SU1597774A1 - Apparatus for checking resistance of insulation of d.c.mains - Google Patents

Abstract

The invention relates to the field of electrical measurements and is intended to monitor the insulation resistance of DC networks. The purpose of the invention is to expand the functionality by ensuring the isolation control of each pole and increasing the reliability of the control. The device contains two resistors 1, 2, three voltage dividers 3-5, two comparators 6, 7, two transistor switches 8, 9, two output relays 10, 11, and a two-pole power supply unit. The device allows monitoring of the insulation isolation level independently at each pole of the network below specified levels at each pole. Due to the fact that the common point of the power supply unit is connected to the negative pole of the network and that the first divider is connected by one output to the positive pole and grounding through resistors, and the second output to the negative pole, the influence of common mode voltage variation on the reliability of control is reduced. 1 il.

Description

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The invention relates to electrical measurements, namely, devices for monitoring the resistance of the insulation of DC networks.

The purpose of the invention is to expand the functionality by ensuring the isolation control of each pole and increasing the reliability of the control.

The drawing shows a diagram of the device.

The device contains two resistors 1 and 2, three voltage dividers 3-5, two co-switches 6 and 7, two transistors keys 8 and 9, two output relays 10 and 11, and a two-pole power supply unit with a common output. The first output of the divider 3 is connected to the negative pole, and the second output is through the first resistor 1 with the instance and via the second resistor with the 2nd positive pole of the network, the output of the divider 3 is connected to the inverting input of the comparator 6 and the non-inverting input of the comparator 7 , the outputs of dividers 4 and 5 are connected to the corresponding poles of the network, and their outputs with a non-inverting input of the comparator

6 and inverting comparator input

7, respectively, the outputs of the comparators 6 and 7 are connected respectively via transistor switches 8 and 9 to the corresponding output relays 10 and 11, the power supply ports of the comparators are connected to the corresponding terminals of the power supply, and their common leads to the common output of the power supply and the negative pole of the network.

The device works as follows.

When there is a voltage on the controlled line (+ E, -E), a current flows through resistor 2 and dividers 3-5, which causes a corresponding voltage drop U, U, U at the outputs of dividers 3-5, respectively. Voltages and, and BZ are the reference, and the voltage U is estimated the state of the insulation resistance of the line.

The voltage U, from the divider 3, goes respectively to the inverting input and the non-inverting input of co-drivers 6 and 7. The voltage U, from the divider 4 is fed to the non-inverting input. the comparator 6, and the voltage U with the divider 5 - to the inverting input of the comparator 7..When the conditions are met and Ui, and, Uj, at the outputs of the comparator

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The tori 6 and 7 are set to positive potentials, the transistor switches 8 and 9 are closed, the windings of the relays 10 and 11 are de-energized.

By reducing the insulation resistance of the positive pole of the network to or below the permissible level, fn, the voltage U increases and becomes equal to or greater than the voltage U, which causes a low potential at the output of the comparator 6, which through the transistor switch 8 turns on the relay 10, the pins of which are used to signal the reduction of the isolation of the positive pole of the network. By reducing the insulation resistance R1 of the negative pole of the network to or below the permissible level R ,. The voltage U becomes lower than the voltage and, as a result, a low potential is set at the output of the comparator 7, which through a transistor switch 9 turns on the relay-11, the contacts of which are used to signal a decrease in the insulation of the negative pole of the network. When the insulation resistance of the monitored network is restored, the device returns to its original state.

Thus, the proposed device provides simultaneous control of the permissible level of insulation resistance decrease of the monitored network at each pole with a given setpoint, can be applied to networks with different voltages, since it is self-powered, increases the reliability of control by compensating for common-mode variations. marriages poles network.

Claims (1)

Invention Formula A device for monitoring the insulation resistance of the DC network, containing two comparators, the first voltage divider whose output / is connected to the inverting input of the first comparator and the non-inverting input of the second comparator, and the first output to the negative pole of the network, two resistors, and a two-pole A power supply unit, characterized in that, in order to expand the functionality by providing control of the isolation of each pole and increasing the reliability of the control, second and third dividers are introduced into it voltage, two transistor switches and two output relays, the first voltage divider by the second output is connected to the instance through the first resistor, and the positive pole through the second resistor, the outputs of the second and third voltage dividers are connected to the network poles, and the outputs, respectively, are non-inverting the input of the first comparator and inverting the input of the second comparator, the outputs of the comparators are connected via corresponding transistor switches to the corresponding output relays, the power supply ports of the comparators are connected to the corresponding terminals of a two-pole power supply unit, the common output of which is connected to the common outputs of the comparators and the negative pole of the network.