SU1661689A1 - Device for determining breakage place of cable-core insulation - Google Patents

Abstract

The invention can be used to determine the distance to the point of damage of two cable cores. The purpose of the invention is to increase the sensitivity and reduce the measurement time. The device contains two unbalanced bridge circuits connected at opposite ends of the cable to the damaged conductors and cable sheath. Sources of measuring voltages in these circuits are included opposite to each other, and as indicators in the diagonal of bridges are included indicating measuring instruments, according to which the distance to the place of damage is calculated. In this case, the formula for calculating includes the resistance value of one of the damaged cores and the resistance value of the shoulder of the bridge circuit. 2 Il.

Description

The invention relates to electrical measuring equipment and can be used to determine the distance to the point of damage to the insulation of two cable cores.

The aim of the invention is to increase the sensitivity of the circuit and reduce the measurement time by using two unbalanced bridge circuits in which the sources of measuring voltage are included in the opposite direction, and indicating indicators are included in the diagonal of the bridges as indicators.

FIG. 1 is a diagram of the proposed deviceJ in FIG. 2 is an equivalent circuit for deriving a calculation formula.

R1 R + Rxa, R5 R + Rxsr;

R2 R + Rrta - Rya

HZT5 &

R6 -R + r.

xS;

where R is the resistance of the shoulder of the unbalanced bridge circuit;

Ryas Ry5 resistance to cable core damage;

RAQ, RAЈ cable core resistance;

Rn, Rn - transients

at the site of damage, R3 R4 are damping resistances in the diagonal feeds of unbalanced bridge circuits.

In addition, in FIG. 2, 11, 12, 13, 4 — the values of the loop currents, respectively, in the first, second, third, and fourth circuits E1, E2 — are sources of measurement voltages.

The device contains an unbalanced bridge circuit 1, connected to one side of the tile being monitored (point A) and consisting of a resistive edge B 2 of the ratio of an unbalanced bridge circuit showing the measuring device 3 (milli-volt meter voltmeter), a constant-voltage source 4. toKa and resistor 5 to limit toKa in the measuring circuit; matching 6 cable cores to the fault point; transitional resistance 7 between the core cable and the ground (cable sheath), drive resistance 8 to the damage point from the opposite side of the cable, unbalanced bridge circuit 9, connected at the opposite end of the cable (point B), consisting of resistors 10.shoulder unbalanced bridge circuit, showing device 11, measuring voltage source 12 and direct current resistor, 13 to limit the current .

At the same time, on the one side of the cable, two identical resistors 2 are connected, forming with series-connected resistances 6 cores white to the point of damage and transitional resistances 7 on the ground at the point of damage, a quadrilateral resistance, in one of the diagonals of which is shown a measuring device 3 and the other connecting the grounded point is a series-connected DC measuring voltage source 4 and a resistor 5; on the opposite side of the cable, to the damaged conductors 8 are connected two identical resistors 10, which, with damaged cores 8 and with resistances 7, form a similar quadrant to the first quadrangle with a measuring device 11 in one diagonal and a series string consisting of measuring voltage source 12 and a resistor 13, in another diagonal at In this case, the polarity of the source 12 of the measuring voltage is inverse to the polarity of the source 4 of the measuring voltage, included in the diagonal of the quadrilateral resistance of the opposite sides s cable

The device works as follows.

Unbalanced bridge circuits 1 and 9 are connected to both ends of a damaged pair of wires with a comparison arm with a voltmeter (millivoltmeter), in the indicator diagonal and

5 by sources 4 and 12 of the measuring voltage with limiting resistors 5 and 13 in the supply diagonal. The two other shoulders of the unbalanced bridge circuit are elements of damage to a pair of cores.

In the measurement scheme of the proposed device, the voltage unbalance is counted directly according to the readings of a voltmeter (millivolt5 meter), for example digital, and the resistance to the point of damage to the insulation of the cores is calculated using the formula CB ........ UB-UA

Rx uft n-ib

RA + UA + and.

R,

(ABOUT

where Uft, Ug - voltmeter readings

respectively in paragraphs A and B

Kd - resistance of one drive damaged

couples lived

R is the resistance value of the impedance of the unbalanced bridge circuit.

The proposed device significantly reduces the time spent on carrying out the measurements themselves - eliminating the need for balancing compensation circuits, the need to maintain communication between the operator during the measurement — only the measurement result is reported, which is practically obtained instantaneously by connecting to the line of the corresponding devices. Operator qualification requirements are also reduced.

Claims (1)

Invention Formula A device for determining the location of damage to the insulation of cable cores containing a closed quadrilateral resistance, two of which are yute 16 with resistors of the same rating, and the other two are series-connected resistances of the cable cores to the damage site and contact resistances to earth at the site of damage, the measuring voltage source is included in one quadrilateral diagonal, and the indicator is different in the other. sensitivity 96 circuitry and measurement time reduction, at the opposite end of the cable, damaged wires are included in a similar resistance quadrilateral, with the measuring voltage sources at both ends of the damaged circuit turning on the opposite side through damping resistors, and indicating meters are used instead of indicators. Editor I. Shulla Compiled by V. Kovalenko Tehred M. Morgental Corrector M. Samborska Order 2121 Circulation b2 7 VNIIPY State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, 4/5 Raushsk nab. Item B Fia1 FIG. 2 Subscription