| 摘要 |
In order to make possible reliable and accurate detection of changes in the flow resistance of a screen arranged on the inlet side in front of the inlet of a water turbine of a small power station without using mechanical components, static measuring probes are provided which are arranged in a fixed manner, dipping into the stream water, in front of and behind the screen and are connected to a sensor circuit only via electric leads outside the stream. Each measuring probe has two measuring rods, which are connected to a low-voltage A.C. circuit having a measuring bridge and which detect a conductivity of the water column between the rods, which conductivity changes as a function of the change in the water level, and convert it into electrical measured quantities. Via the measured values determined in a simple manner in this way, a display can be triggered or a control circuit for an automatically operating screen-cleaning arrangement actuated.
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