SU1594446A1 - Self-sustained transducer of electric conduction of liquid - Google Patents

Abstract

The invention relates to a measurement technique and can be used to convert the electrical conductivity of liquid media during an electrical oscillation period. The aim of the invention is to increase the sensitivity by introducing a pump transformer. The converter contains an amplifier 1, a transformer multi-pole 2 with windings 3.4, a threshold element 6, a time setting resistor 7, a two-pole voltage regulator 8, an amplifier 9, a pump transformer 10 with a pump winding 11. 2 Il.

Description

The invention relates to a measurement technique and can be used to convert the electrical conductivity of low media into a period of electrical oscillations.

The purpose of the invention is to increase sensitivity.

Figure 1 shows the functional diagram of the device; 2aib - current diagrams in the field winding

 The device contains an amplifier 1, a transformer multi-pole 2 with windings 3-5, a threshold element 6, 4 times a driving resistor 7, a stabilizer 8 for a two-pole voltage,: | silitel 9, a pump transformer 10 with a winding 11 pumping,

; As the coupling circuit between the pump transformer 10 and the transformer multi-pole 2 uses - 4 short-circuited output winding S of the latter, which is itself. 1: | distributed coil of the investigated DOS,

; The converter works as follows,

 At the initial moment of time, the threshold element 6 is in one of. Two possible states, for example, when positive voltage saturates Qi at its output, respectively, at the output of stabilizer 8 of two-pole voltage, we have a stabilized positive voltage, which applied to the non-inverting 9CD of the threshold element 6, to the input of the amplifier 9 and through the winding. 3 to the input of the amplifier 1. The output voltage of the amplifier 1 generates a current in the measuring winding 4 of the transformer multi-terminal 2. This current induces an EMF E, .. in an inductively coupled coil 5 of the liquid. Similarly, the voltage at the output of the amplifier 9 creates a current in the winding 11 of the pump transformer

10 pumping, which in turn induces EMF E in coil 5 liquid Bones, Induction current Ig in coil: 1 is proportional to the sum of EMF E

and E

.

where is e

 (E,,, and E. - EMF induced in the turn by a transformer multi-terminal and pump transformer, respectively;

 the conductivity of the circle of intestine,

one

R,

where Rg is the resistance of the liquid coil. EMF EJ and E have the same shape and in-phase, and the choice of the number of turns of the windings 4 and 11 and the gain factor of the amplifier 9 can be ensured

chit ej e

Current in a coil of fluid

induces an emf in winding 4, which is equivalent to introducing a loss, into this winding, ... :

When the voltage at the output of the stabilizer 8 is constant, negative feedback through the winding 3 ensures the voltage constant on the winding 3 and, consequently, a linear change in the current in the winding 4. Accordingly, the voltage drop across the time-voltage-supply resistor 7, At the moment of the equality of this voltage to a stabilized voltage at the non-inverting input of the threshold element 6, the threshold element 6 and the stabilizer 8 are transferred to the opposite state with negative, output voltages en mi The sign of the voltage on the outputs of the amplifier 1 and 9 changes accordingly. At the moment of switching on the resistor 7, there is a voltage jump proportional to the losses introduced into the winding 4, and therefore proportional to the conductivity of the liquid coil, then the voltage on the resistor 7 changes linearly (decreases) At the moment when the voltages are equal at the inputs of the threshold element, the threshold element and the voltage regulator B are again transferred. The process then repeats. Thus, the device is an oscillator, the oscillation period of which linearly depends on the conductivity of the liquid coil. In the absence of losses (FIG. 2a), the oscillation period is determined by the relation

T „24 t

2Л1

 dt

where Tg is the period of electrical oscillations. in the absence of losses; 4t - half period;

51594446

and I is the amplitude of current oscillations in the winding 4;

 - rate of change of current in

winding 4. Because

. - conductivity of the liquid coil;

- transformation ratio - the ratio of the number of turns of the windings 5 and 4.

If a

U4

L

L1

2UcT

CT

t

0

4 R; uf

where and - the absolute value of eg CP

stabilization of the stabilizer of the bipolar voltage;

L, is the inductance of the winding 4;

R is the resistance of the resistor 7;

and - a constant voltage applied to the winding 4. Fig. 26 shows a diagram of the current in the winding 4 in the presence of losses. The surge current Lg due to the loss of em., Made to the winding 4.

The period change due to this jump can be calculated from

 41

Ji72

4T

U.

- change of the oscillation period,

due to losses; - the period of the device in the absence of. loss; 35 - current jump in the winding 4.

2UcT. only -

Ku

40

The surge current 4i in the winding 4 is proportional to the current in the coil of fluid

and E

le 5.4,

- CURRENT AND EMF in the coil of fluid, respectively;

Eg E, + E, E, (1 - -----),

where K is the gain of the amplifier 9; n is the ratio of the number of turns o6, I

hank 11 and 4,

then

TO

T T, -4 (1) 6, L ,.

tt.4

Claims (1)

Invention Formula The self-generating transducer of the fluid conductivity containing a transformer multi-pole with excitation and feedback windings, an amplifier whose input is connected to the first side of the feedback winding, and the output to the first output of the excitation winding, resistor, including the second output of the excitation winding and common bus, the threshold element, the inverting input of which is connected to the second step of the excitation winding, and the non-inverting input - to the second output of the return winding, the output of the threshold element after one hundred The bilizer is connected to the second end of the feedback winding and the output bus of the device, which means that, in order to increase the sensitivity, a second amplifier and a pumping transformer are introduced into it, and the input of the second amplifier connected to the output of the stabilizer, and the output is connected to the first output winding of the pump transformer, the second output winding of which is connected to a common bus. . 2 ..