RU1809319C - Electrically conductive liquid level capacitive pickup - Google Patents

Abstract

The inventive device contains discrete receiving electrodes (1), a dielectric film (2), 1 operational amplifier (3), 2 resistors of the same resistance (4), 1 feedback resistor b), 1 dielectric mast (6), 1 alternator voltages (8), 1 common electrode (9). Electrodes, an operational amplifier and resistors are located inside the mast. One of the ends of each electrode is brought to the surface of the mast and covered with a dielectric film. 1-3-5-3. 4-3, 8-9. 4 ill.

Description

The invention relates to instrumentation, and in particular to devices for monitoring the level of conductive liquids.

The aim of the invention is to simplify the design.

Figure 1 is a schematic diagram of an inventive device; figure 2 is a view of the device in section aa; Fig. 3 is a circuit diagram of the claimed device; Fig. 4 is a graph of the dependence of Quout in OY on the liquid level in the inventive device.

The device consists of a series of discrete receiving electrodes 1, one end of which is brought to the surface of the mast 6 and is covered with a dielectric film 2. The electrodes 1 themselves are located along the mast at regular intervals. All discrete receive electrodes are connected to the inverting input of the operational amplifier 3. A feedback resistor Roc 5 is connected between the output and the inverting input of the operational amplifier.

Each input of the operational amplifier is connected to ground through a resistor of the same value R0 4. The operational amplifier, feedback resistors, and one rating are located inside the mast body. The common electrode 9 is connected to the master oscillator 8 through a power amplifier 7.

Capacitive meter works as follows.

An alternating voltage is applied to the common electrode 9 from the master oscillator 8 through the power amplifier 7. When a conductive liquid 10 appears, it fills a certain number of discrete receiving electrodes 1. Between the common electrode, which is the source of the alternating signal Uc, and these receiving electrodes, only the dielectric film 2 remains, which has some capacitive resistance X1 for the alternating signal. A single value current flows through each of the discrete receiving electrodes, i.e. capacitive resistors (L

WITH

00

about u

Yu

the laziness of the electrodes created by a dielectric film of the same thickness are equal.

As a result, at the OY output, the Ovich begins to grow in steps, linearly, proportional to the number of discrete receiving electrodes filled in, and therefore to the liquid level, which is determined as

N - V Uc for the first time, XC |

where Roc is a feedback resistor; Xci is the capacitance of the receiving electrode. The RO resistors are used to set the DC OY mode.

Claims (1)

The claims Capacitive level meter of conductive fluid, containing horizontally arranged through equal the distance of the conductive receiving electrodes connected to the signal processing circuit and the common electrode connected to the alternating voltage generator, characterized in that, in order to simplify the design, a mast of dielectric material is inserted into it, inside of which are receiving electrodes and a processing circuit signal, made in the form of an operational amplifier with a resistive feedback link and the first and second resistors of the same resistance connected to a common bus and, respectively, to the direct and inverse input m operational amplifier, the inverse input of which is also connected to one of the ends of each receiving electrode, others whose ends are brought to the surface of the mast and covered with a dielectric film. Phys. 1 Fie.Z