RU1781624C - Current tester - Google Patents

Abstract

The invention relates to electrical engineering and can be used in automated measuring systems for monitoring current in resistive circuits. The current monitoring device comprises a current-voltage converter 1, a voltage adder 2, a reference voltage source 3, an analog-to-digital converter 4, a control unit 5, an information processing and control unit 6, a switching element unit 7. 14 ill.

Description

The invention relates to electrical engineering and may find application in automated measuring systems for monitoring current in circuits consisting of resistors connected in series.

A device for monitoring low currents comprising a high-resistance meter, a resistor, an input terminal, an output terminal, a common terminal, contacts of a switching type switching relay, contacts of a switching type switching relay, wherein the inverse input of a high-resistance meter is connected to an input terminal and fixed contacts the switching relay of the closing type, and the second input of the high-resistance meter is connected to the input terminal and the fixed contacts of the switching relay of the closing type, and the second input of the high-resistance meter and second fixed contacts of the switching relay of the switching type connected to the common terminal, outputs a high-resistance meter connected to the output terminal and the first fixed

contact switching relay of the switching type, the resistors of the first outputs are connected respectively to the movable contacts of the switching relay of the closing type, and the second outputs to the moving contacts of the switching relay of the switching type.

The disadvantages of this device are:

the impossibility of measuring current without breaking the circuit;

the reliability of the operation of the monitored object is low due to the lack of on-line monitoring of the current in the measured circuits and the lack of the possibility of conducting self-monitoring with accuracy to the unit, and a large investment of time in operations associated with measuring current.

The closest technical solution is a digital measuring device comprising an input unit, a reference voltage driver, a synchronization unit, a switch, an analog-to-digital converter, a unit for comparing with settings, an indicator suitable

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the display unit, normalizing resistors, control outputs of the input unit, and the synchronization unit is connected with its outputs to the third input of the input unit, the second input of the switch, the second input of the analog-to-digital converter, the second input of the display unit, the second input of the comparison unit with the settings the output of which is connected to the input of the shelf life indicator, the output of which is connected to the third input of the display unit, the first input of the analog-to-digital converter is connected to the output of the switch, the third input is from W the second output of the voltage reference driver, the second output with the first input of the display unit, the first output with the comparison unit with the settings, the first output of the voltage generator is connected to the second input of the input unit, the first output of which is connected to the first input of the switch, and the control output resistors with corresponding switch inputs.

The disadvantages of this device are the inability to conduct self-monitoring with accuracy to a separate unit; control efficiency is low.

The purpose of the invention is to increase the reliability of the operation of the device.

This is achieved by conducting operational monitoring of the health of the device before starting the measurement.

To this end, a device comprising a current-voltage converter, a reference voltage source, an analog-to-digital converter, an information processing and control unit, the third output of the reference voltage source being connected to the third input of the current-voltage converter, the first output to the first the input of the analog-to-digital converter, the second output - with the second input of the analog-to-digital converter, the first and second outputs of which are connected, respectively, to the first and second outputs of the control and processing unit inf The application additionally contains a voltage adder, a control unit, a unit of switching elements, the outputs of which are connected to an external controlled unit, the input inputs are connected to the ninth and tenth outputs of the control and information processing unit, the first and second outputs of the external controlled circuit are connected, respectively , to the first and second input of the current-voltage converter, the first output of which is connected to the second input of the voltage adder, the first input of which is connected to the third output of the reference voltage source, and the output d -; the third input of the analog-to-digital converter, the third, fourth and fifth outputs of which

connected, respectively, with the first, second and third input of the control unit, the address and control inputs of which, respectively, are connected to the address and control output of the control unit and

0 information processing, and the output to the third input of the control unit and information processing, the fourth to seventh outputs of which are connected, respectively, to the first to fourth control inputs

5 current-voltage converters, the eighth output to the control input of the voltage adder, and from the fifteenth to twentieth outputs, respectively, with the first to eighth control inputs

0 sources of reference voltages, from the eleventh to fourteenth outputs - respectively, from the tenth to twelfth control inputs of the source of reference voltages.

5 The control unit contains a comparison element from the third to fifth elements AND, a second trigger, wherein the first and third inputs of the block are connected to the perch and second input of the comparison element, the output of which is keyed to the second input of the third element And, the first input of which is connected to the second input of the block and the output goes to the input S of the second trigger, the input R of which is connected to the output of the fifth element AND, and the output to the third to 5th input of the fourth element And, the output of which is connected to the output of the block, the address input of the block is connected to the first input of the fifth element AND and with the third input of the fourth element AND, the control input of the block

0 is connected to the second input of the fourth and fifth element I.

Figure 1 shows the structural diagram of the device; in FIG. 2 is a diagram of a current-voltage converter; in FIG. 3-circuit diagram M5 of a voltage motor; ia FIG. 4 is a diagram of a reference voltage source; in FIG. 5 is a diagram of an analog-to-digital converter; in FIG. 6 is a diagram of a control unit; in FIG. 7 is a diagram of a control and processing unit

0 information; in FIG. 8 is a diagram of a block of switching elements; in FIG. 9 is a timing diagram of a device; in FIG. 10-14 show a functioning algorithm of the device.

5 The device for monitoring the current (Fig. 1) comprises a current-to-voltage converter 1, a voltage adder 2, a reference voltage source 3, an analog-to-digital converter 4, a control unit 5, an information processing control unit b, a barrel

7 switching elements, which is used if it is necessary to provide current measurement without breaking the input circuit.

In FIG. 1 presents the elements of the external circuit 8. containing resistors 8.1

8.rHk.

The current-voltage converter unit 1 (FIG. 2) contains a first operational amplifier 9. first resistance 10, second resistance 11. third resistance 12. fourth resistance 13, first electronic key 14, second electronic key 15, third electronic key 16 the fourth electronic key 17, the fifth electronic key 18, the sixth electronic key 19, the seventh electronic key 20, the eighth electronic key 21.

The voltage adder 2 (FIG. 3) comprises a second operational amplifier 22, a fifth resistance 23, a third operational amplifier 24, a sixth resistance 25, a seventh resistance 26, a fourth operational amplifier 27, an eighth resistance 28, a fifth operational amplifier 29, and a ninth resistance 30, ninth electronic key 31.

The reference voltage source 3 (FIG. 4) comprises a reference voltage source 32, a tenth electronic switch 33, an eleventh electronic switch 34, a twelfth electronic switch 35, a thirteenth electronic switch 26, a tenth resistance 37, an eleventh resistance 38, and a twelfth resistance 39. thirteenth resistance 40, fourteenth resistance 41, p fifteenth resistance 42, sixteenth resistance 43, seventeenth resistance 44, eighteenth resistance 45, fourteenth electronic key 46, fifth t-eleventh electronic key 47, w the eleventh electronic key 48, the seventeenth electronic key 49, the eighteenth electronic key 50, the nineteenth electronic key 51, the twentieth electronic key 52, the twentieth electronic key 53.

A / D converter 4 (FIG. 5) comprises a sixth operational amplifier 54, a seventh operational amplifier 55, a first HE element 56, a first delay element 57, a first AND element 58, a nineteenth resistance 59, a twentieth resistance 60, a first diode 61, con - the capacitor 62, the twenty-first resistance 63, the second diode 64, the first OR element 65, the twenty-second electronic key 66, the seventh operational amplifier 67, the twenty-second resistance 68, the second HE element 69, the second delay element 70, the second AND element 71, the generator

72 pulses, a frequency divider 73, a pulse shaper 74, a first trigger 75, a pulse counter 76, a first AND / NOT 77 element.

The control unit 5 (Fig. 6) comprises a comparison element 78, a third AND element 79, a second trigger 80, a fourth And element 81, a fifth And element 82.

The control and information processing unit 6 (Fig. 7) contains a microprocessor 83. A pulse generator 84, a control node 85, a read-only memory node 86, a first group of AND elements 87, a first register 88, a second group of elements AND 89 a decoder 90, a second register 91. the third group of elements AND 92, the display unit 93, the third register 94.

Block 7 switching elements (Fig) contains a twenty-third electronic key 95, a twenty-fourth electronic key 96.

In FIG. 9 is a timing chart of signals generated at control points of the device.

In FIG. 10-14 is an algorithm for operating the device.

The current-voltage converter 1 is connected to the first and second inputs of the external controlled circuit 8 by its first and second inputs. The first output of unit 1 is connected to the second input of voltage adder 2. The third input of unit 1 is connected to the third output of reference voltage source 3. The control inputs of unit 1 are connected to the fourth, fifth, sixth, seventh output of the information control and processing unit 6. The output of voltage combiner 2 is connected to the third input of analog-to-digital converter 4. The first input of unit 2 is connected to the third output of reference voltage source 3, and the control input is connected to the eighth output of information and control unit 6. The first and second outputs of the analog-to-digital converter 4 are connected to the corresponding inputs of the control and information processing unit b, and the third, fourth and fifth outputs are connected to the first, second and third inputs of the control unit 5. The first and second inputs of block 4 are connected to the corresponding outputs of the reference voltage source 3, the first to eighth control inputs of which are connected from the fifteenth to the twenty second outputs, respectively, and from the ninth to twelfth control inputs of the block 3 are connected from the eleventh to fourteenth outputs of the control and information processing unit 6. The first output of control block 5 is connected to the third input of block b, and the fourth and fifth inputs are with the first, second output of block 6. The control inputs of block 7 of switching elements are connected to the fourth, fifth output of block b, respectively. The outputs of block 7 are connected to the inputs of an external controlled circuit 8.

The first and third inputs of the control unit 5 are connected to the first and second input of the comparison element 78, the output of which is connected to the second input of the element And 79. The second input of the block 5 is connected to the first input of the element 79, the output of which is connected to the input S of the trigger 80. Direct output trigger 80 is connected to the first input of the AND element 81. The fourth input of the block is connected to the first input of the AND element 82 and to the third input of the element 81. The fifth input of the block is connected to the second input of the element 82, the output of which is connected to the input R of the trigger 80. The second input of the element 81 connected to the fifth block input, and output - with the first block output.

Converter 1 current-voltage (Fig.2) works as follows. From input 1 to the operational amplifier 9 operating in the constant current amplifier mode, a measured constant current (I) is supplied. It is converted to a voltage proportional to it, calculated by the formula.

U2 I Rl,

where Ua is the output voltage of the operational amplifier 9;

RI is the reference resistance (10-13).

By means of the control actions arriving at the inputs qi ,. Mq4 switching elements 14-21 and resistances

1013, one of

four ranges of measurements. During operation of the voltage adder 2 (Fig. 3), the electronic switch 31 opens when the unit 4 is checked.

The reference voltage source 3 (FIG. 4) operates in accordance with the logic determined by the information control and processing unit b, which is represented by the algorithm shown in FIG. 10-14. The control signals Li, ... La act on the corresponding electronic switches 46-53, which are used to check the operation of unit 1 in four ranges, switching output 3 with the corresponding resistances. The electronic switches 33.34, in combination with the resistance 37, are used in block 4 to generate a linearly varying voltage of positive or negative polarity. Electronic keys 35 and 36 are used to check unit 4 for

operability from the source of the reference voltage 32, while the electronic switch 31 of the unit 2 opens upon arrival of the control signal qs.

Analog-Digital Voltage Plots

transducer 4 (FIG. 5) is shown in FIG. 9.

Block 5 control (Fig.6) works as follows. At the time the trigger arrives

0 75 of block 4 to a single state from inputs 1, 3, signals are received that are opposite in phase, having the shape of a meander, while the comparison element 78 does not work (see the time diagram in Fig. 9). it

5 indicates the correct functioning of unit 4. If this condition is violated, element 78 is activated and opens element And 79 if a signal from input 2 of the block is present at its first input. The output signal from element 79 transfers the flip-flop 80 to a single state. The output signal from it opens the element And 81 if there is a corresponding code on the read bus and address bus. The signal received from the output of the And 81 element indicates the presence of a malfunction in block 4 or the presence of a malfunction in the And / NOT 77 element.

Blot 7 switching elements (Fig. 8) operate as follows. According to the control signals qe or q coming from block b, the externally controlled circuit of block 8, with its terminals C or D, is shorted to the case. This is done with

5 using electronic keys 95 and 96.

The device operates as follows (Fig. 10-14). The device has three operating modes:

Control unit self-test mode

0 and information processing;

Mode 1 (measurement mode in a predetermined range);

Mode 2 (mode with automatic search for the required measuring range).

5

In the self-test mode (Fig. 10) of the information management and processing unit b, an initial start-up program is executed. During the implementation of which the correct execution of microprocessor instructions is checked, the health of the read-only memory node is checked by calculating the checksum and comparison with the required one, and the registers are checked for health by writing and reading information into them. An analog-to-digital converter is also tested here. After this, reading is made from the node 85 of the controls of mode 1 or mode 2 of the operation of the device.

When reading mode 1 (Fig. 11), i.e. The measurement mode in the specified range checks the operability of the current-to-voltage converter 1 by sequentially measuring the voltage value iUnTH over four ranges, which are set using electronic keys in block 3.

Voltage plots illustrating the operation of the device in this mode are shown in FIG. 9. The digital code obtained as a result of the conversion, from the output 2 of block 4, is transmitted via the information bus to block b for analysis and decision making. When the condition

Uion mln lUnaM UvioH max

. verification of the correct functioning of the current-voltage converter 1 in the first mode is ongoing. When the condition

Wet Fri min lUnTH UaT Fri max

where On ™ is the voltage at the output of block 2;

Wet Fri min. net ptn max - ranges of voltage changes taken from output 3 of block 3,

the electronic keys are disabled in blocks 1 and 3.

Further, in accordance with the algorithm shown in FIG. 12. The device proceeds to measure the current x in the power supply circuit through the resistance of the external controlled circuit 8. To calculate the current 1X, we use the expression

Un r7

Un

Ri

Un, Un

RJ F

And -l2 Il + l2

where Un is the voltage of the power source;

RI Re ..-. + Re.n-i - the sum of the resistances of one of the arms of an external controlled circuit;

Rj R8.n + R8.n-n + ... + R8.n + k is the sum of the resistances of the opposite arm of the controlled circuit;

And-current flowing through the resistance circuit RJ, provided that the voltage Un is applied to it;

2 - current flowing through the target of resistances RI, provided that the voltage Un is applied to it.

To determine in circuit 1X, two independent currents I and 12 must be measured. To do this, it is necessary to short circuit one of the points D or C in block 8 with electronic keys 95 and 96 in block 7. For measuring current h it is D, for measuring current 2 - C. One of the working conditions

This device is a power supply Un, independent of the meter case, in block C. The operational amplifier 9 of block 1 operates in the constant current amplifier mode and has a very small input impedance, much smaller than RI and RJ. During the execution of the algorithm of the device’s functioning, blocks 1 and 2 are checked after each current measurement. The calculation of the current x occurs in block 6.

When setting the second mode, i.e. of the measurement range search mode, measurement of Ni 2 currents and 1X 5 calculation is carried out based on the algorithms shown in Figs. 13, 14.

At the time of measuring the current and converting the signal in block A, block 5 continuously monitors the parameters 0 of the nodes 72-75, 77 of the analog-to-digital converter.

The advantages of the device are:

Increasing the reliability of the operation of the device by increasing the reliability of the operation of the current-to-voltage converter 1; increasing reliability is proportional to the probability of a malfunction occurring in block 1;

increasing the reliability of the operation of the device by increasing the reliability of the operation of the analog-to-digital converter 4; an increase in reliability is achieved through the organization of control of the magnitude of the voltages 5 + IONGi-IONG;

increasing the reliability of the operation of the device by an amount proportional to the likelihood of a malfunction in the elements 72, 73, 74, 77 0 of the device;

reducing the time for checking the test object by measuring the current without breaking the controlled circuit;

reduction of the verification time of the test object 5 due to automatic search of the measurement range 1X.

The claims

A current monitoring device comprising a current-voltage converter, 0 reference voltage source, an analog-to-digital converter, a control and information processing unit, the first and second outputs of the reference voltage source being connected respectively to the first and second inputs of the analog digital converter, and the third output with the third input of the current-voltage converter, the first and second outputs of the analog-to-digital converter are connected respectively to the first and

the second inputs of the control unit and information processing, characterized in that, in order to increase AND, the RS-trigger, the first and second inputs of the comparison element are respectively the third and first inputs of the control unit, and the output of the comparison element is connected to the second input of the first logic element And, the first input of which is the second input of the control unit, and the output is connected to the S-input of the RS-flip-flop, the R-input of which is connected to the output of the second logical element And, and the output - to the third input of the third logical element And, the output to which is the output of the control unit, the first and

the third inputs of the second and third logical elements AND are respectively connected to the address input of the control unit, and the second inputs of the second and third logical elements And are connected to the control input of the control unit.

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