SU966623A1 - Device for measuring two-wire line insulation resistance - Google Patents

Description

The concept refers to electrical measuring equipment and can be used to continuously monitor and measure the insulation resistance of a two-wire DC line under operating voltage.

A device for monitoring the isolation and protection of two-wire current-current networks, comprising a bridge / formed by two arms of a potentiometer and line busbar insulation resistance, a comparison unit included in the bridge diagonal, and a sensitive element in the form of a blocking generator t; 1

However, the device does not measure the current value of the insulation resistance of each bus line, regardless of the insulation condition of the other bus.

(The closest in technical essence and the achieved result to the proposed is a device containing a measuring bridge, which includes insulation resistance of controlled tires and a digital-controlled resistor, a source of compensation voltage:, comparison unit, control unit, digital an indicator, a switch, with a digital resistance resistor connected by one pin through a normally open contact of the first group and a normally closed contact of the second group of commutator-5 torus, respectively, with a crush and mine the source of the compensation voltage source, and another output — with the input of the comparison unit and ground; the output of the comparison unit through the control unit

10 is connected to the control of the digital input; A controllable resistor, plus a power supply line, is connected to normally open contacts of the second and third groups of the switch, and the mini – to normally close the contacts of the first and third groups, the ground contact of which is connected to the second input of the comparison unit C2j.

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However, this device is characterized by an insufficient accuracy of measuring the insulation resistance, which

Claims (2)

i is due to the presence of a compensating voltage source in the device and the need to maintain a computer25. siruk tse. voltage equal to or pro-rational voltage of the power source of the line, it requires significant instrumental costs when implementing a device with high metrological characteristics. The purpose of the invention is to improve the measurement accuracy of the insulation resistance. This goal is achieved by the fact that the device for measuring the resistance of the insulation is a two-wire line, containing a comparison unit, a control unit, the outputs of which are connected respectively to the control inputs of the keys, the display unit and to the control terminals of the digitally controlled resistor, the second output of which is connected to the leads of the first and second keys, the first leads of the third and fifth keys are connected to the plus, and the fourth and sixth keys - to the minus of the power source of the two-wire line, two current sensors are inserted, two override resistors, the second pins of the third and fourth switches are connected via the first current sensor to the first input of the comparison unit and to the first terminal of the first limiting resistor, the second output of which is connected to the housing ground), the second terminals of the first and second switches are connected to positive and negative the power source of the two-wire line; the second terminals of the first, sixth and sixth keys are connected via a second current sensor to the second input of the comparison unit and to the first terminal of the second limiting resistor, the second A output of which is connected to the third terminal tsifroupravl emogo ican D, a fourth terminal connected to the output of comparison block, and a fifth output - to the input of the indication unit. The drawing shows a functional diagram of a device for measuring the insulation resistance of a two-wire line. A device for measuring the insulation resistance of a two-wire line contains a comparison unit 1, a control unit 2, which may include a master oscillator, a frequency divider and an element of the initial installation, an indication unit 3 consisting, for example, of a decoder and indicator, keys 4 , 5, 6, 7, 8 and 9, the digitally controlled resistor 10, current sensors 11 and 12, and limiting resistors 13 and 14. The device operates as follows. Measurement of the insulation resistance of the tire Plus R and tire Minus R,. the monitored line relative to the system case connected to the monitored line is made by connecting the measuring device to the system case and alternately connecting the keys 4, 5, 6, 7, 8 and 9 to the bus Plus or Minus. The voltage due to the insulation resistance of one of the monitored buses is removed from the current sensor 11 and fed to one input of the comparison unit 1, and the voltage due to the resistance of the digital-controlled resistor 10 is removed from the current sensor 12 and fed to the second input of the block 1 comparison. , When measuring: the insulation resistance R key 4 connects the bus Plus to one of the pins of the digital-controlled resistor 10, and the keys 7 and 9 nofl switch on the Minus wire to the current sensors 11 and 12, respectively. The voltages taken from the current sensors 11 and 12 are applied to the corresponding inputs of the comparison unit 1, where they are compared, and the resulting signal is fed to the control input of the digital-controlled resistor 10. The maximum resistance of the digital-guided resistor 10 at the beginning of the measurement cycle decreases according to the signal coming from the unit 1 of the comparison. The decrease in resistance of the digital-controlled resistor 10 ends when the voltages on the current sensors 11 and 12 are equal. In this case, at the output of the comparison unit 1, a signal of opposite polarity appears, the offset of the digital-controlled resistor 10 is stopped, and it is set to the state when its value is equal to the insulation resistance R.. The measurement result of the insulation resistance after decoding is highlighted by the display unit 3. When measuring the insulation resistance, 5 connects the output of the digital-controlled resistor 10 to the bus Minus, and the keys 6 and 8 connect the Plus to the current sensors 11 and 12, respectively; The resistance of the digital-controlled resistor 10 is set to maximum and the measurement of the busbar insulation resistance Minus the monitored line relative to the system case is performed similarly to the process of measuring the insulation resistance R. The invention makes it possible to measure the insulation resistance with a higher accuracy, because currents flowing from the same source (controlled line) flow through the current sensors. Therefore, the instability of this source and its pulsations do not affect the measurement result. the two-wire line, containing a comparison unit, a control unit, the outputs of which are connected respectively to the control inputs of the keys, the display unit and the digital output control terminal A second resistor is connected to the terminals of the first and second keys, the first terminals of the third and fifth keys are connected to the plus, and the fourth and sixth keys are connected to the power supply source of the two-wire line, in order to improve the accuracy measurements, two current sensors, two limiting resistors are introduced, the second outputs of the third and fourth switches are connected via the first current sensor to the first input of the comparison unit and to the first output of the first limiting resistor, the second output of which oedinen Szemley with the body, The second pins of the first and second switches are connected respectively to the plus and minus of the power source of the two-wire line, the second pins of the fifth and sixth keys are connected via the second current sensor to the second input of the comparison unit and to the first output of the second limiting resistor, the second output of which is connected to the third the output of the digitally controlled resistor, whose fourth output is connected to the output of the comparison unit, and the fifth output to the input of the display unit. Sources of information taken into account in the examination 1, Copyright certificate. USSR 353214, cl. G 01 R 27/16, 1971.. 2. Authors certificate of the USSR 744339, cl. G 01 R 17/10, 1975.