RU2313799C1 - Mode of controlling reduction of resistance of insulation in a line of feeding voltage to a load and an arrangement for its execution - Google Patents

Abstract

FIELD: the invention refers to measuring technique.

SUBSTANCE: the essence in that constant voltage from the primary feeding source is attached to the load and the current leakage is measured in the feeding line. Then at the switched on primary feeding source of voltage they attach to the voltage feeding line an additional feeding source and measure once more the summary current leakage in the feeding line. The difference of made metering is defined and the received value is compared with permissible value of leakage. The arrangement has a main source of voltage connected to the line of feeding voltage to a load (for example, a pressure sensor). The plus output of the source is connected through a commute arrangement to the minus output of the additional source of voltage. The second output of the commute arrangement is switched to the plus output of a stabilizer diode connected with the minus output with the plus output of the additional source and with input of a divisor of voltage. The divisor is connected with the scheme of the analysis of measuring.

EFFECT: provides possibility to control the resistance of insulation without disconnection of a working source at simplification of measuring means and increasing of accuracy of control.

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Description

The invention relates to measuring equipment, in particular to means for determining a decrease in insulation resistance in a linear path.

A known method and device for measuring the insulation resistance described in p. RF No. 2026565, CL. G01R 31/08, z. 06/28/91, op. 01/09/95.

The known method consists in changing the ratio of the resistance of the resistive circuits between the output buses of the remote power supply current source and ground to reach the minimum value of the differential current through them to the ground and finding a section with reduced insulation resistance, for which alternating grounding of the points along the remote power loop with at each grounding of the differential current through the resistive circuits from the output buses of the remote power supply current source to the ground, and the location of the section with izhennym insulation resistance is performed by grounding a point with minimum deviation concomitant ground differential current from its initial value achieved.

The known device contains resistive circuits made in the form of resistance stores, and a differential current meter in the form of a milliammeter, with the first resistive circuit connected between the positive output bus of the remote power current source and the first output of the differential current meter, the second resistive circuit connected between the negative output bus of the source current and the first terminal of the differential current meter, the second terminal of which is connected to the ground bus.

A disadvantage of the known means is the difficulty of carrying out a large number of measurements.

A known method and device for measuring insulation resistance, described in p. RF No. 2054185, CL. G01R 31/08, z. 11/04/91, op. 02/10/96.

The known method consists in applying a constant voltage to the object, forming a reference voltage, measuring the voltage distribution at appropriate points along the object between the ground bus and the power bus, adjusting the reference voltage during measurement, subtracting it from the reference voltage to obtain a zero difference value, then apply additional voltage to certain points of the object, after a time delay, re-measure and judge by the zero value of the difference the place of decrease from disobedience isolation.

The known device contains a DC power source isolated from earth, connected to a family of nodes of an electrical installation containing load resistances, insulation resistance of the plus and minus power buses relative to the housings of the nodes, a reference voltage source containing alternating and constant resistors connected to the buses by the first and second terminals power supply, and the middle output - to the inverting input of the measuring unit containing a differential DC amplifier with high-resistance input AMI and indicator. In addition, the device also contains an additional source of direct current, the negative wire of which is connected directly to one of the points of the housing, and the positive wire is connected through a key element.

A disadvantage of the known means is the complexity of the implementation due to the large number of measurements, as well as the complexity of the measurement scheme due to this. In addition, the known means make it possible to determine only the place of lowering the resistance, making it impossible to measure the leakage current.

The closest to the intended purpose is a device and method for controlling the decrease in insulation in a cable line, presented in p. RF №2007874, class. HB04 3/46, s. 12.13.90, op. 02/15/94, and selected as a prototype.

The known device (figure 1) contains a series-connected circuit for generating a ringing combination of control signals, including a button, a trigger, an OR element, four AND elements, a delay element, used to store the signal from the outputs of the aforementioned three blocks of elements AND three registers, three blocks a display, a counter, three decoders, three blocks of AND elements, and an encoder, a resistive divider connected by an input to a cable line screen including a signal circuit and a signal core, and an output with three parallel devices you indicate the status of the indication associated with the inputs of the three And circuits connected by the second inputs through the decoder and the one-shot with the signal circuit, and the connected outputs to the transcoding unit connected by the output to the circuit for generating the ringing combination of control signals. In this case, the indicating devices (Fig. 2) contain a first voltage divider connected at its low-potential end to the cable screen, connected by an output in parallel with three adjustable voltage dividers setting the corresponding threshold values, connected by outputs to three operational amplifiers, connected by outputs to three indicators connected through the above AND circuits with a transcoding block.

A disadvantage of the known device is that the device has a very complex and large circuit, since the circuit for generating a ringing combination of control signals is very complex. In addition, such a circuit requires checking each of the wires of the line separately when the operating voltage of the line is off, since the display circuit is connected between the screen and the signal circuit and the operating voltage distorts the result of measuring the insulation resistance.

The known method consists in the fact that in the measurement mode, a voltage divider is connected to the signal line and the output voltage of the divider is compared with the reference voltage, and the comparison result is fed to an indication circuit that indicates a signal “normal”, or “warning” (below normal), or “ crash".

The task is to provide the ability to control the insulation resistance without disconnecting the working source while simplifying the measurement tools and increasing the accuracy of the control.

The problem is solved in that:

- in the method for controlling the decrease in insulation resistance in the supply voltage line to the load, a control signal is supplied to the controlled line, a response signal is received, stored, analyzed and displayed, according to the invention, the leakage current in the line is measured in the controlled line when the main load voltage source is turned on supply, then to the controlled line with the main source turned on, simultaneously supply the voltage of the additional source, again measure the leakage current in the supply line, remembering m measured signals and using a difference signal obtained by subtracting the signals of the first and second measurements, to analyze the obtained difference signal is compared with the allowable leakage current value and the comparison result as the control signal is judged on the presence or absence of a leak;

- in the device for controlling the decrease in insulation resistance in the supply line of the supply voltage to the load, which includes a control signal generation circuit connected to a controlled line connected to the voltage divider, a memory device for storing the measured values of the control signal from the controlled line associated with the results analysis circuit measurements, and a circuit for indicating the results of the analysis, according to the invention, the control signal generating circuit includes a main voltage source pi voltage connected to the line supply voltage to the load, and an additional voltage source connected to the negative terminal with the positive terminal of the main source through a switching device connected to the positive terminal of the zener diode connected by the negative terminal to the positive terminal of the additional source and to the input of the voltage divider connected output with a circuit for analyzing measurement results, consisting of a series-connected analog-to-digital Converter, a storage device, calculating itelnogo device and comparison circuit whose output is connected to the display circuit.

The simultaneous connection of the main and additional voltage source to the object supplying voltage to the object and measuring the total voltage on the voltage divider in total, followed by subtracting the voltage measured on the divider from the main voltage from the total voltage, and comparing the difference with the permissible voltage allows you to sufficiently disconnect the main voltage source it is simple and very accurate to determine the presence of a leak in the voltage supply to the load line.

The implementation of the control signal generation circuit in the form of the main and additional voltage sources with the above connection of an additional voltage source to the power supply line in conjunction with the analysis circuit analysis of the signal measured on the voltage divider in the form of series-connected signal converter, storage device, computing device and comparison circuit makes it possible with a very simple circuit and with sufficient accuracy regardless of voltage stability determine whether the main source of leakage in the supply line of the supply voltage to the load without shutdown on the measurement main power source voltage.

The technical result is the provision of the ability to control the insulation resistance without disconnecting the line from the power source while simplifying the monitoring means and increasing the accuracy of determining the decrease in insulation resistance.

The inventive method has a novelty in comparison with the prototype, differing from it by the presence of such essential features as measuring the leakage current in the line when the main voltage source is on, measuring the leakage current in the line when the main and additional voltage sources are on, determining the difference of the measured values, evaluating it by comparison with the permissible value and conclusions based on the results of an assessment of the presence or absence of a leak in the supply voltage to the load supply lines, which together ensure the achievement of ad result.

The inventive device has a novelty in comparison with the prototype, differing from it by the presence of such essential features as the implementation of the control signal generation circuitry in the form of the main and additional power supply sources, and the measured signal analysis circuitry - from a series-connected computing device and a comparison circuit for the above connections and already existing elements of the scheme, which together ensure the achievement of a given result.

The applicant does not know the technical solutions possessing the above distinguishing features, which together ensure the achievement of a given result, so he believes that the claimed method and device meet the criterion of "inventive step".

The inventive method of controlling the decrease in insulation resistance in the line supply voltage to the load and the device for its implementation can be widely used in measuring equipment, and therefore meet the criterion of "industrial applicability".

The invention is illustrated by drawings, which are shown in:

- figure 1 is a functional diagram of a control device for lowering the insulation resistance in the line supply voltage to the load;

- figure 2 is a schematic diagram of a control device for lowering the insulation resistance in the line supply voltage to the load.

The inventive method of controlling the decrease in insulation resistance in the line supply voltage to the load is as follows.

A constant voltage from the main power source is applied to the load and the leakage current in the power line is measured. Then, with the main power supply turned on, a supply voltage is applied to the line from an additional power source and the total leakage current in the power line is measured again. The difference in the measurements taken is determined and the obtained value is compared with the allowable leak value: the difference should not exceed the allowable value.

The inventive device (Figs. 1 and 2) contains a main voltage source 1 connected by outputs (plus and minus terminals) to a power supply line 2 to a load (for example, a pressure sensor). The positive output of the source 1 is connected through a switching device 3, which includes the key element 4 (relay) and the key element 5 (relay), with the anode of the zener diode 6 and with a resistor 7 connected through the second key element 5 to the negative terminal of the additional voltage source 8, the positive terminal of which is connected to the cathode of the zener diode 6 and the resistor voltage divider 9-10. The resistor divider 9-10 is connected to the circuit 11 of the analysis of the measurement results, consisting of series-connected analog-to-digital Converter 12, a storage device, a computing device and a comparison circuit made in the form of a controller 13, and connected to the indicator 14. The power supply line 2 consists from plus 15 and minus 16 wires of the power bus. The positive wire 15 is connected to the first key element 4. The purpose and implementation of the nodes and elements is as follows.

The main source 1 of the supply voltage is designed to convert the mains voltage of 220 V into a stabilized voltage of 36 V and the power of pressure or temperature sensors. It can be, in particular, the Metran-600 power supply unit.

Line 2 supply voltage serves to power the load (pressure sensor, temperature or flow, etc.) and is a bus from the plus and minus wires 14 and 15.

The switching device 3 is designed to provide alternate connection to the circuit 11 of the analysis of the results of measuring the leakage current in the voltage supply line when only the main source 1 is turned on and when the main and additional sources 1 and 8 are turned on.

Key element 4 (relay) is designed to switch channels and break the line in the absence of measurements.

The key element - relay 5 is used to connect an additional voltage source 8 to line 2 of the supply voltage.

Zener diode 6 is designed for the passage of current when you turn off the additional source 8 and stabilize the voltage of the additional source 8 when measuring.

The resistor 7 serves to limit the current in the circuit of the additional source 8.

An additional source of direct current 8 serves to create additional voltage, which serves to ensure measurement.

Resistors 9 and 10 form a voltage divider to convert the measured leakage current to voltage and limit the operating voltage for the ADC 12.

The circuit 11 for analyzing the measurement results is intended to convert, store the obtained measurement values, obtain their difference and compare the latter with an acceptable value, as well as to indicate the results of control. It consists of a series-connected analog-to-digital Converter 12, a storage device, a computing device and a comparison circuit (not indicated).

An analog-to-digital converter 12 is designed to convert an analog signal taken from a voltage divider into a digital signal supplied to a storage device.

A storage device is used to store measurement values.

The computing device is designed to determine the difference in measurement values.

The comparison scheme is used to compare the difference of measurements with an acceptable value.

Structurally, the last three nodes are made in the form of a controller 13, which simultaneously serves to store the allowable value of the leakage voltage, the measured signals with the main and additional sources, subtract them, compare the difference with the allowable value of the leakage voltage.

The indicator 14 is designed to indicate the presence of leakage.

The inventive method of controlling the decrease in insulation resistance in the line supply voltage to the load using the inventive device is carried out in two stages and is implemented as follows. At the first stage, the relay 5 is open and the additional source 8 is not connected to the measurement circuit. Relay 4 is closed and current I ut. from the main source 1 flows through a zener diode 6 to a voltage divider 9-10, from where it is removed as an analog signal to the ADC 12, where it is converted into a digital signal and then transferred to the controller 1, where it is stored and stored.

At the second stage, relay 4 and 5 are closed. The total leakage current from the main source 1 through the circuit - relay 4 is a zener diode 6 and the current from an additional source 8 is supplied through a resistance 7 and zener diode 6 to a voltage divider 9-10, and then to circuit 11 , i.e. on the ADC 12 and the controller 13, where it is stored and stored.

In the controller 13, the voltage values received from the main source and the total voltage from the sources 1 and 8 are turned on at the same time. The difference is compared with the permissible value of the leakage voltage and, if the latter is exceeded, the comparison result is displayed on indicator 14.

Compared with the prototype, the inventive method and device allows, with the main power supply voltage turned on and a fairly simple device circuit to accurately determine the presence of leakage.

Claims (2)

1. The method of controlling the decrease in insulation resistance in the supply voltage to the load line, which consists in supplying a control signal to the monitored line, receiving a response signal, storing it, analyzing it and indicating it, characterized in that in the monitored line with the main source turned on the supply voltage of the load measures the leakage current in the supply line, then the auxiliary voltage is simultaneously supplied to the monitored line with the main source turned on, the leakage current is measured again in supply lines, store the measured signals and use the differential signal obtained by subtracting the signals at the first and second measurements as a control signal, compare the received differential signal with the acceptable value of the leakage current for analysis and, based on the results of the comparison, judge the presence or absence of leakage. 2. A control device for lowering the insulation resistance in the supply line of the supply voltage to the load, including a control signal generating circuit connected to a controlled line connected to a voltage divider, a memory device for storing the measured values of the control signal from the controlled line connected to the results analysis circuit measurements, and a circuit for indicating the results of the analysis, characterized in that the control signal generation circuit includes a main supply voltage connected to the supply voltage line to the load, and an additional voltage source connected to the negative terminal with the positive output of the main source through a switching device connected to the positive terminal of the zener diode connected to the negative terminal with the positive terminal of the additional source and to the input of the voltage divider connected output with a circuit for analyzing measurement results, consisting of a series-connected analog-to-digital Converter, a storage device, calculating tion device and comparison circuit whose output is connected to the display circuit.

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