SU1638678A1 - Method for damage site location in power transmission and communication lines - Google Patents

Abstract

The invention can be used to locate damage sites on power lines and communications. The aim of the invention is to increase the sensitivity and range of measured distances when receiving reflected signals from a monitored line. The method is based on matching the output impedance of the probe pulse generator with the wave impedance of the line, sending the probe signals to the line and determining the distance to the fault site by the time delay of the pulse reflected from the damage relative to the probe pulse. The reception of reflected signals during a group of probing cycles is performed so that in each cycle they take one instantaneous voltage value from the line corresponding to a certain value of the time delay, and at the same time, the output impedance of the probe generator with the impedance of the line increases completely. 2 Il. 3 (L

Description

The invention relates to electrical measuring equipment and can be used to locate damage points on power lines and communications.

The aim of the invention is to increase the sensitivity and range of measurable distances by mismatching the output impedance of the probe pulse generator (HID) with the line impedance by increasing it by receiving the instantaneous value of the reflected signal voltage from the LINE.

 Figure 1 shows a block diagram of a device for implementing the proposed method; 2 shows the impulse response for the case of receiving the reflected signal npi matching the output impedance of the probe pulse generator with the input line impedance (dotted line) and for the case of mismatch at the time of reception (solid line),

FIG. 2 amplitude of the probe pulse; U QT - amplitude of the reflected pulse with a consistent resistance GZI and wave sooboo oo oo

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of the reflected pulse at the mismatch of the GZI resistance and line wave impedance.

The device contains a control unit 1 consisting of a clock generator 2 and an automatic shift unit 3, a receiver 4, a probe pulse generator 5 (GZI), consisting of a probe pulse generator 6 and a matching-matching unit 7 monitored line 8. The output clock the generator 2 is connected to the control input of the automatic shift unit 3 and the generator input of the emf of the probing pulse 6, the output of the automatic shift unit 3 is connected to the control inputs of the receiver 4 and the matching and matching unit 7, the output of the emf of the probing and The pulse 6 is connected through the block 7 of the matching - mismatch with the controlled line 8 and the second input of the receiver 4.

The essence of the method lies in the fact that when receiving the reflected impulses, a short-term mismatch of the GZI input impedance is made in each cycle of the probing by increasing it and the wave impedance of the line.

The device works as follows.

The output pulses of the clock generator 2 start the auto-shift unit and start the generator EMF of the probe pulse with internal resistance R NR - O, which through the matching and matching unit, including the generator resistance Rr and the key K, triggers probe pulses with amplitude E - , q in line 8. Output impedance

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The treatment is equal to the sum of R gb, x Rr + R where R CL | key resistance K.

If k is closed, then R Kft1 0, if open, then R4A1-} co. Control of the matching and timing unit is performed by a gating pulse generated by the gating pulse auto-shift circuit.

The input circuits of the receiver are a key circuit with a large input impedance, which is opened for the signal to pass by a gating pulse arriving at the control input of the receiver.

Thus, the output resistance of the GZI is connected to the measured

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the lines are always, except for the moment of opening the input circuits of the receiver. At the moment of reception, the key K is opened under the action of a strobe pulse. In this case, a complete mismatch of the output impedance of the GZI with the wave impedance of the line is achieved.

Since the input impedance of the receiver 4 is several orders of magnitude greater than the wave impedance of the line, it does not shunt the line input, and it can be assumed that the idle mode takes place during the time of the strobe pulse action, i.e. for reflected signals arriving at the beginning of the line, the line is open and the reflection coefficient tends to unity (K0-I). Therefore, ideally, a doubling of the amplitude of the received instantaneous value of the voltage from the line occurs. This amplitude is recorded by the receiver. As soon as the voltage reception from the line ends (the strobe pulse ends), the matching is restored before the arrival of the next strobe pulse. The process then repeats until the receiver captures all instantaneous voltage values from the line in order to eliminate reflections from the line input during a mismatch, and the instantaneous values of the reflected voltage pulses are received during a group of probing cycles, in each cycle the line is probed and only one instantaneous voltage value is received, which corresponds to the instantaneous time delay value relative to the probing moment determined by the auto-shift unit. At the same time, the time of reception, and consequently, the error, is small.

Claims (1)

Invention Formula The method of determining the location of damage to power lines, and communication, based on matching the output impedance of the probe pulse generator with the line impedance, sending voltage probing pulses to the line, receiving reflected pulses and determining the distance to the damage point by the time delay of the pulse reflected from the damage relatively ( probing, characterized in that, in order to increase the sensitivity and range of measured distances, the reception of reflected pulses is carried out at full 8678 by matching the output impedance of the probe pulse generator with the wave impedance of the line by increasing it by receiving the instantaneous value of the voltage from the line. U behind Compiled by V. Kovalenko i Editor M. Tsitkina Tehred S. Migunova Proofreader T. Kolb Order 927 Circulation 426 VCHIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk nab. 113035 eight Fig, 1 Yirp-worp FIG. 2 Subscription