SU411303A1 - - Google Patents

Description

one

The invention is intended to measure the volumetric rate of electrowinning fluids, which are biological.

An electromagnetic flowmeter is known that includes a sensor and a measuring circuit including a bias current generator (rectangular shape), a useful signal amplifier, a time gate circuit for the required part of the measured voltage, a phase detector and a dial indicator.

The main disadvantage of the known flow meter is that, but because of the final input resistance of the measuring amplifier connected to the sensor, ed. with., induced on the electrodes of the sensor, depends on the conductivity of the liquid. This leads to a discrepancy in the results of measurements of the flow rates of liquids with different values of electrical conductivity.

In order to increase the accuracy of measurement and expand the range of permissible values of conductivity of the measured notes in the proposed device, an additional amplifier with equalized gain is included between the amplifier and the gating circuit, the control input of which is through the correction unit and the amplitude; The detector is connected to the output of a coupled amplifier.

The drawing shows a diagram of the described flow meter, consisting of sensor 1, to which a square wave excitation voltage is supplied from generator 2, and amplifier 3 connected to sensor with cascade 4, which has electrical gain control, amplitude detector 5 of the quadrature component of the correction unit 6, gating circuits 7 and indicator 8.

When an electrically conducting fluid moves through the sensor, an e occurs at its electrodes. d. The latter is connected to a measuring amplifier 3 with a cascade 4, from the output of which

The signal is sent to the circuit 7 for time selection of the necessary part of the measured voltage (flat vertex of right-angle pulses) with the subsequent linear detection of the measured voltage. Arrow switch

indicator 8 is a meter reading device.

At the output of the amplifier 3, the sensor signal also contains a quadrature component (noise), which has the form of pulses coinciding with the moments of a change in the sign exciting the voltage sensor. The amplitude of these pulses considerably exceeds the amplitude of the useful string and does not depend on the rate of change of the excitation 1, its sensor n: i-direction and electronic conductivity measured

fluid. With constant parameters of the excitation generator and the flowmeter sensor, the amplitude of the quadrature component pulses is determined by the electrical conductivity of the fluid and, therefore, can be used to correct the useful signal when measuring flow rates of liquids with different electronic conductivities. A decrease in the electrical conductivity of the liquid leads to an increase in the amplitude of the pulses and a decrease in the measured voltage.

Correction unit 6 allows to obtain the desired dependence of the gain of the cascade 4 on the amplitude of the quadrature pulse, and in general, the serial connection of the amplitude detector 5, the correction unit 6

and an adjustable stage 4 eliminates the effect of a change in the conductivity of the fluid on the output voltage of the amplifier.

Subject invention

An electromagnetic flowmeter containing a sensor connected to a generator and an amplifier, a gating circuit and an indicator, in order to improve the accuracy of measurement and extend the range of permissible values of electrical conductivity of the measured flux, between the amplifier and the gating circuit included extra

an amplifier with a controlled gain, the control input of which is connected to the output of the main amplifier through a correction unit and an amplitude detector.