circuit 13 in which, when the occurrence of eddy current is recognized, a control 14 is operated by the signal of the decision circuit 13 to control a flow regulating valve 6 and reduce discharge amount of the pump 3. Thus, inflow speed of water sucked from a pump suction port 3a is also reduced so that the eddy current 8a is eliminated and the pump can be run under the optimum conditions. |