SU1246028A1 - Device for checking cables - Google Patents

Abstract

This invention relates to instrumentation technology. Maybe. be used in automatic cable control systems when determining its length and location of damage. The aim of the invention is to increase the productivity of the control. For this purpose, a device comprising a generator 1, a pulse shaper 2, a frequency meter 5, a recording unit 6, triggers 18, -19, elements 15, 16 ,. element OR 24, amplifier 7, voltage follower 8, storage capacitor 9, keys 10, 11, source with S to 4 G O N9 CX are entered

Description

12voltage generator

13 trigger pulses, a clock generator 14, a third element AND 1 7 comparators 20, 21, 22, a pulse expander 25, a division unit 26, a subtraction element 27, memory registers 28, 29, and a trigger driver 30. The goal is achieved by automatic .1

The invention relates to instrumentation technology and can be used in automatic control systems for köbel in determining its length and the location of damage.

The purpose of the invention is to improve the performance of monitoring the automatic change of the ret generator frequency, automatic recording of the moment of combining the direct and reflected pulse sequences, automatic measurement of the generator frequency at the time of registration fixation and automatic calculation of the cable from its beginning to the point of damage. ..

FIG. 1 is a block diagram of the device; FIG. 2 shows diagrams explaining his work.

The device for controlling cables contains a generator 1, a pulse shaper 2, a connecting 3 and a controlled 4 cables, a frequency meter 5, block 6, registration, an amplifier 7, a voltage follower 8, a storage capacitor 9, the first 10 and the second 11. keys, a source 12 constant voltage, 13 starting pulses, 14 clock pulses, first 15, second 16 and third 17 elements And, first 18 and second 19 triggers, first 20 and second 21 and third 22 comparators, inverter 23, element OR 24 , expander 25 pulses, block 26 division, element 27 subtract audio, the first 28 and second 29 registers, memory and the driver 30 starts.

The output of generator 1 is connected via a pulse shaper 2 to a terminal for connection to the control object. and with the input of amplifier 7, the output of the latter is connected to the combined

of the generator frequency, automatic fixation of the moment of combining the direct and reflected pulse sequence and automatic measurement of the generator frequency at the moment of combining fixation and automatic calculation of the cable length from its beginning to the point of damage. 2 Il.

the inputs of the first 20, second 21 and third 22 comparators, the output of the first comparator are connected to the second input of the element —OR 24 and the first input of the recording unit 6, the output of the second comparator 21 is connected to. the first input of the first element 15, the output of which is connected to the first input of the element OR 24, and the second input of the registration unit 6., the output of the third comparator 22 is connected via an inverter 23 to the second input of the first element 15 and the output of the element OR-24 is connected to the input of the expander 25 pulses and with the first input of the second trigger 19, the second input of which is connected to the output of the starting pulse generator 13, the output of the pulse extender 25 is connected to the first input of the frequency meter 5, the first output of which is connected to the first input of the division unit 26, the second input connected to the output of the nepBdro memory register 28, the output of dividing unit 26 is connected to the first input of the subtracting element 27, the second input of which is connected to the output of the second memory register 29, the output of the subtracting element 27 is connected to the third input of the registering unit 6, the fourth input of which is connected with the output of the trigger generator 30, the input of which is connected to the second output of the frequency meter 5, the output of the second trigger 19 is connected to the combined first inputs of the second 16 and third 17 elements And the output of the second element 16 is connected to the first input of the second first key 11, the output of the third AND gate 17 is connected to the first input of the first switch 10, a second input coupled to a source 12, DC voltage a second input of the second switch 11 is connected

with a source of constant voltage .12 and the first output of the storage capacitor 9, the second output of which is connected to the output of the first key 10, the input of the voltage follower 8 and the output of the second key 11, the output of the voltage follower 8 is connected to the generator 1 / generator output 14 clock pulses are connected to the input of the first trigger 18, the first and second codes of which are connected to the second inputs 16 and the third 17 elements I.

The device works as follows.

The generator 1 generates signals to the generator 2 lj, the frequency of which depends on the voltage applied to its input from the voltage repeater 8. As such generator 1 any high-frequency generator can be used, the frequency of which is controlled by the supply of external voltage Generator elements 2j. Short pulses through the connecting cable 3 are fed to the controlled cable 4 and to the amplifier 7. Passing the cables 3 and 4, the pulses are reflected from the open end of the cable 4 or from any break point (fig. 2a) and in the same polarity but smaller amplitude from - due to attenuation in the cable -, return back. The repetition frequency NIN of the pulses of the generator 1 is chosen such that at the maximum length of the Cable to be monitored, the reflected pulses are between the sent ones. When reflected from a short circuit, pulses are reflected in reverse polarity (Fig. 2b).

Direct and reflected pulses go to amplifier 7, which is a conventional nanr-second pulse amplifier. If the frequency of the oscillator 1 varies, then a moment is possible when the direct and reflected pulses coincide in time (Fig. 2c, d) and the total amplitude of the pulses increases or decreases, depending on the type of fault. If at this moment the change in the frequency of the oscillator 1 is stopped and the resulting frequency is measured, then the pulse transit time can be obtained in cables 3 and 4:

2..i,

t

where f is the oscillator frequency 1.

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The location of the fault can be determined according to the formula

Vt

V 4G

or

t

f - „

0

five

0

five

five

0

0

five

five

5 where C

k.k.

c, k

length to defect in the monitored cable; length of the connecting cable;

с - coefficient characterizing this cable:

  ();

f, is the oscillator frequency at the moment of pulse coincidence.

The frequency of the generator 1 is changed by applying to it, through the follower 8, a voltage and voltage from the storage capacitor 9, which is charged from the source 12 to the constant-PQ voltage through the first switch 10 and discharged through the second switch 11.

The operation of the keys 10 and 11 is controlled by a circuit consisting of the following elements: a generator of 13 starting pulses, a generator of 14 clock pulses, a first 18 and a second 19 triggers and a second 16 and a third 17 I. elements.

The trigger pulse generator 13 detects the start of operation of the entire device. It is a Single Pulse Generator, controlled either from an external device, or produces single pulses after a certain period of time determined by the repetition period of the entire device. As such a generator, a conventional standby or self-oscillating multivibrator can be used.

The impulse from the generator 13 transfers the second trigger 19 to a state in which the voltage that resolves the operation of the second 16 and third 17 elements is removed from its output. The generator of 14 clock pulses, represents-. A conventional multivibrator, implies a continuous sequence of rectangular pulses arriving at the counting input of the first trigger 18. The antiphase outputs of the first trigger 18 are connected to the second inputs of the second 16 and third 17 elements I. When entering the first inputs of these elements And the permissive voltages from the second trigger 19, they in turn, depending on the state of the 1NII of the outputs of the trigger 18, are included; and input the signals opening the first 10 or second 11 keys.

In this case, for example, when opening the first key 10, the memory con-; The capacitor .9 is charged from a constant voltage source 12 through this key, and then when the first trigger 18 is switched to the second position, when the second element 16 is turned on and the second key 11 is opened, it is discharged through the second key 11. Ta- In the CMR manner, the voltage across the storage capacitor 9 alternately, with the frequency of operation of the first trigger 18, then increases, then decreases. This variable voltage through the voltage follower is fed to the input of generator 1 and, according to the same law, changes its frequency. The magnitude of the voltage deviation and frequency is selected by means of a constant voltage source 12 such that, it is possible to coincide in time with the direct and reflected pulses along the entire length of the cable being monitored. When a coincidence occurs, an increase or decrease in the amplitude of these pulses occurs (Fig. 2c, d).

To ensure the normal operation of subsequent circuits, the pulses from the output of the driver 2 pulses are fed to amplifier 7. From its output, they arrive at the "inputs of the three comparators 20-22. As the comparators, any high-frequency threshold circuits can be used that allow the pulses to pass to the output reached a predetermined amplitude value (e.g., a CA1 521 chip).

When the pulses reflected from the open end of the cable coincide (break) and the resulting amplitudes increase (Fig. 2c), the first comparator 20 is triggered. The output pulses of the latter through the element OR 24 after-. tuttaut at the first input of the second trigger 19 and return it to its original position. In this case, the second 16 and third 17 elements And operate and close the keys 10 and 11. The storage capacity is isolated from the constant voltage source 12 and remembers the voltage that occurred at the time of the pulses coinciding. This voltage is applied through the voltage follower 8 to the generator 1 and determines the pulse coincidence rate. A voltage follower 8 is needed so that the storage capacitor 9 does not discharge

to the input of generator 1, therefore, any circuit having a large input voltage can be used as a repeater.

resistance and non-distorting input- 5 no. signal, for example, a source follower on a field-effect transistor.

From the switch; the element OR 24, the pulses of a constant frequency simultaneously arrive through the expander 25 impulse0. There are 25 pulses required for extending the duration of nanosecond pulses passed through amplifier 7, comparator 20 and the OR element 24, so that 5 would ensure the normal operation of frequency meter 5. Any extended multivib circuit can be used as an extension circuit for bodies of 25 pulses. . rator or waiting for the trigger.

0 When the amplitude of the sum of pulses decreases (Fig. 2d) from reflection during a short circuit, the comparators 21 and 22 operate in the monitored cable. Comparator 21 is tuned to an amplitude of any pulses, therefore it always works when there are pulses. The comparator 22 is configured for the amplitude of the pulses, reduced in amplitude (fig.2g). The output of the comparator 21 is connected to the first input of the first element I 15, and the output of the comparator 22 to the 1 second output of the same element through the inverter 23. The output of the element 15 and the pulses will be only when its inputs have single-phase, for example, positive impulses or voltage. At the first input, the pulses from the comparator 21 are present-comfort. always, and at the second input the positive voltage due to the presence of the inverter 23 will be when the comparator 22 is turned off, i.e. when the total amplitude of the pulses at the inputs of the comparators falls when the direct ones coincide. pulses and reflected from the place of the co-) - closeout (figd). The resulting pulses from the output of the first AND 15 element arrive at the first input of the OR 24 element and further along the described circuit to the trigger 19 for closing the AND 16 and 17 elements, the .10 and 11 keys and storing the voltage on the capacitor 9. These same pulses through the expander 25 pulses arrive at

5 frequency counter -5. Simultaneously, from the output of the first comparator 20 and the output of the first element I 15, depending on their response, the pulses arrive at

0

five

0

five

0

1.1246028

First or second. Inputs of block 6 of registration, which imprints the type of e 1 right: open circuit or short circuit.

As a frequency meter 5, any standard frequency meter operating in automatic mode can be used when pulses are applied to its input and outputting measurement results in digital form. From the second output of the frequency meter 5, the information on the pulse frequency is fed to the division unit 26 and to the spin element 27 in order to perform calculations using the formula

ten

with him shi ne IL with IL th

J5 tue on poo so po

V .sl. n ".k f VK

The values of c and t are constant and are taken from memory registers 28 and 29, where they are stored preg; visually. The outputs of memory registers 28 and 29 are connected, respectively, to the second inputs of block 26 and element 27.

The results of the calculations from the output of the subtracting element 27 are fed to the third input of the registration unit 6. As the latter, any digital printing machine can be used, working on an external command and allowing to obtain a printout of the measurement results on a paper tape in digital or alphabetic form. The operation of the registration unit 6 is controlled by a start driver 30, which is a stand-by type of multivibrator type driver. It generates an impulse to start the registration unit 6. after the operation [of the operation of the frequency meter 5 and the memory registers 28 and 29 is stopped. The starter 30 runs from pulses taken from the second output of the frequency counter 5.

To repeat the measurements, the trigger pulse generator 13, on its own or from a command from outside the device, introduces a new single pulse, which triggers the trigger 19 to the initial state, and in a manner described changes the charge memory of the capacitor 9 and the oscillator frequency 1.

Thus, the proposed device allows automation of the cable control process and, consequently, an increase in labor productivity during cable control.

eight

Claims (1)

Invention Formula A device for controlling cables, comprising a generator, a pulse shaper, a frequency driver, a recording unit, first and second triggers, first and second elements AND, OR, the output of the first element AND connected to the first input of the element) OR, characterized in that the purpose of improving the performance of the control, an amplifier, a voltage follower, a storage capacitor, the first and the second keys, a source of constant voltage, the generator of the starting im-. pulses, pulse generator, third element, AND, first, second and third comparators, inverter, pulse expander, dividing unit, subtraction unit, first and second memory registers, start driver, with generator output connected via pulse generator with a terminal for connecting to the control volume and with the amplifier input, the amplifier output is connected to the combined inputs of the first, second and third comparators, the output of the first comparator is connected to the second input of the OR element and the first input of the recording unit, the output of the second comparator is connected to the first input of the first element AND, the output of the third comparator is connected via an inverter to the second input of the first element AND, the first input of the element OR is connected to the second input of the registration unit, the output of the element OR is connected to the input of the expander impulse Both the first input of the second trigger, the second input of which is connected to the output of the starting pulse generator, the output of the pulse expander is connected to the input of the frequency meter, the first output of which is connected to the first input of the division unit, the second input of which is connected to the output of the first memory register connected to the first input of the subtraction element, the second input of which is connected to the output of the second memory register; the output of the subtraction element is connected to the third input of the registration unit; the fourth input of which is connected to, Shaper start output, input. which is connected to the second output of the frequency meter, and the output of the first trigger is connected to the combined first the inputs of the second and third elements And the output of the second element And connected to the first input of the second key, the output of the third element And connected to the first input of the first key, the second input of which is connected to a source of constant voltage, the second input of the second key connected to a source of direct voltage wives and the first conclusion storage capacitor, second 10 cops I. ak one. FIG. 2 Editor N.Egorova Order 3995/38 Compiled by Y. Kushch Tehred O. Sopko Corrector C Tyrals 728Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 the output of which is connected to the output of the first key, the input of the voltage follower and the output of the second key, the output of the voltage follower is connected to the input of the generator, the output of the clock pulse generator is connected to the input of the second trigger, the output of which is connected to the second inputs of the second and third corrector S. Shekmar