RU2026561C1 - Direct-current system ground detector - Google Patents

Direct-current system ground detector Download PDF

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RU2026561C1
RU2026561C1 SU5005490A RU2026561C1 RU 2026561 C1 RU2026561 C1 RU 2026561C1 SU 5005490 A SU5005490 A SU 5005490A RU 2026561 C1 RU2026561 C1 RU 2026561C1
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measurement
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В.И. Банщиков
В.А. Наумов
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Завод экспериментального машиностроения научно-производственного объединения "Энергия" им.акад.С.П.Королева
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Abstract

FIELD: instrumentation engineering. SUBSTANCE: offered device, its analogs and prototype are noted for their ability to measure during detected time instants equivalent insulation resistance (Rи.э) of poles of mains under check to ground; each time before taking measurements electric bridge two of whose arms are essentially Rи.э components of insulation resistance and two other ones are sides of controlled resistive voltage divider, is balanced out; for each measurement, d.c. voltage source is connected across two diagonally opposite terminals of bridge with indicating resistor by means of switching component. Each time after measurements calculations are made using equation given in description of invention. EFFECT: improved validity of measurement results, improved electric safety due to precise determination of measurement time as result of continuous balancing of bridge at any step of device operation, timely measurement at slow variation of Rи.э, generation of noise-immune signals indicating necessity of subsequent measurements or transients in main under check. 2 cl, 1 dwg

Description

 The invention relates to measuring technology, in particular to devices for measuring insulation resistance relative to the hull (earth), under the operating voltage of two-wire DC networks, and can be used in electrical tests and operation of various technical objects, such as spacecraft, ships, characteristic features of DC networks which are their complexity and significant branching, and as a consequence, the large capacity of live parts tionary housing, as well as a wide range of variation of the resistance and capacitance of insulation in time determined by the dynamics of changes in the composition of controlled network when activating and deactivating power consumers.
 A device for automatically controlling the insulation resistance of direct current networks, comprising a DC bridge, two arms of which represent the insulation resistance of each pole of the controlled network relative to the ground, and the other two, included potentiometric resistance, a tracking system with an amplifier, a recording system consisting of an amplifier, an indicator and included in the diagonal of the aforementioned bridge of the measuring source and signal resistance, as well as two keys rigidly interconnected with normally closed and normally open contacts and a light source, which is connected through a servo amplifier and normally closed contacts of these keys to potentiometrically connected resistances made in the form of a resistive divider of constant resistance and variable controlled resistance, for example a photoresistor, and the indicator is connected through an amplifier of the recording system and normally open contacts of the keys to the signal resistance [1].
This device allows periodic measurements of the equivalent insulation resistance (R I.E. ) of the monitored network with storing the result of each last measurement, and before each measurement cycle, a bridge balancing cycle is determined, determined by the recharge time of the capacities of the monitored network.
The main and significant drawback of such a device is its unacceptably low measurement accuracy. The bridge balancing cycle can never end with its actual equilibrium, since the output voltage of the amplifier of the servo system with a storage capacitor monitors the input voltage of the specified amplifier all the time while the cycle of balancing the bridge is carried out. Therefore, the end of each balancing of the bridge for different values of R and. should be characterized by a zero value of the voltage at the said capacitor for various corresponding values of the output voltage of the amplifier of the servo system, which is not feasible (G. Korn and T. Korn. Electronic analog and analog-digital computers, M.; Mir, 1968, p. 47- 59). In addition, the specified known device has other disadvantages:
- measurements of R.I. are carried out without taking into account the influence on their result of two bridge arms representing potentiometric resistance included, made in the form of a resistive divider of constant resistance and variable controlled resistance, which also reduces the measurement accuracy. The resistances of the indicated resistive divider in order to obtain permissible measurement errors should be much smaller than the insulation resistances of the poles of the controlled network (so that they can be neglected), which is unacceptable for most objects due to the deterioration of electrical safety during measurement;
- during the measurement cycle, the unbalance of the bridge uncontrolled by the device is possible due to a change in the value of R i.e. after the corresponding switching in the controlled network, which distorts the measurement results, i.e., reduces the reliability of the control;
low noise immunity of the device from transients in a controlled network caused by the dynamics of changes in its composition and characterized by overcharging of the capacities of this network. If the fact of the presence of interference in the measurement cycle cannot be detected even by the movement of the indicator arrow due to its inertia, then when carrying out the bridge balancing cycle under the conditions of the indicated transient processes due to interference, it is not possible to accurately determine the necessary moment of switching into the measurement cycle, t. e. the moment when the bridge is really balanced, as a result of which the transition to the measurement cycle is possible with an unbalanced bridge, which also distorts the measurement results.
 It is also known a device for measuring the insulation resistance of direct current networks, containing a bridge, two arms of which are formed by the insulation resistances of each pole relative to the ground, and two other alternating resistors connected in series with an indicator, a switch and a DC voltage source connected to an input terminal, which is one of the vertices of the bridge, as well as a differentiating element, a polarity inverter, a threshold element, a delay element, a key, an OR element, and two channels, each of which consists of it consists of a key, an OR element, a trigger, and a delay element, while the trigger output of each channel is connected through the first OR element to the control input of the first key and through the corresponding delay element to the control input of the key of another channel, and the key and the OR element are connected to the trigger inputs , the input of the differentiating element is connected to the input terminal, which is one of the vertices of the bridge, and an indicator is connected to the potential input of the first key, the second input of the differentiating element is connected to the output of the first key and simultaneously to to the top of the bridge, and the output of the differentiating element is simultaneously connected to the key of the first channel and to one of the inputs of the OR element of the second channel, through a polarity inverter - to one of the inputs of the OR element of the first channel and the key of the second channel through the first delay element and the threshold element connected in series - with another input of the OR element of the first channel and another input of the OR element of the second channel [2].
This device also allows periodic measurements of R i.e. , each of which is performed in two stages: balancing the bridge and measuring, respectively. In this case, the measurement results in the presence of interference from the aforementioned transients are produced with higher reliability compared to the previously considered analog. In case of any, including private switching on and off of consumers of the controlled network during the process of these two stages, the interference is monitored and the transition process of establishing a new voltage (current) value on the sections of the controlled network when capacitor recharge currents flow in them and when the device indicator is turned off by opening the key in the diagonal of the bridge.
The specified known device has the following disadvantages:
- measurements of R.I. are carried out without taking into account the influence on their result of two variable resistors forming a voltage divider, which reduces the measurement accuracy. The requirements and the possibility of using for the values of the values of the indicated variable resistors are the same as for similar resistors in the analogue considered earlier;
- during the measurement phase, the unbalance of the bridge uncontrolled by the device is possible due to a change in the value of R i.e. after the corresponding switching in the controlled network, which distorts the measurement results, i.e., reduces the reliability of the control;
- insufficiently complete noise immunity of the device. In the process of performing the stage of balancing the bridge, a protective opening of the key in its diagonal from interference in the controlled network is possible, which can be perceived as the equilibrium of the bridge. The subsequent transition to the measurement step in this case distorts the measurement results. In addition, the signal of the trailing edge of interference of any polarity initiates the closure of the specified key until the end of the transient process that caused the interference, because the closure of this key occurs when the device generates a signal of the trailing edge of the noise, and the noise, changing exponentially, has not yet taken a value close to zero. It also reduces the reliability of the control during the measurement phase;
- the complexity of the electrical circuit of the device to identify the presence of interference in a controlled network is overestimated.
 Closest to the proposed invention in technical essence is a device for measuring the insulation resistance of direct current electric networks, comprising a bridge, the two arms of which are formed by the insulation resistances of each pole of the network relative to the housing, and the other two by the arms of the potentiometer, current sensor, reference voltage source, two keys , the first and second threshold elements, the OR element, a switch, the first output of which is connected to the housing, and the input to the first input of the voltage meter, to the output of which о an indicator is connected, the first differentiating unit, the output of which is connected to the input of the polarity inverter, a control unit, four outputs of which are connected to the controlled inputs of two keys, a switch, and to the middle output of the potentiometer, the second differentiating block, element And, and a timer, and to the middle output of the potentiometer connected the second output of the switch and the input of the current sensor, the output of which is connected to the second input of the voltage meter and the first output of the source of operational voltage, the second output of which is through the first the beam is connected to the first output of the switch, the output of the inverter of polarity is connected to the input of the first threshold element, the output of which is connected to the first input of the element And, the second input of which is connected to the output of the second threshold element, the input of which is connected to the output of the second differentiating unit, the input of which is connected to the top the bridge formed by the first arm of the potentiometer and the insulation resistance of the first pole of the network relative to the housing, the input of the first differentiating unit is connected to the top of the bridge formed by the second with the left arm of the potentiometer and the insulation resistance of the second pole of the network relative to the housing, the output of the AND element is connected to the input of the second key, the output of which is connected to the first input of the OR element, the output of which is connected to the input of the control unit, and the second input to the output of the timer, the two inputs of which are connected with the fifth and sixth outputs of the control unit [3].
This device allows measurements to be made at detected time points R i.e. , before each of which the bridge is balanced, and their implementation is initiated by the corresponding output signals of the first and second differentiating blocks or by the output signal of the timer and is performed using the control unit.
After connecting the device to the monitored network using the control unit, the first key and switch are set to a position that enables the inclusion of a voltage meter in the diagonal of the bridge. Then, by changing the values of the shoulders of the potentiometer using the control unit, the bridge is balanced until the voltage values at the vertices of the bridge formed by the common point of the shoulders of the potentiometer and the housing are balanced. After that, according to the signal from the control unit, to the controlled inputs of the first key and switch, the operating voltage source is connected to the indicated diagonal of the bridge instead of the voltage meter, and the voltage meter is connected to the output of the current sensor. The magnitude of the voltage drop across the current sensor from the current of the source of operational voltage, taking into account the small values of the resistance values of the arms of the potentiometer (which can be neglected), is uniquely associated with the value of R I.e. , which is indicated on the indicator. At the same time, both at the stage of balancing the bridge and at the measurement stage, an operator is used as a feedback element in the control loop. In the first case, to fix the moment of balancing the stress values at the tops of the bridge at the zero reading of the indicator, in the second case, to take the measurement result from the indicator and fix the moment of its completion.
At the same time and after measuring R IE the voltage values at the poles of the controlled network with respect to the housing are differentiated by the first and second differentiating blocks. However, at the stages of balancing the bridge and measuring, the output of the AND element with the help of the second key is disconnected from the input of the control unit, and therefore no information from the joint operation of these differentiating blocks comes to its input. After the measurement is completed, the second key is closed by the signal from the control unit and the timer starts. The tracking mode begins for the constancy of the state of the insulation resistances of the poles of the controlled network.
 If the voltage at the poles of the monitored network remains unchanged or changes simultaneously in one direction, this means that the values of insulation resistances remain unchanged, since the change in voltage is caused either by a change in load or by some other reasons not related to the state of insulation. In this case, the next next measurement does not make sense and you can use the result of the previous measurement.
 If the first and second differentiating blocks detect voltage changes at the poles and establish that these changes occur in different directions, then the bipolar signals from the outputs of these differentiating blocks are made unipolar with a polarity inverter and cause both threshold elements to trip, and the output of the And element signal to the control unit for the next measurement.
 In order to eliminate the omission of the case when the insulation resistance of both poles at the same time decreases or increases by the same amount (when voltage changes at the poles of the controlled network do not occur), and also exclude the case of non-response to a slow change in the value of insulation resistance at which the rate of change voltage at the poles of the network will be insufficient for its fixation by the said differentiating blocks, it is provided after each next measurement to start the timer, ing between the measurements gives a control unit the expiration of the time signal maximum pause. If, during the pause determined by the timer, the signal of the element And about the need for an extraordinary measurement arrives at the control unit, the timer returns to the initial state by the signal from the control unit and will be restarted only after this measurement.
This device is characterized by the following disadvantages:
- low accuracy in determining the need for measurements and the time of measurements. In the process of monitoring the state of the insulation resistance of the poles of the controlled network, the values of the indicated resistances before and after transients in this network are often almost the same, which is especially typical for complex technical objects containing controlled networks, for example, spacecraft, with a large number of switched circuits and consumers. In this case, the first and second differentiating blocks, fixing the interference from these transients, causing voltage changes at the poles of the network in relation to the housing in different directions, initiate the next measurement when it is not necessary, since it is possible to use the result of the previous measurement. This unreasonably worsens electrical safety during measurement and increases the amount of interference introduced into the controlled network. In addition, with the mentioned slow change in the values of the insulation resistances of the poles of the monitored network relative to the housing, the start of the next measurement initiates a timer with the output signal for the expiration of the maximum pause time between measurements. In this case, unacceptable values of R and. will be recorded later than their occurrence, which does not fully ensure the fire safety of the controlled network and the electrical safety of staff. In addition, during the measurement phase, the unbalance of the bridge uncontrolled by the device is possible due to a change in the value of R i.e. after corresponding switching in a controlled network. Moreover, in the device, the tracking mode for the invariance of the insulation resistance of the poles of the monitored network is turned off, which does not ensure the timely conduct of the next measurement. This distorts the measurement results, i.e. reduces the reliability of control. The indicated interference from the transients of the controlled network caused by the dynamics of changes in its composition during switching of electricity consumers reflects the overcharging of the capacities of this network distributed in it relative to the housing as an integral part of the insulation of its current-carrying parts. During the implementation of the stage of balancing the bridge, it is possible to false balance the voltage values at the tops of the bridge from these interference, as a result of which the transition to the measurement cycle occurs prematurely, i.e. with an unbalanced bridge, which also distorts the measurement results;
- measurements of R.I. are carried out without taking into account the influence on their result of two arms of the bridge formed by the arms of the potentiometer, which reduces the accuracy of the measurement. The arm resistances of the indicated potentiometer in order to obtain permissible measurement errors should be much smaller than the insulation resistances of the poles of the monitored network (so that or could be neglected), which is unacceptable for most objects, for example, due to the deterioration of electrical safety during measurement. According to electrical safety conditions, the resistance values of the shoulders of the indicated potentiometer tend to be chosen as large as possible, however, a relatively accurate graduation of the indicator is possible only when the values of these resistances tend to zero;
- the device does not provide continuity in the initiation of the output data, because after each next measurement step, the indicator loses the measurement results by switching the voltage meter, which causes inconvenience in operation.
The aim of the invention is to increase the reliability and electrical safety when measuring due to a more accurate determination of the time of measurement. Other goals are to facilitate monitoring of the isolation state of the network by ensuring continuity in the display of current values of R and. , as well as improving the accuracy and electrical safety during measurement by ensuring that the influence on the measurement result of two bridge arms formed by the arms of the potentiometer is taken into account.
 This is achieved by the fact that in the known device containing the first key and the first OR element connected in series, the output of which is connected to the first input of the control unit, the second and third inputs of which are connected respectively to the first and second outputs of the first threshold element, the first and second outputs, respectively to the start and reset inputs of the timer, the third output is connected to the control inputs of the second key and the first switch, and the fourth output is connected to the control input of the first controlled resistor of the first divider voltage, the other arm of which is formed by the first resistor, the second threshold element, the input of which is connected to the output of the differentiating unit, the first input terminal of which is connected to the terminal for connecting to the body of the control object connected through a second key, a DC voltage source and a current sensor connected in series the middle terminal of the first voltage divider, the extreme terminals of which are connected respectively to the terminals for connecting to the poles of the controlled network, the display unit, the buffer will repeat Only voltage, inverter and AND element, analog-to-digital converter, division block, subtractor, adder, reference voltage source, pulse generator, second switch, four delay elements, third, fourth and fifth keys, second, third, fourth and fifth elements are introduced OR, a second voltage divider formed by a second controlled resistor identical to the first controlled resistor and a second resistor identical to the first resistor, with the average output of the first voltage divider directly and through the buffer The voltage follower is connected respectively to the second input terminal of the differentiating unit and the terminal for connecting to the body of the test object, the output of the voltage buffer follower is connected to the first inputs of the adder and the division unit, the second inputs of which are connected to the output of the current sensor, the output of the division unit is connected to the first input of the subtractor , the second input of which is connected to a common bus through a second controlled resistor, and through the second resistor to the first output of the reference voltage source, whose second output is is dined with the third input of the adder, the output of which and the output of the voltage buffer follower are connected respectively to the first and second information inputs of the first switch, the output of which is connected to the input of the first threshold element, the first and second outputs of which are connected respectively to the first and second inputs of the second OR element, the output which through the first delay element is connected to the signal input of the second switch, the first output of which through the third key is connected to the fourth input of the control unit and to the second delay element, the output of which through the third OR element is connected to the first input of the AND element, the control input of the first key and the inverter input, the output of which is connected to the second input of the first OR element, the second output of the second switch through the fourth OR element and the fourth key connected in series to the fifth input of the control unit, the fourth output of which is connected to the control input of the second controlled resistor, and the third output directly and through the fifth key and the pulse generator is connected respectively to the control input of the second switch and the clock input of the analog-to-digital converter, the analog input of which is connected to the output of the subtractor, the ready output through the third delay element is connected to the second input of the fourth OR element, and the information outputs are connected to the inputs of the digital display unit, the first and second outputs of the second threshold element are connected respectively to the first and second inputs of the fifth OR element, the output of which through the fourth element is delayed LCD is connected to the control inputs of the third, fourth, fifth keys and the second input of the AND element, the output of which is connected to the second input of the third OR element, the timer output is connected to the signal input of the first key.
 In this set of distinctive features from the prototype of the signs and the aforementioned set of well-known features of the analogue of ed. USSR N 482694 identical signs are a voltage divider formed by a variable controlled resistor and a constant resistor, and keys, and in comparison of these distinctive signs and known signs of an analogue by author. St. USSR N 606143 identical signs are a voltage divider, switch, delay elements, keys and OR elements. Other analogues (except the prototype) are less close in their technical essence to the claimed solution, and with the continuation of the specified comparative analysis with their known features, the identity of the features also appears only for part of the totality of the distinctive features of the developed solution.
 The control unit in the proposed device contains a reversible counter, the Addition and Subtraction control inputs of which are the second and third inputs of the control unit, a digital-to-analog converter, the output of which is the fourth output of the control unit, a pulse generator, the input of which is the fourth input of the control unit, trigger, a single input and direct output of which are respectively the first input and the third output of the control unit, the element And, the first input of which is the fifth input of the unit control window, and an inverter, the output of which is the first output of the control unit, the second output and the first input of which are combined, and the output of the pulse generator is connected to the counting input of the reversible counter, the outputs of which are connected to the inputs of the digital-to-analog converter, the direct output of the trigger is connected to the input of the inverter and the second input of the AND element, the output of which is connected to the zero input of the trigger.
The specified set of newly introduced elements with their connections and distinctive features determines the manifestation of new technical properties that characterize the proposed device in comparison with the device adopted for the prototype:
- the property of continuous balancing of the measuring bridge circuit (the two arms of which are formed by the insulation resistances of each pole of the network relative to the housing, and the other two by the arms of the first voltage divider) throughout the entire device’s operation, including the measurement steps with a DC voltage source connected in the diagonal of the bridge, which prevents uncontrolled imbalance of the bridge, which is possible in the prototype device when performing the measurement step due to the newly established values of the isol the poles of the network after the corresponding switching in the control object;
- the property of continuously displaying the current values of the value of R i.e. throughout the entire operation of the device, including the stages of balancing the bridge, which facilitates monitoring the state of network isolation;
- the property of timely conducting the stages of balancing the bridge and measuring both with an extremely slow change in the value of insulation resistance with respect to the housing of any pole, and with increased (including the maximum possible) dynamics of changes in the composition of the controlled network due to switching consumers of electricity;
- the property of generating noise-immune control signals that reflect the need for regular measurements or the need to switch from the stage of balancing the bridge to the measurement stage for any nature of transients in the controlled network. The generation of false control signals for the next measurements is prevented, which is characteristic of the prototype device, at the same values of the insulation poles of the network poles before and after transients, the interference from which causes a change in the voltage at the network poles with respect to the housing in different directions. In addition, the possibility of false transitions from the stage of balancing the bridge to the stage of measurement characteristic of the device - the prototype is prevented in the presence of interference causing false balancing of the voltage values at the vertices of the measuring bridge circuit;
- the property of taking measurements taking into account the influence on the result of the resistance of the shoulders of the first voltage divider, which removes the restrictions on the choice of the maximum values of the values of these resistances, which in the prototype device should be significantly less than the controlled insulation resistances.
 The presence of these new properties in the proposed device leads to the achievement of a new useful result, which is expressed in improving the accuracy, reliability and electrical safety during measurement, as well as in facilitating monitoring of the insulation state of the network.
Improving the accuracy of the measurement is expressed in the implementation of measurements of R and. taking into account the influence on the result of the resistance of the shoulders of the first voltage divider.
Improving the reliability of the measurement is expressed in preventing the influence on the measurement results:
- unbalance of the bridge, which is possible in the measurement process due to the newly established values of the insulation poles of the network poles after the corresponding switching in the control object;
- interference from transients of the controlled network, causing false balancing of the voltage values at the vertices of the measuring bridge circuit.
Increased electrical safety during measurement is expressed by:
- in the timely issuance of measurement results, including unacceptable, at any low rate of change in the value of insulation resistance with respect to the housing of any pole, which simultaneously increases the fire safety of the controlled network;
- to reduce the number of measurement cycles by preventing the inherent prototype device from initiating them from those transients, interference from which causes a change in the voltage at the poles of the network in relation to the housing in different directions at the same values of the insulation resistance of the poles of the network before and after these transients, which simultaneously reduces the amount of interference introduced into the controlled network.
Facilitation of monitoring the state of network isolation is expressed in providing continuous indication of the current values of R and. throughout the entire life of the device.
 The drawing shows a functional diagram of the proposed device.
 It contains a control unit 1, a timer 2, a differentiating unit 3, an analog-to-digital converter 4, a division unit 5, a subtractor 6, an adder 7, first 8 and second 9 threshold elements, a pulse generator 10, a first voltage repeater 11, a current sensor 12 made in the form of a parallel-connected signal resistor 13 and a second voltage buffer repeater 14, a DC voltage source 15, a reference voltage source 16, a first voltage divider 17, made in the form of a first controlled a resistor 18 and a first resistor 19, a second voltage divider 20, made in the form of series-connected second controlled resistor 21 and a second resistor 22, an indication unit 23, an inverter 24, an And 25 element, a first 26, a second 27, a third 28 and a fourth 29 delay elements , first 30 and second 31 switches, first 32, second 33, third 34, fourth 35 and fifth 36 keys, first 37, second 38, third 39, fourth 40 and fifth 41 OR elements, terminals 42 and 43 for connecting to the poles of the controlled network terminal 44 for connection to the body of the object of control.
The drawing also shows the equivalent circuit 45 of a controlled two-wire DC network, containing R (+) , R (-) and C 1 , C 2 - insulation resistance and capacitance, respectively, of the plus and minus poles of the network relative to the housing, R n - equivalent load resistance.
The extreme conclusions of the first voltage divider 17 are connected respectively to the terminals 42 and 43 for connecting to the poles of the controlled network and with their working (connected) state of resistance R (+) and R (-) of the insulation of the controlled network, the first controlled resistor 18 and the first resistor 19 form balanced bridge, in the diagonal of which (points A and B) a measuring circuit is connected, including a signal resistor 13 connected in series, a DC voltage source 15, a second switch 33 and a terminal 44 for connecting to the body of the monitoring object I. Between the middle terminal of the first voltage divider 17 and the terminal 44 for connecting to the control object case, a differentiating unit 3 and a first voltage buffer follower 11 are connected in parallel, the output of which is connected to the first inputs of the adder 7 and the division unit 5, the second inputs of which are connected to the output of the second buffer voltage follower 14, the output of the timer 2 through the first key 32 and the first OR element 37 connected in series to the first input of the control unit 1, the second and third inputs of which are connected respectively, to the first and second outputs of the first threshold element 8, the first and second outputs, respectively, to the inputs of the start and reset of timer 2, the third output is connected to the control and signal inputs of the second 33 and fifth 36 keys, respectively, as well as to the control inputs of the first 30 and second 31 switches, and the fourth output is to the control inputs of the first 18 and second 21 controlled resistors, the output of the division unit 5 is connected to the first input of the subtractor 6, the second input of which is connected to a common bus through a second controlled resistor 21, through the second resistor 22 - with the first output of the source 16 of the reference voltage, the second output of which is connected to the third input of the adder 7, the output of which and the output of the first buffer follower 11 voltage are connected respectively to the first and second information inputs of the first switch 30, the output of which is connected to the input of the first threshold element 8, the first and second outputs of which are connected respectively to the first and second inputs of the second element OR 38, the output of which is connected through the first delay element 26 to the signal input the ode of the second switch 31, the first output of which through the third key 34 is connected to the fourth input of the control unit 1 and the input of the second delay element 27, the output of which through the third element OR 39 is connected to the first input of the AND element 25, the control input of the first key 32 and the input of the inverter 24 the output of which is connected to the second input of the first OR element 37, the second output of the second switch 31 through the fourth element OR 40 connected in series and the fourth key 35 is connected to the fifth input of the control unit 1, the output of the fifth key 36 through the pulse generator 10 is connected to the clock input of the analog-to-digital converter 4, the analog input of which is connected to the output of the subtractor 6, the ready output through the third delay element 28 is connected to the second input of the fourth OR element 40, and the information outputs are connected to the inputs of the digital indication block 23, the output differentiating unit 3 is connected to the input of the second threshold element 9, the first and second outputs of which are connected respectively to the first and second inputs of the fifth element OR 41, the output of which is through the fourth element nt 29 delay connected to the control inputs of the third 34, fourth 35, fifth 36 keys and the second input of the element And 25, the output of which is connected to the second input of the third element OR 39.
 The control unit 1 contains a reversible counter 46, the Addition and Subtraction control inputs of which are the second and third inputs of the control unit 1, a digital-to-analog converter 47, the output of which is the fourth output of the control unit 1, a pulse generator 48, the input of which is the fourth input of the unit 1 control, trigger 49, a single input and direct output of which are respectively the first input and third output of the control unit 1, element And 50, the first input of which is the fifth input of the control unit 1 and an inverter 51, the output of which is the first output of the control unit 1, the second output and the first input of which are combined, the output of the pulse generator 48 being connected to the counting input of the counter 46, the outputs of which are connected to the inputs of the digital-to-analog converter 47, a direct trigger output 49 is connected to the input of the inverter 51 and the second input of the AND 50 element, the output of which is connected to the zero input of the trigger 49.
In the proposed device:
differentiating unit 3 on operational amplifiers (J. Kara. Design and manufacture of electronic equipment. - M .; Mir, 1986, pp. 356-360) with a high input impedance is used to generate bipolar output signals proportional to the rate of change of the input variable - the interference signal any polarity during transients in a controlled network with a changing structure;
each of the first 8 and second 9 threshold elements is two-output (see the book Conversion of information in analog-to-digital computing devices and systems. Edited by Petrov. M .; Mashinostroenie, 1973, pp. 85-93) with a deadband symmetrical with respect to zero level, the width of which slightly exceeds the step of the digital-to-analog converter 46 (voltage corresponding to the unit of the least significant bit), i.e. at the first and second outputs, single signals are generated when the amplitude of the input voltage exceeds the lower or upper limits of the specified dead band, respectively, and in other cases, the zero outputs are indicated at the indicated outputs;
the fourth delay element 29 (V. A. Kiblitsky. Control systems with contactless logic elements. - M .: Energia, 1976, p. 69-70, Fig. 32) serves to delay the trailing edge of its input signal for a time characterizing the completion of a predetermined degree of accuracy of the transient in the controlled network when the amplitude of the output signals of the differentiating block 3 decreases below the threshold levels of the second threshold element 9, forming its deadband, while preventing the device from generating false signals s of control at the end of transients in the monitored network due to the delay with respect to it of the end of the associated transient in the corresponding sets of device elements, the trailing edge of the specified input signal is additionally delayed so that the total duration of the output signal 1 of the fourth delay element 29 exceeded the total time of the corresponding transient in the controlled network and the accompanying transient in aggregates of elements s device responsive to start and stop transients in the system being monitored;
- the first 18 and second 21 controlled resistors, made, for example, in the form of identical optocouplers, each of which contains optically coupled radiation source 52 (53) and a photodetector 54 (55) with optically controlled conductivity;
- reversible counter 46 (Shlyandin V.M. Digital measuring transducers and devices, Moscow: Vysshaya Shkola, 1973, pp. 96-97, Fig. 2.26) serves to generate time-fixed signals for balancing the measuring bridge;
- a digital-to-analog converter 47 (Analog Integrated Circuits. Edited by J. Connelly, M .; Mir, 1977, pp. 328-343) serves to interface a digital reversible counter 46 with controlled resistors;
- timer 2 serves to generate a signal for the expiration of the maximum pause time between measurements (see the book by J. Kara, pp. 58-61, Fig. 3.6);
- the source of DC voltage 15 is stabilized, with an excitation potential (for example, 5V) equal to the reference potential at the second output of the source 16 of the reference voltage;
- the first 19 and second 22 resistors are identical to each other and the resistance of each of them is, for example, 1 MΩ, and the resistance of the signal resistor is 13-0.1 MΩ, and reference stability requirements are imposed to the indicated resistors (19, 22, 13) and accuracy;
- a source of 16 reference voltages is used to generate the following levels of reference potentials: 1V - at the first output (the specified voltage is used to simplify the calculation of R IE ), 5 V - at the second output (the specified voltage and output voltage of the source 15 must be stable one relative to another);
- each of the first 11 and second 14 buffer voltage followers is made in the form of a non-inverting follower on an operational amplifier with a single transmission coefficient and high input impedance (see the book of J. Carr, p. 108-110);
- division block 5 (Prager I.L. Electronic analog computers. - M .: Mashinostroenie, 1985, pp. 229-230, Fig. 116) is made with a transmission coefficient of 1/10, selected taking into account its correspondence to the signal resistance value a resistor 13 equal to 0.1 MΩ. The first and second inputs of the division unit 5 perceive the voltage as a dividend and a divider, respectively;
- the subtractor 6 (see the book by I.L. Prager, p. 74) is made with a unit transfer coefficient, and the first and second inputs of the subtractor 6 perceive the voltage as decreasing and subtracting, respectively;
an analog-to-digital converter 4 of the tracking type (see the book under the editorship of J. Connelly, pp. 342-343, 355-357) is used to convert the analog output of the calculation into a digital output word that initiates a digital display;
- adder 7, for example, in the form of a bipolar adder on an operational amplifier (see the book by J. Carr, pp. 107-108) is made with a single transmission coefficient for each input, and the first input of adder 7 is inverting, and the second and third inputs are non-inverting;
- block 23 indication (Biryukov SA Digital devices on integrated circuits. M; Radio and communication, 1987, p. 54-62) is used to display in a digital form the current values of R i.e. ;
- the first delay element 26 (Margolin Sh.M. Functional units of automatic control circuits. - M .; 1983, p. 38-39) serves to delay its input signal 1 along the leading edge, which ensures the delay in the moment of signal 1 from the first or second the outputs of the second switch 31, respectively, to the signal inputs of the third 34 or fourth 35 keys with respect to the moment signals 1 arrive at their control inputs in the event of interference from transients in a controlled network;
- the third delay element 28 serves to delay its input signal 1 on the leading edge, which ensures the delay of the moment of signal 1 from the ready output of the analog-to-digital converter 4 to the signal input of the fourth key 35 with respect to the moment the signal 1 arrives at its control input in case of interference from transients in a controlled network;
- the second delay element 27 serves to delay its input signal 1 on the trailing edge, which ensures the delay of the disappearance of signal 1 from the first input of the third element 39 OR relative to the moment the signal 1 arrives at its second input when interference from transients occurs in the controlled network;
- each of the generators 10 and 48 pulses is used to convert its input signal 1 into one or a sequence of pulses, the number of which determines the duration of the specified input signal (see the book by J. Carr, p. 226-228);
- each of the inverters 24 and 51 serves to generate an output pulse from the trailing edge of its input signal 1 (see the book by V. A. Kiblitsky, pp. 35-36, Fig. 14e);
- first 32, third 34, fourth 35 and fifth 36 keys are normally closed, i.e. shorted by a low level of control signals;
- the second key 33 is made on a relay with an NC contact, the controlled output of the relay winding is the control input of the key 33, and the first and second conclusions of the NC contact are switched conclusions of the key 33;
- elements 25, 50 AND, first 37, second 38, third 39, fourth 40 and fifth 41 elements OR - of a potential type;
- the first switch 30 is made on a relay with switching contacts, from which the output of the movable contact is the output of the switch 30, and the conclusions of the making and opening contacts are the first and second information inputs of the switch 30, the controlled output of the relay winding is the control input of the switch 30.
The proposed device operates as follows. In a DC network 45 operating under operating voltage, having a complex and branched system of connections and characterized by increased dynamics of its structure changes when switching consumers of electricity, the plus and minus bands of the power supply are connected to the housing through insulation of the corresponding live parts, which, taking into account its replacement by equivalent circuits represented as R (+) and C 1 included in parallel, as well as R (-) and C 2 .
In the case when, after connecting the device to the controlled network 45, the bridge formed by the resistances of the arms 18, 19 of the first voltage divider 17 and the insulation resistances R (+) and R (-) is unbalanced, then the output voltage of the first voltage follower 11 through the first switch 30 to the input of the first threshold element 8, there is an automatic balancing of the specified bridge depending on the direct or reverse imbalance of the bridge. With direct (reverse) imbalance of the bridge, signal 1 is generated at the first (second) output of the first threshold element 8, because the amplitude of its input voltage goes beyond the upper (lower) limit of its deadband. The specified signal direct (reverse) unbalance acting on the input Subtraction. (Addition) of the reversible counter 46 of the control unit 1, causes a sequential subtraction (addition) of units of the least significant digit from the code stored in it (with the code stored in it) by the pulse signals supplied to its counting input from the output of the 48 pulse generator, triggered by the above a direct (reverse) unbalance signal supplied to its input through the second OR element 38 connected in series, the first delay element 26, the second switch 31, and the third key 34.
In this case, the analog output signal of the digital-to-analog converter 47 begins to decrease (increase) stepwise in accordance with the decrease (increase) of the contents of the reverse counter 46, i.e. in accordance with the change in its digital output word, perceived by the digital input of the digital-to-analog converter 47. These changes in the analog output signal cause corresponding identical decreases (increases) in the currents through radiation sources 52, 53, and therefore their light fluxes. This leads to a corresponding identical increase (decrease) in the resistance of the photodetectors 54, 55 of the first 18 and second 21 controlled resistors, respectively, which is accompanied by a sequential decrease in the unbalance of the bridge and, consequently, a decrease in the amplitude of the output voltage of the first voltage buffer follower 11 until the bridge will not be balanced by the newly established resistance value of the photodetector 54, at which
R
Figure 00000001
R (+) = R ~
Figure 00000002
R
where R ~ is the resistance value of the first controlled resistor 18 (i.e., the photodetector 54), R is the resistance value of the first resistor 19. In this case, the input voltage of the first threshold element 8 is set in its deadband and the signal from its first (second) output and, consequently, the input signal of the pulse generator 48 of the control unit 1 goes into the zero state, which characterizes the end of the bridge balancing stage.
In this case, the inverter 24 generates an output pulse supplied through the first OR element 37 to the single input of the trigger 49 of the control unit 1, which characterizes the beginning of the measurement stage, during which the output signal 1 of the trigger 49 acts;
- to the control input of the second key 33, causing it to be closed, which ensures that the diagonal of the bridge is connected to a series-connected current sensor 12 and a DC voltage source 15;
- through the fifth key 36 to the input of the pulse generator 10, which provides a sequential change in the state of the analog-to-digital converter 4 by the pulses arriving at its clock input from the output of the pulse generator 10;
- to the control input of the first switch 30, causing the contact to open between its first information input and output and closing the contact between its second information input and output, which provides control over the possibility of unbalance of the bridge during the measurement phase;
- to the control input of the second switch 31, causing the opening of the contact between its input and the first output and the closure of the contact between its input and the second output, which makes it possible to hang up the measurement stage when the bridge is unbalanced during the measurement phase;
- to the second input of the And 50 element, which ensures the passage of the signal for holding the trigger 49 to its original position;
- to the input of the inverter 51 of the control unit 1, which ensures the generation of an output pulse by it at the end of the measurement stage, i.e. on the trailing edge of signal 1 from the output of trigger 49.
When, after the indicated switching of the device to the measurement step, the bridge equilibrium is maintained, the sum of the absolute values of the voltages incident on the signal resistor 13 (U c ) and between points A and B (U AB ) is equal to the output voltage (U) of the DC voltage source 15, and the voltage of the monitored network 45 does not affect the values of the indicated voltages (U s , U AB , U), and therefore the current in the measuring diagonal of the bridge, regardless of the change in this voltage in magnitude or in polarity. In this case, the output voltages of the first 11 and second 14 buffer voltage followers and the output voltage from the second output of the source 16 of the reference voltage, acting through a series-connected adder 7 and the first switch 30 to the input of the first threshold element 8, cause it to generate zero output signals, which makes it possible the issuance of measurement results R IE after performing the corresponding computational operations, which are based on the expression for a balanced current bridge flowing in the measuring diagonal
I =
Figure 00000003
=
Figure 00000004
,
i.e., U c R I.E. + U c
Figure 00000005
+ U c R c = UR c , where R c is the resistance value of the signal resistor 13;
R
Figure 00000006
- the resistance value of the second controlled resistor 21 (i.e., the photodetector);
R is the resistance value of the second resistor 22.
After the corresponding transformations and taking into account the fact that UU c = U АБ , the expression taken as the basis for calculations is simplified, changing as follows:
U c R I.E. = R c (UU c ) -U c
Figure 00000007
, R I.E. = R c
Figure 00000008
-
Figure 00000009

(1)
R measurement is performed on its quasi-analog model (simulating balanced electrical circuits) in accordance with equation (1) when using direct current voltages (active values) and electrical resistances (passive values) as their initial values, ensuring that the range and dimension of possible solution results from zero to 10 In the range and dimension of the measured values of insulation resistances from zero to 10 MΩ (with reference to the spacecraft), i.e. The results of solutions, modeled by voltages in units of V, mV, and μV, represent the same numerical values for R and. in units of megohms, ohms and ohms, respectively. In this case, the voltage U AB and U s through the first 11 and second 14 buffer voltage followers respectively act on the first and second inputs of the division unit 5, which causes them to produce an output voltage U out.5. expressing the result of the solution for the next part of equation (1)
U out. 5 = 0.1
Figure 00000010
= R c
Figure 00000011
= idem, where idem is an indication of the same numerical values for a given similarity criterion.
The output voltage from the intermediate tap of the second voltage divider 20 U vyh.20 based on the value of the output voltage from the first output of reference voltage source 16 is equal to 1, expresses solutions result for the next part of the equation (1)
U out. 20 =
Figure 00000012
= idem.
The output voltage of the division unit 5, acting simultaneously with the voltage from the middle terminal of the second voltage divider 20 to the first and second inputs of the subtractor 6, respectively, causes it to generate an output voltage U output 6 , which expresses the result of solving equation (1), i.e. the value of R IE
U out.6 = U out.5 -U out.20 = R c
Figure 00000013
-
Figure 00000014
= R I.E. = idem
The output voltage U o. 6 acts on the analog input of the analog-to-digital converter 4 and when the measurement step is performed, a digital output word is generated at its information outputs under the influence of the aforementioned pulse signals from the output of the pulse generator 10. The specified digital output word, acting on the inputs of the display unit 23, initiates the display of measurement information in it in digital form, according to the readings of which the value of R value is judged at a given time . The end of the measurement is accompanied by the generation of a signal 1 from the ready output of the analog-to-digital converter 4, which, through the third delay element 28, the fourth OR element 40, the fourth key 35, and the And element 50, is connected to the zero input of the trigger 49, which causes the signal 1 to disappear output and as a result, the transition of the device to its original state, i.e. into the tracking mode of the need for the next stages of the bridge balancing and measurement. If, when performing the measurement step, an unbalance of the bridge occurs, accompanied by the generation of the corresponding output voltage by the adder 7, due to the newly established value of R i.e. after the corresponding switching in the control object, in this case the measurement step is interrupted by signal 1 from the corresponding output of the first threshold element 8 depending on the direct or reverse imbalance of the bridge. The specified output signal 1 through a series-connected second element 38, the first delay element 26, the second switch 31, the fourth element OR 40, the fourth key 35 and the element And 50 of the control unit 1 will produce the above-described hang-up of the measurement phase, after which the next stages of balancing the bridge and measurements.
 To eliminate the omission of the case when the insulation resistances of both poles are reduced or increased at the same time relative to the housing, i.e. if there is no unbalance of the bridge during the pause determined by timer 2, the end of each measurement step is accompanied by a pulse signal from the output of the inverter 51 of the control unit 1 to the start input of the timer 2, which is supplied through the first key 32 and the first OR 37 element in series to block 1 control output signal of the expiration of the maximum pause time between measurements, initiating the next measurement step. At the same time, to prevent premature interruption of the bridge balancing stage, which is possible when timer 2 generates an output signal, the passage of the latter is blocked for the duration of signal 1 from the output of the third element OR 39 to the control input of the first key 32. If, during the mentioned pause, the control unit 1 to go to the measurement stage through the first element OR 37 will receive the output pulse of the inverter 24, then the pulse signal from the second output of the control unit 1, received at the reset input of timer 2, the last It returns to its original state and will be restarted only after the completion of the measurement phase.
In the process of carrying out the indicated steps of balancing the bridge and measuring when interference signals of any polarity occur, caused by the aforementioned transients in the controlled network with the resistive-capacitive nature of the insulation impedance, the current stage is interrupted. In the event of an interference signal of positive (negative) polarity, its leading and trailing edges through sequentially connected differentiating unit 3 and the second threshold element 9 sequentially act on the first and second (second and first) inputs of the fifth element OR 41, the duration of the input signals of which is determined the amplitude and duration of their corresponding output bipolar pulses of the differentiating block 3. Since the unit signals from the output of the fifth element OR 41, received at the input of the fourth delay element 29, delayed by it on the trailing edge, then the output single blocking signal of the fourth delay element 29, received at the control inputs of the third 34, fourth 35 and fifth 36 keys and the second input of the And 25 element, affects not only the leading and trailing edges of the signal interference, but also in the interval between them. For the duration of the specified signal 1 lock occurs:
- opening the third key 34, which prevents the possibility of false control of the reverse counter 45 of the control unit 1 at the stage of balancing the bridge in the presence of interference;
- fixing the input signal 1 of the inverter at the stage of balancing the bridge by supplying signal 1 to the second input of the And 25 element, as a result of which the possibility of transitions from the stage of balancing the bridge to the measurement stage is prevented due to interference causing false balancing of the voltage values at the vertices of the measuring bridge circuit ;
- opening the fourth key 35, which prevents the premature end of the measurement phase in the presence of interference, causing false imbalance of the bridge or false readiness of the analog-to-digital Converter 4 during the measurement phase;
- opening the fifth key 36, which prevents the possibility of false control of the clock pulses of the analog-to-digital Converter 4 at the measurement stage in the presence of interference.
 With any character of the trailing edge of the interference signal of any polarity, the disappearance of the generated single blocking signal is possible only after the amplitude of the output pulse of the corresponding polarity of the differentiating unit 3 decreases (positive for the interference signal of negative polarity, negative for the interference signal of positive polarity) below the threshold level of the corresponding sign of the second threshold element 9, which characterizes the end of the transition process in a controlled network, when the interference signal n inimaet value close to zero. In this case, the differentiating unit 3, the second threshold element 9, the fifth element OR 41, and after the corresponding time delay, the fourth delay element 29 come to the initial state, which causes the third 34, fourth 35 and fifth 36 keys to close and signal 1 disappears from the second input of element 25 And, i.e., the interrupted phase of the bridge balancing or measurement is restored. Further operation of the device takes into account the last steady state in a controlled network similar to that described above.
The use of the invention in comparison with the specified prototype, which is the base object, will allow:
- to increase the reliability and electrical safety during measurement due to a more accurate determination of the time of measurement of the equivalent insulation resistance with respect to the housing of the poles of the controlled DC network under operating voltage;
- to improve the accuracy and electrical safety during measurement by ensuring that the influence on the measurement result of the resistance of two shoulders of the first voltage divider is taken into account;
- facilitate monitoring the state of network isolation by ensuring continuity in the display of current values of R and.
Improving the reliability of measurements is expressed in preventing the influence on the measurement result:
- the imbalance of the bridge, which is possible in the measurement process due to the newly established values of the insulation poles of the network poles after the corresponding switching of electricity consumers in the controlled network, which is achieved by providing the possibility of continuous balancing of the measuring bridge circuit at the required time throughout the device’s operating time, including measurement steps with a DC voltage source connected to the diagonal of the bridge. In the prototype device, when performing the measurement step, uncontrolled imbalance of the bridge, distorting the measurement result, is possible;
- interference from transients of the controlled network, causing a false balancing of the voltage values at the vertices of the measuring bridge circuit, as a result of which the possibility of false transitions from the stage of balancing the bridge to the measurement stage, which are inherent in the presence of interference to the prototype device, in which the measurement results are also distorted, is prevented.
Increased electrical safety during measurement is expressed by:
- the timely issuance of measurement results, including unacceptable, at any low rate of change in the value of insulation resistance with respect to the housing of any pole, which simultaneously increases the fire safety of the controlled network. This is achieved by initiating the steps of balancing the bridge and measuring the imbalance of the measuring bridge circuit at any stage of the device’s operation, and only if the imbalance reflects the newly established value of R i.e. in the absence of interference in a controlled network. In the prototype device, with a slow change in the values of the indicated insulation resistances relative to the housing, the beginning of the next measurement initiates the timer output signal, while the values of R i.e. will be fixed later than their occurrence;
- reducing the number of measurement cycles, which at the same time reduces the amount of interference introduced into the controlled network by initiating the execution of measurement cycles according to the corresponding imbalance of the measuring bridge circuit, reflecting the newly established value of R and. in the absence of interference from transients in a controlled network. In the prototype device, the initiation of the execution of these cycles is possible without setting new values of R and. when interference from transients causes voltage changes at the poles of the network relative to the housing in different directions for almost the same values of the insulation resistance of the poles of the network before and after these transients, which is especially typical for complex objects of control with a large number of consumers of electricity and switching elements .
Improving the accuracy of the measurement is expressed in the implementation of measurements of R and. taking into account the influence on the result of the resistances of two arms of the first voltage divider, which reduces the restrictions on the choice of maximum values of these resistances, which in the prototype device should be significantly less than the controlled insulation resistances, which is unacceptable for most objects of control.
Facilitation of monitoring the state of network isolation is expressed in providing continuous indication of the current values of R and. throughout the entire life of the device. In the prototype device, after each subsequent measurement step, the indicator loses the measurement results by switching the voltage meter.
 These advantages result in an increase in the efficiency of monitoring the state of isolation of the controlled network and, as a result, an increase in its operational reliability.

Claims (2)

 1. DEVICE FOR MEASURING RESISTANCE OF DC NETWORK INSULATION, containing the first key and the first OR element in series, the output of which is connected to the first input of the control unit, the first and second outputs are connected respectively to the timer start and reset inputs, the third output is connected to the control inputs of the second the key and the first switch, and the fourth output is to the control input of the first controlled resistor of the first voltage divider, the other arm of which is formed by the first resistor, the second sometimes the second element, the input of which is connected to the output of the differentiating unit, connected via a second key connected in series, a DC voltage source and a current sensor with the middle terminal of the first voltage divider, the extreme terminals of which are connected respectively to the terminals for connecting to the poles of the controlled network, display unit, inverter and element And, characterized in that, in order to increase the reliability and electrical safety when changing by more accurately determining the time of measurement, enter buffer voltage follower, analog-to-digital converter, division unit, subtractor, adder, reference voltage source, pulse generator, second switch, four delay elements, third, fourth and fifth keys, second, third, fourth and fifth OR elements, second divider voltage generated by a second controlled resistor identical to the first controlled resistor and a second resistor identical to the first resistor, with the average output of the first voltage divider directly and through the buffer the voltage torch is connected respectively to the second input terminal of the differentiating unit and the terminal for connecting to the body of the test object, the output of the voltage buffer follower is connected to the first inputs of the adder and the division unit, the second inputs of which are connected to the output of the current sensor, the output of the division unit is connected to the first input of the subtractor the second input of which is connected to a common bus through a second controlled resistor, and through the second resistor to the first output of the reference voltage source, the second output of which is connected to the third input of the adder, the output of which and the output of the voltage buffer follower are connected respectively to the first and second information inputs of the first switch, the output of which is connected to the input of the first threshold element, the first and second outputs of which are connected respectively to the first and second inputs of the second OR element, the output of which is through the first delay element is connected to the signal input of the second switch, the first output of which through the third key is connected to the fourth input of the control unit and the input of the second of the first delay element, the output of which through the third OR element is connected to the first input of the AND element, the control input of the first key and the inverter input, the output of which is connected to the second input of the first OR element, the second output of the second switch through the fourth OR element and the fourth key connected in series the fifth input of the control unit, the fourth output of which is connected to the control input of the second controlled resistor, and the third output directly and sequentially connected to the fifth key and the generator the pulse torus is connected respectively to the control input of the second switch and the clock input of the analog-to-digital converter, the analog input of which is connected to the output of the subtracter, the ready output through the third delay element is connected to the second input of the fourth OR element, and the information outputs are connected to the inputs of the digital display unit, the first and the second outputs of the second threshold element are connected respectively to the first and second inputs of the fifth OR element, the output of which is connected through the fourth delay element with the control inputs of the third, fourth, fifth keys and the second input of the AND element, the output of which is connected to the second input of the third OR element, the timer output is connected to the signal input of the first key, the second and third inputs of the control unit are connected respectively to the first and second outputs of the first threshold element, the first input terminal of the differentiating unit is connected to a terminal for connection to the body of the object of control.
 2. The device according to p. 1, characterized in that the control unit contains a reversible counter, the inputs of the addition and subtraction of which are respectively the second and third inputs of the control unit, a digital-to-analog converter, the output of which is the fourth output of the control unit, a pulse generator whose input is the fourth input of the control unit, a trigger, a single input and direct output of which are respectively the first input and the third output of the control unit, element And, the first input of which is the fifth input of the control unit, and an inverter, the output of which is the first output of the control unit, the second output and the first input of which are combined, and the output of the pulse generator is connected to the counting input of the reversible counter, the outputs of which are connected to the inputs of the digital-analog converter, the direct output of the trigger is connected to the input of the inverter and the second input of the AND element, the output of which is connected to the zero input of the trigger.
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RU2602994C1 (en) * 2015-09-21 2016-11-20 федеральное государственное автономное образовательное учреждение высшего образования "Южный федеральный университет" Device for controlling electrical parameters of pyrotechnic devices
EA028362B1 (en) * 2015-06-01 2017-11-30 Республиканское Унитарное Предприятие "Производственное Объединение "Белоруснефть" Device for continuous control of electrical cable insulation resistance

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Publication number Priority date Publication date Assignee Title
EA028362B1 (en) * 2015-06-01 2017-11-30 Республиканское Унитарное Предприятие "Производственное Объединение "Белоруснефть" Device for continuous control of electrical cable insulation resistance
RU2602994C1 (en) * 2015-09-21 2016-11-20 федеральное государственное автономное образовательное учреждение высшего образования "Южный федеральный университет" Device for controlling electrical parameters of pyrotechnic devices

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