SU851238A1 - Device for measuring humidity - Google Patents

Description

The invention relates to (} isicochemical analysis and can be used to determine the moisture content of bulk and liquid materials. A device for measuring humidity, containing a ferrite transformer, is known, the primary winding is connected to the output of the high-frequency generator, and the secondary winding is split on two midpoint and both halves are included in the difference circuit. A capacitive sensor is included in one arm and a t1I reference capacitor in the other. balancing to a zero difference circuit, in which a reference capacitance has a reference capacitance. To increase accuracy in this device, the primary winding is connected to the secondary one by means of a capacitor. However, this capacitor is able to balance the circuit at one point with certain capacitance values They cannot provide sufficient measurement accuracy in a wide range of changes in the active and reactive components of the sensor, especially in a wide frequency range. Closest to the present invention is a device for controlling the composition of mixtures according to the magnitude of electrical conductivity, comprising an alternator, a closed magnetic circuit with a winding connected to one generator output, a receiving closed magnetic circuit with a measuring winding, one input which is connected to the second generator output, the other is with the measuring winding, and the output of the synchronous detector is connected to the input of the measuring device G23. However, the known device allows measuring the humidity of a material with high accuracy.

3

The purpose and: zobothochich is the measurement of 1 h jiCTH measurements.

The goal is achieved by the fact that the device contains an alternator, a closed magnetic circuit with a winding connected to one generator output, a receiving closed magnetic circuit with a measuring winding, a synchronous detector, one input of which is connected to the second generator output, and the other to the measuring winding and the output of the synchronous detector is turned on. to the input of the measuring device, a sensor with electrodes is inserted, which are connected by a conductive jumper so that they form a closed loop with it, and pe1) Single cores passes through openings, moreover, amplitude meter further introduced into the device, whose input is also connected to the measurement winding, and an output - with a measuring device.

Fig. I shows the structure of the sensor; Fig. 2 is a block diagram of a device for measuring humidity.

The sensor included in the moisture meter consists of two electrodes 1 and 2, which may be flat or, depending on the purpose, have a different configuration. The electrodes are connected to each other by means of a conductive rod 3 and are placed in material 4, the humidity of which is to be measured. The conductive rod 3 passes through the central holes of the transmitting 5 and receiving 6 ferrite rings.

On the rings there are toroidal windings: transmitting 7 and 8 on the transmitting ring 5 and receiving 9 on the receiving ring 6. Ferrite rings with windings enclosed in a dielectric insulating sheath 10.

Transmit windings 7 and 8 are connected to the outputs of generators 11 and 12. Priene winding 9 is connected to the input of a wideband amplifier 13, which has two outputs. One of the outputs of the amplifier 13 is connected with the first inputs of synchronous detectors 14 and 15, the other with the frequency separation circuit 16. The second inputs of the synchronous detectors 14 and 15 are connected to the outputs of generator II and 12. The outputs of the synchronous detectors 14 and 1.5 and the outputs of the separation circuit 16 are connected to the inputs

four

Information processing unit 17, the KOTOpoio output is connected to the input of the indicator device 18.

The device works in the following way.

Consider first working with a single frequency channel. Alternating current from the generator 12c frequency flows through the transmitting winding 7 of the transmitting ring 5, creating in it a magnetic flux equal to

G- (.

2P “G”

ъ /

iQ GN / M;

 410

Where

7 - the number of turns of the winding 7; $ 5 - cross section of ring 5; Gd - the average radius of the ring 5; jUc - relative permeability

rings 5;

J - the amplitude of the current in the winding 7. In accordance with the second Maxwell equation, this variable flow excites in the jumper 3 EMF

-.f sec.

This EMF excites in a closed circuit formed by jumper 3, electrodes 1 and 2, and a gap filled with the substance under study, an electric current consisting of two components — a bias current caused by the dielectric constant of the substance, and a conduction current caused by a non-zero conductivity between electrodes 1 and 2, filled with substance 4.

In a complex form, this current can be written as

-i4; r-.

 2 J gap capacity I and 2 filled

substance 4;

where p is the component of active substance loss;

E is the dielectric constant of the substance; K - geometrical coefficient

electrodes.

Thus, the module of the complex of the current flowing through jumper 3,

equals

-4 .. c)

0

Claims (2)

5 fach;) TijKa i vidhavi ranna, (5) Thus, we have two unknowns gf and two equations (4) (5). Consequently, the system allowed. To find ff and 6, it is necessary to determine the modulus and phase of the current. It is known because it determines the known values — the value of the generator current 12, the number of turns of the winding 7, the material and the shape of the ring 5. A further circuit measures the modulus and phase of the current 3f ,. When a 3fj current flows through jumper 3, it excites a mantle flow in the receiving ring 6, the value of which is equal to, V-FoA b6b2S K - -, n), (6) where lUft is the magnetic permeability of ring 6; G is the average radius of the ring 6. This magnetic flux induces in the winding 9 an emf (where / s) is the number of turns of the winding 9. The signal from the output of the winding 9 is amplified by the amplifier 13 and fed to one of the inputs of the synchronous detector 15, to the reference the input of which is alternating voltage from the generator 12. The output voltage of the synchronous detector is proportional to the amplitude and phase of the output signal of the amplifier 13, i.e. amplitude and phase of current C} y4 The signal from the output of amplifier 13 through the frequency separation circuit 16 at the corresponding output enters the information processing block 17, which converts the signal from the output of amplifier 13, proportional to the amp current of Zn and from the output of the synchronous detector 14, where the signal is proportional flax and amplitude and phase, in magnitudes and further in a voltage proportional to humidity. This voltage is fed to the input of the indicator device 18, where the humidity value is already indicated. 8 ". If a mixture of several substances is present, it is necessary to know the values for each substance in order to correctly measure the humidity. To this end, the system has several generators with different frequencies (jj 1-, etc. (generators P, 12, etc.) and several synchronous detectors 14, 15, etc. Frequency separation circuit 16 in this case section At the outputs, signals with different frequencies ijL, jj, etc. Synchronous detectors also select signals proportional to the amplitudes and phases of currents whose frequencies are equal to the frequencies of the oscillators, the voltage of which is used as a reference in the corresponding synchronous detectors. It doesn’t improve the accuracy of measuring wet The invention includes a device for measuring humidity, containing an alternator, a closed magnetic circuit with a winding connected to one generator output, a receiving closed magnetic conduit with a measuring winding, a synchronous detector, one input of which is connected to the second generator output, the other with a measuring winding , and the output of the synchronous detector is connected to the input of a measuring device, characterized in that, in order to improve the measurement accuracy, a sensor with electrodes, which are connected jumper boiling water so as to form with it a closed circuit, wherein the web extends through the openings of magnetic cores, in addition, the apparatus further introduced amplitude meter, whose input is also connected to the measuring winding and the output of the measuring device. Sources of information taken into account during the examination 1. USSR author's certificate 437957 G 01 N 27/22, 1972. 2. USSR author's certificate 659944, cl. G O N 27/02, 1977 (prototype). J 5 3 6