The Research Of Stability And Reliability Of Inductive Digital Water Level Sensors

Inductive digital water level sensors are developed according as the need of Yellow River project. The inputs of the sensors are digital quantity. But D/A conversion are adopted in the design according as the need of the project, so that digital signals are transformed into analog electronic current signals to output. There are D/A conversion, amplifying circuit and other analog circuit in the sensors, so that it is difficult to avoid the effect of operational environment temperature variation. Thus the sensors outputs signals would have errors of temperature drift.Inductive digital water level sensors applied widely inhydraulic engineering, groundwater, electric power plant and other places for water level automatic monitoring. After they ran many years, the phenomenon of error code and missing data was found especially in closed small system and small container.Temperature drift, error code and missing data affect directly stability and reliability of inductive digital water level sensors, application and popularizing of ones. Therefore the research of stability and reliability of inductive digital water level sensors is listed as nation science and technology brainstorm project and become a subitem of the project—"the research of digitized level measurement sensors technique".The cause, this theme reaearch is listed as nation science and technology brainstorm project, is not simply in order to improve stability and reliability of inductive digital water level sensors. More important cause is that many water level sensors do not entirely settle stability andreliability of onsite signals at home and abroad at the present time, and it badly restrict the advance of industrial automation.The problem of stability and reliability of sensors embarrassed the research of digitized level measurement sensors all along. Thus this project team had to turn attention into the research of basic theory. And it becomes technical key, difficulty and innovation to research electrical signals transfer characteristic in different measuring materiel, such as water, coal dust and so on, and to research internal circuit principle of sensors. Of course, these are also technical key, difficulty and innovation of inductive digital water level sensors. Thus the theme concrete content is clear.The thesis outspread research concrete content according to the technical key, difficulty and innovation brought forward by the project team. And it put the emphases and innovation into the research of electricalsignals transfer characteristic in water and the research of influencing factors and taches of electrical signals transferring. In addition, temperature drift of sensors electronic circuit is researched. Under the direction of my tutor, my main research is as follows:1. Research the concrete transferring process of electrical signals in water.2. Research the characteristic of electrical signals transferring in water.3. Discuss the phenomenon of error code and missing data.4. Discuss factors and taches of arosing weak electrical signals in water.5. Research electrodes spoilage, electrodes corrosion mechanism and corresponding countermeasure.6. Research electronic circuit amelioration of inductive digital water level sensors.All in all, the blank, the research of the characteristicof electrical signals transferring in water, is made up. In detail, there are following several fruits:1. It is clear on paper that the concrete transferring process of electrical signals and the characteristic of electrical signals transferring in water.2. It is elementally clear that the main cause of occurring error code and missing data.3. It is elementally clear that influencing factors and taches of weak electrical signals in water.4. It is clear that electrodes spoilage, electrodes corrosion mechanism. And corresponding feasible countermeasures are put forward.5. Finish the research of sensors electronic circuit amelioration under my tutor's direction.In the whole research, my innovation is as follows: 1. It is clear on paper that the concrete transferring process of electrical signals and the characteristic of electrical signals transferring in water, such as transferringmode, transferring impetus, influencing factors and so on. Breakthrough of the water field research of the characteristic of electrical signals transferring in measuring material is realized. It offered the basic theory for developing the sensors with high stability and high reliability.2. "Sampling system" research method is put forward in the research of the characteristic of electrical signals transferring in water. This method at large considers the effect of electrical signals transferring in water to water level sampling and disposes objectively and scientifically the indivisibility and integrity of sampling circuits and water when water level signals are been sampled .3. A new view, the anode passivation phenomenon caused by electrode polarization is the main cause resulting in error code and missing data, is put forward.4. A new view, the chemical reaction velocity between electrode and aqueous solution interface is controlling unitcausing weak electrical signals in water, is put forward.5. Electrodes spoilage and electrodes corrosion mechanism are clear.In addition, water level sensors classifying ideal is brought forward since there was not scientifical and uniform classifying for water level sensors currently.