CN86206128U

CN86206128U - In-circuit capacitance testor

Info

Publication number: CN86206128U
Application number: CN 86206128
Authority: CN
Inventors: 扬英宇
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-08-19
Filing date: 1986-08-19
Publication date: 1987-05-27

Abstract

The utility model belongs to a capacitance tester; the purpose is to provide a tester which can conveniently test the capacitance on line to enhance speed determination of the capacitance failure. The utility model comprises an oscillator [1], a constant voltage amplifier [2], a testing proportional amplifier [4], and an AC voltmeter indicating device [5]. The testing range is from 1 microfarad to 500 microfarad; changing correction point can expand the measuring range to 2500 microfarad. The utility model has the advantages of simple structure, low cost, small size, and accuracy.

Description

In-circuit capacitance testor

The utility model belongs to the measuring instrument of electric capacity.

Existing capacitance meter instruments and meters though be that precision is higher when surveying capacity cell separately, when electric capacity connects, has the influence of the elements such as diode, triode and resistance that are connected with capacitor in circuit, can not measure capacitance value truly.Because the large percentage that capacitor is occupied in circuit, and failure rate is higher, if adopt common instrument detecting, just can't get rid of and the influencing each other of electric capacity associated components, can not judge the fault of capacitor, have to check judgement, burn-on under the weldering like this under the condenser welding, artificial lines that cause wiring board and element damage in various degree, and the serviceable life that has prolonged servicing time and reduced equipment.

The purpose of this utility model provides a kind ofly can carry out the electric capacity on-line measurement easily, improves the detecting instrument of electric capacity fault judgement speed.

Description of drawings:

Fig. 1 is the circuitry block scheme of electric capacity on-line testing device.

(1) is oscillator among the figure, and (2) are constant-voltage amplifier, and (3) are measured capacitance CX, and (4) are the measurement scale amplifier, and (5) are the A.C. voltmeter indicator.

Fig. 2 is the circuitry schematic diagram of electric capacity on-line testing device.

IC among the figure ₁～IC ₄Be integrated amplifier, μ A is a reometer, BG ₃, BG ₇Be field effect transistor, BG ₁, BG ₂, BG ₄～BG ₆Be diode, C ₂₃～C ₂₅Be standard capacitance, R ₂₂～R ₂₄For adjusting resistance.

The utility model is made up of four parts such as oscillator (1), constant-voltage amplifier (2), measurement scale amplifier (4), A.C. voltmeter indicators (5). Measured capacitance C_XAs input capacitance, one terminates at the output of constant-voltage amplifier (2), and the other end is connected on the IC of measurement scale amplifier (4)₃Inverting input, standard capacitance C₂₃(or C₂₄、C ₂₅) as IC₃Negative-feedback electric capacity consist of measurement scale amplifier (4), the ac voltage signal of its output detections and measured capacitance C_XCapacitance be directly proportional, this signal is delivered to the IC of A.C. voltmeter indicator (5)₄Input, its output is presented on the indicator by 1:1 by ammeter. Measurement category is divided third gear in 1 microfarad～500 microfarads, each is measured shelves and has selected respectively different frequency, the selected of its frequency determined by RC frequency-selective network in the oscillator (1), and when 500 microfarad shelves are that 60 hertz, 100 microfarad shelves are 200 hertz, 10 microfarad shelves are 1300 hertz. But change the check point expanded range to 2500(1～2500) microfarad. The IC of measurement scale amplifier (4)₃Output is connected to and measures corresponding three the adjusting resistance (R of class₂₂～R ₂₄), to (4) three three standard capacitance (C that measure class of measurement scale amplifier₂₃～C ₂₄), compensate adjustment. Measured capacitance C_XA, B two point measurement voltages far below the valve voltage of diode, be 75～80 millivolts, in order to guarantee thoroughly to get rid of be parallel to the measured capacitance two ends the elements such as diode to measuring the impact that causes.

The obtained effect of the utility model compared with prior art, can make things convenient for online rapidly open circuit, short circuit and the volume change situation of measuring electric capacity, have simultaneously simple in structure, cost is low, volume is little, advantage such as accurate, use on-line testing device can improve the maintenance efficiency of equipment, prolongs the serviceable life of equipment.Can find in time that by checking some had lost efficacy but also do not reach the obvious rotten capacity cell that influences the line work performance, and to get rid of these potential failure factors, to make owing to the capacity cell equipment failure rate that causes that goes wrong reduces greatly.

Specific embodiment of the utility model is as follows: referring to Fig. 2.Among the figure with IC ₁For main element constitutes oscillator (1), wherein C ₅, C ₆, R ₆, R ₇The RC circuit of decision oscillation frequency when being 500 microfarad shelves, the corresponding C that is respectively of 100 microfarad shelves with 10 microfarad shelves ₇, C ₈, R ₉, R ₁₀And C ₉, C ₁₀, R ₁₂, R ₁₃, resistance R ₈, R ₁₁, R ₁₄Be respectively the adjustment resistance of each grade leveling oscillating voltage.K among the figure ₁₀, K ₂₀, K ₃₀, K ₄₀The position, the state when being 500 microfarads and measuring shelves.During oscillator work, by C ₅, C ₆, R ₆, R ₇The oscillation frequency voltage of decision is through R ₈, K ₁₁, K ₁₀, C ₄, R ₃Be connected to IC ₁In-phase input end feeds back to C again through output terminal 8 after amplifying ₅, C ₆, R ₆, R ₇The RC circuit of forming forms the positive feedback vibration, and the vibration output voltage has one the tunnel in addition through IC ₁8 ends, C ₂To BG ₁, BG ₂Be that a negative dc pulse voltage adds to R after the rectification ₁, C ₁After two ends filter Alternating Component, arrive BG again ₃Grid, make BG ₃Working current reduce, internal resistance strengthens, because BG ₃Source (S) leak (D) the two poles of the earth through C ₃Be connected to IC ₁Inverting input 13, BG ₃Source-drain electrode between the result that strengthens of resistance, make IC ₁Vibration can infinitely not raise, and only can be stabilized on the suitable value, make IC ₁Stable low-distortion sine wave signal of 8 ends output.IC ₁Ac output voltage after full scale is adjusted potentiometer W dividing potential drop, be added to IC ₂In-phase input end 1.

With IC ₂Be the constant-voltage amplifier (2) of main element formation, because IC ₂Output terminal 8 directly be linked to be full negative-feedback circuit, IC with inverting input 13 ₂Output voltage identical with input voltage, and output impedance is lower, has adopted like this to have to do to measure than the AC signal of low output impedance and has used signal source.IC ₂The constant voltage AC signal one road to K of 8 ends output ₄₂Usefulness during as the alignment full scale, another road is to external measurement terminal A, through measured capacitance C _XTo external pelivimetry connection terminal B is entered IC again ₃Inverting input 13.

With IC ₃What constitute for main element is measurement scale amplifier (4), and its output terminal 8 is through C ₂₃(or C ₂₄, C ₂₅), K ₂₁(or K ₂₂, K ₂₃), K ₂₀To inverting input 13, constitute negative-feedback amplifier, IC like this ₂The alternating voltage of output terminal 8 is through measured capacitance C _XTo IC ₃Input end 13, formed electric current is through C ₂₃(or C ₂₄, C ₂₅) by IC ₃8 ends absorb, make IC ₃The output end voltage signal is directly proportional with the capacity of CX.

With IC ₄Be the A.C. voltmeter indicator (5) that main element constitutes, its input end is connected on IC ₃Output terminal 8, measurement result is reflected on the gauge outfit indicator, pointed numerical value is the capability value of Cx, the K in this circuit part ₄₀With K ₄₁Join and be measurement state, K ₄₀With K ₄₂Joining is correcting state, and tested voltage is by K ₄₀Through R ₂₅, C ₃₁Enter IC ₄In-phase input end 3 is exaggerated the back from output terminal 6 outputs, through C ₃₃C ₃₄, BG ₄, BG ₆Arrive the microampere meter gauge outfit after the rectification, and to IC ₄Inverting input 2, form negative feedback, when the DC voltage after the rectification during much larger than gauge outfit full scale voltage, BG ₅The conducting shunting is with the anti-tamper microampere meter.During operate as normal, BG ₅Be open-circuit condition, do not influence indicated value.R ₂₆Be the negative feedback divider resistance, change R ₂₆Can adjust the sensitivity of electronic alternating-current voltmeter.BG is set ₇Be to constitute current source loads.

This tester is nonpolarity measurement, only connects arbitrarily the measured capacitance two ends namely with two slotted lines Readable. Compare with the electric capacity nominal value when very little when the measured capacitance reading value, measured capacitance lost efficacy, on the contrary exceed nominal value so that each grade all beyond full scale, and external circuit is not when having other short trouble, measured capacitance is punch through damage.

IC among the figure₁～IC ₃Model is BH7331, IC₄Model is 8FC7, BG₁、BG ₂、BG ₄、BG ₆Model is 2AK10, BG₅Model is 2CP9, BG₃、BG ₇Model is 3DJ6E, and gauge outfit is 59C5 type 50 μ A, and W is potentiometer, and R is resistance, and C is electric capacity, and K switch adopts the KZJ-5 type.

Claims

1, a kind of electric capacity on-line testing device is characterized in that it is by oscillator [1], constant-voltage amplifier [2], measurement scale amplifier [4], the quaternaries such as [5] of A.C. voltmeter indicator; Measured capacitance Cx is as input capacitance, and one terminates at the output terminal of constant-voltage amplifier [2], and the other end is connected on the IC of measurement scale amplifier [4] ₃Inverting input, standard capacitance C ₂₃(or C ₂₄, C ₂₅) as IC ₃Negative feedback electric capacity constitute measurement scale amplifier [4], ac voltage signal that its output detects and the electric capacity of measured capacitance Cx were presented on the indicator by 1: 1.

2, according to the described tester of claim 1, it is characterized in that measurement range is at 1 microfarad～500 microfarad steppings, each is measured shelves and has selected different frequency respectively for use, the selected of its frequency determined by RC frequency selection network in the oscillator (1), 500 microfarad shelves are 60 hertz, 100 microfarad shelves are 200 hertz, and 10 microfarad shelves are 1300 hertz, but change the check point expanded range to 2500 microfarads.

3,, it is characterized in that the IC of measurement scale amplifier (4) according to the described tester of claim 1 ₃Output terminal is connected to and measures corresponding three of class and adjusts resistance (R ₂₂-R ₂₄), to (4) three three standard capacitance (C that measure class of measurement scale amplifier ₂₃～C ₂₅) compensate adjustment.

4, according to the described tester of claim 1, it is characterized in that the A, B two point measurement voltages of measured capacitance CX valve voltage far below diode, be 75～80 millivolts.