SU1196778A1 - Method of contactless measurement of liquid electric conductivity and apparatus for accomplishment of same - Google Patents

Abstract

The invention relates to the field of liquid electrometry, it can be used to measure the electrical conductivity of a current drilling rig. solution when conducting wells. The purpose of the invention is to improve the measurement accuracy by reducing the influence on the measurement results of frequency instability and amplitude of oscillations of the alternating voltage source. The magnetically hard insert (MB) is forced into the gap by the magnet of the soft core of the supply transformer (ПТ) 4 for 5 s. rectangular hysteresis loop. During the evaluation of MB, the magnetic flux is proportional to the current. The remap time MB is equal to the current measurement time. In the liquid-current loop 7, the emf is induced. The voltage taken from the measuring transformer 6 contains a useful signal from the current pulse in the capacitive loop 7 and induced quadrature interference. A potential pulse of the same form, resulting from a jump-like change in the inductance of the PT 4 winding, is fed to one of the inputs of the quadrature interference block 8, the second input of which is connected to the measuring transformer 6. The output of the compensation block 8 is connected to the block input through the high-frequency filter 9 double integration 10, the output of which is connected to the input of detector 11. 11. The output of detector fI is connected to the input of the smoothing filter 12. 2c. n. f-ly, 3 ill. 00

Description

 one

The invention relates to the field of liquid electrometry, and, in particular, can be used to measure the electrical conductivity of a current solution level when conducting a well.

The purpose of the invention is to increase the measurement accuracy by reducing the effect on the measurement results of frequency instability and the amplitude of oscillations of the alternating voltage source. . .,

The method of contactless measurement of the electrical conductivity of a liquid is that a current is excited in the liquid coil by means of an excitation circuit fed by a sinusoidal current whose amplitude is greater than the value corresponding to the primary state of the exciter circuit. The magnitude of the electrical conductivity of the fluid is determined by the area and time interval between the opposite-polarity pulses taken from the measuring circuit.

FIG. 1 is a block diagram of a device implementing a method for measuring the conductivity of a fluid; in fig. Figures 2 and 3 show stress diagrams at characteristic points of the device during its operation.

The device contains a source of alternating voltage 1, connected through an additional active resistance 2 (R, on) and resistance 3 of the communication line to the winding of the supply transformer (PT) 4, the core of which contains a magnetic hard insert (MB) 5. PT 4 and measuring transformer 6 are interconnected by a liquid coil 7 formed when measured by a closed spatial contour filled with the liquid under study. The measuring transformer 6 is connected through one of the inputs of the quadrature disturbance compensation unit 8 through the resistance 3, the input of which through the resistance 3 of the communication line is connected to the PT 4 winding. Compensation block 8 is connected through a high-frequency filter 9 to the integrator 10 whose output is connected to the input of the detector 11. The output of the detector 11 is connected to the input of the smoothing filter 12.

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The device works as follows.

A sinusoidal current 5 I of sufficiently large amplitude is passed through the winding of the supply transformer, while the magnetic flux F of the core is changed as follows.

At the time of the steady state MB, the magnetic flux F is proportional to the current I; during the time dt of the magnetization reversal process MB, the magnetic flux changes abruptly (comparatively, quickly), and the time ut of this change J5 is equal to the time of current change 1

between certain values of its magnitude and depends on the amplitude and frequency of the current 1. In the liquid coil, an emf is induced and a current i flows,

20 proportional to the derivative -; - and

at

the electrical conductivity of coil 6. The change in the magnetic field of current i is removed by a measuring transformer, 25 of which is useful in it.

EMF t is proportional to the derivative

di

7-, therefore, the product

at,

6 --- 30 ti

The voltage U. ,, (т. 13), removes from the measuring transformer, contains the useful signal from the current pulse in the liquid coil and induced quadrature interference proportional to the derivative and in form identical to the current in the liquid coil i. A similarly shaped potential impulse resulting from an abrupt change in the inductance of the PT winding is removed from step 14 and fed to one of the inputs of the quadrature interference compensation unit, which is a summing amplifier with an adjustable transmission coefficient. The second input of the compensation unit is supplied with a signal from the measuring transformer (v. 13).

After suppressing the low frequency by the RF filter (vol. 15) and with subsequent double integration (vol. 16), the amplitude of the signal does not depend on the time interval dt, which is determined by the transition time of the MB from one state to another, and 55 therefore, on the amplitude and current frequency I, and is proportional to the product (ef, and the value of df is constant. After detecting

(t, 17) smoothing (v. 8) the signal in analog form corresponds to the electrical conductivity of the liquid.

F. formula

1. A method for contactless measurement of the electrical conductivity of a fluid, which means that with an excitation circuit to which an alternating voltage is applied, a current is excited in the fluid coil, the magnitude of which is proportional to the electrical conductivity of the fluid, the magnitude of which is judged by the oscillations in the measuring circuit, differing from that, in order to increase the measurement accuracy while reducing the requirements for frequency stability and amplitude of oscillations of the alternating voltage source, along the exciting skip circuit A sinusoidal current, the amplitude of which is greater than the magnitude corresponding to the full state of the core of the exciting circuit, the magnetic flux of the core varies between the values of the normal state, and the magnitude of the electrical conductivity of the fluid is determined by the area and the time interval between the alternating pulses

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from the measuring circuit.

2. A device for contactless measurement of electrical conductivity; The bones containing the alternating voltage source, the power supply and the measuring transformers connected to each other by a liquid coil are different in that in order to improve the accuracy of JO measurements while reducing the requirements for frequency stability and amplitude of oscillations of the alternating voltage source , by the magic of the soft core of the supplying transformer, the transformer is open, and a magnetic-hard insert with a rectangular hysteresis loop is inserted into its gap, the supply transformer through high active resistance and the resistance of the communication line is powered by an alternating voltage source and simultaneously connected to one of the inputs of the quadrature interference compensation unit, the second input of which is connected to the instrument transformer, the output of the compensation unit is connected through a high-frequency filter to the input of the double integration unit, the output of which is connected to the input detector, the output of the detector is connected to the input of a smoothing filter.

and

IS

and

P

Fig.Z.

Claims (3)

Claim 1. The method of non-contact measurement of the electrical conductivity of a liquid, which consists in the fact that using an exciting circuit to which an alternating voltage is applied, a current is excited in a liquid coil, the value of which is proportional to the electrical conductivity of the liquid, the value of which is judged by the fluctuations in the measuring circuit, characterized in that, in order to increase the accuracy of measurements while reducing the requirements for stability of the frequency and amplitude of oscillations of an alternating voltage source, I pass along the exciting circuit t is a sinusoidal current, the amplitude of which is greater than the value corresponding to the saturated state of the core of the exciting circuit, while the magnetic flux of the core varies between the values of the saturated state, and the electrical conductivity of the liquid is determined by the area and time interval between bipolar pulses, 1196778 ⁹ with the measuring circuit. 2. A device for non-contact measurement of electrical conductivity of a liquid containing a source of 5 variable voltage supply and measuring transformers connected by a liquid coil, characterized in that, in order to increase the accuracy of 10 measurements while reducing the requirements for stability of the frequency and amplitude of oscillation of the AC voltage source, the soft magnetic core of the supply transformer _{5 is} open, and a magnetically hard insert with a rectangular hysteresis loop is inserted into its gap, and the supply transformer is fed through a large resistance and the resistance of the communication line from AC voltage source and is simultaneously connected to one of. the inputs of the quadrature interference compensation unit, the second input of which _{25 is} connected to the measuring transformer, the output of the compensation unit is connected through a high-pass filter to the input of the double integration unit, the output of which is connected to the detector input, the output of the detector is connected to the input of the smoothing filter. Fig g