CN1185585A - Medium consumption automatic measuring instrument - Google Patents

Medium consumption automatic measuring instrument Download PDF

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Publication number
CN1185585A
CN1185585A CN96122991A CN96122991A CN1185585A CN 1185585 A CN1185585 A CN 1185585A CN 96122991 A CN96122991 A CN 96122991A CN 96122991 A CN96122991 A CN 96122991A CN 1185585 A CN1185585 A CN 1185585A
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China
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signal
analog
circuit
digital conversion
voltage
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CN96122991A
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Chinese (zh)
Inventor
罗卓林
张茂城
黄智佳
孔高祥
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罗卓林
广州白云轻工实业公司
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Priority to CN96122991A priority Critical patent/CN1185585A/en
Publication of CN1185585A publication Critical patent/CN1185585A/en

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Abstract

A medium-consumption automatic meaturing instrument includes a signal convertor, a data processor, a display, a control system, power supply circuit and shield case and an insulation box etc., which is characterized in that the input voltage of said signal convertor are two analogue signals, the output signal is fed in the processor which can calculate, without distortion, the peak valve of the reference signal and the signal to be measured and the included angle theta, and also the medium-consumption factor and capacity, conduct compensation and anti-pulse interference treatment to stray capacitance, then implement curve fit and formalize the peak valve tec.. Said instrument can also be used for meaturing capacitance and the phase angle of two signals.

Description

Medium consumption automatic measuring instrument

The instrument that the present invention relates to a kind of automatic measurement power equipment medium consumption factor tg δ and electric capacity C and measure the angle theta between two AC signal.

Measure the dielectric loss and the electric capacity of power equipment at present both at home and abroad, the Schering bridges that adopt are realized more, China extensively adopt be on marine products QS-1 electric bridge, this electric bridge is the electric bridge of manual balance, its shortcoming is: adjust balancing run and not only bother but also time-consuming, and the local galvanometric light belt strong at light is difficult to see clearly, in medium matter loss factor and the time dependent occasion of electric capacity because of can't balance not adopting the QS-1 electric bridge, and be subjected to the restriction of applied voltage, can not be used for very high voltage (generally be used for≤10KV occasion).In addition, also have some surveying instruments abroad,, be not suitable for being used for measuring the medium consumption factor tg δ and the C of power equipment because they all are to adopt high frequency and low-voltage.For addressing the above problem, the patent No. is 88104054.1 (electric system dielectric loss and electric capacity automatic measuring instrument), though can replace the QS1 electric bridge, owing to be subjected to the restriction of mimic channel accuracy, its accuracy of measurement is only suitable with the QS1 electric bridge.Along with the raising of power equipment quality, be equivalent to the accuracy of measurement of QS1 electric bridge, can not meet the demands, for example, modern film-type capacitor requires medium consumption factor tg δ≤0.001, the absolute error of accuracy of measurement can not meet the demands up to 0.003 instrument and equipment.At present, at the measurement of testing laboratory's application and the instrument of verification medium consumption factor, as QS30 type electric bridge or similar products, though accurately higher, because operation equilibrium process complexity also is badly in need of replacing with the new type measuring instrument device.

The purpose of this invention is to provide a kind of novel, simple in structure, the measuring accuracy height, speed is fast, measurement range is big, operates very easy a kind of medium consumption automatic measuring instrument.

The objective of the invention is to be achieved by the following scheme: comprise that signal converter, data processor, display, control system, power circuit, shielded box and insulated case constitute, wherein the input voltage of said signal converter is two simulating signal U NAnd U X, U wherein NBe reference signal, U XBe measured signal, U NAnd U XCan distinguish or obtained by RC divider, capacitive divider, resitstance voltage divider, mutual inductor, current-to-voltage converter, photoelectric commutator or amplifier simultaneously, the output signal of signal converter 1 is a digital signal, that is reference signal U NAnd measured signal U XCarried out analog to digital conversion in signal converter 1, conversion accuracy is by the figure place decision of the analog to digital converter that is adopted in the signal converter, and the signal of signal converter 1 output is delivered to data processor 2, obtains U by this processor undistortedly NAnd U XFirst-harmonic U N1And U X1, obtain U NAnd U XPeak value (U NmAnd U Xm), obtain U N1And U X1Peak value (U N1mAnd U X1m), obtain U N1And U X1Between angle δ obtain medium consumption factor tg δ, obtain electric capacity C, carry out the compensation of stray capacitance, carry out anti-impulse disturbances and handle, carry out curve fitting, to peak value U Nm, U Xm, U N1m, U X1m, tg δ, C formatd, wherein data processor 2 is made up of ROM (read-only memory) Eprom and storer Ram, its output signal is delivered in the display 3 measurement result U Nm, U Xm, tg δ and C show, this display 3 can be LCD, charactron display or screen display; Can be used for the measuring media loss factor, the phasing degree between electric capacity and two signals.

The said signal converter 1 of the present invention comprises reference signal change-over circuit 11, measured signal change-over circuit 12, reference signal analog to digital conversion circuit 13, measured signal analog to digital conversion circuit 14, phase lock circuitry 15 and analog-digital conversion control circuit 16 are formed, and wherein the input signal of reference signal change-over circuit 11 is U N, this circuit is mainly by 6 noninductive resistances, and a four blade 6 is thrown switch (K4D6W), and a voltage follower and a voltage comparator are formed, wherein at terminal U NAnd insert a resistance R between the E N, R NHave 6 different numerical value,,, make U to adapt to different applied voltage V by the determining positions of K4D6W Nm=0.5~5 volts, the value of a single chip microcomputer mouth of determining positions of other of K4D6W three cuttves, the output of change-over circuit 11 has two the tunnel, leads up to voltage follower with U NDeliver to signal analog to digital conversion circuit 13, another road by voltage comparator with U NDeliver to phase lock circuitry 15; Said measured signal change-over circuit 12 is mainly by 6 noninductive resistances, and a four blade 6 is thrown switch (K4D6W) and a voltage follower composition, wherein at terminal U XAnd insert a resistance R between the E X, R XHave 6 different numerical value, its output terminal is leaded up to voltage follower with U XDeliver to analog to digital conversion circuit 14, the value of a single chip microcomputer mouth of determining positions of other three cuttves of K switch 4D6W in the signaling conversion circuit 12, so that the notice single chip microcomputer carries out corresponding calculated or processing, wherein analog to digital conversion circuit 13 and 14 is formed by analog to digital converter AD676 and conventional peripheral cell, phase lock circuitry 15 mainly is made up of CD4046, CD4040 and conventional peripheral cell, and analog-digital conversion control circuit 16 is made up of GAL20V8,74LS123,74LS125,74LS74 and conventional peripheral cell.

Frequency and signal frequency that the said phase lock circuitry of the present invention produces are synchronous, do not change with the variation of signal frequency with the sampling number that guarantees weekly ripple, realize that weekly the sampling number of ripple is fixed; The sampled signal that analog-digital conversion control circuit 16 produces is given reference signal change-over circuit 13 and measured signal analog to digital conversion circuit 14 simultaneously, is gathered simultaneously to realize two paths of signals; Analog-digital conversion control circuit 16 produces a check and correction pulse signal earlier before sampling, give simultaneously with reference to analog to digital conversion circuit 13 and measured signal analog to digital conversion circuit 14, start the check and correction of two-way analog to digital converter, after check and correction finishes, analog-digital conversion control circuit 16 produces sampling pulse signal again, give 13 and 14 simultaneously, accurate to guarantee the data of gathering.

The said data processor 2 of the present invention can carry out error compensation and curve fitting respectively, thereby guarantee to have identical accuracy of measurement under the various duties (comprising under positive opposition method and each the amount retaining) under the various duties.

The power supply technique scheme of power circuit 5 has two, one for adopting rechargeable battery during the said opposition method of the present invention, and two for adopting high voltage isolating transformer.

The said signal converter 1 of the present invention, data processor 2, display 3, control system 4, power circuit 5 all is installed on the inside of shielded box 6, thereby has extremely strong anti-outer interference capability.

When the present invention was used for opposition method, the insulation scheme of shielded box 6 had two, one to be the scheme of insulated case 7, shielded box 6 is contained in the inside of insulated case 7.Two for adopting insulation column and faraday cage scheme.

Single-chip microcomputer or microcomputer formations such as said control system 4 employings 8098 of the present invention or 80C31.

Compare with the equipment of existing measuring media loss factor, advantage of the present invention is: in light weight, volume is little, directly reading, accuracy is high, measuring speed is fast, need not operate or easy and simple to handle the restriction of the voltage that is not put to the test, can use under the high voltage arbitrarily, measurement range is big, the measurement range of tg δ be the measurement range of angle between ± 0~∝), two signals be ± (0~π); Both can be used for the quality inspection of power equipment preventive trial or power product, the online mirror that can be used for the charging equipment insulation is again surveyed; Both can be used to do the testing equipment of on-the-spot usefulness, can be used to the calibration equipment of using as testing laboratory again; And the ability of the anti-harmonic interference of the present invention and the ability of anti-impulse disturbances are all very strong.

Below in conjunction with drawings and Examples, the present invention is described in further detail.

Fig. 1: medium consumption automatic measuring instrument theory diagram;

Fig. 2: the positive facial contour synoptic diagram of medium consumption automatic measuring instrument main frame;

Fig. 3: medium consumption automatic measuring instrument main frame back side profile synoptic diagram;

Fig. 4: the positive connection key wiring diagram of medium consumption automatic measuring instrument

Fig. 5: medium consumption automatic measuring instrument opposition method key wiring diagram

Fig. 6: the wiring diagram that medium consumption automatic measuring instrument is used for online mirror when surveying

Fig. 7: medium consumption automatic measuring instrument circuit block diagram

As Fig. 1, the present invention is mainly by signal converter 1, data processor 2, and display 3, control system 4, power circuit 5, shielded box 6, and insulated case 7 is formed.

The present invention is the first-harmonic angle theta of measuring between two analog signal voltages, and two signal voltages that measure are very high usually, from ten thousand volts of hundreds of volts to 50; And simulating signal is not easy to handle and analyze usually; Therefore need be changed, high voltage is converted to low-voltage and analog signal conversion is become digital signal.Two kinds of conversions of this of signal are finished by signal converter 1.The input voltage of signal converter 1 is two simulating signal U NAnd U XU NBe reference signal, U XBe measured signal; U NAnd U XCan distinguish or simultaneously by RC divider, capacitive divider, resitstance voltage divider, mutual inductor, current-to-voltage converter, photoelectric commutator or amplifier obtain; The output signal of signal converter 1 is a digital signal, that is reference signal U NAnd measured signal U X, in signal converter 1, carried out analog to digital conversion, conversion accuracy is by the figure place decision of the analog to digital converter that is adopted in the signal converter, and for example, when adopting 12 analog to digital converters, precision is 2.44 * 10 -4When adopting 16 bit A/D converters, precision is 1.53 * 10 -5When adopting 20 analog to digital converters, precision is 9.54 * 10 -7, when adopting 24 analog to digital converters, precision is 5.96 * 10 -8Or the like.Adopt the AD converter of how many positions, can be by user's actual needs decision.Adopted simultaneous techniques during analog to digital conversion, to guarantee that times of collection and phase place are completely fixed in each signal cycle.Correct for the phase differential that guarantees two signals, as to have adopted two signals to sample simultaneously technology.The output of signal converter 1 is delivered in the data processor 2.

Data processor 2 is finished following task: obtain U NAnd U XPeak value (U NmAnd U Xm); Obtain U undistortedly NAnd U XFirst-harmonic U N1And U X1Obtain U N1And U X1Peak value (U N1mAnd U X1m); Obtain U N1And U X1Between angle δ, obtain medium consumption factor tg δ; Obtain electric capacity C; Carry out the compensation of stray capacitance; Carry out anti-arteries and veins and disturb processing; Carry out curve fitting; To U Nm, U Xm, tg δ, C is formatd; Or the like.The input of data processor 2 is the output of signal converter 1; Data processor 2 is output as U Nm, U Xm, tg δ and C.Data processor 2 is made up of ROM (read-only memory) Eprom and storer Ram.Display 3 is delivered in the output of data processor 2.

According to U NAnd U X, obtain U N1And U X1, be commonly referred to as filtering technique.General digital filtering technique, the phasing degree of signal can produce certain error before and after the digital filtering, and this is unallowable for the measurement of high precision dielectric loss.The present invention has adopted no rugged parameter word filtering technique, and its accuracy is by the error of calculation decision of setting, thereby its accuracy can be arbitrarily.

Now illustrate as follows.If: U N=0.3+sin (ω t+0.3)+0.3sin (3 ω t+0.3)+0.3sin (5 ω t+0.3) U X=0.6+0.7sin (ω t+0.2999999)+0.6sin (3 ω t+0.6)+0.6sin (5 ω t+0.6) (1)

Know U by (1) formula NFirst-harmonic:

U N1=sin(ωt+0.3)

U XFirst-harmonic:

U X1=0.7sin(ωt+0.2999999)

Be U N1With U X1Between angle theta=0.0000001 radian.

If the U that the medium consumption factor automatic measuring instrument is measured N1With U X1Between angle be δ, when computational accuracy is enough, be easy to accomplish:

δ=0.0000001 radian

In the qualified industrial frequency experiment voltage, its harmonic component is little more than 1 formula; DC component and harmonic component have all been striden greatly in 1 formula, and purpose is explanation, and the function of the no rugged parameter word filtering technique that the present invention adopts is very strong, and promptly measurement result is not subjected to the influence of harmonic component.

According to U N1And U X1Data, can calculate tg δ and C, and the data-switching of tg δ and C is become display format easily.

If: U X1=U X1MSin (ω t+ θ X)

U N1=U N1Msin(ωt+θ N)

θ=θ then NX

tgδ=tgθ C = U X 1 M U N 1 M · kc - - - - ( 2 )

In the formula (2), K CBe scale factor.K CValue, by the decision of various concrete conditions.For example, U NFor flowing through standard capacitor C NCurrent i nIn resistance R NOn pressure drop, U XFor flowing through test product C XCurrent i XAt R XPressure drop, then K C = R X R N And C is C X/ C NRatio.Work as C NWhen=50PF immobilizes, K CBecome K C = R X R N 50 But C also direct representation is C = U X 1 M U N 1 M · R X R N · 50 PF Or the like.In a word, data layout should be decided by actual requirement.

The data that other need be handled are described in further detail below in conjunction with embodiment again.

The task of display 3 is that the parameter from data processor 2 is shown, and also is about to measurement result U Nm, U Xm, tg δ and C show.Display 3 can be brilliant liquid display panel, charactron display or screen display or the like.Display format can be direct reading formula, or floating-point format or the like.Displaying scheme can each parameter show simultaneously, or the touring automatically demonstration of each parameter, or each parameter shows or the like by button.Figure place showing determines as required.

Control system 4 can by 8098 or single card microcomputer such as 80C31 or microcomputer form.Measuring instrument each several part 1-3 all carries out work under control system 4 controls.If when requiring measuring speed quick, then should do control system with microcomputer.

The used power supply of instrument can be chargeable direct supply or AC power, according to actual needs decision.

For example, online mirror is surveyed, generally used AC power; Again for example, make the instrument of test with opposition method, more convenient and safety with chargeable direct supply.Power circuit 5 is by transformer, 5 volts of mu balanced circuits, and ± 9 volts of mu balanced circuits, ± 12 volts of chargeable direct supplys and multitool are thrown switch more and are formed.Four duties are arranged: interchange, direct current, disconnection, charging when generally throwing switch with 4.More work state if desired, the switch of available more throwings obtains.As throwing switch, 6 duties can be arranged with five cuttves 6.The input of power circuit 5 or 220 volt of 50 all alternating current, or ± 12 volts of rechargeable batteries, throw switch by multitool more and switch, when change-over switch is positioned at ac position, then be used for the alternating current input; When being positioned at direct current, then use ± 12 volts of chargeable dc-battery inputs; Be positioned at charge position and then be ± 12 volts of rechargeable battery chargings with alternating current.Because equipment circuit is in noble potential (being generally 10,000 volts to 500,000 volts), can not use alternating current during opposition method, generally can only use ± 12 volts of rechargeable batteries or other suitable rechargeable battery.

As for trial voltage is 10,000 volts occasion, during opposition method, and also available alternating current scheme, at this moment, power transformer will adopt high voltage isolating transformer.When adopting the scheme of high voltage isolating transformer, volume will be bigger, and price will be more expensive.

Shielded box 6, purpose are to eliminate outer electrical interference.The panel of instrument and backboard are the parts (two faces) of shielded box 6, and the good conductor material is adopted, as formations such as copper coin or aluminium sheets in other four sides of instrument container.All circuit elements devices are installed in the shielded box, and the E point among shielded box and Fig. 3-5 is connected.That is positive connection and online mirror be when surveying, and shielded box is in electronegative potential, and during opposition method, shielded box is in noble potential.

Insulated case 7 is made of insulating material, as organic glass, and four polyvinyl fluoride, bakelite, plastics etc., (material that ability is lived trial voltage during opposition method all can).Shielded box is contained in insulated case inside.Insulated case is mainly used in opposition method.Therefore, with the occasion of positive connection, insulated case can be omitted for only; When being used for online mirror and surveying, insulated case also can be omitted.Trial voltage is when 10,000 volts of left and right sides, and adopting the scheme of insulated case during opposition method is easily.If trial voltage is very high, for example, 500,000 volts, then should not adopts the insulated case scheme, and adopt insulation column scheme and faraday cage scheme.

For the occasion that does not need to do opposition method, insulated case can be omitted.

More than be main machine structure of the present invention, some annexes illustrate it in conjunction with the embodiments again.

Schematic diagram and above-mentioned explanation according to Fig. 1 can produce various forms of medium consumption automatic measuring instruments.

Embodiment:

Below in conjunction with Fig. 2~Fig. 7 specific embodiment is described.

Medium consumption automatic measuring instrument is made up of main frame, two 2 meters long leads, 10 meters long leads, a hook stick and a packing case.

Main frame outside drawing such as Fig. 2, shown in Figure 3.

Among Fig. 2,3, L 1, cabinet.(shielded box)

L 2, insulating material.

L 3, power switch (divide charging, outage, direct current and

Exchange fourth gear)

L 4, the test product electric current selects waver, is divided into 6 grades.

L 5, positive connection and opposition method switch.

L 6, 8 figure place sign indicating number tube displays.

L 7, measure reset switch.

L 8, trial voltage selects waver, is divided into 6 grades.

L 9, the charge power supply socket.

L 10, Insurance Block.

L 11, U NConnection terminal.

L 12, the E connection terminal.

L 13, U XConnection terminal.

Two meters long lead-in wire are used for being connected (positive connection) or being used for E and holding be connected (opposition method) with high-pressure side of E end and earth terminal.Two meters long leads of another root are used for U NEnd and standard capacitor C NThe connection of end.10 meters long lead-in wires are used for U XEnd and test product C XThe connection of end.Medium consumption automatic measuring instrument generally without any need for operation, if when needing operation (for example magnitude of current shelves select inappropriate), is operated with hook stick, to guarantee safety in the measuring process.

The effect of packing case has two, one for transport equipment time protection instrument, one places instrument during for test.

Trial voltage amount shelves selector switch (L 8), be applicable to various trial voltage (3-1000KV) or be applicable to the standard capacitor of various electric capacitys.For trial voltage and the fixing occasion of standard capacitor electric capacity, when for example being used to insulate preventive trial, trial voltage is used 10KV always, and the standard capacitor electric capacity is used C always N=50PF, at this moment, the trial voltage that can omit among Fig. 2 is selected waver (L 8).Electric current selected amount shelves divide 6 grades, are applicable to the scope of test product electric current at 50 μ A~4A.The amount shelves are not enough, suitably the extensive magnitude shelves.Whether the amount shelves are selected correct, are decided by signal voltage U NAnd U XAmplitude whether between 0.5~5 volt.If U NMAnd U XMNot 0.5~5 volt of scope, suitable change amount shelves reach target to guarantee the accuracy of measuring.Fig. 4~Fig. 6 is for being applicable to positive connection, the test connection figure when opposition method and online mirror are surveyed.The influence of stray capacitances such as lead-in wire can be eliminated by compensation.The angle error or the C of voltage transformer pt when online mirror is surveyed PTMedium consumption factor, can be compensated in advance.

Fig. 7 is the circuit block diagram of medium consumption automatic measuring instrument.Omitted 6 among Fig. 1 and 7 among Fig. 7, that is among Fig. 7 a daytime go out the structure division relevant with circuit, do not go out daytime and structure division that circuit is irrelevant.Shielded box in the present embodiment is made of the 2mm aluminium sheet, and panel and backboard are the parts of shielded box, other of shielded box is aluminium sheet on four sides, and all circuit in the present embodiment all are contained in the shielded box, therefore, present embodiment has the performance of very strong anti-outer electrical interference.In the present embodiment, insulated case is made of four polyvinyl fluoride, has very high electric strength, is applicable to that trial voltage is 10,000 volts a occasion.

Among Fig. 7, signal converter 1, by reference signal change-over circuit 11, measured signal change-over circuit 12, reference signal analog to digital conversion circuit 13, measured signal analog to digital conversion circuit 14, phase lock circuitry 15 and analog-digital conversion control circuit 16 are formed.Reference signal change-over circuit 11 be input as U NThe reference signal change-over circuit is mainly by 6 noninductive resistances, and a four blade 6 is thrown switch (K4D6W), and a voltage follower and a voltage comparator are formed; Terminal U NAnd insert a resistance R between the E N, R NHave 6 different numerical value,,, make U to adapt to different applied voltage U by the determining positions of K4D6W Nm=0.5~5V; The value of a single chip microcomputer mouth of determining positions of other of K4D6W three cuttves is so that the notice single chip microcomputer carries out corresponding calculated or processing; 11 output has two the tunnel, leads up to voltage follower, with U NDeliver to 13, another road by voltage comparator with U NDeliver to phase lock circuitry 15.12 be input as U X12 mainly by 6 noninductive resistances, and a four blade 6 is thrown switch (K4D6W) and a voltage follower composition; Terminal U XAnd insert a resistance R between the E X, R XHave 6 different numerical value,,, make U to adapt to different test product electric currents by the determining positions of K4D6W Xm=0.5~5V; 12 road output is with U by voltage follower XDeliver to the value of a single chip microcomputer mouth of determining positions of other three cutter of 14,12 K4D6W, so that the notice single chip microcomputer carries out corresponding calculated or processing.13 and 14 by analog to digital converter AD676 and conventional peripheral component composition.Phase lock circuitry 15 is mainly by phase locking unit CD4046, and counter CD4040 and conventional peripheral component are formed phase lock circuitry, and the 15 pulsating wave frequencies that produce are with U NSignal frequency is synchronous, establishes U NFrequency be f, then 15 frequencies that produce are 256f, (during f=50,256f=12800HZ); The rated frequency of electric system is 50 cycles, but actual frequency is not 50HZ just in time, general frequency range is that f=50 ± 0.2HZ all is qualified, sample weekly 256 times, if the time interval between the double sampling is Δ t, when Δ t is fixed as Δ t=(0.02/256) S=78.125 μ S, then when the frequency of electric system be not 50HZ just in time, will cause that the measurement result of each cycle is inconsistent.For example, f=49.8HZ, then the time is 0.02008321 second weekly, weekly sampling number m1=0.02008321 * 10 of ripple 6/ 78.125=257.0281124 time, so, will there be phase differential in the sampling phase that two adjacent cycles are first 2 π - 2 π f 50 = 0.025059695 Radian, this will cause unallowable error for the high precision medium consumption automatic measuring instrument; The scheme of present embodiment head it off is to adopt simultaneous techniques, even also 15 oscillation frequency changes with f, adopts Δt = 2 πf 256 , that is the time interval Δ t between the double sampling changes with frequency f, so, no matter how many frequency f is, always all guarantee identical and sampling number ripple weekly of the phase place of two adjacent cycle first sampled points 256 times, do not change with f.16 mainly by GAL20V8,74LS123, and 74LS125,74LS74, and conventional peripheral component forms, 16 task is, under controlled by single chip microprocessor, realizes that two signals sample simultaneously and realizes sampling before 256 times, and the two-way analog to digital converter is proofreaded once; This is to guarantee one of high-precision gordian technique of measurement result.In the present embodiment, because the effect of 15 and 16 circuit, binary signal is gathered and is changed simultaneously, and ripple gathers 2 weekly nIndividual data, n is generally 3~9 promptly enough, and the size of n need be decided on specific requirement, and n=8 in the present embodiment establishes n HBe the higher harmonics number of times in the signal voltage, though in general (2 n-1)>n HGet final product, but sampling number should meet sampling thheorem.For reduce impulse disturbances with the filtering mean value of gathering 40 cycle data as display result.Be every display result once, gather 2 * 40 * 2 nIndividual data.Owing to adopted phase lock circuitry to guarantee that the acquisition phase of each cycle is in full accord, and the times of collection in each cycle is in full accord.In order to reduce the influence that the instrument fluctuating factor brings, before each image data analog to digital converter is proofreaied and correct once.By the sampling precision requirement, determine the figure place of analog to digital converter; Present embodiment adopts 16 analog to digital converters, and accessible precision is resolution 2 * 10 -5, the measuring error of tg δ≤± (1%+10 -4); The measuring error of electric capacity≤± (1% reading+5PF).Sampling and verification are by control system 4 commanders.

For the purpose of clear and definite, now three relevant with 1 in present embodiment gordian techniquies are repeated.In the present embodiment, realize U NAnd U XCai Yang technical scheme is to adopt No. two analog to digital converters 13 and 14 simultaneously, by 16 sampling pulse signals that produce, gives 13 and 14 simultaneously, samples simultaneously to realize two paths of signals.In the present embodiment, realize that synchronous technical scheme is for adopting phase lock circuitry 15, with synchronizing signal U NGive 15, making 15 sample frequency that produce is 256f, and sample frequency is changed with power system frequency f, always to realize that weekly ripple gathers 256 times.In the present embodiment, realize that the technical scheme of proofreading before the sampling is, 16 produce a check and correction pulse signal earlier before sampling, give 13 and 14 simultaneously, start the check and correction of two-way analog to digital converter, after check and correction finished, 16 produced sampling pulse signal again, give 13 and 14 simultaneously, two road signals are sampled simultaneously.

In the present embodiment, data processor 2 is made up of ROM (read-only memory) 27128 and 2 storeies 6264.Data processor 2 receives the 1 digitalized data U that sends here NAnd U X, handled then, draw U Nm, U Xm, tg δ, C send to display 3.Now, be described below the several gordian techniquies in the data processing:

According to U N, U X, obtain first-harmonic U N1And U X1Be commonly referred to as filtering technique, as previously mentioned, what present embodiment adopted is undistorted digital filtering technique, at this moment, when the data of gathering have 9 position effective digitals, for example, it is as follows that one cycle is gathered 8 data: Un[1]=0.77283233 Ux[1]=0.20686408Un[2]=1.05911065 Ux[2]=0.61914244Un[3]=1.25533649 Ux[3]=0.66873556Un[4]=0.89193917 Ux[4]=0.32659246Un[5]=-0.17283233 Ux[5]=-0.20686408Un[6]=-0.45911065 Ux[6]=-0.61914244Un[7]=-0.65533649 Ux[7]=-0.66873556Un[8]=-0.29193917 Ux[8]=-0.32659246 these data are delivered to filter function piece (3) and handle after, can draw: U N1=sin (ω t+0.3) U X1=0.7sin (ω t+0.2999999)

It is δ=0.0000001 radian.In fact, this is an accurate values.Promptly there is not error.As seen when analog-digital bit is enough, can accomplish not have rugged change filtering.But specific to present embodiment,, in the data of collection, have only 5 position effective digitals because what adopt is 16 analog to digital converters, at this moment, the accurate situation of measurement, with five groups of data declarations it.

First group of data

Un[1]=0.77283 Ux[1]=0.20686

Un[2]=1.0591 Ux[2]=0.61914

Un[3]=1.2553 Ux[3]=0.668745

Un[4]=0.89194 Ux[4]=0.326592

Un[5]=-0.17283 Ux[5]=-0.20686

Un[6]=-0.45911 Ux[6]=-0.61914

Un[7]=-0.65534 Ux[7]=-0.66874

Un[8]=-0.29194 Ux[8]=-0.32659

Accurate θ=0.0000001 tg θ=0.0000001

Tg δ=3.8810 of measuring -6

Absolute error Δ tg δ=3.7810 -6<10 -4

Second group of data

Un[1]=0.77283 Ux[1]=0.20680

Un[2]=1.0591 Ux[2]=0.61911

Un[3]=1.2553 Ux[3]=0.66876

Un[4]=0.89194 Ux[4]=0.32665

Un[5]=-0.17283 Ux[5]=-0.20680 Un[6]=-0.45911 Ux[6]=-0.61911 Un[7]=-0.65534 Ux[7]=-0.66876 Un[8]=-0.29194 Ux[8]=-0.32665 accurate θ=0.0001 tg θ=110 -4Tg δ=0.000096530 of measuring

Δ tg δ=-3.4710 -6<10 -4The 3rd group of data Un[1]=0.77283 Ux[1]=0.20017 Un[2]=1.0591 Ux[2]=0.61585 Un[3]=1.2553 Ux[3]=0.67077 Un[4]=0.89194 Ux[4]=0.33277 Un[5]=-0.17283 Ux[5]=-0.20017 Un[6]=-0.45911 Ux[6]=-0.61585 Un[7]=-0.65534 Ux[7]=-0.67077 Un[8]=-0.29194 Ux[8]=-0.33277 accurate tg δ that θ=measure 0.01 tg θ=0.01000=0.0099763 absolute error Δ tg δ=2.403310-5<10 -4The 4th group of data Un[1]=0.77283 Ux[1]=0.13907 Un[2]=1.0591 Ux[2]=0.58344 Un[3]=1.2553 Ux[3]=0.68605 Un[4]=0.89194 Ux[4]=0.38677 Un[5]=-0.17283 Ux[5]=-0.13907 Un[6]=-0.45911 Ux[6]=-0.58344 Un[7]=-0.65534 Ux[7]=-0.68605 Un[8]=-0.29194 Ux[8]=-0.38677 accurate tg δ that θ=measure 0.1 tg θ=0.10033=0.10033

Δ tg δ=0 the 5th group data Un[1]=0.77283 Ux[1]=0.13907 Un[2]=1.0591 Ux[2]=0.38677 Un[3]=1.2553 Ux[3]=0.68605 Un[4]=0.89194 Ux[4]=0.58344 Un[5]=-0.17283 Ux[5]=-0.13907 Un[6]=-0.45911 Ux[6]=-0.38677 Un[7]=-0.65534 Ux[7]=-0.686055 Un[8]=-0.29194 Ux[8]=-0.58344 accurate tg δ that θ=measure 0.5 tg θ=0.5463=0.54630

Δtgδ=0

From above five groups of data as can be known, in the present embodiment, there is no filter distortion, when θ hour, because the data number of significant digit of gathering has only 5, must cause truncation error, that is to say, above-mentioned first group to the 3rd group data, its source of error is a truncation error, rather than the error that causes of filtering.Owing in the present embodiment, require δ hour Δ tg δ<0.0001 just to arrive target, so the measurement of five groups of data is to have reached target.Higher if desired accuracy, then the number of significant digit of image data is some more.In above-mentioned five groups of data, harmonic component is all above 30%; And its harmonic component of qualified trial voltage or power-frequency voltage is less than 7%, and as seen, the ability of the anti-harmonic wave of present embodiment is very strong.

Second gordian technique in the data processing is anti-jamming techniques of pulse.Harmonic interference is a kind of stable interference, can eliminate its influence with undistorted filtering technique.And impulse disturbances is a unsettled interference, and for example, the experiment power supply capacity is big inadequately, and will there be impulse disturbances in test when electric welding machine work is arranged simultaneously the time.In the present embodiment, adopt the method for filtering mean value, eliminate the influence of impulse disturbances, anti-impulse disturbances ability is not less than 40%.(ultimate value of anti-impulse disturbances ability is 50%).

The 3rd gordian technique in the data processing is for eliminating the compensation technique of stray capacitance influences.During with QS37 or 2801 bridge measurement tg δ, the influence of stray capacitance adopts screen potential to be eliminated.No matter in the present embodiment, adopt the method for compensation to eliminate the influence of stray capacitance, owing to can compensate respectively under various duties, therefore, in the present embodiment, be positive connection, opposition method, or under the various amount shelves, the accuracy of measurement all is duplicate.

The 4th gordian technique in the data processing is curve fitting technique, the application curves fitting process, can make display result, in full accord with the calibration equipment result displayed, therefore, it is consistent with the accuracy of calibration equipment that the accuracy of measurement of present embodiment can reach, and can carry out curve fitting respectively under various duties.

In the present embodiment, in order to save components and parts, data processor and monoboard microcomputer shared 27128 and 6264.

In the present embodiment, display 3 is made up of display control circuit 31 and 8 charactrons 32.Display control circuit 31 mainly by 8279 and peripheral component constitute, 32 are made of 8 charactrons.Display 3 receives from the 2 data U that send here Nm, U Xm, tg δ and C are sent to 32 and show after the processing.The displaying contents of 8 charactrons is: first display parameter, and d represents the value of tg δ, and C represents the value of electric capacity, and 1 represents U NMaximal value, 2 represent U xMaximal value.The symbol of second display parameter, when parameter be on the occasion of the time, show=number, when parameter is negative value, show-number.Other 6 is the numerical value of parameter.For example: d=0.00005 represents tg δ=+ 0.00005; D-0.00016 represents tg δ=-0.00016, and 1=4.9567 represents U NM=4.9567 volts or the like.In the present embodiment, display format is the touring U that shows Nm, U Xm, tg δ and C.(display format can change by customer requirements).In the present embodiment, the automatic touring 1=xxxxxx that shows, 2=xxxxxx, C=xxxxxx, d=xxxxxx does not need operation, front 9 times, the single measurement result of demonstration C and tg δ, the tenth time smothing filtering mean value that shows ten measurement results.After showing three smothing filtering mean value, automatically reset and restart and measure.This display mode, it is fast and have a very strong anti-impulse disturbances ability to take into account measuring speed.When tg δ>9.9999, show θ=xxxxxx (unit is a radian), θ is U N1With U X1Between angle, like this indication range of θ be ± (0~π), and the indication range of tg δ is ± (0~∝), but | tg δ |>9.9999 o'clock, need through converting.

In the present embodiment, control system 4 is realized by the monoboard microcomputer that 8098,27128,2 6264 and conventional peripheral component are formed.4 can abbreviate monoboard microcomputer as again.Be to save components and parts, 4 and 2 shared identical 27128 and 6264.

In the present embodiment, instrument power source is an AC/DC; Direct supply is ± the 12V rechargeable battery; AC power is the 220V50HZ civil power, and by the power transformer step-down, rectification and voltage stabilizing obtain the instrument power supply.

Because in the present embodiment, all circuit all are contained in the shielded box, therefore, have very strong anti-dispatch from foreign news agency interference capability.

In the present embodiment, the insulation scheme during opposition method, the scheme of employing insulated case.

Because the measurement range of tg δ of the present invention is big, even test product is subjected to strong outer electrical interference and impedance disturbances, also available accurately positive antiphase method and resistance variation method are measured the exact value of tg δ easily.

Claims (8)

1, a kind of medium consumption automatic measuring instrument, comprise signal converter (1), data processor (2), display (3), control system (4), power circuit (5), shielded box (6) and insulated case (7), can be used for the measuring media loss factor, phasing degree between electric capacity and two signals is characterized in that: the input voltage of signal converter (1) is two simulating signal U NAnd U X, U wherein NBe reference signal, U XBe measured signal, U NAnd U XCan distinguish or obtained by RC divider, capacitive divider, resitstance voltage divider, mutual inductor, current-to-voltage converter, photoelectric commutator or amplifier simultaneously, the output signal of signal converter (1) is a digital signal, that is reference signal U NAnd measured signal U XCarried out analog to digital conversion in signal converter (1), conversion accuracy is by the figure place decision of the analog to digital converter that is adopted in the signal converter, and the signal of signal converter (1) output is delivered to data processor (2), obtains U by this processor undistortedly NAnd U XFirst-harmonic U N1And U X1, obtain U NAnd U XPeak value (U NmAnd U Xm), obtain U N1And U X1Peak value U N1mAnd U X1m, obtain U N1And U X1Between angle δ obtain medium consumption factor tg δ, obtain electric capacity C, carry out the compensation of stray capacitance, carry out anti-impulse disturbances and handle, carry out curve fitting, to peak value U Nm, U XM, U 1mU X1m, tg δ, C formatd, wherein data processor (2) is made up of ROM (read-only memory) Eprom and storer Ram, its output signal is delivered in the display (3) measurement result U Nm, U Xm, tg δ and C show, this display (3) can be LCD, charactron display or screen display.
2, measuring instrument according to claim 1, it is characterized in that: said signal converter comprises reference signal change-over circuit (11), measured signal change-over circuit (12), reference signal analog to digital conversion circuit (13), measured signal analog to digital conversion circuit (14), phase lock circuitry (15) and analog-digital conversion control circuit (16) are formed, and wherein the input signal of reference signal change-over circuit (11) is U N, this circuit is mainly by 6 noninductive resistances, and a four blade 6 is thrown switch (K4D6W), and a voltage follower and a voltage comparator are formed, wherein at terminal U NAnd insert a resistance R between the E N, R NHave 6 different numerical value,,, make U to adapt to different applied voltage U by the determining positions of K4D6W Nm=0.5~5 volts, the value of a single chip microcomputer mouth of determining positions of other of K4D6W three cuttves, the output of change-over circuit (11) has two the tunnel, leads up to voltage follower with U NDeliver to signal analog to digital conversion circuit (13), another road by voltage comparator with U NDeliver to phase lock circuitry (15); Said measured signal change-over circuit (12) is mainly by 6 noninductive resistances, and a four blade 6 is thrown switch (K4D6W) and a voltage follower composition, wherein at terminal U XAnd insert a resistance R between the E X, R XHave 6 different numerical value,,, make U to adapt to different test product electric currents by the determining positions of switch K4D6W Nm=0.5~5 volts, its output terminal is leaded up to voltage follower with U XDeliver to analog to digital conversion circuit (14), the value of a single chip microcomputer mouth of determining positions of other three cuttves of K switch 4W6D in the signaling conversion circuit (12), so that the notice single chip microcomputer carries out corresponding calculated or processing, wherein analog to digital conversion circuit (13) and (14) are formed by analog to digital converter and conventional peripheral cell, phase lock circuitry (15) mainly is made up of phase locking unit, counter and conventional peripheral cell, and analog-digital conversion control circuit (16) is made up of GAL20V8,74LS123,74LS125,74LS74 and conventional peripheral cell.
3, measuring instrument according to claim 2 is characterized in that: frequency and signal frequency that phase lock circuitry produces are synchronous, do not change with the variation of signal frequency with the sampling number that guarantees weekly ripple, realize that weekly the sampling number of ripple is fixed; The sampled signal that analog-digital conversion control circuit (16) produces is given reference signal change-over circuit (13) and measured signal analog to digital conversion circuit (14) simultaneously, is gathered simultaneously to realize two paths of signals; Analog-digital conversion control circuit (16) produces a check and correction pulse signal earlier before sampling, give simultaneously with reference to analog to digital conversion circuit (13) and measured signal analog to digital conversion circuit (14), start the check and correction of two-way analog to digital converter, after check and correction finishes, analog-digital conversion control circuit (16) produces sampling pulse signal again, give (13) and (14) simultaneously, accurate to guarantee the data of gathering.
4, measuring instrument according to claim 1, it is characterized in that: data processor (2), can carry out error compensation and curve fitting respectively (comprising under positive opposition method and each the amount retaining) under the various duties, thereby guarantee to have identical accuracy of measurement under the various duties.
5, measuring instrument according to claim 1 is characterized in that: the power supply technique scheme of power circuit during opposition method (5) has two, one for adopting rechargeable battery, and two for adopting high voltage isolating transformer.
6, measuring instrument according to claim 1 is characterized in that: signal converter (1), data processor (2), display (3), control system (4), power circuit (5) all is installed on the inside of shielded box (6), thereby has extremely strong anti-outer interference capability.
7, measuring instrument according to claim 1 is characterized in that: when being used for opposition method, the insulation scheme of shielded box (6) has two, one to be the scheme of insulated case (7), shielded box (6) is contained in the inside of insulated case (7).Two for adopting insulation column and faraday cage scheme.
8, measuring instrument according to claim 1 is characterized in that: single-chip microcomputer or microcomputer formations such as said control system (4) employing 8098 or 80C31.
CN96122991A 1996-11-20 1996-11-20 Medium consumption automatic measuring instrument CN1185585A (en)

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Application Number Priority Date Filing Date Title
CN96122991A CN1185585A (en) 1996-11-20 1996-11-20 Medium consumption automatic measuring instrument

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101551420B (en) * 2009-05-08 2010-12-08 北京航空航天大学 A weak capacitive detection circuit of MEMS device
CN102109556A (en) * 2010-11-29 2011-06-29 北京航空航天大学 Circuit for detecting dynamic weak capacitance of MEMS device

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101551420B (en) * 2009-05-08 2010-12-08 北京航空航天大学 A weak capacitive detection circuit of MEMS device
CN102109556A (en) * 2010-11-29 2011-06-29 北京航空航天大学 Circuit for detecting dynamic weak capacitance of MEMS device
CN102109556B (en) * 2010-11-29 2013-01-30 北京航空航天大学 Circuit for detecting dynamic weak capacitance of MEMS device

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