SU1383229A2 - Device for checking state of electric ciruit insulation - Google Patents

Abstract

The invention relates to the field of instrumentation technology and can be used to monitor and diagnose the state of isolation of electrical circuits, such as electrical machines. The invention allows to increase the reliability and speed of control, which is achieved by introducing into the device a charge monitoring unit 17, a reverse diode 18 and a switch 16. In addition, the device contains a switch 1, terminals 2 and 3, a charge unit 4, a discharge unit 5, control unit 6, measurement and indication unit 7, calibration unit 8, memory block 9, calculators 10 and 11, capacitance meters 12 and 13, absorption meters 14 and 15. The device provides for automatic shutdown of the charge unit 4, carried out by the unit. 17 at the time of termination of the charge capacity of the insulation of the object of control, which increases the efficiency of the control. 1 il. with

Description

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The invention relates to instrumentation engineering and can be used to monitor and diagnose the state of isolation of electrical circuits, for example, in electrical machines and apparatus, and is an improvement of the device according to the author. St. No. 1064238.

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

The drawing shows a block diagram of the device.

The device for monitoring the electrical isolation state contains a switch 1, connected by a first input to the first terminal 2 for connecting a test object, a second capacitance meter 13 and connected to a capacitance meter 12, which measures the isolation capacitance at a low frequency. The signal proportional to the value of the measured capacitance, the posture terminal 3 for connecting which 20 goes to the input of the calculator 10, is connected to the common bus of the device, the charge unit 4 and the discharge unit 5 connected to the common bus of the device, control unit 6 connected first output with the third input of the switch 1, unit 7 of measurement and indication, connected by the first input with unit 8 ka; calibration, the second input - with the common bus of the device, the third input - with the memory block 9 connected by the third input with the second output of the control unit 6 of the control, the first and the second inputs respectively with the outputs of the first 10 and second 11 calculators connected by the first inputs between themselves and through the first capacitance meter 12 to the second output of the switch 1 connected by the first output via the second capacitance meter 13 to the second input of the first calculator 10, the first 14 and the second 15 absorbance current meters connected by the outputs respectively to the second and tr The other inputs of the second calculator 11, and the inputs, respectively, with the first and second outputs of the switch 16, connected by the second input to the output of the 5th digit unit and the first input to the second output of the charge monitoring unit 17, connected between the second input of the switch 1 and 4 charge reverse diode 18, connected between the first output of the charge control unit 17 and the discharge unit 5.

The device works as follows.

When conducting the insulation test, the control object is connected to the terminal 30

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rum performs the operation of calculating the capacitive frequency coefficient

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L. c

where the capacitance measured at a low frequency;

 capacitance measured at high frequency

and at the first input of calculator 11, where it is memorized.

A signal proportional to the value of KC is fed to the first input of memory block 9, where it is stored, and simultaneously entered into block 7, where it is fixed by a digital pointer.

The control object is disconnected from the meter 12 and connected simultaneously to the charge unit 4 through the charge control unit 17 and to the discharge unit 5 via the reverse diode 18.

At the time of termination of the charge of the capacitance 13col, characterized by the cessation of the change in the charging current, the charge control unit 17 switches off the charge unit 4 and feeds a signal to the switch 16 connecting the first 14 and second 15 adsorption current meters at the set times, respectively, t, and t 2 (after acquiring the signal from the charge control unit 17) to the discharge block 5, where the insulation capacitance is discharged, starting from the moment the charge block 4 is disconnected, and the circuit of the test object is not discharged, which excludes the possibility of to e insulation of high voltage pulses, okazy40

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The control unit 6, in accordance with the monitoring program, sets the control signals on the switch 1, providing a following operation sequence.

The control object is connected via switch 1 to a capacitance meter 13, which measures the isolation capacitance at a high frequency. The signal, proportional to the magnitude of the measured capacitance, is fed to the input of the calculator 10 and is memorized.

Control object is disconnected from

a capacitance meter 13 and connected to a capacitance meter 12, which. measures isolation capacitance at low frequency. The signal, proportional to the magnitude of the measured capacitance, is fed to the input of the calculator 10, in which

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rum performs the operation of calculating the capacitive frequency coefficient

": TC W out 5

L. c

where the capacitance measured at a low frequency;

 capacitance measured at high frequency

and at the first input of calculator 11, where it is memorized.

A signal proportional to the value of KC is fed to the first input of memory block 9, where it is stored, and simultaneously entered into block 7, where it is fixed by a digital pointer.

The control object is disconnected from the meter 12 and connected simultaneously to the charge unit 4 through the charge control unit 17 and to the discharge unit 5 via the reverse diode 18.

At the time of termination of the charge of the capacitance 13col, characterized by the cessation of the change in the charging current, the charge control unit 17 switches off the charge unit 4 and feeds a signal to the switch 16 connecting the first 14 and second 15 adsorption current meters at the set times, respectively, t, and t 2 (after acquiring the signal from the charge control unit 17) to the discharge unit 5, at which the insulation capacity is discharged, starting from the moment the charge unit 4 is disconnected, and the circuit of the test object is not broken, which eliminates the possibility of e insulation of high voltage pulses, okazy0

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destructive effect on the insulation of the object of control and causing malfunctions in the operation of the device blocks, which increases the reliability of the device and the reliability of the control.

The automatic shutdown of the 4 rd block, carried out by the charge monitoring control unit 17 at the time of termination of the charge of the insulation of the test object, increases the efficiency of the control.

Signals proportional to the values of the absorption current, measured at times t and t, (after the beginning of the discharge of the isolation capacitance) are fed to the inputs of the second calculator 11, in which the operation of calculating the differential absorption coefficient is performed.

l (ti) - KtO

UjCHv (t, -tJ

where I (t), I (t) are the values of the discharge current, measured respectively at the instants of time t, and 12 after the start of the isolation discharge;

and - voltage value of block 4 charge. A signal proportional to K, is fed to the input of memory block 9, where it is memorized, and simultaneously input into block 7, where a previously recorded Kc value is recorded by a digital pointer of the shift.

Ka

Such consistent fixation of Kj values. and Cd in block 7 of measurement and indication as they are calculated without a special command set by the operator, increases the efficiency of the control.

If necessary, the obtained measurement results K and K can be sequentially re-entered into block 7 by a command given by the operator from control block 6 and read from the digital pointer.

Claims (1)

Invention Formula A device for monitoring the state of isolation of electrical circuits by the author. No. 1064238, characterized in that, in order to increase the reliability and speed of the control, a control unit — a charge, a reverse diode, a switch — is introduced into the device, and the input of the charge control unit is connected to the output of the charge unit, the first output of the charge control unit Yes, it is connected to the second input of the switch and, through a reverse diode, to the discharge unit, the output of which is connected to the first input of the switch, the control input of which is connected to the second output of the charge control unit, the first and second outputs of the transducer. and a second current measuring devices absorption, respectively, the second output of the control unit: connected to the third input of the memory unit.