| 摘要 |
A capacitive system for sensing the level of material includes a conductive member connected to ground potential, a probe (10) including a sensing element (12) establishlishing a capacitance between sensing element (12) and conductive member which is determined by the level and a shielding element (14) interposed between conductive member and sensing element (12) to form an electrically neutral zone therebetween to reduce the effect of a conductive buildup of the material on the probe (10) on said capacitance, and a first circuit (30) connected to the sensing and shielding elements for applying the same potential to these elements, having an output which varies in response to changes in said capacitance. A compensating device measuring an electrical characteristic of the shielding element (14) being related to the conductivity of the buildup of material on the probe (10) is connected to a second circuit (90) adjusting automatically the sensitivity of the first circuit (30) in response to changes in the electrical characteristic. |
