SU1000769A1 - Level indicator for electroconductive liquids - Google Patents

Description

The invention relates to a device structure, namely to devices. for level control, and can be used in various industries and agriculture to measure the level of conductive liquids.

Level meters of liquid electrically conductive media are known, containing a sensitive element made up of electrodes arranged throughout the measurement range, a signal converter circuit, a recording device and a power source G T The disadvantage of such meters is low accuracy and reliability of operation due to imperfect converter circuit and output instability signal with changes in conductivity of the controlled medium and fluctuations in supply voltage.

The closest to the proposed technical essence is a level gauge for electrically conductive veins, containing height-set electrodes, an excitation source, a measuring transformer converter with partitioned primary and secondary windings, in whose circuits oscillatory circuits are introduced, through which the outputs of the sexes are connected to the electrodes, and C2J.

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 The disadvantage of the known level gauge is the low measurement accuracy due to the distance between the electrodes and the instability of the properties of the medium.

The purpose of the invention is to improve accuracy.

This goal is achieved by

15 that in the gauge for electrically conductive liquids containing electrodes installed uniformly in the metal case, the excitation source, measuring converter and indicator, the excitation source is made multiphase, the measuring converter is made in the form of a multiphase transformer, the primary windings of which

25 are connected to the excitation source, the secondary windings have a midpoint, connected to the ends of the electrodes. ladies, the midpoints of all the windings are interconnected, forming a zero

Claims (2)

The 30 point, and between the zero point and the housing an indicator is turned on, pulsed as a phase meter. FIG. 1 shows the basic electrical circuit of the proposed device; in fig. 2 are vector diagrams explaining his work; in FIG. 3 - dependence of the output signal on the level of the controlled medium. The level gauge contains a three-phase excitation source, the measuring transformer converter 1 converts a three-phase voltage system into a six-phase voltage, the primary windings of which are connected to the power source and the secondary ones have middle points interconnected to form a double star. The ends of the secondary windings are connected to electrodes 2 installed in the process tank 3 is uniform in height. Between the zero point and the case of the process tank 3 made of metal, the current input of the phase meter 4 is turned on, the second input of which is connected to one of the secondary windings. The outputs of the secondary windings of the converter are connected to the electrodes in such a way that the rotation of the vector of the total current from the electrodes to the core with increasing level is ensured. In the initial state, i.e. when the surface of the controlled medium is located below the electrodes, there is no current in the circuit between the process capacitor body and the electrodes, and there is no current between the case and the zero point of the star in the secondary windings. As the level rises, the medium in the process tank is controlled to the lower electrode. A current flows between the electrode and the housing, closing through the phase meter to the zero point of the converter. As the level in the zone of the low electrode increases, an increase in the area of contact of the controlled medium with the electrode occurs and the amount of current increases (Fig.). but in phase the current coincides with the voltage vector. As the level of the controlled medium continues to rise, it comes into contact with the second electrode from the bottom; a current flow through the current winding of the phase meter is equal to the geometric sum of the currents generated in the controlled medium by the phase windings a and c. with the increase in the phase current C, the resultant current vector I will rotate with respect to the vector and c by an angle O ... b0 ° and, accordingly, will change while taking the phase meter (Fig.). Similarly, raising the controlled environment to a third, fourth, etc. electrodes will cause the current vector to rotate at a larger angle (Fig. 2.6). And when ascending to the seventh electrode, vector I will complete a full turn (Fig. 2). Currents between the electrodes immersed in the controlled medium will also flow through the controlled medium. , but since they do not close to the casing of the process tank, they will not affect the phase of the current to the zero point of the converter and, therefore, the readings of the phase meter. Thus, a rise in the level of the monitored medium from the first to the seventh electrode of the sensing element leads to a change in the phase angle from 0 to 360 ° and by graduating the scale of the phase meter in units of level, it is possible to measure the level (Fig. 3). In the event that the level measurement is performed in a process vessel made of non-conductive material, it is advisable to install the sensing element in a metal pipe, which is electroplated with phase meter. In order to approximate the dependence of the phase shift angle on the level of the monitored medium to the linear distance between the electrodes, it should be related to their height no more than 1: 5. Changes in the conductivity of the monitored medium and fluctuations in the supply voltage affect only the amplitudes of the currents and have little effect on the phase angles and, therefore, on the accuracy of the level measurements. A level meter for electrically conductive liquids containing electrodes installed uniformly in a metal case, an excitation source, a measuring transducer and an indicator, characterized in that, in order to improve accuracy, the excitation source is made multiphase, the measuring transducer is made in the form of a multiphase transformer. the windings of which are connected to the excitation source, the secondary windings have a midpoint, are connected by ends to the electrodes, the midpoints of all The windings are interconnected, the image is a zero point, and between the zero point and the case an indicator is turned on, made in the form of a phase meter. Sources of information taken into account during the examination 1. USSR author's certificate No. 522118, cl. G 01 F 23/24, 1973. 2. USSR author's certificate number 328340, cl. G 01 F 23/26, 1970 (prototype). -III t t-t Cl- s Uai irh ". loi lai IQ, SO feO 270 .3 3SO