SU949515A1

SU949515A1 - Compensating bridge measuring circuit

Info

Publication number: SU949515A1
Application number: SU802969296A
Authority: SU
Inventors: Юрий Владимирович Братусь; Валентина Павловна Карпенко
Original assignee: Институт Электродинамики Ан Усср
Priority date: 1980-08-04
Filing date: 1980-08-04
Publication date: 1982-08-07

Description

(54) КОМЛЕНСЛЦИОННО-МОСТОВАЯ ИЗМЕРИТЕЛЬНАЯ(54) COMMERCIAL BRIDGE MEASURING

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Изобретение относитс к электроизмерительной технике и может быть ис пользовано дл измерени параметров комплексных сопротивлений.The invention relates to electrical measuring equipment and can be used to measure impedance parameters.

Известен трансформаторный мост, содержащий две параллельных цепочки, перва из которых состоит из последовательно соединенных измер емого и образцового сопротивлений, а втора цепочка - из двух плечевых обмоток трансформатора, источник питани , включенный в первую диагональ моста, и детектор равновеси , включенный во вторую диагональ. Точность измерений в трансформаторном мосте выше, чем в четырехплечем, за счет использовани .плечевого трансформаторного делител напр жени l3.A transformer bridge is known that contains two parallel chains, the first of which consists of series-connected measured and reference resistances, and the second chain consists of two shoulder windings of the transformer, a power supply included in the first diagonal of the bridge, and an equilibrium detector included in the second diagonal. The accuracy of measurements in a transformer bridge is higher than that of a four-arm, due to the use of a shoulder transformer voltage divider l3.

Недостатком таких мостов вл етс ограниченна точность измерений, обусловленна наличием магазина сопротивлений или проводимостей дл уравновешивани моста по второй составл ющей комплексного сопротивлени , и ограниченные пределы измерений, а также сложность автоматизации процесса измерений при применении полупроводниковых переключающих устройств.The disadvantage of such bridges is the limited accuracy of measurements, due to the presence of a resistance box or conductance to balance the bridge over the second component of the complex resistance, and limited measurement limits, as well as the difficulty of automating the measurement process when using semiconductor switching devices.

Наиболее близким к предлагаемому по технической сущности вл етс комЦЕПЬThe closest to the proposed technical essence is komtsep

пенсационно-мостова цепь, содержаща цепочку из последовательно соединенных измер емого объекта и образцовой меры , источник питани , подключённый к зажимам цепочки, два прецизионных делител напр жени , подключенных соответственно к зажимам измер емого объекта ri образцовой меры, сумматор, два входа которого подключены к выходам двух делителей соответственно, и детектор равновеси , включенный на выходе сумматора 12.a sensing-bridge circuit containing a chain of measuring object connected in series and an exemplary measure, a power source connected to the chain terminals, two precision voltage dividers connected respectively to the terminals of the measured object ri, an exemplary measure, an adder whose two inputs are connected to the outputs two dividers, respectively, and the equilibrium detector, included at the output of the adder 12.

Недостатком известного устройства вл етс наличие погрешностей измерений , возникающих из-за шунтировани измер емого и образцового сопротивлений входными сопротивлени ми делителей напр жени , ограничивающих возможности применени устройства дл измерени в широких пределах.A disadvantage of the known device is the presence of measurement errors arising due to the shunting of the measured and exemplary resistances by the input resistances of the voltage dividers, limiting the possibilities of using the device for measuring within wide limits.

Целью изобретени вл етс повышение точности измерений компенсационно-мостовой цепи.The aim of the invention is to improve the measurement accuracy of the compensation-bridge circuit.

Claims

The goal is achieved by the fact that in a compensation-bridge measuring circuit containing a chain of elements consisting of a series-connected measured object and an exemplary measure, a power source connected to the terminals of the chain, two precision voltage dividers, the first clamp of the first voltage divider connected to the first terminal of the power source, the adder, to the two inputs of which the first outputs of the two voltage dividers are connected and the second outputs of the dividers and the adder are connected to the common bus of the circuit, and equilibrium vector, the second input terminal of the first divider is connected to the common bus of the device, the second divider input is connected in parallel to the first divider input, the output terminal of the adder is connected to the second one of the power supply, the balance detector is connected between the junction point of the measured and reference elements in the signal box and common bus chain. The drawing shows a block diagram of the device. The device contains a power source 1, a measured object 2, a sample measure 3, (elements) precision voltage dividers 4 and 5, an adder .6, an equilibrium detector 7. The device is balanced by adjusting the transfer factors of dividers 4 and 5, with one of the dividers, such as divider 4, adjusting the amplitude of the voltage applied to it, and the second divider 5 adjusting the phase. As a divider 4, an operational amplifier or a digital-to-analog converter (DAC) can be used, which has a high accuracy of the transmission coefficient, and the second divider can be made using a phase-shifting operational amplifier or a cascade connection of the DAC and phase shifter. The control of the state of equilibrium of the circuit is provided by the detector 7, which compares the ratio of the voltages on elements 2 and 3 with the total divisor transfer coefficient. At the moment of equilibrium of the circuit, the equality is satisfied where Zj, Z are the resistances of the measured 2 and exemplary 3 o elements K.K.TJK is the total transfer coefficient of the dividers; K is the transfer coefficient of division 4; K is the transmission coefficient of divider 5. From equality (1), we obtain 2, 23 () -. (2) The upper sign before jK corresponds to the inductive character of the measured resistances in a sequential replacement circuit of the measured object. The bottom sign corresponds to the measurement of capacitance resistance parameters. When it is necessary to measure the conductivities by the parallel replacement scheme of the object being measured, elements 2 and 3 are reversed. Thus, an increase in the measurement accuracy is ensured with the exception of the error due to the shunting of the resistances of the object being measured and an exemplary measure by the input resistance of precision voltage dividers. At the same time, smaller requirements are imposed on the input resistance of the dividers, which allows to simplify the design and reduce the cost of these dividers. In addition, the exclusion of shunting of the compared resistances allows one to significantly expand the limits of measurements without measuring the structure of the measuring circuit circuit. The invention of the Compensation-bridge measuring circuit., Comprising a chain of elements consisting of a series-connected measuring object and an exemplary measure, a power source connected to the terminals of a chain, two precision voltage dividers, the first input terminal of the first divider connected to the first power supply terminal , the adder, to the two inputs of which the first outputs of the two voltage dividers are connected, and the second outputs of the dividers and the adder are connected to the common bus of the circuit, and the equilibrium detector, which differs so that, in order to improve the measurement accuracy, the second input terminal. the first divider is connected to the common bus of the circuit, the input of the second divider is connected in parallel to the input of the first divider, the output terminal of the adder is connected to the second terminal of the power source, the equilibrium detector is between the terminals of the measured and exemplary elements in the chain of elements and a common bus chain. Sources of information taken into account in the examination. 1. Transformer measuring bridges. Ed. K. B. Karandeeva. Energy, M., 1970, p.22, 86.

2. Digital devices and systems for measuring capacitor parameters. Ed. S.L. Epstein. .Soviet radio M., 1978, p.68 (prototype).