SU879516A1 - Device for checking electrical mounting insulation value - Google Patents

Description

one

The invention relates to electrical measuring equipment and can be used to control the resistance value of electrical insulation j of products containing a large number of disconnected circuits, namely: printed circuit boards, electrical cables and wiring.

A device for controlling JQ is known.

quality of installation, connecting cables and harnesses, containing control and monitoring units, connected through switching groups of relay contacts to switching units containing multiple coordinate connectors and switching relays connecting the controlled product. In order to improve the accuracy of control of the insulation resistance of products containing a large number of chains, the unambiguous contacts of multiple coordinate connectors are interconnected and with a common point normally n. and n.z. .contacts relay switching, and nv .. contacts of these elements are united by a common bus LI.

A disadvantage of the known device is low accuracy and reliability when testing products with the number of extended circuits exceeding 10 -

10, since the control result is affected by the resistance value of the isolation of the switching relay, the insulation resistance of the coordinate connectors and the mounting of the device itself. Moreover, as the number of monitored circuits increases, the measurement error increases. It is also known a device for controlling electrical circuits, comprising a distributor made in the form of a binary matrix decoder, a combinator made in the form of a shift register, valves, an address register connected to the generator, a switch connected to the meter, a switching unit connected to the input and control unit connected to the storage unit and the element of the ban 2J.

The disadvantages of the known device are low, the accuracy and reliability of the control of the insulation resistance between the disconnected circuits due to the influence of the insulation resistance of the commutator, the switching elements of which are connected to the measuring buses in parallel with the monitored circuits. When inspecting products with a number of isolated circuits of 2000 or more, the actual insulation resistance of the switch, reduced to monitored circuits, may be 0.1 or less than the monitored circuit, which leads to loss of accuracy and reliability of the control. In addition, the intrinsic insulation resistance of any monitoring device may vary depending on temperature, humidity, environmental composition, etc. and if all this is not taken into account, the measurement result of the insulation resistance of the monitored object may differ from the true value by 3050% or more. The aim of the invention is to improve the accuracy and reliability of control of objects with a large number of isolated circuits. This goal is achieved by connecting the second input of the switching unit through the encoder to the first output of the clock counter, the second input to the device containing the connection block connected to the switching unit, the first input of which is connected to the output of the switching unit through the encoder through the memory block of the connected circuits. the output of which is connected to the control unit whose first output is connected to the input of the information input unit, the second output of the control unit is connected to the comparison unit, the third output of the control unit is connected to the display unit registration and with the output of the clock generator, the output of which is connected to the inputs of the display and recording units, comparison, clock counter, with the first input terminal of the measuring unit, the first output and second input terminals of which are connected respectively to the switching unit, a value memory is entered own leakage currents and a subtraction unit, the first output of the clock counter being connected to the first input of the memory unit and the values of the own leakage currents, the second input of which is connected to the second output terminal of the measuring unit and the first input of the subtraction unit, the second input of which is connected to the output of the clock generator and the third input of the memory block of the values of the corresponding leakage currents, the output of the second is connected to the third input of the subtraction unit, the output of which is connected to the input of the comparison unit, and the third output of the control unit connected to the fourth input of the memory block of the common leakage currents /, the block / measurement contains the source voltage and the analog-digital current converter, and the outputs of the source voltage reference voltage are connected to the The first input of the analogue-digital current converter and the first you, the quick terminal of the measuring unit, the second input-analogue-digital current converter is connected to the first input terminal of the measuring unit, the third input of the analogue-digital current converter, the second output terminal of which connected to the output of the analog-digital current converter. The drawing shows a schematic diagram of the device proposed. The device for monitoring the insulation resistance value includes a connection unit 1, a switch 2, a block 3 of addresses of connected circuits, a control block 4, a block for information input 5, a block 6 measuring device that includes an analog-digital converter 7 current (ADCT) and the source 8 of the reference voltage, the encoder 9, the counter 10 cycles, the clock generator 11, the storage unit 12 of the values of leakage currents, the subtraction unit 13, the comparison unit 14, the display and recording unit 15. Block 1 is designed to connect the monitored product and to the switch 2, Switch 2 and the encoder 9 serve to divide the controlled circuits (points) of the product into two groups and connect common groups to measurement block 6, block 3 serves to memorize the addresses of the points of the product chains that need to be monitored , and switch 2 key management for allowing connections to groups of monitored circuits (points). The generator 11 serves to synchronize the operation of the ADC 7, blocks 12-15. The device works as follows. The product is monitored by a group method, and, in order to simplify the device, the insulation resistance value is controlled by controlling the leakage current, which is inversely proportional to the insulation resistance value. The information about the isolated chains (points) of the controlled product is entered in block 3 through block 5, for example, from punched tape using a photo-reading device. At the same time, preparation for control is performed, and the preparation of the device for production control for each type of product being tested, since the intrinsic insulation resistance of the device, brought to controlled circuits, will be different for different products, and it can also vary considerably depending on climatic conditions. conditions (humidity and temperature). To perform the operation and preparation, a full cycle of operation of the device is performed without connecting the controlled device to unit 1 and switch 2, but using the same testing program.

The preparation operation consists of writing to the block 12 the values of the leakage current of the insulation of the circuits of the block 1 and the switch 2 involved in the monitoring. During each operation cycle of the device (each division of the monitored circuits into two groups), the number of circuits 1 and 2 of the switch connected to different groups will be different, which means that the leakage current is different, therefore measuring and recording the measured value of the own current Leaks are conducted for all work cycles (combinations of connecting points), the number of which is determined by the number of controlled points of the object.

The signal of the generator 11 on each step of the device is used to turn on the block b and record the measured value of the device’s own leakage current in the binary (binary-decimal) code from ADCT 7 into the corresponding cell of block 12. The number of cells in block 12 is equal to the number of combinations connection points (the number of cycles of the device).

After finishing the preparation of the device for monitoring, the control object is connected via block 1 to switch 2 and the insulation resistance value of the control object is monitored. In this case, the signal from block 4, block 12 is transferred to the information reading mode, and the generator 11 is started. The signals from generator 11 increase the state of counter 10 by one after each clock cycle, which determines the cell address of block 12. The leakage current at each clock cycle the control measured by block b will be the sum of the leakage current of the monitored product and the device’s own leakage current. At each control cycle, this total leakage current from the output of ADCT 7 is input to the input decreases the number 13 of the block 13, the output of which is subtracted from the information output of block 12 enters the value of the device’s own leakage current recorded during the device preparation operation to work.

In block 13, the leakage current of the controlled product is extracted by subtracting the value of the device’s own leakage current from the total value of the leakage currents. The magnitude of the leakage current of the article being inspected from the difference output of block 13 is fed to the input of block 14, where it is compared with the value of the permissible leakage current that goes to block 14 from block 4. The allowable reference value of the leakage current can be set in block 4, for example using the switch (in the drawing

not shown) in a binary (binary-decimal) code. When the magnitude of the measured leakage current exceeds the permissible value, block 14 generates a BRACK, which is fed to the block 15.

The use of this object permits measurements to be made with an accuracy of 5–10% for a device’s own insulation resistance of two orders of magnitude lower than that monitored.

Claims (2)

1. A device for monitoring the value of the insulation resistance of an electrical installation, containing a connecting unit connected to a switching unit, the first input of which is connected to control units and information input through a block of addresses of connected circuits, the second input of switching unit is connected via a cipherto to the first output a clock counter, the second output of which is connected to the control unit, the first output of which is connected to the input of the information input unit, the second output of the control unit is connected to the "1 comparison block, the third output the control unit is connected to the display and registration unit and to the input of the clock generator of the generator, which is connected to the inputs of registration and registration, comparison, clock counter, with the first input unit luieMMDe of the measuring unit, the first output and second input terminals of which are connected respectively to the unit switching, characterized in that, in order to increase the accuracy and reliability of control of objects with a large number of isolated circuits, a block of memory of values of intrinsic leakage currents and a subtraction block are entered into it, the first The clock counter is connected to the first input of the storage unit of its own leakage currents, the second input of which is connected to the second output terminal of the measurement unit and to the first input of the subtractor, the second input of which is connected to the output of the clock generator and to the third input of the storage unit leakage currents, the output of which is connected to the third input of the subtraction unit, are you. the stroke of which is connected to the input of the comparison unit, and the third output of the control unit is connected to the fourth input; house of the storage unit of values of own currents of leakage. 2. A device according to claim 1, characterized in that the measurement unit comprises a source of reference voltage and an analog-to-digital unit. a current spreader, the non-source voltage outputs are connected to the first analog-digital current converter input and the first output terminal of the measuring unit, the second analog-digital current converter input is connected to the first input terminal of the measuring unit, the third analog-digital current converter is connected to second input terminal 5, measurement location, second output the terminal of which is connected to the output of the analog-digital converter. Sources of information taken into consideration during the examination 1. Author's certificate) USSR № 347697, cl. G 01 R 31/04, 1968. 2. USSR author's certificate number 529432, cl. G 01 R 31/02, 1975 (prototype).