SU892318A1 - Device for automatic measuring of cable wire resistance - Google Patents

Description

(5) DEVICE FOR AUTOMATIC MEASUREMENT OF RESISTANCE OF LABELS OF THE CABLE

one

The invention relates to a measurement technique and can be used for electrical testing of cables during their manufacture and operation.

A device is known for automatically measuring the conductor resistance of a cable containing a DC bridge, in one of the arms of which a measuring cable core is connected with two selectors. A zero-body is connected to the bridge diagonal, connected to a digital-to-analog converter of the code of the number to the resistance value with which the bridge is balanced during the measurement process. To compensate for the disturbances induced in the cable to be measured by external electromagnetic fields, the device uses the same voltage induced in another auxiliary conductor 0.

The disadvantages of the device include its complexity, low speed and accuracy of measurements.

The closest to the technical essence of the invention is a device for automatic measurement of the cable core resistance, containing two selectors with potential and current contacts, a current stabilizer connected to the first selector, a pulse distributor connected to a digital-to-analog converter, a zero-organ, two memory constants. measuring contactors, a reference resistor, an alternating voltage generator, two linear detectors and an inductive voltage divider 2 "When used as As a standard temperature-dependent resistance resistor, the measurement result is automatically reduced to temperature.

Disadvantages of the device - low

20 measurement accuracy due to the influence of errors in the current stabilizer of the cable to be measured, linear detectors and inductive divider in the formation of the reference voltage, the signal storage circuit on the measured conductor. Multiple storage of analog signals causes a slow response of the device. In addition, this device is difficult. The purpose of the invention is to improve the measurement accuracy, speed and simplification of the device. The goal is achieved in that the device for automatic measurement of cable resistance contains two selectors with potential and current contacts, a reference resistor and an impulse distributor unit connected to digital-to-analog units. a log converter and comparator, a current source and a differential amplifier unit are introduced, the output of the current source connected to the first current contact of the first selector, the first sweat The social contact is connected to the first input of the differential amplifier, the second input of which is connected to the second potential contact of the first selector, the second current contact of which is connected to the first input of the digital-to-analog converter unit and the first output of the reference resistor, the second output of which is connected to the ground bus. the differential amplifier is connected to the first input of the comparator unit, the second input of which is connected to the output of the digital-to-analog converter unit. The drawing shows block diagrams of a device for automatic measurement of cable conductor resistance. The device contains a source of 1 current, a comparator 2, a distributor of 3 pulses, a differential amplifier 4, a digital-to-analog converter 5, a reference resistor 6, selectors 7 and 8 with potential and current contacts , auxiliary conductors 9 and 10. The device operates as follows. In the static state, the source current flows through the control object, the auxiliary core 10, the reference resistor 6 and the current contacts of the selectors 7 and 8. . The voltage caused by the flow of this current through the reference resistor 6 is a reference voltage and is applied to the analog input of the D / A converter. 5. Voltage caused by 4 current flowing through current source 1 through the control object through series auxiliary conductor 9 and potential contacts of selectors 7 and 8 is fed to the input of differential amplifier 4, the output of which is connected to the first input of comparator 2 Pulse distributor 3 is in zero state In this case, all bits of the D / A converter 5 are turned off, and zero voltage is applied to the second input of the comparator 2. With the arrival of the starting pulse, the distributor 3 alternately, starting with the older one, turns on the digital-to-analog converter 5 bits. When each bit is turned on, comparator 2 compares the output voltage of the digital-to-analog converter 5 and the voltage drop on the control object, taking into account the gain of the differential amplifier. If the output voltage of the D / A converter 5 is greater, then the comparator 2 switches off the corresponding discharge through the pulse distributor 3, otherwise it remains turned on. After testing all the bits of the D / A converter 5, its output voltage becomes equal to the voltage at the output of the differential amplifier. This completes the measurement process. The measurement result recorded in the code of the digital-analog converter 5 corresponds to the resistance of the test object. Kdu .an where Ry is the resistance of the object of control; gain factor of the differential amplifier C; resistance of the reference resistor 6; conversion factor of digital-to-analog converter 5; measurement result. By varying the gain of the differential amplifier k and the resistance of the reference resistor 6, it is possible to set the required measuring range for the resistance of the wires. The device uses one exemplary element — a reference model.

Claims (2)

Claim A device for automatically / measuring the resistance of a cable _core containing two selectors with potential and. current contacts, a reference resistor and a pulse distributor unit) connected to the blocks of a digital-analog converter and a comparator, characterized in that, in order to increase the measurement accuracy, speed and simplify the device, a current source and a differential amplifier block are introduced into it, and the source output current is connected to the first current contact of the first selector,, ^{into the} first potential contact of which is connected to the first input of the differential amplifier, the second input of which is connected to the second potential contact of the first selector, the second current contact of which is connected to the first input of the digital-to-analog converter unit and the first output of the reference resistor, the second output of which is connected to the ground bus, ^{m the} output of the differential amplifier unit · is connected to the first input of the unit ·: parator, second the input of which is connected to the output of the digital-to-analog converter unit. ²⁵ Sources of information taken into account in the examination 1. Gorodetsky S.S. and Lakernik R.M. Testing cables and wires. M., Energy, 1971 "with. 242. 2 ° 2. USSR Copyright Certificate No. 600458, cl. G 01 R 17/10, 1978 (prototype). Order 11243/66 Mintage 735 Pb VNIIIPI of the USSR State Committee for Inventions and Discoveries 113035, Moscow, Zh-35 "Raushskaya nab., 4/5 Branch of PPP Patent Uzhhorod, st. Project, 4