CN201417260Y - Fractional-octave type insulator equivalent salt deposit density measuring instrument - Google Patents

Abstract

The utility model discloses a fractional-octave type insulator equivalent salt deposit density measuring instrument which comprises an electrical conductivity sensor, a multipath switching circuit andan automatic gain A/D circuit which are electrically connected in turn, wherein an input end of the electrical conductivity sensor is electrically connected with a fractional-octave generator, and the multipath switching circuit, the automatic gain A/D circuit, the fractional-octave generator, a temperature sensor, a data memorizer, an input device and an output device are respectively and electrically connected with a central processor. The fractional-octave type insulator equivalent salt deposit density measuring instrument adopts fractional-octave sine wave checking, adopts a digital temperature sensor and the automatic gain A/D circuit, solves manual table look-up and curve errors, overcomes the measurement errors caused by distributed capacitance of a measurement system, has simple structure and convenient operation, realizes equivalent salt deposit density measuring intelligentization of contamination accumulated on the surface of insulators, solves the problems of great measurement errors, low precision, and bad instrument stability and repeatability in existing instruments, and improves the accuracy degree.

Description

A kind of minute frequency multiplication formula insulator equivalent salt density measuring instrument

Technical field

The utility model relates to a kind of minute frequency multiplication formula insulator equivalent salt density measuring instrument, when it is used for the anti-pollution flashover work of power industry electrical equipment, to the detection of the strong and weak degree of insulator surface dunghill electric conductivity.

Background technology

In order to guarantee safe operation of power system, electric system will detect strong and weak degree--the equivalent salt deposit density of the long-pending dunghill electric conductivity of insulator surface when carrying out environment to the assessment of the degree of electric network pollution.Measure equivalent salt deposit density at present and mainly contain two class methods: the one, according to the method test of existing correlation standard, promptly adopt conductivity meter to measure the conductivity of the long-pending dunghill solution of insulator surface, with thermometer measure dunghill solution temperature, the standard equivalent salt deposit density when tabling look-up and looking into curve calculation and obtain corresponding 20 ℃ then; This method complexity is loaded down with trivial details, not only is not easy to operation, and its result to be subjected to human factor to influence deviation bigger.The 2nd, according to the single-chip microcomputer of the measuring principle utilization of conductance instrument measurement data is carried out data processing and obtain final measurement, table look-up and the complicated loaded down with trivial details work of curve though solved, reduced error; There is a common fault in above measuring method: promptly when measuring the conductivity of liquid, adopt the direct current method to measure, then can can't accurately measure in the polarization of the generation on the electrode of conductance electrode sensor; Therefore normal employing is the AC measurment mode, but there is distributed capacitance measuring system in self, not only it can change in real time because measurement environment is different, but also have that error is big can cause measuring the time, stability of instrument and poor repeatability problem, though surveying instrument adopts various compensatory devices, but can't thoroughly eliminate the influence of distributed capacitance to measuring, big, the poor repeatability of the inevitable error of the equivalent salt deposit density measured value that provides for electric system, directly influenced the assessment of environment, influenced the judgement of gradation for surface pollution and the formulation of insulation measures the electric network pollution degree.

Summary of the invention

Goal of the invention: the utility model provides a kind of minute frequency multiplication formula insulator equivalent salt density measuring instrument, with solve cause at present because of measuring system self distributed capacitance measuring error greatly, the problem of stability of instrument and poor repeatability, for electric system provides equivalent salt deposit density measured value really and accurately, guarantee accurately to estimate the degree of environment to electric network pollution.

Technical scheme: in order to solve the problems of the technologies described above, the utility model has adopted following technical scheme: a kind of minute frequency multiplication formula insulator equivalent salt density measuring instrument, it is characterized in that: comprise the conductivity sensor, multi-way switch circuit, the automatic gain A/D circuit that are electrically connected successively, the input end of conductivity sensor is electrically connected with the frequency multiplication generator, and multi-way switch circuit, automatic gain A/D circuit, frequency multiplication generator, temperature sensor, data-carrier store, input media and output unit are electrically connected with central processing unit respectively.

Wherein, described frequency multiplication generator is the frequency multiplication generator that exportable minute frequency multiplication concerns frequency.

Wherein, described input media is a keyboard.

Wherein, described output unit comprises display and the printer that is electrically connected with central processing unit respectively.

Wherein, described central processing unit is electrically connected with external communication interface.

Principle of work of the present utility model is: utilize the sinusoidal wave detection method of branch frequency multiplication to eliminate the influence of measuring system distributed capacitance to measurement result, at first add a fixed frequency f at two interpolars of conductivity sensor ₁Constant voltage sine wave AC signal, measure its voltage and electrode current, obtain impedance Z ₁-it is the capacitive reactance Xc of measuring system distributed capacitance ₁With electrical conductivity of solution σ inverse Synthetic complex impedance $Z_{}$ ${}_1=\frac{1}{\mathrm{\&sigma;}}+\mathrm{<figure-callout\; id="1"\; label="j\; X\; C"\; filenames="Y2009200440810008H1.png"\; state="\{\{state\}\}">j</figure-callout>}{X}_C{1}_{};$ Apply the branch frequency multiplication f of this fixed frequency then again at two interpolars of conductivity sensor ₂Constant voltage sine wave AC signal is measured its voltage and electrode current, obtains impedance Z ₂, i.e. the capacitive reactance Xc of measuring system distributed capacitance ₂With electrical conductivity of solution σ inverse Synthetic complex impedance $Z_{}$ ${}_2=\frac{1}{\mathrm{\&sigma;}}+\mathrm{<figure-callout\; id="2"\; label="j\; X\; C"\; filenames="Y2009200440810007H1.png,Y2009200440810008H1.png"\; state="\{\{state\}\}">j</figure-callout>}{X}_C{2}_{};$ The AC signal frequency that front and back are applied for twice is 0.5f for dividing the multiple relation ₁=f ₂, because $X=\frac{1}{\mathrm{\&omega;C}},$ ω=2 π f are Xc then ₂=2Xc ₁,

Formula one:

$2Z_1-{\mathrm{<figure-callout\; id="2"\; label="Z"\; filenames="Y2009200440810007H1.png,Y2009200440810008H1.png"\; state="\{\{state\}\}">Z</figure-callout>}}_2=2\&times;(\frac{1}{\mathrm{\&sigma;}}+j{X}_{C1})-(\frac{1}{\mathrm{\&sigma;}}+j{X}_{C2})=2\&times;(\frac{1}{\mathrm{\&sigma;}}+j{X}_{C1})-(\frac{1}{\mathrm{\&sigma;}}+2j{X}_{C1})=\frac{1}{\mathrm{\&sigma;}}$

Z wherein ₁, Z ₂Be to add frequency f at two interpolars of conductivity sensor ₁, f ₂Constant voltage sine wave AC signal, two impedances that measure respectively; Xc ₁, Xc ₂Be that two interpolars of conductivity sensor add frequency f ₁, f ₂The capacitive reactance of ac signal measurement system distributed capacitance;

It is electrical conductivity of solution σ inverse.

By a pair of testing result calculation process of above-mentioned formula, can thoroughly eliminate of the influence of measuring system distributed capacitance to measurement result, reduce measuring error.

Beneficial effect: of the present utility model minute frequency multiplication formula insulator equivalent salt density measuring instrument adopts and divides frequency multiplication sinusoidal wave detection, adopt digital temperature sensor, automatic gain A/D, digital smoothness filtering improves antijamming capability, floating-point operation guarantees technology such as operational precision, solved and manually tabled look-up and curve error, overcome the measuring error that the measuring system distributed capacitance is caused, simple in structure, easy to operate, the equivalent salt deposit density measurement that has realized the long-pending dunghill of insulator surface is intelligent, it is big to have solved present apparatus measures error, precision is low, stability of instrument and poor repeatability problem have improved order of accuarcy.

Description of drawings

Fig. 1 is the utility model theory diagram;

Fig. 2 is branch frequency multiplier circuit figure.

Embodiment:

Below in conjunction with accompanying drawing the utility model is done further explanation.

As shown in Figure 1, conductivity sensor 1 is electrically connected with multi-way switch circuit 2, and multi-way switch circuit 2 is electrically connected with automatic gain A/D circuit 3, and automatic gain A/D circuit 3 is electrically connected with central processing unit 9; Frequency multiplication generator 4 is electrically connected with conductivity sensor 1 and central processing unit 9 respectively; Central processing unit 9 also is electrically connected with temperature sensor 5, data-carrier store 6, input media 7, output unit 8 and external communication interface 10, power supply respectively.

During work, conductivity sensor 1 and temperature sensor 5 place solution to be measured.

Energized enters the self-correcting working stage automatically.Whether the software instruction of setting by central processing unit 9 carries out verification to measuring instrument, can detect as conductivity sensor or temperature sensor to have problems, and whether measured value surpasses the measurement range of instrument etc., and measurement result can be by showing on the display.When the self-correcting instrument normal, central processing unit 9 sends control signal makes 4 timesharing of frequency multiplication generator send the sine wave signal of two high stabilities with branch frequency multiplication relation to conductivity sensor 1, detect 1 two voltage across poles of conductivity sensor and current signal, obtain two resistance values under the solution Current Temperatures surveyed; Temperature sensor 5 directly detects the solution Current Temperatures of surveying, temperature value is that digital signal directly deposits central processing unit 9 in, program obtains temperature compensation coefficient, operation program adopts formula one to obtain eliminating under the Current Temperatures conductivity of electric capacity variable influence, and final program carries out computing again and obtains conductivity value and the equivalent salt deposit density measured value of tested solution in the time of 20 ℃.

Fig. 2 realizes branch frequency multiplication exciting signal source concrete grammar: adopt sine wave signal generator integrated circuit modules U commonly used ₆, as the central processing unit 9 control figure potentiometer U that sends instructions ₇, change digital regulation resistance U ₇Resistance value, reach control sine wave signal generator U ₆Change the frequency of waveform, digital regulation resistance U ₇The resistance value difference, sine wave signal generator U ₆It is just different to produce waveform frequency; As central processing unit 7 control figure potentiometer U ₇Resistance change, sine wave signal generator integrated circuit modules U ₆Just can realize being produced as two different signal sinusoidal waveforms of branch frequency multiplication relation.

Because the dynamic range of measuring is big, input signal is a variable, and in order to guarantee the measuring system precision, system will control the signal intensity of input.Usually data acquisition system (DAS) is often wished to gain and can in time be adjusted, and to improve the precision of data acquisition, at present typical integrated circuit can be adjusted automatically to signal gain under programmed control, and this adopts manual setting more superior than in the past.For example Chang Yong integrated circuit (IC) chip such as AD603 all have this function, and it is the integrated circuit (IC) chip that auto-gain circuit and A/D converter are integrated.Automatic gain A/D circuit 3 adopts the cost performance height, has the chip of the A/D of automatic gain, and this has promptly simplified circuit and has also improved measuring accuracy simultaneously.

Multi-way switch circuit 2 is equivalent to a single pole multiple throw, connect which passage as long as can finish by programmed control.For example utilize the PIN pipe under the positive reverse bias of electric current, to have conducting or turn-off characteristic, realize " single pole multiple throw " function, reach the change circuit connecting relation, this mode that the chip of multi-way switch circuit 2 adopts has exactly realized that the programmed control multichannel automaticallyes switch, reach multipath electric and connect automatic switchover, for example this class chip of the CHDK-3-0520X on the market all has " single pole multiple throw " function.

Described measurement data all can be saved in the data-carrier store 6 according to measuring needs, calls fully in the future, still can keep when the instrument power down.

Described input media 7 is used to measure initial value, measurement, data preservation, exports the mode selection of measurement data etc.; Described output unit 8 is used to show testing result.

The above only is a preferred implementation of the present utility model; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the utility model principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection domain of the present utility model.

Claims (5)

1, a kind of minute frequency multiplication formula insulator equivalent salt density measuring instrument, it is characterized in that: comprise the conductivity sensor (1), multi-way switch circuit (2), the automatic gain A/D circuit (3) that are electrically connected successively, the input end of conductivity sensor (1) is electrically connected with frequency multiplication generator (4), and multi-way switch circuit (2), automatic gain A/D circuit (3), frequency multiplication generator (4), temperature sensor (5), data-carrier store (6), input media (7) and output unit (8) are electrically connected with central processing unit (9) respectively.

2, according to claim 1 minute frequency multiplication formula insulator equivalent salt density measuring instrument is characterized in that: described frequency multiplication generator (4) concerned the frequency multiplication generator of frequency for exportable minute frequency multiplication.

3, according to claim 1 minute frequency multiplication formula insulator equivalent salt density measuring instrument, it is characterized in that: described input media (7) is a keyboard.

4, according to claim 1 minute frequency multiplication formula insulator equivalent salt density measuring instrument, it is characterized in that: described output unit (8) comprises display and the printer that is electrically connected with central processing unit (9) respectively.

5, according to claim 1 minute frequency multiplication formula insulator equivalent salt density measuring instrument, it is characterized in that: described central processing unit (9) is electrically connected with external communication interface (10).

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