CN209590197U - A kind of cable fault positioning device based on time-domain pulse reflection method - Google Patents
A kind of cable fault positioning device based on time-domain pulse reflection method Download PDFInfo
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Abstract
The utility model discloses a kind of cable fault positioning device based on time-domain pulse reflection method, which includes display module, processing module and TDR module；In addition to this it is possible to choose to install parameter input module；Display module, parameter input module and TDR module are electrically connected with processing module.When carrying out cable fault positioning using the positioning device, the amplitude of transmitting pulse signal can be determined according to calculated result, thoroughly solve the problems, such as in the past because by rule of thumb come determine signal emission parameter due to bring it is various.
Description
The application be on 2 9th, 2018, application No. is 201820236603.5, a kind of entitled " base the applying date
In the cable fault positioning device of time-domain pulse reflection method " patent application divisional application.
Technical field
The utility model relates to cable fault the field of test technology, relate generally to a kind of electricity based on time-domain pulse reflection method
Cable fault locator more particularly to a kind of cable fault TDR positioning device for considering cable attenuation characteristic.
Background technique
Cable be connected between power supply and electrical equipment and each equipment room connection hinge, be responsible for electric power conveying, letter
Number transmission and the tasks such as distribution.As application of the electric power in various equipment is more and more wider, cable fault (such as short circuit or disconnected
Road) affect it is also increasingly severe.Cable on such as aircraft is dispersed throughout aircraft everywhere, due to for a long time by steam, ultraviolet
The influence of the factors such as line, vibration, salt air corrosion, cable are easy to happen the failures such as short circuit and open circuit.Plane cable fault, gently then shadow
Flying quality is rung, it is heavy then jeopardize flight safety, or even initiation aircraft accident.Due to aircraft, naval vessel inner cable be often arranged in it is narrow
In small space, the positioning of failure cannot be mostly completed using traditional method for visual inspection.
It the use of more mature method is TDR method, i.e. time domain at present for the positioning of aircraft, naval vessel inner cable failure
Pulse-echo method.It when using this method positioning failure, needs to use TDR positioning device, is infused by TDR positioning device to cable
Enter pulse signal, pulse signal on cable when impedance mismatch point by reflecting, by calculating transmitting pulse signal and instead
The product of time difference for penetrating between pulse signal and pulse signal spread speed in the cable obtains fault distance, so that it may complete electricity
The positioning of cable failure.For aircraft, naval vessel inner cable, a cable may be by plug connector, hinged in wiring process
The impedance variations point (i.e. impedance mismatch point) of the diversified forms such as point, pad, in that case using TDR positioning device and
It, can also be in addition to other than fault point (such as short circuit or open circuit) forms failure reflected impulse signal when method carries out fault location
Non-faulting reflected impulse signal is formed at above-mentioned impedance variations point, biggish interference is formed to the positioning of cable fault, is provided " empty
It is alert " signal, the precision of cable fault positioning is influenced, or even cause to judge by accident, increases maintenance cost.Moreover, fixed using TDR
When position device and method carry out cable fault positioning, TDR positioning device is gone forward side by side usually using the pulse signal injection cable of low pressure
Row detection, but due to not considering that signal in the actual attenuation characteristic of cable, can only rule of thumb determine the transmitting ginseng of signal
Number (voltage for being primarily referred to as signal), and lack theoretical direction, fault bit can not be detected at all when emission parameter setting is lower
It sets, and then will appear when emission parameter setting is higher and be difficult to realization or the higher problem of cost of implementation.
Utility model content
There is the problems such as signal emission parameter is only empirically determined, the utility model to solve existing cable fault location
Propose a kind of cable fault positioning device based on time-domain pulse reflection method.
A kind of cable fault positioning device based on time-domain pulse reflection method of the utility model, which includes: TDR mould
Block, processing module, display module；TDR module receives reflected impulse signal for generating transmitting pulse signal；Processing module
For analyzing the waveform of reflected impulse signal, fault point and possible breakdown point d are judged whether there is, analyzes possible breakdown point d's
Reasonability, and determine fault type and fault point distance L；Display module is for showing selected parameter, possible breakdown point d and failure
The information of point；Display module, processing module and TDR sequence of modules above-mentioned are electrically connected, and TDR module is electrically connected with tested cable.
Preferably, the TDR module in positioning device is electrically connected by impedance matching connector with tested cable.It is hindered by setting
Anti- matched junction can reduce influence of the link position to fault location.
Preferably, the TDR module in positioning device is made of pulse signal generator and signal picker, pulse signal hair
Raw device is used to acquire the reflected impulse signal in impedance mismatch position for generating transmitting pulse signal, signal picker.
Preferably, the amplitude of pulse signal generator generation transmitting pulse signal is adjustable, to realize according to tested cable
Characteristic select TDR transmitting pulse signal amplitude Vin, reduce because by rule of thumb come determine the emission parameter of signal due to bring is asked
Topic.
Preferably, parameter input module is additionally provided in positioning device, parameter input module is for inputting TDR transmitting pulse
The amplitude V of signalinOr calculate VinRequired tested cable data, parameter input module are electrically connected with processing module.When according to quilt
The characteristic of cable is surveyed, V is selected or calculate in advanceinWhen, it can directly pass through parameter input module for VinInput, processing module will
According to the V of inputinSize, the amplitude for the transmitting pulse signal that control TDR module generates；When knowing tested cable data, and not
V is calculated in advanceinWhen size, V will can be directly calculatedinRequired tested cable data typing parameter input module, by processing mould
Block calculates Vin, and according to the resulting V of calculatinginSize, the amplitude for the transmitting pulse signal that control TDR module generates.Pass through setting
Parameter input module, in the past various problems of bring due to by rule of thumb to determine signal emission parameter.
Preferably, tested cable data specifically refers to the length l of tested cableH, it is tested the equivalent resistance R of cableL, it is tested
The characteristic impedance Z of cable0, it is tested the equivalent conductance G of cableL。
Preferably, when the tested cable data of input calculates VinWhen, processing module calculates V using following methodsin,
Wherein, V1It (d) is the limiting value of interference noise in tested cable.
Preferably, V1(d) value is 0.5V.According to a large amount of experiment test, for common cable, act on
The amplitude maximum of various noises thereon is 0.5V or so, and noise herein includes external noise and making an uproar due to connector introducing
Sound etc., when emitting pulse signal by tested cable distribution, amplitude can gradually decay, and when decaying to the range, TDR is fixed
Position method will be unable to identify, therefore select 0.5V as judgment threshold.
In order to illustrate more clearly of a kind of cable fault positioning device based on time-domain pulse reflection method of the utility model
Composition and connection relationship, the method for carrying out fault location using the positioning device is described below, this method mainly includes
Five steps below:
Step S1 selectes the amplitude V of TDR transmitting pulse signal according to the characteristic of tested cablein；The tested cable
Characteristic be primarily referred to as the attenuation characteristic of cable, mainly consider following influence factor: the length l of tested cableH, it is tested cable
Equivalent resistance RL, it is tested the characteristic impedance Z of cable0, it is tested the equivalent conductance G of cableLDeng.
Step S2 generates transmitting pulse signal and is injected into tested cable, then acquires in impedance mismatch position
Reflected impulse signal；In TDR localization method, transmitting pulse signal is specifically generated by pulse signal generator, and adopted by signal
Storage acquires reflected impulse signal.
Step S3 carries out breakdown judge according to reflected impulse signal；In particular it is necessary to analyze the wave of reflected impulse signal
Shape, and according to the amplitude and phase relation of reflected impulse signal and transmitting pulse signal, that is, it can determine fault type.But due to
It is influenced by external environment, and the inside shadow by being generated when connector (including plug connector, hinge joint, pad etc.)
It rings, it is possible that " false-alarm " phenomenon, or erroneous judgement.In order to improve the accuracy of breakdown judge, event is carried out using following methods
The judgement of barrier:
(1) when the absolute value of reflected impulse signal amplitude | V (td) | when >=1V, then determine that there are failures for tested cable, and
Determine fault type and fault point distance L；It can determine fault point distance L according to TDR localization method.
(2) when 0.5V≤| V (td) | when < 1V, then determine that there may be failures for tested cable, then calculate possible breakdown
The distance l of point dd, the wherein distance l of possible breakdown point ddIt is also to be determined according to TDR localization method.
(3) as | V (td) | when < 0.5V, then determine that failure is not present in tested cable, and go to step S5.
Step S4, according to the attenuation characteristic of cable, judge possible breakdown point d reflected impulse signal amplitude V (td) whether
Rationally；If rationally, L=ld, that is to say, the distance l of possible breakdown point ddAs fault point distance L；It, can if unreasonable
Energy fault point d is false-alarm, goes to step S5.
Step S5 terminates cable fault positioning.
Preferably, the reflected impulse signal amplitude V of possible breakdown point d is judged according to the attenuation characteristic of cable in step S4
(td) whether it is reasonable when, specifically with the following method:
Step S41, it is assumed that tested cable is uniform cable, calculates possible breakdown point d reflected impulse signal theory amplitude
Absolute value | V (d) |, that is, calculate the reflected impulse signal reason of the possible breakdown point d corresponding position when tested cable is uniform cable
By the absolute value of amplitude | V (d) |；
Step S42, if | V (td) | > | V (d) |, the reflected impulse signal amplitude V (td) of possible breakdown point d does not conform to
Reason；Otherwise, then rationally.
Preferably, in step S41 | V (d) | calculation method specifically:
Wherein, ldFor the distance of possible breakdown point d, RLFor the equivalent resistance for being tested cable, Z0For the characteristic resistance for being tested cable
It is anti-, GLFor the equivalent conductance for being tested cable.
Preferably, the amplitude V of pulse signal is emitted in step S1inMethod for selecting specifically:
Wherein, V1It (d) is the limiting value of interference noise in tested cable, lHFor the length for being tested cable；By determining Vin,
The problem of can solve the emission parameter that can only rule of thumb determine signal in the past, also avoids that thus bring is various to ask
Topic.
Preferably, V1(d) value is 0.5V.According to a large amount of experiment test, for common cable, act on
The amplitude maximum of various noises thereon is 0.5V or so, when emitting pulse signal by tested cable distribution, amplitude meeting
Gradually decay, when decaying to the range, TDR localization method will be unable to identify, therefore select 0.5V as judgment threshold.
Preferably, the calculation method of fault point distance L is replaced in step S4 are as follows:
Wherein,C is the light velocity, εrFor the relative dielectric constant for being tested cable insulation material, Δ t is transmitting pulse
Time difference between signal and reflected impulse signal.
A kind of cable fault positioning device based on time-domain pulse reflection method of the utility model, can be special according to tested cable
Property determine transmitting pulse signal amplitude Vin, thoroughly solve in the past that bring is each due to by rule of thumb to determine signal emission parameter
Kind problem.
Detailed description of the invention
Fig. 1 is positioning device structure schematic diagram.
Fig. 2 is TDR module composition and TDR module and tested cable connection schematic diagram.
Fig. 3 is the flow chart that cable fault positioning is carried out using the positioning device in the utility model.
Fig. 4 is the positioning device structure schematic diagram with parameter input module.
Fig. 5 is that there are the transmitting signals of open circuit fault cable and anti-at test 87m when being 5.5V for transmitting pulse signal amplitude
Penetrate signal waveforms.
Fig. 6 is that there are the transmitting signals of open circuit fault cable and anti-at test 87m when being 3.3V for transmitting pulse signal amplitude
Penetrate signal waveforms.
Fig. 7 is to emit the transmitting signal of test 100m cable and reflection signal waveforms when pulse signal amplitude is 5.5V.
Specific embodiment
1 to attached drawing 7 with reference to the accompanying drawing, introduces specific embodiment of the present utility model.
As shown in Figure 1, a kind of cable fault positioning device based on time-domain pulse reflection method of the utility model, main to wrap
Include TDR module, processing module, display module；Furthermore it is possible to choose to install parameter input module as needed.
In order to more preferably illustrate a kind of cable fault positioning device composition based on time-domain pulse reflection method of the utility model
And working principle, being specifically described below in the utility model is how to consider cable attenuation characteristic.
During along tested cable distribution, frequency does not change high-frequency pulse signal substantially；Waveform due to
External signal interference and transmission line self-characteristic can be distorted；The amplitude of signal is due to dielectric loss, conductor wire losses and spoke
The reasons such as loss are penetrated, there can be certain decaying, and as the frequency of signal is higher and propagation distance is remoter, signal can decay
It is more serious.
Decaying is to damage the characteristic of transmission line, it is to solve for the direct knot that second order damages RLCG distributed constant circuit model
Fruit.Usually use αnIndicating the decaying of unit length, unit is napier/rice, it is defined as follows:
Wherein: RLFor the equivalent resistance of transmission line, unit Ω；GLFor the equivalent conductance of transmission line, unit S；LLFor transmission line
Equivalent inductance, unit H；CLFor the equivalent capacity of transmission line, unit F；ω is the frequency of signal on transmission line.
It is damaged in transmission line uniformly, it can be indicated are as follows:
In formula: Z0For the characteristic impedance of transmission line, unit Ω.
When signal is along uniform cable distribution, influence of the conductor wire losses to signal mainly makes signal amplitude decay.Such as
Fruit is V for transmitting pulse signal amplitudeinSignal propagate on the transmission line, signal amplitude is not linear with the increase of distance
Decline, but as the variation of distance exponentially declines, input signal and output signal magnitude relation on transmission line are as follows:
In formula, VinIndicate the amplitude of transmitting pulse signal, unit V；V (d) indicates the voltage magnitude of d point on transmission line, single
Position V；AnIndicate complete attenuation, unit napier；ldFor the distance of d point, the specially distance of signal input part to d point, unit rice；αn
For the decaying of transmission line unit length, unit napier/rice.
Since decibel use is more common, calculating is more convenient, can use the transformational relation in following formula (4), by αnTurn
Become a decibel form:
By above formula, the relationship that input voltage and output voltage are indicated with decibel is obtained:
The form that formula (2) is turned to decibel by the transformational relation of formula (4), then obtain the decaying dB/ of transmission line unit length
Length are as follows:
By formula (5), formula (6) it is known that transmitting signal is with attenuation characteristic formula on the transmission line are as follows:
The above-mentioned analytic process for cable attenuation characteristic, according to cable attenuation characteristic model in given high-frequency pulse signal frequency
The relationship of high-frequency pulse signal amplitude and propagation distance on a certain cable is obtained on the basis of rate and amplitude.
Sketch the cable fault Location Theory for being based on TDR (i.e. time-domain pulse reflection method) again below.TDR is managed substantially
By being transmission line theory；It is special on transmission line using cable as element with distributed parameters in transmission line principle, and in uniform transmission line
Property impedance be certain value, wherein the characteristic impedance of cable can be indicated by formula (8):
In formula, LL1For the inductance of unit length cables, CL1For the capacitor of unit length cables.
During electric impulse signal transmits in the cable in transmission line theory, if transmission medium is uniform, signal meeting
It is transmitted always along cable, if cable breaks down (open circuit or short circuit), transmission medium is uneven, and pulse signal can be in impedance
The place of variation is reflected.Reflection coefficient on transmission line at impedance mismatch is the ratio between reflected voltage and emitting voltage:
In formula, VreFor reflected impulse signal voltage amplitude, ZlFor the input impedance of cable run barrier point, Z0For cable
Characteristic impedance.By (9) formula it can be concluded that following three features:
(1) when cable is normal, Z0=Zl, ρ=0, transmitting signal, which will be finally supported, to be absorbed without reflecting；
(2) when electric discontinuity of cable, Zl→ ∞, ρ=1, the electric pulse reflected at this time is identical as initial transmissions impulse amplitude, phase
Position is consistent；
(3) when cable short circuit, Zl→ 0, ρ=- 1, the electric pulse of reflection is identical as initial pulse amplitude, but phase phase
Instead.
In transmission line theory, signal is propagated in the form of an electromagnetic wave on the transmission line；In cable one end plus electricity
After pressure, due to the inertia of capacitor in its distribution parameter, signal transmitting needs the regular hour.The then propagation of signal in the cable
Speed v are as follows:
In formula, ε0For permittivity of vacuum,μ0For space permeability, μ0=4 π × 10-7, εrFor insulation
The relative dielectric constant of material, μrFor the relative permeability of insulating materials, generally 1.ε0、μ0、μrValue substitute into formula (10)
:
In formula, c is light velocity c=3 × 108m/s；
The relative dielectric constant for being only insulated from material by the spread speed of signal in cable known to (11) formula is related, with
Other factors are unrelated.Signal has the same speed in the cable of same dielectric material；
Time domain reflectometry passes through the time difference Δ t for measuring the reflected impulse at transmitting pulse and impedance mismatch, according to
(11) formula calculates the spread speed of signal in the cable to determine fault distance, fault distance are as follows:
In formula, L is test lead at a distance from fault point, and v is the spread speed of signal in the cable, and Δ t is transmitting pulse
With the time difference of reflected impulse.
By analyzing the waveform of reflected impulse signal, when reflected impulse signal is obvious (as previously described due in cable
Noise level is about 0.5V, is more than that noise level is more when the absolute value of reflected impulse signal amplitude is more than or equal to 1V, it is believed that
Reflected impulse signal is obvious), then directly judge that there are failures for tested cable；When reflected impulse signal is unobvious (when reflection arteries and veins
When rushing the absolute value of signal amplitude between 0.5V and 1V, it is believed that reflected impulse signal is unobvious), then judge that tested cable can
Can have failure, measure reflected impulse signal it is unobvious when reflected impulse signal amplitude, then according to transmitting pulse signal with
The product of time difference between reflected impulse signal and pulse signal spread speed in the cable obtains " fault distance ", finally ties
The theoretical amplitude that cable attenuation characteristic calculates the reflected impulse signal of the position is closed, comprehensive descision obtains fault diagnosis result.
As shown in Fig. 2, being carried out when by the positioning device of the utility model and tested cable connection by impedance matching connector
Connection；Pulse signal generator in TDR module sends transmitting pulse signal to tested cable by impedance matching connector, works as quilt
It surveys there are when impedance mismatch position in cable, reflected impulse signal is by impedance mismatch connector by the signal picker of TDR
Acquisition.
When carrying out cable fault positioning using the utility model, specific method is as shown in Figure 3.Wherein judge possible breakdown
The reasonability of point is optional step, and when possible breakdown point is not present, this step be can be omitted, therefore dotted line table is used in Fig. 3
Show.
Embodiment 1:
It is described below and how to be positioned using a kind of cable fault based on time-domain pulse reflection method of the utility model
Device selectes transmitting pulse signal amplitude.
As shown in figure 4, parameter input module is arranged in positioning device, parameter input module is electrically connected with processing module.
In the present embodiment, parameter input module calculates V for inputtinginWith tested cable data needed for fault point distance L.
If tested cable is one section of aircraft inner cable, it is tested the characteristic impedance Z of cable0=50 Ω, equivalent resistance RL=
0.0062 Ω, equivalent conductance GL=0.00046S is tested the relative dielectric constant ε of cable insulation materialr=2.25, length lh=
100 meters, open circuit fault is artificially manufactured in 87 meters of positions of the cable, two kinds of different amplitudes is selected respectively but frequency is 100MHz
Transmitting pulse signal TDR positioning is carried out to it.The amplitude for emitting pulse signal in Fig. 5 is 5.5V, emits pulse signal in Fig. 6
Amplitude be 3.3V.
As shown in Figure 5 and Figure 6, there is transmitting pulse signal 1 in two figures.But there are reflected impulse signal 2 in Fig. 5, according to
Traditional TDR localization method determines that corresponding position is fault point；And reflected impulse signal 2 is not present in Fig. 6.
It is compared by two figures it is found that can not be positioned to failure when emitting pulse signal amplitude is 3.3V.Traditional
In TDR localization method, the amplitude for emitting pulse signal is determined according to previous experiences.As previously described when selected transmitting arteries and veins
Rush signal amplitude it is lower when, then cannot achieve the definition to failure；And when selected transmitting pulse signal amplitude is higher, then gesture
The cost that TDR element must be improved even cannot achieve in engineering when amplitude is excessively high.
It is commonly used to generate the operating voltage of the chips such as the FPGA of TDR transmitting pulse signal to be 3.3V, can be put by operation
The pulse signal that core chips generates is carried out amplitude amplification and exported by big circuit.The amplification of high-frequency pulse signal is wanted
(slew rate refers to the output voltage time change of closed loop amplifier when input is step signal to the slew rate of consideration operational amplifier
The average value of rate is exactly a key index for determining the signal rate of climb in simple terms), if slew rate is too small, generation
Pulse signal rising edge is not enough unsatisfactory for TDR Test requirement suddenly, and the big device price of slew rate is relatively expensive.Pass through the example above
It is found that us can be helped preferably to design circuit by the amplitude of selected transmitting pulse signal, and select relatively cheap device
Part has biggish economic value.
In order to realize that reasonable selection transmitting pulse signal amplitude will be tested by parameter input module in the present embodiment
The length l of cableH, it is tested the equivalent resistance R of cableL, it is tested the characteristic impedance Z of cable0, it is tested the equivalent conductance G of cableLIt is defeated
Enter.V is calculated by processing modulein, especially byCalculate VinSize, wherein V1(d) it is
It is tested noise amplitude in cable, selects 0.5V as judgment threshold V in the present embodiment1(d) value thinks signal in cable
0.5V is decayed in communication process then to think not identifying.
According to above-mentioned calculation method and V1(d) value, is calculated VinAmplitude when being about 5.06V, use TDR technology
Cable fault positioning can be carried out to aforementioned 100 meters long of tested cable.It will also realize that by the analysis, work as V as shown in Figure 6in=
When 3.3V, cable fault positioning cannot achieve at all, because reflected impulse signal is submerged in noise completely.
Embodiment 2:
It is described below and how to be positioned using a kind of cable fault based on time-domain pulse reflection method of the utility model
How device carries out failure reasonability judgement, and completes the positioning of failure.
In the present embodiment, it is identical with embodiment 1 to be tested cable data, emits the frequency of pulse signal as frequency
100MHz.It describes in detail below with reference to method above-mentioned.
Step S1 selectes transmitting pulse signal amplitude
Such as the calculating in embodiment 1, VinAmplitude when being about 5.06V, can be to aforementioned 100 meters long using TDR technology
Tested cable carries out cable fault positioning.In order to enable reflected impulse signal can become apparent relative to noise, in this implementation
V is properly increased in exampleinAmplitude, specifically take Vin=5.5V.V in the present embodimentinCalculating carry out in advance, inputted by parameter
Module, which directly enters, calculates resulting Vin, the amplitude for the transmitting pulse signal that control TDR module generates, the V of typinginIt will display
On the display module.
Step S2 emits and acquires reflected impulse signal
As shown in fig. 7, the amplitude of the transmitting pulse signal 1 occurred by pulse signal generator in TDR module is 5.5V,
Frequency 100MHz；And the time difference by emitting pulse signal and reflected impulse signal is Δ t=500ns；Signal picker is adopted
The reflected impulse signal 2 collected, amplitude are V (td)=0.99V.
Step S3 carries out breakdown judge according to reflected impulse signal
According to the method above-mentioned introduced in the utility model, relevant treatment and judgement are carried out by processing module, due to
0.5V≤| V (td) | < 1V, then the point is possible breakdown point.
Step S4 judges the reasonability of possible breakdown point
According toPossible breakdown point reflection pulse signal is calculated by processing module
V (d)=1.73V is obtained by calculation in theoretical amplitude V (d).
Cause | V (td) | < | V (d) |, it is thus possible to rationally, then judgement should by the reflected impulse signal amplitude V (td) of fault point
Possible breakdown point is fault point.Further analyze reflected impulse signal, it is known that the fault type of the fault point is " open circuit ".
For the computational accuracy for further increasing fault point distance, according toWith Δ t, byCalculating is out of order
Point distance is L=50 meters, i.e., distance of the fault point away from test lead is 50 meters.
The information of possible breakdown point d and fault point is also all displayed on display module, and specifying information includes possible breakdown
The reasonability judging result of the V (td) and V (d) size of point d, possible breakdown point；In addition, when determining that possible breakdown point is fault point
When, also to show fault point distance, fault type etc..
Step S5 terminates cable fault positioning.
Finally it should be noted that above description is merely a prefered embodiment of the utility model, it is not limited to this reality
With novel, although utility model is described in detail with reference to the foregoing embodiments, for those skilled in the art,
It is still possible to modify the technical solutions described in the foregoing embodiments, or part of technical characteristic is carried out etc.
With replacement.Within the spirit and principle of the utility model, any modification, equivalent replacement, improvement and so on should all include
It is within the protection scope of the utility model.
Claims (6)
1. a kind of cable fault positioning device based on time-domain pulse reflection method, which is characterized in that including TDR module, processing mould
Block, display module；Display module, processing module and the electrical connection of TDR sequence of modules, TDR module are electrically connected with tested cable；
The TDR module is made of pulse signal generator and signal picker, and pulse signal generator is for generating transmitting arteries and veins
Signal is rushed, signal picker is used to acquire the reflected impulse signal in impedance mismatch position；The pulse signal generator produces
The amplitude V of pulse signal is penetrated in hair tonicinIt is adjustable.
2. a kind of cable fault positioning device based on time-domain pulse reflection method as described in claim 1, which is characterized in that
TDR module is electrically connected by impedance matching connector with tested cable.
3. a kind of cable fault positioning device based on time-domain pulse reflection method as described in claim 1, which is characterized in that fixed
Parameter input module is additionally provided in the device of position, parameter input module is used to input the amplitude V of TDR transmitting pulse signalinAnd frequency
Or calculate VinRequired tested cable data, parameter input module are electrically connected with processing module.
4. a kind of cable fault positioning device based on time-domain pulse reflection method as claimed in claim 3, which is characterized in that quilt
Survey the length l that cable data specifically refers to tested cableH, it is tested the equivalent resistance R of cableL, it is tested the characteristic impedance Z of cable0,
The equivalent conductance G of tested cableL, it is tested the relative dielectric constant ε of cable insulation materialr。
5. a kind of cable fault positioning device based on time-domain pulse reflection method as claimed in claim 4, which is characterized in that when
It inputs tested cable data and calculates VinWhen, processing module calculates V using following methodsin,
Wherein, V1It (d) is the limiting value of interference noise in tested cable.
6. a kind of cable fault positioning device based on time-domain pulse reflection method as claimed in claim 5, which is characterized in that V1
(d) value is 0.5V.
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| CN110940896A (en) * | 2019-12-19 | 2020-03-31 | 苏州裕太车通电子科技有限公司 | Damage diagnosis method for ultra-long cable |
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