SU1093992A1 - Automatic device for measuring capacity and loss angle tangent - Google Patents

Abstract

AUTOMATIC DEVICE FOR MEASURING THE CAPACITY AND TANGLES OF ANGLE LOSS, containing series-connected source of test voltage, terminals for connecting the measurement object and the first current-voltage converter, series-connected reference capacitor, second current-voltage converter and the first phase shifter, and the free terminal of the capacitor is connected to the output of the test voltage source / adder, the output of which is connected to the first input of the comparison unit, the display unit and the To control, characterized in that, in order to increase speed, a second phase shifter, two voltage code converters and two pulse counters are introduced into it, and the reference input of the first code converter is voltage connected to the first phase shifter, the control input - with the output of the first pulse counter, the counting input of which is connected to the first output of the comparator unit, the output of the first converter code - voltage is connected to the reference input of the second converter code - voltage and to the input of the second phase converter The driver whose output is connected to the first input of the adder, the second input of which is connected to the output of the second converter, the voltage code, the second input of the comparison unit is connected (L to the output of the first converter, current to voltage, the third input to the output of the second phase shifter, the fourth input to with the output of the first phase shifter, the second output of the comparator unit is connected to the counting input of the second counter I1 1 pulses, the output of which is connected to the control input of the second transducer code - voltage, the outputs of the pulse counters are connected The outputs of the control unit are connected to the inputs for setting zero pulse counters and to the input for setting the initial state of the comparison unit.

Description

The invention relates to a measurement technique and can be used in automation to control the properties of substances in terms of capacity and loss tangent. A device for automatically measuring the capacitance and loss tangent of capacitors, containing a power generator (source of test voltage), included in the diagonal of a bridge circuit, in one of the branches of which the object is measured, is known, the reference voltage circuit is connected in another reference capacitor (display unit), unbalance amplifier, the output of which is connected to the signal inputs of the quadrature detectors; the reference input of the first quadrature detector is connected to the output of the pi generating reference voltages and to the input phase shifter whose output is connected to the reference input of the second quadrature detector, each of the first and second outputs of the quadrature detector connected to responsibly to the first and second input E of the control unit. The device allows simultaneous balancing of the bridge and obtaining the results of measuring the capacitance and loss tangent numerically fij. The drawback of the device is low speed, due to the need to balance the bridge circuit over several cycles due to galvanic coupling between the bridge elements. The closest to the invention to the technical essence is an automatic device for measuring capacitance and capacitor loss coefficient, which contains terminals for connecting a measurement object, the output of which is connected through successively connected reference capacitor and first current-voltage converter to the reference input of the first phase-sensitive rectifier , the input of the phase shifter and the first input of the first multiplication unit, and through the serially connected object of measurement and the second transducer current - for example The first input of the subtraction unit, the second input of which is connected to the output of the first current-voltage converter, to the first input of the subtraction unit, the second input of which is connected to the output of the first current-voltage transducer, the output of the subtraction unit comparison, the output of which is connected to the control input of the first phase-sensitive rectifier and to the control input of the second phase-sensitive rectifier, the reference input of which is connected to the output of the phase shifter and to the first input of the second smart block The output of which is connected to the first input of the adder, the output of which is connected to the BTopbfivi input of the comparison unit, the output of the first phase-sensitive rectifier is connected to the second input of the first multiplication unit, to the first input of the display unit and to the first input of the arithmetic unit whose output is connected with the second input of the display unit, the output of the second phase-sensitive rectifier is connected to the second input of the second multiplication unit and to the second input of the arithmetic unit, and also contains a control unit 2. A disadvantage of the known device is the low speed due to the long time of the double voltage conversion due to the fact that compensation must be made on alternating current and measurement is constant. Moreover, to obtain the true value of the loss tangent after the end of the compensation mode, an additional arithmetic operation is necessary carried out in the arithmetic unit, which also reduces the speed of the device. The purpose of the invention is to increase speed. The goal is achieved in that an automatic device for measuring capacitance and loss tangent, containing a series-connected test voltage source, terminals for connecting the measurement object and the first current-voltage converter, the reference capacitor serially connected, the second current-voltage converter and the first a phase shifter, the free output capacitor connected to the output of the test voltage source, an adder whose output is connected to the first input of the comparison unit , the display unit and the control unit, the second phase shifter is entered, two converters are voltage and two pulse counters, the reference input of the first converter is voltage code connected to the output of the first phase shifter, the control input with the output of the first pulse counter, the counting input of which is connected to the first output of the comparison unit, the output of the first converter, the voltage code is connected to the reference input of the second converter, the voltage code, and the input of the second phase chopper, the output of which is connected

The first input of the adder, the second input of which is connected to the output of the second converter, is the voltage code, the second input of the comparison unit is connected to the output of the first converter, the current is voltage, the third input is connected to the output of the second phase shifter, the fourth input is connected to the output of the first phase shifter, the second the output of the comparison unit is connected to the counting input of the second pulse counter, the output of which is connected to the control input of the second converter, the voltage code, the outputs of the pulse counters are connected respectively to the inputs of the indication unit The output of the control unit is connected to the inputs for setting zero pulse counters and to the installation input for the initial state of the comparison unit.

The measurement time of the measurement object parameters in a known device consists of the conversion time in the compensation unit, the additional conversion time in the counting unit, and the time of the analog-digital conversion in the display unit. - Introduction to the proposed device for two converters code - voltage of two pulse counters and the second phase shifter allows simultaneous conversions in the compensation unit and the formation of a digital code of the measurement result. The sequential inclusion of code-voltage transducers eliminates the need for additional transformations in a countable-resanch block.

The use of the proposed technical solution in automation systems for controlling the properties of substances increases the speed of the automatic device for measuring the capacitance and the tangent of loss angle by 1.6–2 times, depending on the measurement accuracy.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 is a block diagram of a comparison block; in fig. 3 - timing diagrams of the operation of the comparator when measuring capacitance: a - a sequence of pulses at the output of the comparator 30; b - a sequence of pulses at the output of the comparator 36; in - the signal at the output of the imaging unit 35 pulses; g - the signal g - the signal at the output of R5-Trigger 32; e is a sequence of pulses at the counting input of the first counter of 14 pulses; W - signal at the output of the logic circuit 31.

FIG. Figure 4 shows the timing diagrams of the operation of the comparator when measuring the loss tangent:

a - sequence of pulses ha output of comparator 30; b - a sequence of pulses at the output of the comparator 37; in - the signal at the output of the imaging unit 38 pulses; (d) signal at the output of the driver 42 pulses; d - the output signal is triggera 41; e is a sequence of pulses at the counting input of the second counter 16. pulses; W - signal

0 on the logic of the logic circuit 39. Automatic device For measuring the capacitance ri of the loss tangent (FIG. 1) contains the source

5 1 of the test voltage, the output of which is connected through the object 2 of measurement to the input of the first converter 3 current - voltage and through the reference capacitor 4 - with the input of the second converter 5 current. The output of the first converter 3 is current - the voltage is connected; With the input 6 of the compensator 7, the output of the second converter 5 is current - voltage - with the input 8 of the compensator 7.

The output 9 of the compensator 7 is connected to the first input of the display unit 10, the output 11 of the compensator 7 is connected to the second input of the display unit 10.

The compensator 7 contains the first phase shifter 12, whose input is the input 8 of the compensator 7, the output of the phase shifter 12 is connected to the reference input of the first converter 13 code - voltage, fulfilled, for example, in the form of a controlled resistive matrix -2R, the control input of the first Converter 13, the voltage code is connected to the output of the first counter of 14 pulses, the second

0 converter 15 code - voltage, the reference input of which is connected to the output of the first converter 13 code - voltage, control input with the output of the second counter 16 and 5 pulses, second phase shifter 17, the input of which is connected to the output of the first converter 13 code - voltage , the output of the second phase shifter 17 is connected to the first input

l adder 18, the second input of which is connected to the output of the second converter 15 code - voltage. The output of the first current-to-current converter 3 is through the input 6 of the compensator 7 connected to the second input 19 of the unit.

20 comparison, the output of the adder 18

connected to the first input 21 of the comparator unit 20, the output of the second phase shifter 17 is connected to the third input 22 of the comparator unit 20. Output

0 of the first phase shifter 12 is connected to the fourth input 23 of the comparison unit 20, the first output 24 of which is connected to the counting input of the first counter of 14 pulses, the output of which

5 is the output 9 of the compensator 7. The second output 25 of the comparator unit 20 is connected to the counting input of the second counter 16 pulses, the output of which is the output 11 of the compensator 7. The output of the control unit 26 is connected to the input 27 of the initial state setting of the comparator 20, to the input 28 setting the zero of the first counter 14 pulses and with the input 29 setting the zero of the second counter 16 pulses, Comparison Flop 20 (FIG. 2) contains two channels. The first channel contains a comparator 30, the first and second inputs of which are connected respectively to the 15 inputs 19 and 21 of the comparison unit 20, the logical element I 31, the first input of which is connected to the output of the comparator 30, RS is the trigger 32, the R input of which is connected to the output 20 AND 31, the output of the RS flip-flop 32 is connected to the second input of the logic element and 33, the first input of which is connected to the output of the pulse generator 34, and the output 25 of the AND 33 logic element is connected to the first output 24 of the comparator unit 20, while the second input of the logical element and 31 Connected to the output of pulse generator 35, the OQ input of which is connected to the output of the comparator 36, the first input of which is connected to the input 22 of the comparison unit 20, and the second input is grounded, The second channel contains the comparator 37, the first input of which is connected to the input 23 of the comparison unit 20, the second the input is grounded and the output is connected to the input of the pulse generator 38, the output of which is connected to the second input of the logic element and 39, the first input of which is connected to the output of the comparator 30, and the output of the logical element AND 39 is connected to the second input of the logical the element OR 40, the first input of which is connected to the 5-input of the R5-trigger. 32 and the installation input 27 of the initial state of the comparison unit 20, and the output of the logic element OR 40 is connected to the R input of the Trigger RS 41.5, input 50 of which is connected to the output of the pulse shaper 42 whose input is connected to the RS output of the trigger 32, the output of the trigger 41 is connected to the second input of the logic element And 43, 55 whose first input is connected to the output of the pulse generator 34, and the output of the logic element And 43 is connected to the output 25 of the comparison unit 20. The device (Fig. 1) operates 60 as follows. A sinusoidal voltage with a frequency of, for example, 50 Hz from the output of the generator 1 of the test voltage is fed to the input of the object 65 2 on the right side of the projectile where the sample is where the nose of the perpendicular code is 14 and to the reference capacitor 4. The current through the measurement object 2 with a parallel replacement circuit can be represented in the form of two components: yx - capacitive and active IrUriwCx + gr (1) test voltage; phase shift operator; circular frequency; capacity in parallel replacement circuit; RX is the resistance in a parallel replacement circuit. The signal in the form of current c in the measuring object 2 is fed to the input current transducer 3 - pressure. The voltage at the output of this generator is proportional to ix S UnriUTi Cx -Xn ,, (2) is the conversion coefficient of the first converter 3 current-voltage. The current through the reference capacitor 4 en 1 "-it1 C" 7 - (3) Sc is the capacitance of the reference capacitor 4. The voltage at the output of the second device 5 current - voltage is proportional to the current IK S Un; - UTlUCN-Kn ,, Kr - the conversion factor of the second current-to-current converter 5 is voltage. The voltage at the output of the first faceplate, 1 2 is phase shifted relative to Up by 90 ° (quarter of the pedal). The voltage at the output of the first faceplate 12 serves as the reference transducer 13. The voltage at the output of the transducer 13 code is proportional to the reference voltage, as well as the digital y recorded in the first pulse counter: I T1 | .JlL on, Ugn - reference voltage of the first converter code - voltage 13;

N4 - the current value of the digital g code in the first counter 14 pulses; t - the maximum value of the digital code in the first counter is 14 pulses. Substituting the value UQH equal to the voltage at the output of the first phase shifter 12, from equation (5) to equation (6), we obtain

Iohpkn; t Sleep; - (7)

The reference input of the second converter 15 is a voltage-voltage signal in the form of a voltage from the output of the first converter 13 voltage code. This voltage is the reference for the second code-converter voltage-15.

On the control input.second converter code 15 - the voltage drops the signal in the form of a digital code from the output of the second counter of 16 pulses. Then the output voltage of the second converter 15 is the voltage code equal to:

N-1

.P1, and-UYKPKN / M 7

JebiifnKHj BbixnKH,

N,

- the current value of the digital code in the second counter is 16 pulses;

N - maximum value

171 digital codes in the second counter 16 pulses. Substituting the value of the equation (7) into equation (8), we get

e, .xa.H, U, iwC, .k, -j. (9)

The signal is in the form of a voltage from the output of the first converter 13, the voltage code is fed to the input of the second phase shifter 17, where the phase voltage is shifted by -90 °. Then for the output voltage of the second phase shifter 17 you can write

N,

. (ten)

U ji ebixnkH UT-OCN Knj

The signal in the form of voltage from the output of the second phase shifter 17 is fed to the first input of the adder 18, the signal in the form of voltage from the output of the second converter 15 code - the voltage is fed to the second input of the adder 18. At the output of the adder 18, a voltage equal to

u, U / jO) C, .K, .U, uC,.,. J-l., b.ni)

At the first input of the comparator 30 (Fig. 2), connected to the input 19

of the comparison unit 20, the measured voltage from the output of the first converter 3 current is supplied to the voltage, the second input of the comparator 30 connected to the input 21 of the comparison unit 20 5 receives the compensation voltage Uj from the output of the adder 18. The comparator 30 compares the specified sinusoidal voltages generates a sequence of rectangular

0 pulses (square wave) with a constant amplitude (Fig. 3a, 4a), sufficient to trigger subsequent logic circuits (usually 5 V), and the phase of the formed sequence of rectangular pulses depends on the size and phase measured by Ufj and compensation-ij; stress At the first input of the comparator 36, connected to the input 22 of block 20

0 comparison, the voltage is supplied from the output of the second phase shifter 17, the first input of the comparator 37, connected to the input 23 of the comparison unit 20, is supplied with the voltage Unj

5 from the output of the second converter 5 current - voltage. The last two voltages are shifted by one relative to the other by 90. Comparators 36 and 37 transform sinusoidal QQ spindle 0 (.p and Ung in a sequence of rectangular pulses (meander) with a constant amplitude (Fig. 36 and 46, respectively). Coal pulses at the outputs of the Comparators 36

 and 37 are also shifted one relative to the other by 90. From the decay of rectangular pulses, short rectangular pulses are generated from the outputs of comparators 36 and 37 using shapers 35 and 38 of impulses (respectively, Fig. 4v and 4c).

At time i ((start of measurement) on the Start command supplied from the output of control block 26

5 (Fig. 3), the installation of the RS-triggers 32 and 41 and the counters 14 and 16 pulses to the initial state is carried out. In this case, the RS-trigger 32 is set to state 1 (FIG. 3).

0 R5-trigger 41 - to the state O and counters 14 and 16 pulses - to the state O.

The signal at the output of the R5 trigger 32 allows the passage of pulses

5 from the output of the generator 34 pulses through the logic circuit And 33 to the counting input of the first counter of 14 pulses (Fig. Ze). The signal at the output of the RS flip-flop 41 prohibits the passage of pulses from the generator output 34 pulses. through the logical element And 4.3 on the counting input of the second counter 16 pulses. There is an accumulation of pulses (counting) in the first counter 5 of pulses and a proportional increase in the amplitude of the voltage and output, and at the output of the first converter 13 the code is the voltage that is the capacitive component of the compensation voltage. The enxntHt voltage of the output of the second converter 15 code — the voltage applied to the second input of the adder 18 is zero, since the pulse counter 16 is in the state O. Thus, the second input of the comprator 30 and the first input of the comparator 36 voltage Uj, whose shape is proportional to the cyan code at the output of the first counter of 14 pulses. As the voltage Uj- is increased at the output of the second phase shifter 17, the phase of the sequence of rectangular pulses at the output of the comparator 30 changes with respect to the phase of the sequence of rectangular pulses at the output of comparator 36 (not shown). At time 2 P, the equalities of the capacitive components of the measured and compensating voltages (up to the measurement error, the component of 1 U1 of the tested voltage remains active. At the same time, the sequence of square pulses at the output of the comparator 30 coincides in phase with the sequence of square pulses at the output comparator 36 (fig.Za, in tg) Time 2 is recorded by passing a short single pulse (Fig. Зж, {, 1) through the logic element And 31 from a pulse 35 of a pulse. converts the RS-trigger 32 into the state O, and the signal from the output of the R5-trigger 34 prohibits the passage of pulses from the generator output 34 pulses to the counting input of the first counter of pulses 14. Thus, the following equation is true at the moment of time: the same scientific research institutes from equations (2) and (11), get ilT-iuC k, tg.k, .UTjwCN.Kn2 (1 N, N / 1 Ur-tO.CH-Kn, j; j Equating the active components of the stresses , we get N, Cx-Kni CNX jf--, (14)

from here

Jb ,

(15)

n / i N2

Cx

- -cj-r kr g -JCxXnj with ;; о i As can be seen from equation (15), the value of the digital code hell for the output of the first pulse counter 14 of pulses at time tj is proportional to the value of the equivalent capacitance of the measurement object 2. At the same time, at the time tg of the voltage drop at the output of the RS-trigger 32, the pulse shaper 42 generates a short single pulse (fig.4g, t2), which sets the RS-trigger 41 to state 1 (fig. 4e, 12). The signal at the output of the R5 trigger 41 allows the passage of pulses from the output of the generator 34 pulses through the logic element and 43 to the counting input of the second counter 16 pulses (Fig. 4e). There is an accumulation of pulses in the second counter of 16 pulses and a proportional increase in voltage ya ,, pkn output of the second converter 15, code 7 voltage. An increase in the voltage yvmpcn4 supplied to the second input of the adder 18 entails a change in the voltage Uj at the output of the adder 18, which in turn leads to a change in the phase of the rectangular pulses at the output of the comparator 30 relative to the phase of the pulses at the output of the comparator 37. At the moment of time t, the equality of the active components of the capacitor and compensatory 6j. the phase voltages of the rectangular pulses at the outputs of the comparators 30 and 37 will coincide (Fig. 4a, 6,1). The time tj is recorded by passing a short single pulse from the output of the pulse generator 38 through the logical element AND 39, the logical element OR 40 to the input of the R5 trigger 41 (Fig. 4g, t3) (5 -thrigger 41 is set to co-act O (Fig. 4e). The signal from the output of the R5 trigger 41 prohibits the passage of pulses from the output of the pulse generator 34 to the counting input of the second counter 16 pulses (Fig. 4e, tj). On the second counter of 16 pulses a digital code is recorded corresponding to the number of pulses accumulated over time Thus, at the moment of time Equations (12) and (13) are equal. Equating the active components of the stresses, we obtain (16). Ksch and N, - (jOCu-Kn Tr RX t, rimj Substitute the equation (16) into JJ from equation (15) get

from here

Ni

(18)

H

 CxR

As can be seen from equation (18), the value of the digital code at the output of the second counter of 16 pulses at a time is proportional to the tangent of the loss angle. Time t} corresponds to the end of the measurement of the capacitance and the tangent of loss angle.

At the same time, the signal in the form of a digital stroke from the output of the first counter 14 pulses through output 9 of the compensator 7 is fed to the first input of the display unit 10, the signal in the form of a digital stroke from the output of the second counter 16 pulses through the output 11 of the compensator 7 is fed to the second input of the display 10.

The measurement time of an object's parameters measured in a known device consists of the conversion time in the compensation block, the additional conversion time in the compensation block, the additional conversion time in the counting-decisive block and the analog-to-digital conversion time in the display unit. Introduction to the proposed device of two transducers, a voltage code, two pulse counters and a second phase shifter allows simultaneous conversions in the compensation unit and the formation of a digital code of the measurement result. Sequential inclusion of transducers code - voltage eliminates the need

additional transformations in the calculating block.

The use of the proposed technical solution in automation systems for controlling the properties of substances increases the speed of an automatic device for measuring capacitance and loss tangent 1.6–2 times, depending on the measurement accuracy. At the same time, it is possible to increase the number of objects to be measured by a factor of 1.6-2 compared with the use of a known measuring device. When you save the same number of measurement objects, the frequency of polling of each measurement object also increases 1.6-2 times.

2Ц To the first counter of impulses

{To Vpuron with him tch i flbcoS

e

.

Fig.Z

I

Claims (1)

AUTOMATIC DEVICE FOR MEASURING CAPACITY AND TANGE ’ANGLE LOSS containing a series-connected test source? voltage converter, terminals for connecting the measurement object and the first current-voltage converter, a series-connected reference capacitor, the second current-voltage converter and the first phase shifter, the free output of the capacitor connected to the output of the test voltage source, an adder whose output is connected to the first input of the comparison unit , an indication unit and a control unit, characterized in that, in order to improve performance, a second phase rotator, two voltage code converters are introduced into it there are two pulse counters, and the reference input of the first code-to-voltage converter is connected to the output of the first phase shifter, the control input is to the output of the first pulse-counter, the counting input of which is connected to the first output of the comparison unit, the output of the first code-voltage converter is connected to the reference input of the second the code - voltage converter and with the input of the second phase shifter, the output of which is connected to the first input of the adder, the second input of which is connected to the output of the second code - voltage converter, the second the first input of the comparison unit is connected to the output of the first current-voltage converter, the third input is to the output of the second phase shifter, the fourth input is to the output of the first phase shifter, the second output of the comparison unit is connected to the counting input of the second pulse counter ”the output of which is connected to the control input of the second code-voltage converter, the outputs of the pulse counters are connected respectively to the inputs of the display unit, the output of the control unit is connected to the inputs of setting the zero of the pulse counters and to the input state of the block 'comparison.