SU539277A1 - Method for measuring cable conductor difference - Google Patents

Description

one

The invention relates to measurements of electrical parameters of communication cables and can be used when measuring the difference between two resistances and the absolute value of one of them.

There is a known method for measuring the cable conductor difference, in which the bridge method is used.

The same method is used to measure the absolute values of the cable core resistance. As a rule, the operations of measuring the cable core resistances and their asymmetries are one common program for monitoring ohmic parameters 1.

However, this method has a low resolution and, as a result, low accuracy, since when measuring ohmic asymmetry less than 1 Ohm, there are considerable difficulties in ensuring the metrological characteristics of the variable resistor in the balance arm. The absolute value of this resistor in the state of equilibrium of the bridge is equal to the measured difference of co-motivations, and if we consider that oi lies in the range of 0 + 10 ohms, then it becomes clear that it is necessary to provide the necessary metrology with this method. The use of this method for automatic measurements of doiolitio is also complicated by the fact that the transitional resistance to superstable keys, which 1 automatically changes the size of the balancing arm, is quite large and can be compared with the resistances of its weight bits.

The purpose of the invention — to improve the accuracy of measuring small values of the resistance difference — is achieved by the method of measuring the difference in resistance of cable lived based on the bridge method, by including them as adjacent shoulders of the bridge circuit, the two other arms of the bridge form two equal resistances, the magnitude of which A / C is times greater than the value of the previously measured resistance of one of the cable cores, and in succession with one of them, they include an equilibrium matching circuit store.

In the drawing, and the scheme is shown in accordance with the proposed method.

The resistance of one conductor is measured by a bridge, consisting of 1 of resistances 1-4, with an analog-to-digital converter and a signal source G. The result code is stored in the TI 7 register, which controls the inclusion of two resistance pairs 8, 9, which are K times more than 1 the weight of the store 10. These interactions, together with the measured resistances of the conductors 11, 12 and store 10, form a four-wing bridge. And his first couple

the opposite shoulders are the resistance of the measured iron 11 n, its resistance increased K times 9, and the second resistance of the conductor 12 and successively, consisting of a magazine 10 n of the second magnified resistance K 9 resistance of the measured core. The bridge is balanced from converter 5 through the magazine 10. The equilibrium state of such a bridge is determined by the BE

. (+ Arl) (1)

or, expressing through 1 and we can write down:

() (+) (2) /SD/.(3)

If is the coefficient / (take a rappE 1m

max.

d / (

THEN the expression (3) can finally be irnvestp to the form:

  Max

It can be seen from equation (4) that the weights of the magazine are common both for isremptoral singularities / kil, and for measuring their asymmetry.

This allows, in the automatic mode, when measuring the resistances of cable cores, to measure their ohmic asymmetry, and to place special demands on the weight elements and the switching keys of the pevarav; ovep iwaii.

F o rmu l invention

The measurement method for measuring the impedance difference of the cable lived on the bridge method by including them as adjacent shoulders of the bridge circuit, which means that, in order to increase the accuracy of the patterns of small differences of conductors, the two other arms of the bridge form of two equal resistances, the magnitude of which is K times greater than the magnitude of the previously measured resistance of one of the cable cores, and consistently with one of them include the resistance shop and the equilibrium resistance.

The source of information taken into account and) and expertise:

1. EF. UKSTIN et al. Measurements of the characteristics of telecommunication cables, ed. “Energia, 1967, p. 37 fig. 2-11.

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