SU1626163A1 - Method for checking error of voltage divider - Google Patents

Abstract

The invention relates to the measurement technique; it is used to be used by the RC. control of dividers apr and the purpose of the invention is to reduce the error of control of voltage dividers by performing additional measurements that eliminate the errors introduced into the measurement result by connecting power conductors, and the insulation resistance of conductors. The device implementing the method contains switch 1 measuring device 2, switch 3, controlled 4 and exemplary 5 voltage dividers, power source 6 equivalent resistance of connecting conductors (resistor ) 7-10 1 yl

Description

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The invention relates to a measurement technique and can be used to control voltage dividers in bridge circuits, one of the poles of the power supply of which has a common point with the body of the measuring instrument and with the grounding bus.

The purpose of the invention is to reduce the error of control of voltage dividers by performing additional measurements and processing their results.

The drawing shows a diagram of the device that implements the method

The device contains a switch 1, a measuring device 2, a switch 3, a controlled and exemplary voltage dividers 4 and 5, a power source 6, the equivalent of 7-10 resistance of connecting conductors (resistors).

Dkh

 AU1 -Khnom ATS2 (1 -Khnom) Ai3

where A Cdop is an additional component of the measurement error due to the final value of the insulation resistance, the final value of the common-mode rejection factor and the input currents of the measuring device;

AUi - bridge unbalance voltage;

A u2. And Oz is the voltage between the points of connection of the controlled and exemplary dividers to the same poles of the power source;

Khn is the nominal value of the division factor of the monitored divisor;

E is the power supply voltage;

AK0 is the division factor of the reference divider.

To eliminate the additional component of the error from the control result, the Cdop switch 1 is set to the position shown by the dotted line, the subdivision Cdop

AU i + Khnom AU2 + (1 -KxHOMJAub

Finally, to determine the error of the division ratio Kx controlid x AUi -Au i-KxHOM (AL) 2-AU2) - (1 - Kx nom) (AU3 - AU3) + d KQ

whence it is seen that the additional component of the measurement error caused by the listed reasons does not affect the result of the ACh measurement.

The device works as follows.

Switch 1 is set to the position shown in the drawing, and using a measuring device 2 and switch 3, the voltages AUi, A 1) 2, A Uz are measured, corresponding to the unbalance voltage of the bridge formed by controlled 4 dividers, and the voltage difference between the points of the controlled 4 and 5 reference dividers to the positive and negative poles of the power supply 6. Resistors 7-10 are equivalent to the total resistances of the respective connecting wires and switch contacts. For this scheme, the following expression is true:

+ A K0 + A Cdop.

the key thus both the vertices of the supply of the diagonal of the bridge to the positive pole of the power source 6. With the help of measuring device 2 and switch 3, measurements of voltages AUi,

AU2, A 1) s, and when measuring the voltage AUi, the voltage of the power source 6 is set equal to the output voltage of the divider 5 during the previous measurements, i.e. equal to E-Conn, where Kön nominal value of the division factor of the divider 5, when measuring the voltage AU21 the voltage of the power source 6 is set equal to the voltage of the bridge, i.e. equal to E when measured

Voltage Aus, the voltage of power supply 6 is set to zero. From the measurement results, the value of the additional component of the measurement error is determined from the following expression

50 dividing divider 4 we obtain the following expression:

Thus, the accuracy of control of the errors of voltage dividers in bridge circuits, one of the poles of the power source of which has a common

point with the meter body and the ground bus,

Claims (1)

Invention Formula The method of controlling the errors of the voltage dividers, based on the fact that the voltage is measured unbalance between the vertices of the measuring diagonal of the bridge formed by the controlled and reference dividers, and the voltage between the points of the controlled and reference dividers to the output and the common source bus is measured power, determine the error of the controlled divider by the values of the measured voltages and the nominal value of the divisor ratio of the dividers, so that, in order to reduce the error trolley bus, connecting the two vertices of the bridge to the power output of the power source measure the voltage between the points of connection of the controlled and reference dividers to the output of the power source, while setting the voltage at the output of the power source equal to its voltage in previous measurements, then the voltage between the vertices of the measuring diagonal of the bridge is measured, the output voltage 0, the power source is set equal to the voltage at the output of the reference voltage divider during previous measurements, as well as a measurement of the voltage between the connection points 5 of the reference and controlled dividers to the common power supply bus, setting the voltage at its output equal to zero, the error value of the division factor of the monitored divider is determined taking into account the values of the additionally measured voltages.