SU1163205A1 - Densimeter - Google Patents

Abstract

A DETECTOR containing a sensitive element, a differential transformer sensor for moving a sensitive element. a bridge circuit for temperature compensation, the measuring diagonal of which is connected in series with the measuring winding of the displacement sensor, and a variable resistor, different from the fact that, in order to improve the measurement accuracy, it is equipped with a capacitor and a transformer whose primary winding is connected in series with the winding of the power supply of the displacement sensor, and is secondary through a capacitor and a variable resistor is included in the supply diagonal of the thermal compensation bridge. (ABOUT

Description

The invention relates to the field of measuring the density of liquid media and can be used in chemical and other industries. A density meter is known that contains a sensitive element, a differential transformer displacement sensor of a sensitive element, a temperature compensation bridge circuit, and a secondary device with an additional displacement sensor whose frame is mechanically connected to the pointer of the secondary device 1. The disadvantage of this density gauge is that the use of ferro displacement sensors The dynamic type together with diffraction transformers considerably complicates the design and adjustment of the instrument, since their electrical characteristics are not identical. Closest to the invention, the technical entity is a density meter containing a sensitive element, a differential transform torx displacement sensor, a sensitive element, a temperature compensation bridge circuit, measured on the diagonal of which is connected in series with the measuring winding of the displacement sensor, and a variable resistor L2J. However, for a known densitometer, insufficient measurement accuracy is characteristic due to the presence of a phase shift between the output voltages in the diagonal of the thermal compensation bridge and the supply voltage of the secondary winding of the movement sensor of the sensitive element. The purpose of the invention is to increase the measurement accuracy. The goal is achieved by the fact that a density meter containing a sensitive element, a differential transformer sensor for moving a sensitive element, a temperature compensation bridge circuit, from the measuring diagonal of which is connected in series with the measuring winding of the displacement sensor, and a variable resistor, is equipped with a capacitor connected in series with the power winding of the displacement sensor, and secondary through a capacitor and variable resistor included in the power supply guide diagonal bridge temperature compensation. . . . The drawing shows the diagram of the densitometer. The core of the differential transformer displacement sensor 1 is rigidly connected to the sensitive element of the densitometer (not shown). In one of the arms of the bridge 2 temperature compensation included thermistor 3, installed in the immediate vicinity of the sensing element (measuring float) densitometer. As a secondary device 4, a device with a differential transformer circuit is used, which includes an additional transformer displacement sensor 5, the pivot core of which is mechanically connected with the pointer of the secondary device (arrow). The thermal compensation bridge is powered from the transformer Tr, the primary winding of which is connected in series with the transformer 6 winding of the power supply circuit of the transformer sensor moving the sensing element. A capacitor 7 and a variable resistor 8 are connected to the secondary winding circuit of the transformer Tr. The density meter works as follows .. At a fluid temperature equal to graduated bridge, circuit 2 is balanced and the voltage at its output and 0. The input Uj of the secondary device A only supplies voltage Uj dependent on the position of the core of sensor 1, i.e. from the density of the controlled solution. The secondary winding of the sensor 5 and the bridge circuit form a feedback circuit, and since at calibration temperature the voltage is O, the voltage U is compensated only by the voltage of the secondary winding of the sensor 5 U and the input voltage is zero at the input of the secondary device, however, the system for testing the readings of the density meter is in a steady state. When the temperature of the analyzed medium deviates from the calibration bridge 2 of thermal compensation, it becomes out of equilibrium and at its output appears the signal AND, equal in magnitude and opposite in sign

a voltage increment of 4U (j depending on the temperature change of the analyzed medium, as a result of which compensation of temperature disturbances occurs.

Since the circuit operates on alternating current, in order to fully compensate the voltages and, consequently, increase the accuracy of the measurements, it is necessary to ensure the matching of the phase voltages and. and U |. For this purpose, the power supply of thermal compensation bridge 2 is carried out from the transformer Tr through a capacitor 7, the capacity of which is selected experimentally.

In order to select the required temperature coefficient of the bridge circuit, a variable resistor 8 is included in the power supply circuit;

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inclusion may be sequential or parallel. The inclusion in the measuring circuit of the transformer Tr provides separation

5 measuring circuit and supply and facilitates matching the phase of the output voltage in the diagonal of the thermal compensation bridge with the supply voltage of the secondary winding

10 displacement sensors.

Thus, the measurement accuracy in transient conditions increases with a change in the temperature of the controlled medium.

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The economic effect of using a densitometer - reducing labor costs for the manufacture and adjustment of a densitometer due to the use of commercially available elements.

Claims (1)

A DENSITY METER containing a sensing element, a differential-transformer sensor for moving the sensor, a bridge temperature compensation circuit, the measuring diagonal of which is connected in series with the measuring coil of the displacement sensor, and a variable resistor, which is equipped with a capacitor in order to increase the accuracy of measurements. and a transformer, the primary winding of which is connected in series with the power winding of the displacement sensor, and the secondary through a capacitor and variable ezistor included in the feed diagonal bridge temperature compensation.