SU883662A1 - Inductive converter of electroconductive medium level - Google Patents

Description

one

 The invention relates to instrumentation and measurement technology and can be used to control the level of electrically conductive media in difficult operating conditions.

Devices are known for measuring the level of electrically conductive media, comprising an inductance coil and using the effect of the interaction of an electric | Q magnetic field of this coil with a controlled medium Ij.

The closest to the present invention is an inductive transducer containing a level of measuring coils distributed over a height of 15 and passive coils carried outside the limits of the measured medium. The measuring and passive coils form a system of parallel bridges, fed by a common generator, of an audio frequency voltage. The connection points of the measuring and passive coils in pairs through one are connected to the voltage indicators 2.

The disadvantages of the known device is the lack of information about the change in the level of the controlled medium between any two adjacent measuring coils, i.e. the presence of 30

considerable discretization error.

The purpose of the invention is to obtain the required type of dependence of the signal from the converter and to improve the accuracy of the conversion.

Claims (1)

This goal is achieved by the fact that an inductive level transducer containing height-distributed measuring coils and passive coils placed outside the controlled medium, forming respectively active and passive arms of bridge measuring circuits, is provided with additional , coils, the length of which is equal to the distance between the measuring coils and located between them, included in the active shoulders of the bridge c m series with the measuring, the ratio of the numbers of turns of the measuring coils and additional equal to the ratio of their length multiplied by the ratio of the derivatives of the signal from these coils by the level defined by the desired signal dependence. Pa flg 1 shows an inductive level converter device; m fi. 2 shows the connection circuit of the coils into the measuring circuit; in fig. 3 - signal dependence on level. The converter contains measuring 1, additional 2 and passive 3 coils. The measuring 1 and additional 2 coils are placed in a protective magnetically permeable case 4, which is welded into the lid 5 of the control object and protects the transducer coils from the influence of the controlled medium 6. The measuring circuit is a system of parallel bridges fed by an acoustic voltage generator 7 ( Fig. 2). The bridges are balanced in such a way that the potential of the connection points of the passive and additional coils are the same in the absence of a controlled medium in the range of the measuring range. The principle of operation of the converter is illustrated by the example of the operation of one of the bridges, made up, for example, of measuring coils C, D ° by additional coils L. passive coils, L. With a change in the level of the controlled medium within I and II in FIG. 3 (i.e., within the additional 8 and measuring 9 coils), the bridge is unbalanced, and the voltage of the signal in the diagonal of the bridge varies according to the law corresponding to the law of variation of the winding density within these areas (the solid curve in Fig. 3). With further level changes (within areas III and IV / the bridge is balanced, and when the bridge is completely flooded, the signal returns to its original state. Obviously, if there are no additional coils, the output signal of the bridge will change only when the controlled medium changes within the measuring coils ( 3. A change in the winding density in different parts of the measurement range can produce any desired dependence of the signal on the level. This dependence is a function of the distribution of turns on Serial and additional coils, as well as a whole number of other factors — geometric parameters of the converter, the number of discrete reference points, etc. The best results can be obtained if the maximum signal in section I is 70-75% of the maximum signal in section II. Such a dependence of the signal on the uroin makes it possible to most effectively combine the advantages of discrete and analog converters, the absence of additional temperature error in discrete converters, and the high accuracy of the analog new ones. Claims of Invention Inductive level transducer of electrically conductive media, containing measuring coils distributed over height, and measuring coils and passive coils placed outside the measuring medium, forming respectively active and passive arms of bridge measuring circuits, characterized in that level and increase the accuracy of the conversion, it is equipped with additional coils, the length of which is equal to the distance between the measuring coil and located between them, included in the active arms of bridge circuits in series with the measuring coils, the ratio of the number of turns of the measuring and additional coils being equal to the ratio of their length multiplied by the ratio of the derivatives of the signal from these coils with respect to the level determined by the required signal dependence. Sources of information taken into account in the examination 1. Jordan, G. Levinson B.A., Kozlov M.G. and others. Instruments for level measurement. Reference Instrument making and automation equipment, v. 2, Vol. 11, Mashgiz, 1964. 2, USSR Authorship Certificate (295992, class G01 F 23/26, 1964 (prototype). Hi Js Level