SU1427272A1 - Conductivity transducer - Google Patents

Abstract

The invention relates to a device for measuring the electrophysical parameters of a liquid. The aim of the invention is to increase the measurement accuracy by reducing the dynamic error. The conductometric chick contains a source of alternating voltage 1, supplying a transformer with excitation winding 7, measuring; transformer with measuring winding 8, measuring circuit 4, closed coil 9 of electrically conductive liquid, loop 10 of electrically conductive material covering both cores 5 and 6 of transformers, comparison circuit 3, adder 2. Loop 10 of electrically conductive material with one output connected to a common bus, and the second - to the first input of the comparison circuit; the second input of the comparison circuit is connected to the output of the adder, the inputs of the adder are connected respectively to the output of the alternating voltage source and the output cxeh4 i of the comparison; an excitation winding is connected to an output of an adder} measuring winding 8 y is connected to a measuring circuit. The small inertia of the comparison and adder circuit reduces the dynamic error in measuring the conductivity of the test liquid in the closed loop 9. 1 sludge. (P

Description

The invention relates to a device for measuring the electrophysical parameters of a liquid and can be used in automatic control systems and chemical regulation, production.

The purpose of the invention is to increase the accuracy of measuring the conductivity of the liquid by reducing the dynamic error.

The drawing shows a functional diagram of a conductivity sensor.

The conductometric sensor contains 15 AC voltage source 1, adder 2, comparison circuit 3, measurement circuit 4, supply and measuring transformers with magnetic cores 5 and 6, respectively, on which excitation windings 7 and measuring winding 8. are wound. Both cores covered by a closed coil 9 of electrically conductive fluid and loop 10 of electrically conductive 25 material.

The device operates as follows.

. We accept the following notation:

U., is the voltage at the output of the source 30 1; - voltage at the output of the adder 2; w _T is the number of turns of the field winding; U ^ _Q is the voltage at the terminals of the loop 10; E ₉ - total EMF induced in the loop 9 of the liquid; E _fe - ^ d EMF induced in the liquid loop by a magnetic field in the measuring core and external sources of electromagnetic field; To _g is the transfer coefficient of the adder 2; Κ _ά is the transfer coefficient of the comparison circuit 3.

Assuming that the stabilized voltage Щ is maintained at the output of the AC voltage source, and at the output of adder 2 we have dd voltage Ts _g , we can write

At the output of the comparison circuit 3, the voltage iad (iad ₀ ) = hell _r (1- ~) -ad _{6 will} appear. . ₅₅

The voltage at the output of the adder 2 is described by the expression

-----------___________ γ-K Kj ¹ - ^ -) 'w ₇ w _r

Total EMF in a liquid loop

-’- hell adad

W-, _____ _ w _r __ ^r _ B ₊

I-K KJ1-1-) ad. (1- I-)

It can be seen from the last expression that when the condition K _g = K _g = 1 is fulfilled, the expression is simplified: E _fl = U ₁ .

Thus, the total EMF in the closed loop 9 does not depend on the transformation coefficient i / wy and the magnitude of the magnetic flux in the measuring transformer and is determined only by the value of the source signal to a wide frequency range (up to AC voltage, which relates to

S - S Hz), determined by the frequency properties of the comparison circuit 3 and adder 2.

The small inertia of the comparison circuit 3 and the adder 2 provides a decrease in the dynamic error of measuring the conductivity of the liquid.

Claims (1)

Claim A conductometric sensor containing an alternating voltage source, a supply transformer with an excitation winding, a measuring transformer with a measuring winding connected to the measuring circuit, a loop of electrically conductive material covering both transformer cores, a closed coil of electrically conductive liquid under investigation, covering both transformer cores, a comparison circuit, characterized in that, in order to increase the measurement accuracy, an adder is additionally introduced, with the first loop output and electrically conductive material connected to the common bus, and the second - to the first input of the comparison circuit, a second input coupled to an output of the adder, the adder inputs connected respectively to the output of the AC voltage source and output of the comparison circuit, the excitation winding is connected to the output of the adder.