SU1647466A1 - Device for measuring the metal-to-ground potential in cathode-protected metal structures - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure protective potentials on underground metallic pipelines and to determine the corrosive hazardous points. The purpose of the invention is to increase the reliability and speed of measurements by eliminating Och VI

Description

dial gauge, as well as by storing and automatic differential amplifier 2, sign display unit 4, comparator 5, control block 7 and memory block 6, which contains a trigger

11, a counter 12, a digital-to-analog converter 13, and an amplifier 14. The device also comprises a portable, non-trimming reference electrode 1, a metal conduit 3, a recording device 8.

9, logic gate 10, multivibrator 1 hp, f-ly, 1 il.

The invention relates to electrical measuring equipment and can be applied to measure protective potentials on underground metallic pipelines and to determine corrosive points.

The aim of the invention is to increase the reliability and speed of measurements by eliminating the dial indicator, as well as by storing and automatically comparing the subsequent measurement result with the previous one.

The drawing shows a diagram of the proposed device.

The device contains a portable non-polarizing reference electrode 1 connected to the first input of the differential amplifier 2, the second input of which is connected to the metal pipe 3. The first output of the differential amplifier 2 is connected to the input of the sign indication unit 4 and the second output to the first input of the comparator 5, the second the input of which is connected to the first output of the memory block 6, and the output to its first input. The second input of the memory block 6 is connected to the first output of the control unit 7, the second output of which is connected to the reset inputs of the recording device 8. made in the form of a digital display unit, and to the reset input of the memory block 6. The second output of the memory block 6 is connected to the input of the registering device 8. The memory block 6 includes a series-connected trigger 9, a logic gate 10, the signal input of which is connected to the output of the multivibrator 11, a counter 12. a digital-to-analog converter 13 and an amplifier 14. whose output is the first output of memory block 6. The first and second inputs of the trigger 9 are respectively the first and second inputs of the memory block 6, the output of the logic gate 10 is its second output, and the second input of the counter 12 is the reset input.

The device works as follows.

When measuring the potential, the reference electrode 1 is installed above the metal pipe 3. The interference signal arising in the pipeline-ground circuit from overvoltages during switching modes in high-voltage networks, influenced by stray currents from electrified railways, enters the inputs of the differential amplifier 2 in phase equal amplitude, and therefore not amplified. The potential of the insulated metal conduit 3 against the comparatively non-trimming reference electrode 1 is amplified by the differential amplifier 2 and fed to the input of the sign indication unit 4. The polarity of the potential, plus or minus, is indicated by

LEDs. From the second output of the differential amplifier 2, the signal is fed to the first input of the comparator 5, which compares the subsequent potential value with the previous one stored in

memory block. When you press the Set button. The control unit 7, which contains a trigger and two mono-vibrators, produces two pulses — a reset pulse and a recording pulse. The reset pulse sets to zero the counter 12, which means that the memory block 6 and the recording device 8. The write pulse arrives at the second input of the memory block 6. Trigger 9 triggers, opens the logic gate 10, and to the input of the counter 12

pulses are output from the multivibrator 11. Next, the digital signal is converted using a digital-to-analog converter 13 to analog. Amplified by amplifier 14 and fed to a second

the input of the comparator 5. When comparing the voltages at the inputs of the comparator, the latter produces a pulse that arrives at the first input of the memory block 6 and stops its operation. At the same time, pulses with

memory unit 6 is fed to the input of digital display unit 8. The fixed result is proportional to the input voltage.

Next, an incomplete electrode 1

the comparison is transferred to a new location, the potential from the output of the amplifier 2 is again fed to the character indication unit 4 and not the input of the comparator 5. where the comparison with the recorded potential occurs in the memory block 6.

with the potential at the input of the amplifier 2 and at the output of the comparator 5, a smaller (larger) sign is indicated by LEDs, thus realizing the algorithm for subtracting (adding) the potential.

If the potential at the output of amplifier 2 is less than that recorded in memory block 6, then using the control block 7, this potential is written back to the memory block. At the same time, the old result is erased. If the potential at the input of amplifier 2 is greater than in memory block 6, no new result is recorded. Further, the potential measurement cycle is repeated.

The fixed points with the minimum protective potential value are the points of the absence of the specified protective potential due to damage to the insulation coating, and a change in the sign of the potential from minus to plus indicates the presence of an anodic zone in this area of the surveyed object.

Claims (2)

Invention Formula 1, A device for measuring the potential of metal-to-ground cathode-protected metal structures, containing a portable non-diaphragous reference electrode and a recording device, which are designed to increase the measurement speed and reliability by incorporating a differential sign indication unit into it, a comparator, a control unit and a memory unit, with the first the input of the amplifier is connected to a portable non-proportional reference electrode, the second is connected to the metal structure, the first output of the differential amplifier is connected to the sign indication unit, and the second is connected to the first input of the comparator, the output of which is connected to the first input of the memory unit; the second input of the memory unit is connected to the first output of the control unit; the first output of the memory unit is connected to the second input of the comparator, and the second output - with a recording device, made in the form of a digital display unit. 2. The device according to claim 1, that is, in order to increase the speed measurements, the memory unit is designed as a series-connected trigger, logic gate, counter, digital-analog converter and amplifier, with the first and second inputs of the trigger being respectively, the first and second inputs of the memory unit, the output of the amplifier is its first output, the signal input of the logic valve is connected to the output of the multivibrator, its output is the second output of the unit memory, and the second input of the counter is the reset input.