SU1287051A1 - Device for checking electric circuits - Google Patents

Abstract

This invention relates to a measurement technique. It can be used to control the insulation resistance of electrical circuits. The aim of the invention is to increase the reliability of the control. The device contains a control unit 1, a software unit 3, a measuring unit 2, a test signal source 7, containing the first 8 and second 9 outputs, a switch 4. To achieve this goal, an operational amplifier 11, a reference element 10, resistors 12, 13 are inserted into the device new functional connections are formed. The switchboard contains the first 5-1, 5-2, ..., 5-p and the second 6-1, 6-2, ..., 6-n switch groups. In the drawing, the object of control 14 is represented, containing controlled circuits 15-1, 15-2, ..., 15-k. Leakage currents between the test object circuits connected to the common bus and the first group of circuits do not affect the measurement accuracy, because. compensated by an operational transducer. 2 Il. O) C

Description

This invention relates to a measurement technique and can be used to control the insulation resistance of an electrical circuit,

The purpose of the invention is to increase the reliability of the control.

Figure 1 shows the structural electrical circuit of the device; Fig. 2 is a block diagram of the control unit.

The device for monitoring electrical circuits contains a control unit 1, a measuring unit 2, a software unit 3, a switch 4 containing the first 5-1, 5-2, ..., 5-n and the second 6-1.6-2, .. .6-n switch groups of test signal source 7, containing the first 8 and second 9 outputs, the reference element 10, the operational amplifier 11, - the first 12, the second 13 resistors. Figure 1 also presents a control object 14, containing controlled circuits 15-1, 15-2,

 r ;, 15-k.

The first output 8 of the source of the test signal 7 is connected to the bus of normally open contacts of the first group of switches 5-1 to 5-n switch 4, the second output 9 of the source of the test signal 7 is connected to the first 16 and second 17 inputs of the measuring unit 2, respectively, through the reference element 10 and directly. The bus normally open contacts of the second group of switches 6-1 to 6-p switch 4 is connected to the first 16 inputs of the measuring unit 2. The first 18 and second 19 inputs of the operational amplifier 11 are connected respectively to the first 16 inputs of the measuring unit 2 and the common bus. The output of the operational amplifier 11 is connected via the first 12 and second 13 resistors, respectively, with the second 17 input of the measuring unit 2 and the common bus. The circuits of the control object 14 through the normally closed contacts of the switches of the first 5-1, ..., 5-p and second 6-1, ..., 6-p groups are connected to the common bus.

The control unit 1 (FIG. 2) contains a 2n-bit register 20, where n is the number of switches in each of the two switch groups of switch 4, executed on digital circuits, for example, type 133IR1, 2n keys 21, made on cn ov-to. microcircuits, for example, type 133LA8. Input 22 re

five

0

five

five

gister 20 is connected to the microcomputer by a communication line. The outputs of the register 20 are connected to the inputs 23-1, 23-2, ..., 23-2p of the keys 21, the outputs 24-1, 24-2, ..., 24-2p are connected to the control inputs of the switch 4. The measuring unit 2 is made, for example, in the form of an analog-digital converter with an operational amplifier having a differential input. The switch 4 is made, for example, on the relay. The source of the test signal 7 can be a precision source of direct or alternating current, made, for example, on operational amplifiers. The reference element 10 is made on resistors or capacitors or in the form of a series-parallel connection of these elements. Operational amplifier 11 is designed as an operational amplifier with high-impedance inputs. As a software block 3 can be used computer type Electronics-60.

The proposed device works in the following way.

The first controlled circuit 15-1 is connected with the switch / 6-1 to the first 16 input of the measuring unit 2. All other circuits of the control object 14 are connected with the help of switches 5-2, 5-3, ..., 5-p to the first 8 test signal source 7 output. At the same time, the leakage current between the first 15-1 controlled circuit and all others flows only through the reference element 10, and the leakage currents of all contacts of the switches of the switch 4 flow through the first 12 and second 13 resistors. Operational amplifier 11 with its inputs 18 and 19 measures the difference between the voltage at the first 16 input of the measuring unit 2 and the common bus and supports it with its output close to zero. The measuring unit 2 measures the voltage on the reference element 10 and transmits the code to the software unit 3. In the software unit 3, the value of the insulation resistance is calculated by the known formula

0

0

pi ,,

de and

ftblX

and:

R

 T

- output voltage of the test signal generator;

at

ET

 - voltage measured on the reference element - value - resistance

reference element. Similarly, the insulation resistance is checked between two control circuit groups. For this, the first control circuit group is connected to the first input of the measuring unit 2, the second depay group - to the first output of the test signal source 7, and all other circuits of the test object 14 remain connected to common bus. Leakage currents between the test object circuits connected to the common bus and the first group of circuits do not affect the measurement accuracy, since they are compensated for by the operating transducer.

Claims (1)

Invention Formula A device for monitoring electrical-: circuits containing a software unit, a control unit, a source of a test signal, a switch, a measuring unit, the output of a software unit is connected to the input of a control unit, the output of which is connected to a measuring unit 30. five 0 five switch input, the power inputs of which are connected to the first output of the test signal source, the first outputs of the switch are connected to the corresponding terminals for connecting the test object, the second outputs of the switch are connected to the first input of the measuring unit, in order to increase the reliability control, an operational amplifier, a reference element, the first and second resistors are inserted into the device, the third outputs of the switch are connected to the common bus of the device, the first output is reference element is connected to the first input of the measuring unit and to the first input of the operational amplifier, the second input of which is connected to the common bus of the device, the output of the operational amplifier is connected through the first resistor to the common bus of the device and through the second resistor to the second input of the measuring unit whose output is connected with the input of the software unit, the second output of the test signal source is connected to the second output of the reference element and to the second input