CS201642B1 - Cell of the capacitous type - Google Patents

Description

The capacitive type cell aa relates to the measurement of the high-frequency conductivity of liquids, the dielectric constant of substances and the dielectric oxide of substances. This can advantageously be used to identify a particular component of the measured handle whose content in the medium is proportional to either the conductivity, the dielectric contact or the dielectric losses.

The cells used hitherto are characterized by having at least two electrodes, all of which are electroplated by electrically insulating material from the measured medium. Depending on the nature of the medium and the method of measurement, these cells can be used to measure either the active components of the impedanoia, possibly admitanoia, or the reactive (imaginary) components of the impedanoia (susoeptanoia), or the effective capacity. The resulting impedance of these members, when measured at constant voltage, is:

re

CU Re K / 2 /

2 2 1 CU He K

CUC where Re is the low frequency resistance of the CO electrolyte is a circular frequency

K is the cell capacity C is the cell wall capacity i = Ti. 2 Z2 + Re Co K

For adelectomy Y:

Re CO C

CUC + Ue ² OQ ³ CK / C + K / + Re ² CO ² / C + K / ² + Re ² CU ² / G + K / / 2 /

It follows from equations 1 and 2 that the best measurement conditions are obtained if the ratio is

C, go maybe the highest. When measuring high conducting systems (over 10 ^J S, S = Siemens),

With a frequency above 100 MHz the active resistance value is close to zero. The reactive resistance value depends on the dielectric constant of the measured medium, since the ratio C cannot be independently increased by K '. It is necessary to use an electrical insulating material with a low wall thickness and a high dielectric constant, a small cell cross-section and a large gap between the electrodes.

According to the invention, the capacitive type cell consists of at least two electrodes disposed on the hollow shaped profile of an electrically non-conductive material, preferably tubular in shape, characterized in that at least one electrode having a surface area of 0.01 to With a polarization capacity of 0.1 to 100 / XF in direct contact with the medium to be measured and on the opposite wall, at least one additional electrode is isolated from the medium to be measured and the resulting cell capacity is 0.005 to 0.5. pp.

With this electrode placement, the polarization capaoity of the electrode immersed in the measured medium is large, equal to approximately 10 ^J K per cm surface. The capacitance of this electrode is negligible even at relatively low frequencies against the medium resistance. E.g.

642 for fs 1 MHz surface 1 om ² Op 4 1θ “^ F, the capacitance is 0.0159 ^.

Cp = polarization capaoity

For the type of electrode-free capacitive salt used so far with 2Oml insulated electrodes S ₂ , the cell capacity C of the salt is:

^C el * ^C e2 ^C sl * ^C s2 'el

At ^C s1 = ^C s2 J ^{e C} 1 = ₂ ^{aI F} = ^F 2 £. F Kapaoita Ko _z is Ko _z = * d * ^C el x and _u Mí, m. ňl _f D Κο _χ 2 4 £ o. F, ° el Kapaoita wall - electrode ^S 1 ^C s2 Kapaoita wall - electrode ^S 2 £ _o dielectric constant of vacuum n 8.86. io ¹² D electrode distance / m / Koj kapaoita of the empty Salt cellar / 1 / ^F 1 * F ₂ electrode surface S ₁ - S _{2 in} m ² C_ is directly proportional to the electrode spacing, kapaóite walls of Salt Ko che electrodes with smaller surface area.

For hezelektródový kapaoitný Slánek sub-topic of the invention and the one electrode and ₂ located Moran handle, the surface of which is 10 to 10Ó0 times the likes of the surface of the isolated electrode S, the following applies: C _p X £> C *, ^C 'i · ^{c' C} II ^E · · ^{B and C} SLJ .l ^C + ^C p

Ko ^ -J. B & P · '·· ^Fg >

JACKET

IX £ c ' ^F 2 and ^C 1

CJ ^C II

CoZaZ submerged electrode capaita / S ₂ / salt wall capa - electrode / 3insulated total cell wall capaita / 1 / empty cell capaoita / 1 / salt wall capaita / 11 / empty salt capaoita / 11 / cell wall capaita - S ₂ / insulated

re

re

OJ

Re ² K ² Re ² ! ^

CUC 1 + Re ^^ K ²

II / 3 /

201 642

Z _Re = Total salt itapedanoia at low-frequency resistance Re ροδί melted from equation / 3 /, ^Z Re —0 Total impedence of the cell at low-frequency resistance Re by O, calculated from equation / 4 /.

The Co ratio for the cell according to the invention is at least twice as high for the same parameters, as can be seen from 1 in the following table:

Dependence '' From the cell impedance of the cell to a low-frequency resistance equal to Re and a low-frequency resistance equal to Re, 0,

ΔΖ = Z _Re “Re

I XX

Re CL Δ ~ ζ / £ = ro / fL Δζ / £> 8o / fl Δζ / £ = ιοζΩ Δ Z / £ = 80 / C1 1 2 3 4 5 0 0 0 0 0 10 - 0.1 0.1 20 0.2 0.4 0.6 0.6 30 0.6 0.8 1.3 1.3 40 1.0 1.4 2.2 2.2 50 1.7 2.2 3.5 3.5 60 2.5 3.2 5.0 5.0 70 3.3 4.4 6.8 6.8 80 4.4 5.7 8.8 8.8 90 5.5 7.2 11.1 11.1 100 6.9 8.8 13.7 13.7 110 8.3 10.7 16.5 16.5 120 9.9 12.7 19.5 19.5 130 11.6 14.9 22.8 22.8 14O 13.5 17.3 26.3 26.4 150 15.4 19.8 30.0 30.1 Loo 17.6 22.5 34.0 34.1 170 19.8 25.4 38.2 38.3 180 22.2 28.4 42.6 42.7 190 24.7 31.6 47.2 47.3 200 28.3 35.0 52.3 52.4 210 31.2 38.5 56.9 57.0 220 34.2 41.8 62.0 62.1 230 37.2 45.9 67.3 67.5 240 40.4 49.9 72.8 73.0

201 024

1 2 3 4 5 250 43.9 54.0 78.4 78.6 260 47.1 58.2 84.2 84.4 270 50.8 62.6 90.1 90.3 280 54.5 67.0 96.2 96.4 29o 58.4 ^r 72.4 102.4 102.7 300 62.3 76.5 108.8 109.1 ÁZjS ^Z ReI ^Z ol ^Z ol ⁵⁵ 717,28 _Ω_ ^ΔΖ ΙΙ ^{= Z} ReII “ ^Z oII ^Z oII ^s 359.44ΪΪ

The table shows the dependence of Δ Z on Re for the cell used up to now by the IUS and for the cell according to the invention II ΔΖ · ^} calculated from equation / 3 / Δ Z = Z _Re - Z _Re θ

The values Δ Z are calculated for both cells for £ = 10 and £ = 80 (measured medium). Cell parameters I. glass tube 0 3.0 oo, £ = 5.0, wall thickness at the electrode site 0.05 µm,

Electrode width 9.0 om, electrode length 5.5 om, surface 50 om ² j Dimensions and surface of the second electrode S ₂ are thicker, distance between them is 11 om, cell resistance constant d = 1.5, considered frequency : 1 MHz.

F £ relative dielectric constant (ermltivity)

The parameters of the cell according to the invention are the same, only the surface of the second uninsulated 2 electrode immersed in the measured medium is reduced to 1 µm. Then, for the cell of the original type, 222 pP, K0. = 0.4 pF and ^C1

Ko.j.

For us the article will be C _{i; j} . = 443 pF, KD. = 0.008 pF, ®tt —— with 55,600 liters of baseline versus baseline increased approximately 100-fold.

^K ° II

It can be seen from the table that the proposed article is the addition of ΔZjj. per unit of Re greater and practically in the range of Re with 0 to 300-µL depending on the medium to be measured.

The position and number of electrodes can be selected according to the nature of the medium to be measured and the method of measurement chosen. The stated capacity in terms of design can also be the sum of the capaoity of several electrodes.

Individual types of cells are deleted in the attached figures 1 to 4, and according to the constructional arrangement ioh can be much more.

The cell of this type shown in Figure 1 can be advantageously used for measuring the conductivity of the most highly conductive aystems, where at a high ratio fC i at a measured frequency!

\ K / less than 10? Hz, with a resistance of Re 10 to 1000-fL (this can be varied by the distance between the submerged or submerged, from the insulated or insulated electrodes), the dependence of the impedance of the cell nearly linear and little dependent on the measured system.

If the submerged electrode is positioned so that it lies inside,

01 04:

The electrode shown in FIG. 2, 3 and 4, the capacitance of the capacitors is equal to the capacitance between the insulated and the submerged electrode (Ko).

For CO frequencies below 10 ³ , resistance below 10 ³ JTL C ss of 100 to 1000 pF, equation (2) shows that the admittance Y of this Clause is equal to:

Y á ícaJC.

In this case, the capacity of the wall C will be directly proportional to the height of the medium to be measured and, in the range considered, independent of its low-frequency resistance Re.

This can be advantageously used to measure the level of conductive liquid, where the dependence is not linear when using an electrode-free cell with a double-biased electrode.

Claims (1)

Capacitive type cell with at least two electrodes disposed on a hollow shaped profile, of an electrically non-conductive material, preferably tubular, characterized in that at least one electrode (Sg) having a surface area of 0.01 to 10 µm is attached to the wall of the shaped profile. With a polarization capacity of 0.1 to 100 in direct contact with the measured medium and on the opposite wall, at least one other electrode ( ^s j) is isolated from the measured medium in comparison with the previous electrode (S ₂ ) and the resulting capacity of the Ko is 0.005 to 0.5. pF.