SU1377777A1 - Device for checking insulation of d.c. power supply lines - Google Patents

Abstract

This invention relates to instrumentation technology. The control device for isolating DC power supply buses contains a source of operating voltage 1, a comparator 2, a voltage sensor 3, a control unit 4, a voltage divider 5, an electronic switch 6, relay elements 7.8, a function control block 9, resistance positive and negative buses 10 and 11, respectively, the load 12 of the network, sources 13,14 constant voltage, terminals 15,16. In the description of the invention, the scheme of the control unit 4 is given. The device has increased reliability and reliability of control results. 1 hp f-ly, 2 ill.

Description

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The invention relates to instrumentation engineering and can be used to control the resistance of insulated power busbars of electrical networks.

The aim of the invention is to expand the functionality by searching for the location of the insulation fault, increasing the reliability by controlling the presence of voltages and the reliability of the monitoring results by reducing the error in the operation of the comparator.

Figure 1 shows the block diagram of the proposed device; figure 2 - diagram of the control unit.

. The device contains an operating voltage source 1, a comparator 2u voltage sensor 3, a control unit 4, a divider 5 of the reference voltage, an electronic switch 6, the first 7 and second 8 relay elements, a function control unit 9, resistance 10 and negative 11 with respect to ground, the load 12 of the network, the first 13 and second 14 sources of constant voltage, the first 15 and second 16 terminals for connection to the test object, the first and second terminals

source 13 is connected respectively with empty and second power inputs of comparator 2, the first terminal of source 14 is connected to a common bus, the first terminal of source 1 is connected to the first input terminals of sensor 3, unit 4 and comparator 2, the second input terminal of which is connected to output divider 5, The first and second inputs of which are connected respectively to the second output of the source 14 and the common bus, the first and second terminals of the source 13 are connected respectively to the third and fourth input terminals

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the second 22 and third 23 inverters and the element 24, the first terminals of the first 17 and second 18 resistors, respectively, are connected to the first and second input terminals of the unit, the third and fourth input terminals of which are connected to the first inputs of the first and second optron elements, respectively the inputs of which are connected to the second terminals of the second 18 and first 17 resistors, respectively, and the outputs to the inputs of the first 21 and second 22 inverters, respectively, the outputs of which are connected to the first and second inputs of the And 24 element, respectively, the output of which is connected to the first output of the unit and the input of the third inverter 23, the output of which is connected to the second output of the unit.

The device works as follows.

The current from source 1 flows through sensor circuit 3 — insulation resistance 10 — load 12 — source 1, go sensor 3, insulation resistance 11 — source 1. Since the resistance value of load 12 is very small compared with sensor resistance 3 and with resistance 10 isolation, then in practice it can be neglected. In this case, we assume that the two circuits are identical. When the insulation is lowered (resistors 10 or (and) 11), the current flowing through sensor 3 increases. In this case, the operational voltage at its terminals varies inversely with the change in the insulation resistance. This voltage is applied to the first input of the comparator 2. The input voltage of the reference voltage of the comparator 2 is supplied with a stabilized voltage from source 14 through a divider 5, Be

By block 4, the output of which is connected 45 the voltage of this voltage is equal to the set input of the first relay element 7, the second terminal of source 1 is connected to the fourth input terminal of block 4, terminal 15 and the first terminal of block 9, the second terminal of which is connected to Q terminal 16, output the comparator 2 is connected to the inputs of the relay element 8 and the key 6, and the third input terminal of the comparator 2, the third terminal of the unit and the second terminal of the sensor 3 are connected to a common thickness.

In FIG. 2, the first 17 and second 18 resistors are designated, the first 19 and second 20 optocouplers, the first 21 ,.

The threshold of the insulation resistance value monitored by the device is equal to the voltage taken from sensor 3 when the insulation resistance reaches 10 or 11 of a certain threshold. Comparator 2 compares reference and operational stresses. In the normal state of isolation, the magnitude of the reference voltage exceeds the magnitude of the operational voltage and there is no signal at the output of the comparator 2. Therefore, the key 6 and the relay element 8 remain in the initial state.

When reducing the insulation resistance 10 or 11 below the set threshold, the voltage on the sensor 3 increases to a value that exceeds the reference voltage setpoint at the second input of the comparator 2. At the same time, the last voltage drops, and a signal appears at its output. Relay element 8 is activated, and its contacts are switched. A signal also appears at the input of the electronic key 6, and the states of the first and second outputs of the key 6 are reversed — 1 and 0, respectively. Thus, the first and second outputs of the electronic key 6 are logical, and the output of the relay element 8 is the high-current output of the device, the signals of which are the signals of the isolation state of the power busbars. The device registers a decrease in insulation resistance at any

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including a short lock on any of the power rails on the case. In addition, the device registers a symmetric reduction of the insulation resistances 10 and 11.

The operation of block 4 is as follows.

In the presence of voltages of sources 1 and 13, a signal is present at the inputs of optoelectronic elements 19 and 20, respectively. The signals from the outputs of these elements are fed through inverters 21 and 22 to the inputs of element AND 24. The output of element 24 is direct, and through inverter 23 is the inverse logical outputs of block 4. The presence of both voltages corresponds to 0 and 1 at the outputs of block 4. In the absence of any of these voltages, the states of the first and second outputs of block 4 are reversed, which corresponds to a malfunction of the device

Claims (2)

1. A control device for isolating DC busbars, containing a comparator, the first and second relay elements, the first and second sources of DC voltage, two terminals for connecting an object to a terminal. Q g n five 5 g 0 The first and second terminals of the first constant voltage source are connected to the first and second comparator power inputs, respectively; the first terminal of the second constant voltage source is connected to a common bus, characterized in that, in order to expand its functionality, increase reliability and reliability control source, an operating voltage source, a control unit, a voltage sensor, a reference voltage divider, a functional control unit and an electronic key are entered into it; the operating voltage is connected to the first input terminals of the voltage sensor, the control unit and the comparator, the second input of which is connected to the output of the voltage divider, the first and second inputs of which are connected respectively to the second output of the second constant voltage source and the common bus, the first and second the terminals of the first constant voltage source are connected respectively to the third and fourth inputs of the control unit, the output of which is connected to the input of the first relay element, the second terminal of the source voltage is connected to the fourth input of the control unit, to the first terminal for connecting the test object and the first output of the function control unit, the second output of which is connected to the second terminal for connecting the test object, the comparator output is connected to the inputs of the second relay element and the electronic switch, and the third the comparator input, the third output of the function control unit and the second output of the voltage sensor are connected to a common bus. 2. The device according to claim 1, characterized in that the control unit contains two resistors, two optocoupler elements, three inverters and an element And, the first terminals of the first and second resistors are connected respectively to the first and second input terminals of the block, the third and fourth input terminals which are connected to the first and the inputs, respectively, of the first and second optocoupler elements, the second inputs of which are connected to the second terminals of the second and first resistors, respectively, and the outputs from 51377777 the inputs of the first and the second, respectively, are connected to the first output of the unit inverters, whose outputs are co-and the input of the third inverter, output dinene respectively with the first ivto which is connected to the second exit ring inputs of the element And, the output of a co-block. / 7 20 13 FIG 2 yy 2ff 2J h