Device for measuring level of dielectric matter

FIELD: electric engineering equipment.

SUBSTANCE: device can be used for measuring electric parameters of two-terminal devices used as physical process detectors (temperature, pressure, level of loose and liquid matters and et cetera) at transportation vehicles and in systems for measuring level of filling of rocket-space equipment. Device for measuring level of dielectric matter has first and second measuring inputs, sinusoidal voltage source, equivalent circuit preset unit, standard which has first output connected with first input of switching unit, current-to-voltage converter, scaling amplifier and analog-to-digital converter. Switching unit is made to be multi-channel one, which has first measuring, input with second output of standard and with output of sinusoidal voltage generator. Control input of the latter is connected with first output of frequency-control unit. Measuring inputs starting from second to (n+1) are connected with corresponding inputs of switching unit which has output connected with first outputs of electric capacity and active resistance calculators through current-to-voltage converter, scale amplifier and analog-to-digital converter all connected in series. It is also connected with first input of measurement control input which has outputs connected with control inputs of switching unit, of scale amplifier and analog-to-digital converter as well as with first input of frequency control unit and with second inputs of electric capacity and active resistance calculators. Control input of measurement control unit is connected with control output of mode control unit which has outputs connected with second input of frequency control unit, with equivalent circuit setting unit, with first input of electric capacitance total increment calculator, with first input of level calculator, with first input of electric capacitance current increment calculator and with input switching control unit. Output of the latter is connected with second control input of switch unit. Output electric capacitance calculator is connected with second input of calculator of current increment in electric capacitance. Output of the latter is connected with second input of level calculator. Third and fourth inputs of electric capacitance and active resistance calculators are connected with output equivalent circuit preset unit and with second output of frequency control unit. Output of calculator of current increment in electric capacitance is connected with third input of level calculator. Output of the latter as well as outputs of active resistance calculator and switch control unit have to be outputs of the device.

EFFECT: improved precision of measurement; improved manufacturability; improved efficiency of measurement.

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The invention relates to electrical engineering, and specifically to the measurement of electrical parameters of two-terminal used as sensors of physical processes (temperature, pressure, liquid level and granular media and other industrial objects, vehicles, as well as in systems for measuring the level of filling of rocket and space technology.

As an analogue of the selected device "Multipoint level switch (and its variants)", described in the patent of the Russian Federation No. 2025666, CL G 01 F 23/26, includes a group of measuring capacitive sensors, AC voltage generator, two switches, two transducer current-voltage, subtractive device, a synchronous detector, a comparator, two triggers, a differentiator, a clock generator, schema matching, pulse counter, an adder and a digital indicator. Each sensor consists of two parallel-plate capacitors with different areas of the electrodes, which are arranged horizontally and symmetrically relative to the average of the sensor lines. In addition, instead of the Comparators current transformer of the type used subtractive device that can be built on an integrated circuit.

Another similar device is described in the book "Capacitive samarapungavan level", the authors CBER ndeeba, Fbhrendes, Aievoli, Moscow, publishing house "Energy", 1966, p.28. This sensor is automatic balanced bridge with close inductive coupling. Shoulders bridge enabled capacitive level sensor and compensation capacitors, the magnitude of which is selected by the operator when setting up the device on a specific capacitive level sensor and the dielectric substance. The sum of the currents from the capacitors and capacitive sensor are on summarizing the measuring transformer with close inductive coupling. The equilibrium condition of the measuring circuit with a close inductive coupling is to achieve a minimum amount of current (ideally equal to zero), flowing through the capacitive sensor and the compensation capacitors. Thus the ratio of the number of turns of tightly coupled inductive shoulders determines the relative fill level of the capacitive level sensor of the dielectric substance.

However, the specifics of operation of rocket and space technology for the measurement of parameters of two-terminal address their demands, contributing to the search for new technical solutions in the field of measurements. We denote the most characteristic of them:

- the distance of 500 meters capacitive level sensor from measurement tools. An example is the process of identifying couples who TRS impedance of the capacitive sensor level control refills, built in tank missiles, which is a test case or at the launch site during its refueling propellant;

- high accuracy of measurement remote dvukhpolosnykh, which is a capacitive level sensor. It is obvious that the accuracy of the measurement is directly related to the amount of warranty reserves of fuel on Board the rocket. The higher the accuracy, the less needful to guarantee fuel supplies, the higher the efficiency of a rocket that can take greater payload;

the requirement of high-tech training missiles, excluding pre-setting measuring a human operator, as well as allowing one measurement tools with multiple capacitive level sensors missiles one by one;

- high performance level measurement of the dielectric substance, allowing you to extend the functionality of the device and use it in a similar way in the transmitter side terminal of the automatic control system, which is the control system fuel rockets.

The drawbacks include: reduced precision of the remote for a capacitive distance sensor; low performance in some cases its use, in the example in the alarm device pass level electroconductive liquid-defined elevation of the tank; not enough high technology training missiles, due to the need to pre-configure equipment operator, failure of one means of measuring multiple capacitive level sensors in turn.

The closest in technical essence and the achieved positive effect of the claimed device is the device described in the article authors Urogallus, Dajabula, Voulnteer "Meter analyzer parameters of complex resistances based personal computers" in the journal "Measurement technology" 1996, No. 6, selected as a prototype.

A device for determining parameters of dvukhpolosnykh containing the first and second measuring inputs, the generator of sinusoidal voltage, the unit job circuits, the standard, the first output of which is connected to the first input switch unit, the Converter current-voltage, large-scale amplifier and analog-to-digital Converter.

In the prototype of the schema used for indirect measurement parameters during the formation of voltage sine wave influence on the measuring object, the finder of the application due to the invariance with respect to the nature of the measurement object and its equivalent circuit. In the prototype are measured two integrated current, which is converted into a proportional voltage, to whom the custody of the object of measurement and resistive as the benchmark. To obtain the measurement information required for the calculation of the complex impedance or conductivity, cyclically on signals from a personal computer (PC) can be connected to a measuring circuit at first to the object of measurement, and then to the resistive least with appropriate switching of the phase of the reference voltage incrementswhere n is an integer. The result of each measurement cycle produces a voltage that corresponds to the projection of the vector of the measured voltage vector phase-shifting the reference voltage (symmetrical rectangular waveform). Codes carrying the information on the projections of the vector of the measured voltage vector reference voltage, is supplied to the personal computer to calculate the real and imaginary parts of the voltages on the measurement object and least resistive. From the description it is seen that the measurement scheme used in the prototype requires phase measurements and four-wire wiring diagram of the measured object. When using the prototype to measure the parameters of remote object measurement result is obtained with a large measurement error. This is because the sinusoidal effect on the remote object measurement will get mixed phase shift due to the effect of the long line and therefore in relation to cyclically phase-shifting the reference sinusoidal meander impact would be uncertain phase shift, that will lead to significant measurement errors.

When using the prototype to determine the level of the dielectric substance by using a capacitive level sensor, remote on a sufficiently large distance (500 metres) from the measurement tools, the result is a high degree of error. Low adaptability and lack of precision and performance measurements of the prototype due to the following:

device-prototype does not possess the invariance with respect to the long lines of communication between the measuring tool and the capacitive level sensor, i.e. does not exclude the influence of long lines of communication to the level measurement of the dielectric substance;

the prototype measures the complex current through the capacitive level sensor, which does not take into account the values of the parameters of the dielectric material (the dielectric constant of the substance and of the gas environment on the matter, including temperature, changing the geometric dimensions of the capacitive level sensor due to exposure to cryogenic temperatures). Proceeding from this prior process of filling you want to pre-configure the measurement tools on the settings determine the level of filling for each gauge individually;

the prototype can only work with one capacitive sensor level is I, what characterizes his lack of effectiveness in the presence of a large number of sensors. In addition, the prototype has a four-wire wiring diagram measured dvukhpolosnykh sensor to the measurement tool, which is unacceptable in rockets because of the increased on-Board scales.

Thus, the disadvantages of the prototype are:

- low accuracy level measurement of the dielectric substance at a sufficiently remote from the measuring capacitive level sensor;

- low technological level definitions associated with presetting means of measurements on defined parameters refills;

lack of efficiency associated with the work of the prototype with only one capacitive sensor and increased on-Board weight associated with four-wire connection diagram of a capacitive level sensor.

Objective measurement devices level dielectric substance is to improve the accuracy of its measurement, consisting in the elimination of the influence of the long line on the measurement result, as well as improving technology and efficiency measurement level, including full automation of process level measurement and operation of the device with multiple capacitive level sensor.

The solution of this problem is achieved in that the device for measuring the level dielectric is someone substances, containing the first and second measuring inputs, the generator of sinusoidal voltage, the unit job circuits, the standard, the first output of which is connected to the first input switch unit, the Converter current-voltage, large-scale amplifier and analog-to-digital Converter, unlike the prototype, the switch unit is made multichannel, the first measuring input connected to the second output pattern and the generator output sinusoidal voltage, the control input of which is connected to the first output control unit frequency, and measuring the inputs from the second to the (n+1)-th connected to respective inputs of the switch unit, the output of which through consistently United inverter current-voltage, large-scale amplifier and analog-to-digital Converter connected to the first outputs of the transmitter electrical capacitance and transmitter active resistance, and also to the first input of the control unit of the measurement, the outputs of which are connected respectively to the control inputs of the switch unit, the scale of the amplifier and analog-to-digital Converter and to the first input of the control unit according to the frequency and to the second inputs of the transmitter electrical capacitance and transmitter active resistance, and the control output of the control block dimension is connected to the control turn the control unit control modes, the outputs of which are connected respectively to the second input of the control unit of frequency, to the input unit of assignment circuit, to the first input of the transmitter full incremental electric capacity, to the first input of the transmitter level, to the first input of the transmitter of the current increment of the electric capacitance and the input of the control unit switches, the output of which is connected to the second control input of the switch unit, and the output of the transmitter electrical capacitance connected to the second input of the transmitter current increment electrical capacitance and to the second input of the transmitter full incremental electric capacity, the output of which is connected to the second input of the transmitter level, and the third and fourth inputs of the transmitter electrical capacitance and transmitter active resistance connected respectively to the output unit job circuits and to the second output of the control unit according to the frequency, and the output of the transmitter current increment electrical capacitance connected to the third input of the transmitter level, the output of which, as well as the outputs of the transmitter resistance and control unit switches are the outputs of the device.

The features that characterize the connection of capacitive level sensors through the measuring inputs, on the one hand, through the switch unit to the input of conversions the user the current-voltage, on the other hand, the output of the generator of sinusoidal voltage, provide an exception to the influence of the large parasitic capacitance of the cable line connection on the measurement accuracy of its parameters. This is because the Converter current-voltage with zero input impedance, bypasses from my side parasitic capacitance of the cable line and it does not affect the process of defining parameters. On the other hand, the generator of sinusoidal voltage has a very low output impedance and parasitic capacitance lines does not affect the current through the working tank level sensor. These distinctive features of the prototype signs give the device a new quality, allowing measurements of the parameters of the capacitive level sensor, remote from the measuring devices through the communication line.

The set of features that characterize the connection control unit according to the frequency with sinusoidal voltage generator and transmitter of electrical capacitance sensor, and the connection of the last block through the switch modes with calculator full increment electrical capacitance level sensor is fully immersed in a dielectric substance, provides automated configuration process measurement and achievement improve manufacturability.

On Phi is .1 presents a functional diagram of the device measuring the level of the dielectric substance.

Figure 2 presents the algorithm level measurement of the dielectric substance.

Figure 3 presents the algorithm of the complex current through the capacitive level sensor and the reference.

Figure 4 presents the algorithm for computing the parameters of the capacitive level sensor and R.

Figure 5 presents the algorithm for the extraction of a square root of a number.

Figure 6 presents the algorithm of numerical procedures for the extraction of a square root of a number X.

Presented in figure 1 functional diagram of the device for determining parameters of dvukhpolosnykh contains n capacitive level sensors 1, the generator 2 sinusoidal voltage connected to the Etalon 3, the output of which is connected in series through the switching unit 4, the inverter 5 current-voltage, large-scale 6 amplifier and analog-to-digital 7 Converter connected to the inputs of the control unit 8 measurement and computers electrical capacitance sensor 9 and its active resistance 10, respectively. Capacitive level sensors through the measuring inputs 18, 19-1, ..., 19-n are connected to the switching unit 4, and outputs a control unit dimension is connected to the control inputs of key, large-scale amplifier, analog-to-digital Converter, calculators electrical capacitance and resistance of the sensor and to the input unit 11 of the control frequency, the outputs to the showing connected to the control input of the generator of sinusoidal voltage and computers electrical capacitance and resistance of the sensor, unit 12 job circuits are also connected to the computer 9, 10 electrical capacitance and resistance, block 13 control mode of the connected unit 11 controls the frequency of the transmitter 14 full incremental electric capacity, the transmitter 15 of the current increment of the electric capacity, the evaluator level 16 and unit 17 controls the switch and the transmitter 9 electrical capacitance sensor via the transmitter 15 of the current increment of the capacitance connected to the transmitter 16 level, and the outputs of the transmitter 10 active resistance, transmitter level 16 and unit 17 controls the switching channels are outputs of the device. Moreover, the n capacitive level sensors connected to the measuring 18 19-1, ..., 19-n inputs via shielded cable line 20 connection. The screens of the communication line at the measurement inputs are connected and connected to the ground terminal of the generator of sinusoidal voltage.

The operation of the device consider the example of measuring the level of a dielectric substance, which is used, for example, kerosene and oxygen tanks in a multi-stage rocket. Capacitive level sensors, connected through a line 20 links, removed from the device at a distance of 500 meters. The electrical capacity of the dry level sensor may is 500 pF, the parasitic electric capacity of the LM is a-screen cable communication line, which can be used, for example, cable RK 75 may be of the order of 30000 pF. The electrical equivalent circuit of the capacitive level sensor corresponds to a parallel connected capacitance Cpand active resistance R. the Active component of the impedance of the capacitive level sensor is determined by the condition of the insulation resistance of cable communication lines, grades of kerosene and humidity of the gas cushion of the fuel tank. The value of the active component may be in the range of 200 ohms to 20 Megohms. Therefore this component when determining the complex impedance of the capacitive level sensor is crucial for the accurate measurement of the filling level.

The features that characterize the capacitive connection 1-1, ..., 1-n level sensors through the measuring inputs of the switching unit 4 to the input of the inverter 5, the current-voltage and to the output of the generator 2 sinusoidal voltage, provide an exception to the influence of the large parasitic capacitance of the cable line connection on the accuracy of determination of its parameters. This is because the Converter 5, the current-voltage with zero input impedance, bypasses from my side parasitic capacitance of the cable line and it does not influence the process of defining parameters. On the other hand, enerator sinusoidal voltage is close to zero output impedance and parasitic capacitance lines does not affect the current through the working capacity With pthe level sensor. These distinctive features of the prototype signs allow for measurements of parameters that are remote from the measuring inputs of the device capacitive two-terminal device.

Presented in figure 2 algorithm for level measurement of dielectric substances provides an explanation of the operation of the device according to figure 1. The blocks allocated by the dotted line and including a particular feature of the algorithm, suggest that this function is covered in the unit.

According to algorithm 2, the device consists of two modes:

the mode setting device, which is the measurement through the cable line integrated currents through each sensor and the reference with the subsequent calculation using the measured values of the complex currents of the real electric capacitance of each of the dry (unfilled dielectric substance) capacitive level sensor. Then we can calculate the full increment of electrical capacitance is fully immersed in a dielectric substance of each sensor. When calculating the specified calculated values of the electric capacity is used the calculated value of the electric capacitance of the dry sensor and the set values of dielectric permittivity of oxidizer, fuel and gas cushions. All measured and calculated values are stored in PA is ATI functional blocks of the device;

- mode level measurement, which is the measurement through the cable line integrated currents through each sensor and the reference with the subsequent calculation using the measured values of complex real currents, the current capacitance of each of the filled dielectric substance capacitive level sensor. Then we can calculate the current increment of the electric capacity of each of the medium sensor, and then calculates the relative filling of each capacitive sensor is calculated.

Unit 13 control mode sets the tuning mode of the device.

In this case:

in block 8 of the control dimension is given the number of necessary measurements, in this case 2 for each sensor as a capacitive level sensor is a two-element dvukhpolosnykh. Obtained in the measurement process of the complex values of the currents through each sensor and the reference will be used later to calculate the actual dry electric capacitance of each sensor in setup mode and to calculate the actual current electrical capacitance of each sensor in the measurement mode level (when completing each sensor dielectric substance);

in unit 11 controls the frequency set frequency values (ω1that ω2that will be measure the currents ia;

in the transmitter 14 full incremental electric capacity are given the values of the dielectric permittivity of the oxidizer and fuel, as well as the dielectric constant of the gas medium in the gas cushion. These settings are required to obtain the estimated values of the full increment of the electric capacitance of each capacitive sensor is completely immersed in the corresponding dielectric substance;

unit 12 issuing circuit issues in the transmitter 9 of the electric capacity and the transmitter 10 active resistance respectively calculated according to the following form, in which the above-mentioned blocks are fixed:

where ω1that ω2- values are known and are set by the unit 11 controls the frequency; RFL- the value is known and is given by the block 12 job circuits; Iω1, Iω2- the values of currents that need to be measured, as in the configuration process and the measurement process;

in block 17 of the control switch is set to the number attached to the device capacitive level sensors, as well as receive a signal on which the block 17 through the switching unit 4 controls the connection to a measuring circuit of the Converter 5, the current-voltage of the second measuring input of the first capacitive level sensor).

After the unit 13 of the management regimes made to bring the device to its original state necessary to process its configuration, starts the configuration process.

In this case, according to figure 2, the control unit 8 measurement measurement and recording of the current through the first capacitive level sensor and the reference in accordance with the algorithm of figure 3. Unit 8 management dimension, which is specified by the block 13 control modes number of measurements (in this case 2), puts in unit 11 controls the frequency setting signal of the first frequency, which must be conducted by measuring the current through the first capacitive level sensor and reference 3. According to figure 3 unit 8 sets the index of the current frequency measurement i is 1 and sets in the unit 11 controls the frequency of the corresponding signal. After which the unit 11 controls the frequency sets and registers in the computer 9 electrical capacity in the transmitter 10 resistance value of the first frequency ωiand to the control input of oscillator 2 sinusoidal voltage signal, according to which the last output generates a voltage of a given first frequency ωi. The generator of sinusoidal voltage can be performed in this case, the operational amplifier in the feedback which included the bridge of Wine. Change h is the frequency can be realized through the control of parameters of the timing circuit of the generator. Another example of execution of the generator can be run on the chip HS Xilinx, which is programmed to the formation of the multi-level signal with its subsequent submission to a low pass filter. Voltage preset first frequency Uωiis supplied to the measuring inputs of the device for feeding the connected capacitive level sensor and reference. Next, the control unit 8 measurement sets the sign of the j position of the key unit 4 switch. Positions of the key 2, and the sign of j is set to 1. According to this feature of the first or current capacitive level sensor is disconnected from the measuring circuit, but instead to a measuring circuit connected to the reference 3. As a benchmark can be used a resistor of resistance RFL. Through the pattern of current flow on the measured value of which is determined by the output voltage of the generator 2 sinusoidal voltage according to the expression

The current value is measured as follows. According to figure 1 the current through the reference from the output of the switching unit 4 is supplied through a transformer 5 current-voltage at the input scale 6 of the amplifier. Large-scale amplifier provides a voltage gain in accordance with the scale which he sets unit 8 management dimension. The process of scaling amplifier shown in figure 3. Output of large-scale amplifier voltage is fed to the input of analog-to-digital 7 Converter integrating type. Analog-to-digital Converter (ADC) is designed as a two-stage integrator. The choice of this type of ADC is primarily due to the high linearity, large resolution and good suppression of high-frequency interference. The ADC operates in two bars, the first bar of the charge integrator, the second beat of his discharge. In the first stage of the integration of the input signal, which is a periodic function, the second step is the integration of the signal from the voltage reference. The resolution of the ADC, which determines the resolution of the device in General, proportional to the time of second stage (discharge integrator), and the rate of fill pulses. Control of switching cycles of the ADC and the flow of the filling pulse unit 8 performs control dimension. The digitized value of the measured current supplied to the transmitter 9 of the electric capacity, the transmitter 10 active resistance to its further use in the calculations according to the expressions (1) and (2) in block 8 of the control measure to control the amplification scale. The zoom control gain is aimed at improving the accuracy of the ADC. The scale is constructed so the m way that digital value is removed from the Abkhazian Orthodox Church of the signal should not exceed half of the capacitance of the ADC. On this basis, for example implementation of the invention the algorithm presented in figure 2. According to this algorithm analyzes the numbers αwhich is equal to the ratio of the value of total capacitance of the ADC to the digital value of the measured current. On the basis of the calculated values number α, selects one of the four scales(8; 4; 2; 1). Once you have defined the scale amplification of the measured current in the transmitter 9 of the electric capacity and the transmitter 10 active resistance is recording its value with the measurement scale used for further operations on the parameters of the capacitive level sensor. Further, according to figure 3 if j is not equal to 2, then its value in block 8 of the control dimension is incremented and there is formed a control signal to the switching key unit 4 switch in the second position. This corresponds to the fact that the reference is turned off and connected to a measuring circuit capacitive level sensor. Through capacitive level sensor current flows, the value of which is determined by the expression

Next, the procedure of measuring the current through dvukhpolosnykh is determined by the procedure described for measuring current through the Etalon. After both the height value of the current through the capacitive level sensor will be fixed in the transmitter 9 of the electric capacity and the transmitter 10 active resistance, the algorithm according to figure 3 will proceed to the analysis of the conditions in which j is equal to 2. As the key unit 4 switch is in the second position, then the condition is satisfied and the algorithm crossed to the analysis of the following conditions, which will be the analysis of the current frequency measurement. Since the measurement was made at the first frequency, the condition will not be met, and the algorithm will proceed to the steps for installing a second frequency ωi. The result will be a completed act i:=i+1 and block 8 control measure will put the signal on installing a second frequency ωi. This signal unit 11 controls the frequency generates a signal generator 2 sinusoidal voltage in order to install a second frequency that is used to power capacitive sensor or a measurement standard. Simultaneously, the unit 11 controls the frequency sets and registers in the computer 9 electrical capacity in the transmitter 10 resistance value of the second frequency, which is then used to calculate the parameters of dvukhpolosnykh. After that, the control unit 8 measurement initiates the measurement. The procedure for measuring the current at the second frequency is repeated as described above.

After the number of measurements i is equal to 2, then the condition of the last block of the algorithm according to figure 3 will be executed, algorithmsand their work. This will correspond to the completion of the procedure of measuring the current through the first capacitive level sensor. Then according to algorithm 2, the algorithm computes in blocks 9 and 10 values of electrical capacitance and resistance of the first capacitive level sensor. The results of calculating the value of the electrical capacitance of the block 9 are received in block 14 calculate the full incremental electric capacity and in block 15 of calculation of the current increment electrical capacitance, which are fixed upon the instruction of the block 13 of the control modes in the memory cells corresponding to the number of the connected measuring input. The calculated value of the active resistance from the output of block 10 is supplied to the output R of the device. The value of resistance characterizes the state of ground and on-Board cable networks and analyzed the mating device equipment for compliance with the required performance characteristics.

The control signal unit 13 of the management regimes in the calculator 14 full incremental electric capacity calculation is complete increment of the electrical capacitance of the capacitive level sensor is fully immersed in a dielectric substance according to the following dependence:

where Cdry- electric capacity dry capacity is nogo gauge, calculated based on (1);

εW- the dielectric constant of the dielectric substance;

εg- the dielectric constant of the gas cushion located in a tank missiles over a dielectric substance.

The results of the full calculation of the incremental electric capacity recorded in the computer 16 in the memory cell, the corresponding number of measured inputs (number of capacitive level sensor).

The algorithm then proceeds to the analysis of the condition i=n. The condition is not met, as it was connected to the second measuring input of the first capacitive level sensor). Therefore, the algorithm will proceed to step i=i+1 in block 17 of the control switch, which through the block 4 switch will disable the second measuring input and connect the third measurement input. The features that characterize the connection unit output control modes to the input of the control unit switches, the output of which is connected to the second control input of the switch unit, provide the serial connection of the measurement inputs of the device to the measuring circuit of the Converter current-voltage thereby increase the efficiency of the device, sequentially connecting to the device the combination of capacitive level sensors. Further operation of the device will meet isopycnal action until until the condition i=n, i.e. until the calculated values of the electric capacities of dry level sensors and the calculated values of the electric tanks are fully immersed in the dielectric substance of all n sensors sequentially connected via the cable network 20 to the measuring inputs. If the condition i=n ends configuration mode of the device, and the algorithm proceeds to perform level measurement of dielectric substances. In the measurement mode level of the transmitter 14 full increment of electrical capacitance is switched off, as this function in this mode is not used. The calculated values of electrical capacitance is fully immersed capacitive sensors fixed in the transmitter 16 and will be used when calculating the level of each capacitive sensor measurement mode level.

Unit 13 control mode sets the mode for the level measurement of the dielectric substance and in block 17 controls the switch assigns the first value to 1. Unit 17 controls the switching through the switching unit 4 connects to the measuring circuit of the first measuring input. After that, the block 13 control mode of the forms in block 8 of the control measurement signal, on which the latter starts measuring the current through the fill dielectric substance of the first capacity is Noah and level sensor standard. The procedure for measuring the current through the capacitive level sensor and the reference is made from the blocks 5, 6, 7 and 8 presents the algorithm according to figure 3 and is similar to the above.

After the process of measuring the current through the capacitive level sensor and the benchmark is complete, the algorithm according to figure 2 will proceed to the calculation of the current value of the electric capacitance of the filling level sensor and its resistance using the measured values of the currents through the capacitive level sensor and the reference. The above procedures are performed by blocks 9 and 10. The calculated capacitance value of fill in sensor (CTECHfrom the output unit 9 is supplied to the transmitter 15 of the current increment electrical capacitance which is calculated and recorded an increment value of electric capacitance sensor in the memory cell, the corresponding number of measuring input. The increment value of the electrical capacitance of the medium sensor is calculated according to the following dependence:

where CTECHis calculated based on the measured complex currents of the current value of the electric capacitance of the filled dielectric material level sensor. The analytical dependence of the electrical capacity of the medium sensor can be represented by the expression

where h is the current height of immersion capacitive level sensor in the dielectric substance;

H - total height of immersion of the sensor in the dielectric substance.

The calculated value of the active resistance of the filled dielectric substance capacitive level sensor from the output of block 10 is supplied to the R output of the device and is used to assess the status of sensor and its cable network.

Then, the control exposure unit 13, the control mode of the transmitter 16 level produces a calculation of the relative filling of the dielectric substance capacitive level sensor, and the transmitter 15 sends to the transmitter 16, the current increment value of electric capacitance ΔCTECHfill level sensor.

The transmitter 16 level produces its calculation according to the following dependence:

The value of the total incremental electric capacity fully immersed sensor stored in the memory of the computer 16 level in the configuration mode of the device.

The set of features that characterize the connection evaluator 9 electrical capacity with transmitter 14 full incremental electric capacity and the transmitter 15 of the current increment of the electric capacity and the connection of the transmitter 15 and the transmitter 14 with calculator 16 level, provide real is tion of the expression (8). Note that the calculation of the dry electric capacity, full incremental electric capacity and current increment electrical capacitance produced taking into account the influence of the long line of the same measurement tool. This circumstance provides the exception of the impact of the line on the result of the calculation level. From the analytical dependence (8) it should be obvious, WithDRYand CTECHwas determined by accounting for the effects of line, FromCRit was also determined taking into account the influence of the communication line. Therefore, according to expression (8) the impact of the communication line is virtually eliminated.

Thus, the above set of features describes the device as invariant with respect to the communications line.

The value of the level h/H filling capacitive sensor is fed to the output device, which mates apparatus launch complex that controls the flow through ground processing equipment components fuels (dielectric substance) in tanks missiles.

The algorithm then proceeds to the analysis of the condition i=n. The condition is not met, as it was connected for the first measurement input. Therefore, the algorithm will proceed to step i=i+1 in block 17 of the control switch, which through the block 4 switch will disable the first measuring input and plug the second measuring input. Further operation of the device will meet the above actions until then, until the condition i=n, i.e. until the calculated values of the filling level of a dielectric substance of each of the capacitive level sensor.

If the condition i=n unit 13 of the control modes will assign unit 17 controls the switch i is the unit, resulting in a block of 4 of the switch will connect the first measuring input and the process of measuring the fill level of each of the capacitive level sensor to happen again. The cyclic procedure of measurement of each sensor level dielectric substance will continue to until each tank missiles will not be charged according to the desired flight level job.

Presented in figure 2, 3 working modes include actions aimed at the evaluation of expressions (1) through (7).

In the example of execution of the device algorithm to calculate the parameters of the capacitive level sensor s and R are presented in figure 4. He is a sequence of actions, by definition, intermediate numerical values, which are necessary to calculate the level of the dielectric substance. Presented in figure 4, the algorithm is quite obvious. However, blocks that calculate the values of the parameters, has the following f is ncciu, as the square root.

In the algorithms according to figure 5, 6 shows an example of the numerical solution of the function taking the square root of a number. Moreover, figure 5 presents the algorithm for the extraction of a square root of a number x, which has a nested block Result=SQRoot 2(x), the procedure implementation is shown in Fig.6.

The numerical procedure for the extraction of a square root of a number x, is presented on Fig.6, works with a number whose value is in the range from 0.1 to 1.9.

Thus, an algorithm for extracting square root, presented on figure 5, operates as follows: enter the number x to extract the square root, introduced the initial variables and a constant whose value is in the range from 0.1 to 1.9; the number is analyzed to zero if it is not equal to zero, then the transition to the power conditions in which the value of the number x is mapped to a constant value 1,4121; if the value of the number x is greater than/less constant divided/multiplied by 2 as many times so that the result was less/more constant, while the number N of divisions/multiplications considered; as a result of these operations produces the number x, the value of which is in the range from 0.1 to 1.9. After that, turn the numerical procedure of extracting the square root, the algorithm which is presented on Fig.6. The procedure to extract the deposits of the square root works as follows: enter a numeric value x, from which you want to extract the root, introduced the initial value of the result and the value of the initial approximation to the square root extraction, introduced the initial values of the variables of the algorithm; enter the number of iteration steps, in the specific case of N=128 (this number determines the accuracy of the numerical solution of the square root); by successive approximations through 128 steps is determined by the numerical value of the square root; to display the result.

Then when returning to the algorithm according to figure 5, the following is performed: the number x, which was divided/multiplied by 2 N times, now is multiplied/divided by 2 N times, i.e. the number x returns to the previous zoom level. After these steps, the result of taking the square root of a number is displayed.

The above algorithms are known and are drawn from publicly available literature. Also these algorithms can be implemented using software Foundation Series software package intended for the design of Xilinx Corporation, containing the means of schematic entry, simulation, editing, and synthesis.

The claimed device, the authors tested on models of the product. Currently, the authors create a system for measuring the level of filling of the rocket unit, which is designed for the fashion of the related ground equipment one of the starting launchers polygon "Baikonur".

Literature used

1. Agamalov YU, Bobylev D.A., Kneller has WORKED Meter analyzer parameters complex resistance-based personal computers. Measuring equipment. 1996, No. 6, p.56-60.

2. K.B. Karandeyev, FB Grinevich, A. I. Novik. Capacitive samarapungavan level. M: Energy, 1966, S. 135.

3. A.I. Novik. Automatic trim extreme digital bridges AC. Kiev: Naukova Dumka, 1983, p.9-10.

4. RF patent №2025666, CL G 01 F 23/26, "Multi-point level switch (and its variants)".

5. Patent No. 2144196, CL G 01 R 17/10, 27/02, "a method of measuring the three parameters of two-terminal frequency-independent bridges AC".

Device for measuring the level of a dielectric substance containing the first and second measuring inputs, the generator of sinusoidal voltage, the unit job circuits, the standard, the first output of which is connected to the first input switch unit, the Converter current-voltage, large-scale amplifier and analog-to-digital Converter, wherein the switching unit is made multichannel, the first measuring input connected to the second output pattern and the generator output sinusoidal voltage, the control input of which is connected to the first output control unit according to the frequency, and the measurement input is from the second to the (n+1)-th connected to the corresponding the inputs of the switch unit, the output of which is connected in series through the Converter current-voltage, large-scale amplifier and analog-to-digital Converter connected to the first outputs of the transmitter electrical capacitance and transmitter active resistance, and also to the first input of the control unit of the measurement, the outputs of which are connected respectively to the control inputs of the switch unit, the scale of the amplifier and analog-to-digital Converter and to the first input of the control unit according to the frequency and to the second inputs of the transmitter electrical capacitance and transmitter active resistance, and the control output of the control block dimension is connected to the control output of the control block modes, the outputs of which are connected respectively to the second input of the control unit frequency, to the input unit of assignment circuit, to the first input of the transmitter full incremental electric capacity, to the first input of the transmitter level, to the first input of the transmitter of the current increment of the electric capacitance and the input of the control unit switches, the output of which is connected to the second control input of the switch unit, and the output of the transmitter electrical capacitance connected to the second input of the transmitter current increment electrical capacitance and to the second input of the transmitter full increment system is tion capacity, the output of which is connected to the second input of the transmitter level, and the third and fourth inputs of the transmitter electrical capacitance and transmitter active resistance connected respectively to the output unit job circuits and to the second output of the control unit according to the frequency, and the output of the transmitter current increment electrical capacitance connected to the third input of the transmitter level, the output of which, as well as the outputs of the transmitter resistance and control unit switches are the outputs of the device.



 

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FIELD: high-frequency electrical measurements.

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