SU885902A1 - Device for measuring resistance - Google Patents

Description

(54) DEVICE FOR MEASURING ACTIVE RESISTANCE

one

The invention relates to electrical measuring equipment and can be used in testing and measuring the resistance of a resistor.

Closest to the present invention is a device for measuring the resistance of a resistor, comprising a quadruple resistive bridge, an unbalance signal amplifier, a comparison unit and an integrator 11.

A disadvantage of the known device is its low accuracy due to the temperature and temporal instability of its elements. j

The goal of the invention is to increase accuracy.

The goal is achieved by the device for measuring the active resistance, which contains a quadruples resistive bridge, one of the arms of which includes the resistor under investigation, an unbalance signal amplifier, the output of which is connected to one of the inputs of the comparison unit, and the integrator connected to the second 2S input. , the output of the comparator unit is connected to the integrator input and to the diagonal of the bridge power supply, equipped with two additional resistors, each of

which are connected between the resistors forming the branches of the bridge, two controllable switches, the switching contacts of which are connected to the inputs of the unbalance signal amplifier, and the closing and opening contacts, respectively, to the outputs ka: 1 of each additional resistor.

The drawing shows the functional diagram of the device.

The device contains an integrator 1, made on the operational amplifier 2, the resistor 3 and the capacitor 4} comparison unit 5} four-shoulder resistive bridge 6, whose arms contain this resistor 7,8,9,10 and 11 and the test resistor 12, controlled switches 13 and 14; amplifier 15 signal unbalance; a registration unit 16, a control unit 17 of switches 13 and 14.

The device works as follows.

Claims (1)

The resistance measurement process consists of three cycles: In the first measurement cycle, switch 13 is in position a, and switch 14 is in position b. From the output of bridge 6, the voltage is removed, ve on which raena U 0l5ll 9 nW v p rt. L: IK and: l. I where Uj is the supply voltage of the bridge. The period of the output signal in the first clock is equal to:. T kU + 6,,. where K is the sensitivity of the device (change in the period of the output signal per unit voltage change from m / ha)} D is the initial value of the period. The accuracy of the measurement of the resistance of the resistor is determined by the parameters and and which change under the influence of external conditions. In the second cycle, the switch 14 is thrown to position a, the switch 13 remains in the same position. The voltage U is removed from the output of the bridge b, associated with the measured resistance ratio: ° RTt-V "9 The period of the output signal in this cycle is equal to the value of TX K i + b In the third cycle, both control switches 13 and 14 are set to b, while the voltage is removed from the output of the bridge / 2-1., B- (. The period of the output signal in the third cycle is equal to TV K and J + 6, The measured resistance is determined by solving equations (2), (4 ) and 6) by eliminating the parameters K and A TI - T. g - TI. where A, B - const, 1 (RT + Rg -1- Rg): The device provides a high accuracy measurement of the resistance of the resistor, which is determined mainly by the class of bridge resistors. The invention is a device for measuring active resistance, containing a four-shouldered resistive bridge, in one arm of which a resistor under study is included, an imbalance signal amplifier, the output of which is connected to one of the inputs of the comparator, and the second input of the integrator is connected the integrator and the diagonal of the power bridge, I distinguish it with the fact that, in order to increase accuracy, the device is equipped with two additional resistors, each of which is connected between the resis tori, forming the bridge branches, two controllable switches, the switching contacts of which are connected to the inputs of the unbalance signal amplifier, and the closing and opening contacts, respectively, to the outputs of each of the additional resistors. Sources of information taken into account during the examination 1. A. A. Martyashin. and others. Electrical parameter converters for monitoring and measurement systems. M., Energie, 1976, p. 270-291, fig. 54 (10).