SU1638556A1 - Conductometric level indicator - Google Patents

Abstract

The invention relates to an instrument-making industry for the food industry, in particular to signaling devices for the level of liquid media of different conductivity, which simultaneously form two types of sticking on a primary converter: sticking, insulating electrodes of a flooded primary converter from a controlled medium, and sticking forming a conductive layer between the bare primary electrodes converter The purpose of the invention is to increase the reliability of work in the presence of sticking, insulating electrodes. To achieve this goal, a phase-sensitive amplifier 4 is inserted into the detector, the differential input of which is connected to the bridge diagonal, and the output is connected to the relay unit 5, the bridge is made with a resistance value in the arm adjacent to the primary converter, more flooded and less bare resistance of the interelectrode gap, and the values of the resistances of the two other shoulders of the bridge are equal to each other, the first and second electrodes of the primary converter are made equal in length and equal to the length of the isolators onnogo gap that allows to rebuild the error from sticking by selecting the resistance R. sl с о GJ 00 СЛ СЛ О

Description

FIG. one

The invention relates to instrumentation for the food industry, in particular to signaling devices for the level of liquid media of different conductivity, which simultaneously form two types of sticking on the primary converter: sticking, insulating electrodes of the flooded primary converter from the controlled medium; sticking, forming a conductive layer between the electrodes of the flat primary converter.

The aim of the invention is to increase the reliability of operation in the presence of sticking, insulating electrodes.

FIG. 1 shows the scheme of the proposed device; in fig. 2 - change of resistance by the insulating layer of the sediment (a), conductive layer (b).

The block conductometric signaling device (Fig. 1) contains the first electrode 1, the second electrode 2, the power supply unit 3, the phase-sensitive amplifier 4, the relay unit 5. The first 1 and second 2 electrodes (Fig. 1) are included in the bridge arm, one diagonal of which is supplied by alternating voltage Unep from power supply unit 3, and from another diagonal a signal is taken and fed to the differential input of phase-sensitive amplifier 4, to which the switching power supply voltage Ump from power supply unit 3 coinciding with the half-time alternating voltage is supplied wives power bridge. The output of the phase-sensitive amplifier 4 is connected to a relay device 5, to which Unoci constant voltage is supplied from the power supply unit 3.

The level indicator works as follows.

The work is based on the principle of changing the phase of the alternating voltage taken from the diagonal of the bridge depending on the resistance of the interelectrode gap. If the primary transducer is in a controlled environment, i.e. flooded, the resistance of the interelectrode gap R3ar (Fig. 2) is less than the resistance in the bridge arm adjacent to the primary transducer 3 (Fig. 1), and if the resistances of the two other arms of the bridge R1 R2 are equal, the positive voltage of the bridge unbalance coincides with the phase supplying the phase-sensitive amplifier 4, while the relay unit 5 is turned on.

If the primary transducer is above the level of the monitored medium, i.e. ogolen, the resistance of the interelectrode gap ROI-OL (Fig. 2) is greater than the resistance R3 (Fig. 1). and the negative phase voltage of the unbalance of the bridge coincides with the phase of the power supply of the phase-sensitive amplifier 4, while the relay device 5 is turned off,

In the case of sticking, forming a conductive layer between the electrodes, the resistance of the exposed primary converter decreases along curve b (Fig. 2), however, the operability of the alarm device is maintained until the resistance of the exposed primary converter becomes less or equal to R3.

In the case of sticking, the insulating layer of sediment electrodes flooded primary converter, due to electrolysis (for example in the brewing industry - beer stone, in wine-making - tartar, in water - scale, etc.) the resistance of the flooded interelectrode gap of the primary converter rises a (a Fig. 2), however, the operability of the detector remains until the resistance of the flooded primary converter is greater than or equal to the resistance R3.

With the simultaneous presence of two types of sticking, the functionality of the level indicator is also preserved until the resistance of the interelectrode gap of the submerged and bare becomes equal to each other and equal to the resistance R3, i.e. Raar. Roi-ol. R3. Thus, the resistance R3, standing in the bridge arm adjacent to the primary transducer, is the setting device, by means of which the level indicator is tuned to media with different conductivity and build-up thickness. The optimal ratio of the lengths of the electrodes and the insulator is the equality of the lengths of the electrodes and the insulator between themselves. When the length of the insulation gap is smaller than the length of the electrodes, the resistance of the bare primary converter is less than the resistance R3 with a smaller thickness of the adhering conductive layer. With an insulating gap length longer than the electrodes, the resistance of the flooded primary transducer is greater than the resistance R3, also with a smaller thickness of the adhering insulating layer, which in both cases leads to a failure of the level detector. The supply of an ac voltage to the bridge reduces the effect of electrolysis, at which a precipitate forms on the primary transducer, isolating the electrodes from the medium.

Claims (1)

Claims of the invention A block conductometric signaling device containing a two-electrode primary transducer included in a bridge arm, the output of which is connected to a relay unit, characterized in that, in order to increase reliability in the presence of sticking insulating electrodes, a phase-sensitive amplifier is introduced into it, differential input The bridge is connected to the diagonal of the bridge, and the output is dinene with a relay unit, the electrode lengths of the primary converter are equal to the length of the interelectrode gap, and the resistance in the bridge arm adjacent to the primary converter is equal to the average resistance of the interelectrode circuit in the presence and absence of a controlled medium in it. Roe about lg oh FIG. g may.