SU983552A1 - Electric bridge - Google Patents

Description

(ELECTRICAL BRIDGE

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The invention is intended for J use in measurement and measurement technology, automation and industrial electronics, in particular for the simultaneous measurement of three components: two reactive and one active.

The electrical bridge is known, which contains the power generator, the comparison arm, made according to the replacement scheme of the object under study, and the shoulders of the train are the exemplary elements of the same character 1.

The closest technical solution to the invention is an electric bridge containing a trapezoidal pulse generator, the first branch of the bridge is made as a series connection of a capacitor 20 of constant capacity and the object of measurement with a three-element circuit.

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The disadvantage of such electric bridges is that they are balanced by active and reactive variable elements. The presence of variable resistors lowers the reliability of the device, since the rubbing contact wears off relatively quickly, the resistance in the contact changes during the service life, and sparks and interferences occur during its movement.

Purpose1) Inventions of the invention, etc, increase reliability by reducing the failure rate of a bridge ,

The goal is achieved by the fact that in the electric bridge containing a trapezoidal pulse generator connected to the supply diagonal, the first branch of the bridge is made in the form of a serial connection of the first constant-capacitor and the object of measurement with a three-element replacement circuit in the form of a serial connection 8383

capacitor and circuit of parallel-connected capacitor and resistor, the connection point of the first capacitor and the object of measurement forms one of the vertices of the measuring diagonal, the second bridge branch is made as a serial connection of the second constant capacitor, the first variable capacitor, in parallel with which the second variable capacitor is connected The connection point of the first and second variable capacitors is connected to a circuit consisting of parallel-connected resistors and t variable capacitor, the connection point of the second constant capacitor and the first variable capacitor forms the other top of the measuring diagonal

The drawing shows a schematic diagram of the proposed electric bridge.

The electric bridge contains a reHepatop 1 supplying pulses having a rectangular trapezium Yorm, a capacitor C 2 of one arm of the first branch, a capacitor C 3 of the second arm of this branch, with respect to which parallel-connected resistor R are connected in series and the C 5 constrictor. C 6 of the first shoulder and the group of elements of the second shoulder, KOH of a C 7 sensor connected in series with parallel-connected resistor R8 and a capacitor C 9. A capacitor C 10 is connected in parallel with respect to the sequence flax coupled capacitors G 6 and C 7.

Power generator trapezoidal impulses come from generator 1 to the electric bridge. When exposed to a flat tip of the pulse in a steady state through the capacitors of the bridge a. zero currents are zeroed, so the resistors and R8 voltages are zero. Then the imbalance voltage in this period of time does not depend on the size of resistors R and R 8 and capacitors C 9 and C 10.

By adjusting the capacitance of the capacitor C 5, we bring the flat top of the signal to imbalance to zero on the plot of action of the flat top of the supply trapezoidal signal. As a result, we perform the first equilibrium condition С2С7 СЗСб. According to the known value of the capacitor C 7, we take the count of the values of the measured capacitance of the capacitor C3.

C3 §-C7,

When exposed to a linearly varying part of the supply of its pulse after the termination of transients, capacitors C2, C7 and C 10 are set to constant currents, which on the resistors R 4 and R 8 create unchanging voltages. The capacitors C 5 and C 9 charge up to these voltages, zero currents flow through them, and they do not affect the disequilibrium voltage for the considered period of time.

By adjusting the capacitance of the capacitor C 10, the flat signal vertex of the imbalance signal is zeroed at the site of the linearly varying part of the counting trapezoidal pulse. As a result, the second equilibrium condition Rfr.2C7 M C10 (C6 + C7) + C6C7 is satisfied. The values of the capacitors C 7 and S Yu determine the value of the measured resistance of the resistor RA

,, 8CC 1C6 + G; 7 C6C73 C2Cf

During the action of the supply pulse jump during transient processes, the disequilibrium voltage depends on all three components, but in two of them the bridge is already balanced.

By changing the capacitance value of the capacitor C 9, we reduce to zero the exponential bursts in the measuring diagonal of the bridge, thereby fulfilling the third equilibrium condition C2C7C9 (C6 + C7) + C6C7. From the now known capacitance values of capacitors C 7, C 10 and C.9, we determine the value of the measured capacitance of capacitor C 5

- SShS7S9

 C10 (Cbn-C7) + C6C7

Thus, the bridge has properties of separate balancing. The balancing signal of the balancing signal unambiguously determines the voltage of the balancing of the bridge.

Claims (1)

The use in the balancing branch of variable capacitors favorably distinguishes the proposed electric bridge from the known one. since it is balanced in three components only by variable capacitors, which, as is well known, do not contain rubbing contacts. As a result, increase the reliability of the device. An electric bridge comprising a trapezoidal pulse generator connected to a supply diagonal, a first bridge branch made as a series connection of a first constant capacitor and a measurement object, with a three element replacement circuit as a series connection of a capacitor and a circuit of parallel connected the capacitor and the resistor, the connection point of the first capacitor and the object of measurement forms one of the vertices of the measuring diagonal, o. so that, in order to increase reliability by YU + reducing the failure rate of the bridge; the second branch of the bridge is made as a serial connection of the second constant capacitor, the first variable capacitor, in parallel with which the second variable capacitor is connected, the connection point of the first and second variable capacitors is connected in parallel included resistor and capacitor, variable capacitor, junction point of the second constant capacitor and the first variable e capacitor bone forms another top measuring diagonally. - Sources of information taken into account during the examination 1. USSR Author's Certificate No., Cl, G 01 R 17/10, 197. 2 Measuring converters of electrical circuit parameters. - Abstracts of the All-Union Scientific and Technical Seminar. Ulovsk, 1978, p. (prototype).