RU2519495C1 - Method of measuring electroconductivity of electrolyte solution - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: method of measuring electroconductivity of electrolyte solution, located in liquid contour of first and second primary converters with drive winding, included into circuit of frequency generator, consists in registering outlet signal of voltage of measurement channels depending on solution concentration on condition that measurement is carried out in stabilised temperature field. In accordance with the invention level of sensitivity of first and second primary converters is determined by voltage value at outlet transformer of measurement channel depending on concentration of solution located in liquid contour, its temperature, and is in functional dependence on voltage and frequency of energy source of drive winding of feeding transformer. Measurement of solution electroconductivity is carried out with switching on reactor to operation frequency, determined in experimental analysis of solutions as optimal for analysed range of solution concentration; with registration of value of outlet signal of voltage of measurement channels, which is used to determine solution electroconductivity.EFFECT: increasing accuracy of electroconductivity measuring in wide range of electrolyte solutions concentration.2 dwg

Description

The invention relates to the field of conductometry, concerns the measurement of electrical conductivity of aqueous and other electrolyte solutions in a controlled continuous flow and can be used in physicochemical studies of solutions, in particular, for automatic control of the water-chemical regime of chemical water treatment plants of thermal power plants, district heating boiler rooms and other technological installations.

A known method and device for determining the concentration of electrolytes (RF patent No. 2102734, IPC G01N 27/02, 01/20/1998), based on the conductivity of the solution placed in the cell included in the frequency generator circuit, the method consists in changing the frequency at regular intervals, monitoring resonant frequency and calculation of electrolyte parameters in frequency. The study is carried out in an unstabilized temperature field and additionally monitor on a cell with normalized characteristics in the same temperature field, the generator frequency is controlled, the frequency measurement errors caused by the instability of the temperature field are recorded, the resonant frequency of the electrolyte solution corresponding to the extreme frequency measurement error is determined, and it determines the desired concentration.

To implement the method, an F-meter conductometer is used, containing a working and exemplary conductivity cell, code-frequency and frequency-code converters, information communication and control channels, RAM and a calculator.

The disadvantage of the method and the F-meter conductometer that implements the specified control method is that the electrolyte concentration is controlled indirectly by the resonant frequency and the extreme error of the frequency measurement, which introduces additional measurement errors. Another disadvantage is the complexity of the adopted functional diagram and calculation algorithm. In addition, the method and the F-meter conductometer that implements the specified control method are limited in application (by measurement limits) due to the low sensitivity of the primary transducer at low salt concentrations in the solution.

A known method of measuring the electrical conductivity of a liquid, implemented by a device (RF patent No. 2321977, IPC G01N 27/06, 01/10/2006), comprising supply and measuring transformers, the connection between which is carried out by a liquid circuit with windings connected respectively to an AC voltage source and to the detector and a loop of conductive material with an exemplary resistor introduced into the transformer windings, while a second measuring transformer, a second detector and a computing unit are introduced into the device, s between the supply and the second measuring transformers are made to the liquid circuit. The winding of the second measuring transformer is connected to the input of the second detector. The outputs of both detectors are connected to the inputs of the computing unit, and the output of the computing unit is the output of the device. The value of the measured electrical conductivity of the liquid is calculated in the computing unit.

According to the data of experimental studies, this method allows you to cover the range of measurements of the electrical conductivity of water in the range of 0.5 ... 65 Ohm / m, which is equivalent to a concentration of NaCl in solution of more than 2 g / L.

The closest technical solution is a method for measuring the electrical conductivity of an electrolyte solution located in the liquid circuit of the first and second primary converters with field windings included in the frequency generator circuit, which consists in recording the output signal of the voltage of the measurement channels depending on the concentration of the solution, provided that the measurement is carried out in stabilized temperature field. The known method is implemented by a device (RF patent No. 106375, IPC G01N 27/00, 07/10/2011), which is a transformer converter with two measurement channels and including a low-frequency signal generator, which is a common power source for the measurement channels, a two-channel measuring device, the first and the second, identical to the first, primary converters of the electrical conductivity of the electrolyte solution, each of which contains a series-connected supply and measuring transformers, the connection between which carried out etsya liquid multiturn loop constituting the ion conductor electrical connection filled with measured and normalized respectively, electrolyte solutions, the excitation winding of the second primary converter connected parallel to the excitation winding of the first primary converter connected to the low frequency signal generator. The output signal of the measurement channels is the voltage taken from the secondary winding of the output transformer with an amplitude value proportional to the conductivity of the electrolyte solution in the liquid circuit, and indicated on the functional diagram, respectively, U ₁ - channel I, U ₂ - channel II. The voltage across the measurement channels is fed to the input of a two-channel measuring device, the scale of which is graduated (for aqueous solutions) according to the specific electrical conductivity of the electrolyte C _NCI in units of S / cm.

The main disadvantage of the known methods is the low accuracy of measuring electrical conductivity (in terms of their functionality, they are limited in measuring the electrical conductivity of a liquid with a salt content in a solution determined by the value of mg / L and below).

The objective of the proposed method is to increase the accuracy of measuring electrical conductivity in a wide range of concentration of electrolyte solutions, including (for aqueous solutions) micrograms of the salt content in the solution.

The specified technical result is achieved by the fact that in the method for measuring the electrical conductivity of an electrolyte solution located in the liquid circuit of the first and second primary converters with excitation windings included in the frequency generator circuit, which consists in recording the output voltage signal of the measurement channels depending on the concentration of the solution, provided that the measurement is carried out in a stabilized temperature field, according to the claimed method, the sensitivity level of the first and second primary conversion It is determined by the voltage value at the output transformer of the measurement channel depending on the concentration of the solution located in the liquid circuit, its temperature, and is functionally dependent on the voltage and frequency of the power supply of the excitation winding of the supply transformer, and the conductivity of the solution is measured with the generator turned on at the operating frequency determined during the experimental study of solutions as optimal for the investigated range of concentration of the solution; in this case, the value of the output voltage signal of the measurement channels is recorded, the value of which determines the conductivity of the solution.

The essence of the invention is illustrated by drawings, where figure 1 presents a functional diagram of a device that implements the proposed method for measuring the electrical conductivity of an electrolyte solution. Figure 2 - experimental data of the dependence of the output signal voltage of the measurement channels on the frequency obtained on an aqueous solution of NaCl at a temperature of 25 ° C.

The blocks and elements of the device for measuring the electrical conductivity of an electrolyte solution in a controlled continuous flow are assigned the following positions.

1. Low frequency signal generator.

2. The field winding of the supply transformer channel I measurements.

3. The feed transformer channel I measurements.

4. The secondary excitation winding of the supply transformer channel I measurements.

5. The fluid circuit of the first primary transducer.

6. The primary measuring winding of the measuring transformer channel I measurements.

7. Measuring transformer channel I measurements.

8. The secondary measuring winding of the measuring transformer channel I measurements.

9. The primary winding of the output matching voltage transformer channel I measurements.

10. The output matching voltage transformer channel I measurements.

11. The secondary winding of the output matching voltage transformer channel I measurements.

12. The field winding of the supply transformer channel II measurements.

13. The feed transformer channel II measurements.

14. The secondary excitation winding of the supply transformer channel II measurements.

15. The liquid circuit of the second primary Converter.

16. The primary measuring winding of the measuring transformer channel II measurements.

17. Measuring transformer channel II measurements.

18. The secondary measuring winding of the measuring transformer channel II measurements.

19. The primary winding of the output matching voltage transformer channel II measurements.

20. The output matching voltage transformer channel II measurements.

21. The measuring device.

22. The secondary winding of the output matching voltage transformer channel II measurements.

A device for measuring the conductivity of an electrolyte solution in a controlled continuous stream is a transformer converter with channels I, II of measurements and includes a low-frequency signal generator 1, which is a common power source for channels I, II of measurements and connected to the first and second, identical to the first, primary conductivity converters of electrolyte solutions, as well as a two-channel measuring device 22.

Measurement channel I includes a first primary converter of the conductivity of electrolyte solutions, comprising a supply transformer 3 assembled on a ferromagnetic core with an excitation coil 2, a liquid circuit 5, a measuring transformer 7 assembled on a ferromagnetic core with a measuring winding 8, and an output matching voltage transformer 10 s the primary winding 9 and the secondary winding 11.

Measurement channel II, which is a comparative channel for measuring the electrical conductivity of electrolyte solutions, includes a second, identical to the first, primary converter of electrical conductivity of electrolyte solutions, containing a supply transformer 13 assembled on a ferromagnetic core with field winding 12, a liquid circuit 15, a measuring transformer 17, assembled on a ferromagnetic core with a measuring winding 18, the output matching voltage transformer 20 with the primary winding 19 and the secondary winding 21 th.

Measuring transformers 7 and 17 are identical in technical characteristics: they have the same cores and windings along the cross section of the electrolytic conductor and the number of turns, both primary 6 and 16 (liquid circuit), and secondary 8 and 18 measuring windings made of enameled wire of a certain section .

Output matching voltage transformers 10 and 20 are made identical by winding data and core sizes.

The output of the low-frequency signal generator 1 is connected to the field windings 2 and 12 of the supply transformers 3 and 13, and the field coil 13 of the second primary converter is connected in parallel to the field winding 2 of the first primary converter. The liquid circuits 5 and 15, which are the ionic conductors of the electrical connection of the supply and measuring transformers, are formed by windings 4 and 6, as well as 14 and 16 of the supply 3 and 13, and measuring 7 and 17 transformers with the number of turns w ₄ and w _{6 of the} channel I measurements, and w ₁₄ , w ₁₆ channel II measurements. The connection of the windings 4 and 6, as well as 14 and 16, is performed sequentially in the direction of motion of the measured flow of electrolyte solutions. The liquid circuits 5 and 15 are made of multi-turn flowing PVC pipes and are filled with respectively measured and normalized electrolyte solutions.

The primary windings 9 and 19 of the output matching voltage transformers 10 and 20 are connected to the measuring windings 8 and 18 of the measuring transformers 7 and 17, and the secondary windings 11 and 21, one of the outputs of which are interconnected, are connected to a two-channel measuring device 22, which records the voltage with the output the amplitude value proportional to the electrolyte conductivity and expressed both in the absolute value of the measured value and in relative - in comparison with the normalized solution. The output matching voltage transformer 10 of the first primary converter is capable of balancing its output voltage with the output voltage of the output matching voltage transformer 20 of the second primary converter by introducing additional solders from the secondary winding 11 of the transformer 10. The need for such a switching circuit is due to the fact that it is almost impossible to manufacture transformers with identical transformation ratios across the measurement channels. Balancing is performed provided that the liquid circuits 5 and 15 are filled with the same electrolyte solution with a normalized value of electrical conductivity and under equal conditions in temperature.

A method of measuring the conductivity of an electrolyte solution is as follows.

The essence of the proposed method is to establish the dependence of the output voltage of the Converter on the frequency of the power source of the electromagnetic field of the pathogen, the nature and concentration of the electrolyte placed in the liquid circuit.

The studied electrolyte solution is placed in the liquid circuit 5 with the number of turns w ₄ on the transformer 3 and w ₆ on the transformer 7 of the working measurement channel, and the circuit of the test channel 15 with turns w _{14 of the} transformer 13 and 16 m of the transformer 17 is filled with an electrolyte with normalized values. A supply voltage of a given frequency is supplied to the field windings 2 and 12 of the supply transformers of channels I and II from the generator 1. In this case, the frequency of the power source of the excitation windings of the supply transformers is taken as a variable at certain values of the salt content (concentration) of the electrolyte solution and a constant temperature.

In the liquid circuit, EMF is induced, which creates a current in them, proportional to the corresponding conductivity at a frequency f ₁ :

$${\text{I}}_{\text{one}}={\text{to}}_{\text{one}}\cdot \text{EV}\cdot {\text{g}}_{\text{x}}\text{(one)}$$

$$\text{I}{}_{\text{2}}={\mathrm{to}}_{\text{2}}\cdot \text{EV}\cdot {\text{<figure-callout id="0" label="g" filenames="00000022.png" state="{{state}}">g</figure-callout>}}_{\text{0}}\text{,}\text{(2)}$$

where I ₁ is the current in the liquid circuit 5;

I ₂ - current in the liquid circuit 15;

EV - excitation voltage on the windings 2 and 12;

to ₁ - coefficient determined by the parameters of the transformer 3;

g _x is the conductivity of the electrolyte solution of the liquid circuit 5;

g ₀ - conductivity of the electrolyte solution of the liquid circuit 15.

Measuring transformers 7 and 17 are identical in technical characteristics: they have the same cores and windings along the cross section of the electrolytic conductor and the number of turns as primary (liquid circuit), also secondary, made of enamel wire of a certain section.

Then the EMF on the measuring windings 8 and 18 at a frequency f ₁ equal

$${\text{E}}_{\text{one}}={\text{ê}}_{\text{7}}{\text{I}}_{\text{one}}={\text{<figure-callout id="7" label="ê" filenames="00000021.png,00000022.png" state="{{state}}">ê</figure-callout>}}_{\text{7}}{\text{ê}}_{\text{one}}\text{Åâ}\cdot {\text{g}}_{\text{x}}\text{(3)}$$

$${\text{<figure-callout id="2" label="E" filenames="00000022.png" state="{{state}}">E</figure-callout>}}_{\text{2}}={\text{ê}}_{\text{17}}{\text{I}}_{\text{2}}={\text{<figure-callout id="17" label="ê" filenames="00000021.png,00000022.png" state="{{state}}">ê</figure-callout>}}_{\text{17}}{\text{<figure-callout id="2" label="ê" filenames="00000022.png" state="{{state}}">ê</figure-callout>}}_{\text{2}}\text{Åâ}\cdot {\text{g}}_{\text{o}}\text{(four)}$$

where E ₁ and E ₂ EMF on the measuring windings 8 and 18, respectively; to ₇ and to ₁₇ - coefficient determined by the parameters of transformers 7 and 17.

The voltage removed from the windings 8 and 18 of the measuring transformers is supplied to the input of a voltage transformer 10 and 20 with a transformation ratio of ₁₀ and ₂₀ . The purpose of the output transformer is to coordinate the load on the measuring transformer and increase the output voltage.

At the outputs of transformers 10 and 20, which are identical in terms of winding data and core sizes, a voltage U ₁ and U _{2 is} generated, which is proportional to the electrolyte conductivity at a frequency f ₁ and equal in value to:

$${\text{U}}_{\text{one}}={\mathrm{to}}_{\text{10}}\cdot {\text{E}}_{\text{one}}={\text{to}}_{\text{10}}{\text{<figure-callout id="7" label="ê" filenames="00000021.png,00000022.png" state="{{state}}">ê</figure-callout>}}_{\text{7}}{\text{ê}}_{\text{one}}\text{Åâ}\cdot {\text{g}}_{\text{x}}\text{(5)}$$

$${\text{<figure-callout id="2" label="U" filenames="00000022.png" state="{{state}}">U</figure-callout>}}_{\text{2}}={\text{to}}_{\text{twenty}}\cdot {\text{<figure-callout id="2" label="E" filenames="00000022.png" state="{{state}}">E</figure-callout>}}_{\text{2}}={\text{to}}_{\text{twenty}}{\text{<figure-callout id="17" label="ê" filenames="00000021.png,00000022.png" state="{{state}}">ê</figure-callout>}}_{\text{17}}{\text{<figure-callout id="2" label="ê" filenames="00000022.png" state="{{state}}">ê</figure-callout>}}_{\text{2}}\text{Åâ}\cdot {\text{g}}_{\text{about}},\text{(6)}$$

or, in general form:

$${\text{U}}_{\text{one}}={\text{Ê}}_{\text{è}}\cdot \text{Åâ}\cdot g_{\text{õ}}\text{(7)}$$

$${\text{<figure-callout id="2" label="U" filenames="00000022.png" state="{{state}}">U</figure-callout>}}_{\text{2}}={\text{Ê}}_o\cdot \text{Åâ}\cdot g_{\text{o}}\text{.}\text{(8)}$$

where K _and K _o - the constant measurement channels I and II, respectively.

The value of the output voltage U ₁ and U _{2 is} recorded by a two-channel measuring device.

The measurement is carried out either according to the comparison scheme, or separately through the measurement channels, depending on the connection scheme of the secondary winding of the output transformers of the measurement channels and the algorithm for calculating the measured value.

To exclude the influence of temperature on the measurement results, studies are carried out in a stabilized temperature field.

The sensitivity of the Converter is determined experimentally directly on the device that implements this measurement method. In this case, the frequency of the voltage taken from the signal generator, to which the field windings of the supply transformers are connected, is taken as a variable. The study is carried out in the frequency range 3 ... 20 kHz in an aqueous NaCl solution with a concentration ranging from 10 mg / l - with a serial dilution of the solution to 0.31 mg / l and 0 mg / l (distilled water). All measurements are at 25 ° C. Based on the data obtained, a graph of the dependence of U _o = φ (f) is constructed, which is given in Appendix 2.

According to its functionality, a device that implements this method of measuring the conductivity of a solution is applicable to work in two modes.

In the first mode is carried out:

- study of the dependence of the value of the output signal on the measurement channel on the frequency of the voltage of the power source, the nature of the electrolyte, its concentration, provided that the measurement is carried out in a stabilized temperature field;

- the construction of the amplitude-frequency characteristics of the device in coordinates U _o = φ (f) at a given concentration of electrolyte solution;

- selection of the optimal value of the frequency and voltage of the power source of the converter in order to determine the measurement range, the greatest sensitivity at the control point and the condition for the stability of the values of the output measurement signal.

In the second mode, the device is included in the continuous monitoring of the conductivity of the measured medium.

. В последующих измерениях, частота источника питания повышается с равномерным шагом и регистрируется выходное напряжение. Опыты продолжаются до перехода функциональной зависимости до значения, когда частота источника питания - выходное напряжение достигает некоторого экстремума. На основе полученных данных, строится график зависимости U_вых=φ(f) при данной концентрации электролита. На графике выделяется участок, где зависимость выходного напряжения от частоты источника питания близка к линейной, и по границам участка находят рабочий диапазон частоты источника питания.The device in the first mode operates as follows. The liquid circuit of the measuring channel I is filled with the test solution. The study is carried out in a stabilized temperature field. The temperature is recorded throughout the experiment, and for aqueous electrolyte solutions, the conductivity characteristic is reduced to t = 25 ° C. With the inclusion of the signal generator, sets the initial frequency of the supply voltage of the measurement channel f ₁ and then we get the voltage on the output transformer $$U_i^{\mathrm{one}}$$

. In subsequent measurements, the frequency of the power supply rises with a uniform step and the output voltage is recorded. The experiments continue until the functional dependence passes to the value when the frequency of the power source - the output voltage reaches a certain extremum. Based on the data obtained, a graph is plotted as U _out = φ (f) at a given electrolyte concentration. A plot is highlighted on the graph where the dependence of the output voltage on the frequency of the power source is close to linear, and the working range of the frequency of the power source is found along the boundaries of the plot.

The optimal frequency is selected from the calculation - to obtain the highest value of the output voltage signal, which determines the sensitivity level of the converter in this measurement range, provided that the output signal is stable.

The results of experiments conducted on laboratory samples of an aqueous solution of NaCl, are presented in graphs (figure 2).

The device in the second mode operates as follows.

The liquid circuit of the measuring channel I is filled with the test solution, and the circuit of the channel II is filled with a solution with a normalized conductivity value. With the inclusion of the signal generator, the voltage and frequency of the power source of the excitation windings of the converter are set, and then we get: the voltage value at the output transformer U ₁ through channel I and U ₂ , respectively, through channel II.

The proposed method for measuring the conductivity of solutions improves the accuracy of measurements by increasing the sensitivity of the first and second primary transducers, taking into account that the conductivity of electrolytes depends both on the concentration of the solution, its temperature, and also on the frequency of the power source of the electromagnetic field exciter.

Therefore, the sensitivity of the converter is determined by two variables: depending on the frequency of the power source and on the concentration of the electrolyte, provided that the measurements are carried out in a stabilized temperature field.

The sensitivity of the converter, depending on the frequency of the power source S _H , mV / kHz, is determined by the ratio of the increment of the voltage output signal ΔU _o , mV of the measurement channel to the change in the frequency of the power source Δf, kHz at a constant electrolyte concentration and temperature of 25 ° C, i.e. S _H = ΔU _o / Δf at C _NaCl = const.

According to the results of an experiment conducted at a solution concentration of C _NaCl = 0.31 mg / L at the boundary frequencies of 3 and 8 kHz, the values of the output voltage signals were obtained:

=1,64 мВ,at a frequency f ₁ = 3 kHz $$U_{\mathrm{one}}^{\text{'}\text{'}}$$

= 1.64 mV,

=5,49 мВ. Тогда, при Δf=5 кГц, ΔU_вых= $$U_1^{\text{'}\text{'}}-U_1^{\text{'}}$$

=5,49-1,64=3,85 мВ, получим численное значение чувствительности преобразователя в зависимости от частоты источника питания:at a frequency f ₂ = 8 kHz $$U_{\mathrm{one}}^{\text{'}\text{'}\text{'}\text{'}}$$

= 5.49 mV. Then, at Δf = 5 kHz, ΔU _out = $$U_{\mathrm{one}}^{\text{'}\text{'}\text{'}\text{'}}-U_{\mathrm{one}}^{\text{'}\text{'}}$$

= 5.49-1.64 = 3.85 mV, we obtain the numerical value of the sensitivity of the converter depending on the frequency of the power source:

$$S_h=\frac{\Delta U_{\mathrm{at}sx}}{\Delta f}=\frac{3.85}{5}=0.77\frac{m\mathrm{AT}}{\mathrm{to}Gc}$$

The increase in output voltage (in relative units) is:

$${\epsilon }_h=\frac{U_{\mathrm{one}}^{\text{'}\text{'}\text{'}\text{'}}-U_{\mathrm{one}}^{\text{'}\text{'}}}{U_{\mathrm{one}}^{\text{'}\text{'}}}=\frac{5.49-\mathrm{1,64}}{\mathrm{1,64}}=\frac{3.85}{\mathrm{1,64}}=\mathrm{2,3}o.e.$$

Studies have shown that with an increase in electrolyte concentration, the sensitivity of the transducer in frequency S _h also increases, and at C _NaCl = 10 mg / l it is:

, ε_ч=3,1 o.e. $$S_h=\frac{\Delta U_{\mathrm{at}sx}}{\Delta f}=\frac{21.3-5.2}{5}=\frac{16.1}{5}=3.2\frac{m\mathrm{AT}}{\mathrm{to}Gc}$$

, ε _h = 3.1 oe

, находится по графику зависимости U_вых=φ(f), (приложение 2) и представляет собой отношение приращения выходного сигнала напряжения ΔU_вых, мВ канала измерения к изменению концентрации солей в растворе ΔC_NaCl, мг/л в данном диапазоне измерения, при частоте источника питания f_i=const.The sensitivity of the converter depending on the concentration of the solution S _K , $$\frac{m\mathrm{AT}}{mg/l}$$

is found according to the graph of the dependence U _o = φ (f), (Appendix 2) and represents the ratio of the increment of the voltage output signal ΔU _o , mV of the measurement channel to the change in salt concentration in the solution ΔC _NaCl , mg / l in this measurement range, at a frequency power source f _i = const.

- по значению выходного напряжения U₁, мВ по каналу I и U₂, мВ - соответственно по каналу II на граничных частотах (для сравнения) при 3 кГц и 8 кГц, получим следующие результаты:We give as an example the determination of the sensitivity of the transducer to the measured value in the range of the concentration of salts in the solution C _NaCl = 0.31 ... 0 $$\frac{mg}{l}$$

- according to the value of the output voltage U ₁ , mV for channel I and U ₂ , mV, respectively, for channel II at the boundary frequencies (for comparison) at 3 kHz and 8 kHz, we obtain the following results:

at a frequency f _l = 3 kHz, $$S_{\mathrm{to}}^{\text{'}\text{'}}=\frac{\Delta U_{\mathrm{at}sx}}{\Delta {\mathrm{FROM}}_{NaCl}}=\frac{U_{\mathrm{one}}^{\text{'}\text{'}}-U_2^{\text{'}\text{'}}}{0.31-0}=\frac{\mathrm{1,64}-1.20}{0.31}=1.41\frac{m\mathrm{AT}}{mg/l};$$

at a frequency f ₂ = 8 kHz, $$S_{\mathrm{to}}^{\text{'}\text{'}\text{'}\text{'}}=\frac{\Delta U_{\mathrm{at}sx}}{\Delta {\mathrm{FROM}}_{NaCl}}=\frac{U_{\mathrm{one}}^{\text{'}\text{'}\text{'}\text{'}}-U_2^{\text{'}\text{'}\text{'}\text{'}}}{0.31-0}=\frac{5.49-3.80}{0.31}=5.41\frac{m\mathrm{AT}}{mg/l}.$$

Then, the multiplicity of increasing the sensitivity of the transducer in this measurement range (in relative units) will be:

$${\epsilon }_{\mathrm{to}}=\frac{S_K^{\text{'}\text{'}\text{'}\text{'}}}{S_K^{\text{'}\text{'}}}=\frac{5.41}{1.41}=3.8o.e.$$

The obtained data on increasing the sensitivity level of the converter with increasing frequency of the power source determine the accuracy of measuring the electrical conductivity of the solution, which can be expressed as the ratio of the output signal voltage of the measurement channel U _o , mV to the measurement limit (scale) of the measuring device P _etc. and get the price dividing the device, according to measurement options, as a criterion of efficiency for accuracy.

Thus, the application of the proposed technical solution increases the sensitivity of the primary transducer of the measurement channels by more than three times, thereby increasing the accuracy of measuring electrical conductivity in this concentration range of electrolyte solutions, including (for aqueous solutions): micrograms - salt content in the solution and pure water .

Claims (1)

A method for measuring the electrical conductivity of an electrolyte solution located in the liquid circuit of the first and second primary converters with excitation windings included in the frequency generator circuit, which consists in recording the output voltage signal of the measurement channels depending on the concentration of the solution, provided that the measurement is carried out in a stabilized temperature field, different the fact that the sensitivity level of the first and second primary converter is determined by the voltage value at the output transf in the measurement channel, depending on the concentration of the solution located in the liquid circuit, its temperature and is functionally dependent on the voltage and frequency of the power source of the excitation winding of the supply transformer, the conductivity of the solution is measured with the generator turned on at the operating frequency determined during the experimental study of solutions as optimal for the studied range of changes in the concentration of the electrolyte solution; register the value of the output voltage signal of the measurement channels, which determine the conductivity of the solution.

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