SU1465831A2 - Device for monitoring the condition of insulation of power transformers - Google Patents

Abstract

The invention relates to the field of instrumentation and, in particular, to means of monitoring the state of the insulation of transformers. The purpose of the invention is to increase the reliability of the control. High-frequency pulses and, and and, arisen in the insulation of transformer 3, are amplified by amplifiers 5 and 7 and are fed to the inputs of the formers 8 and 14 pulses, and through the formers 19 and 22 of the pulses duration

Description

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The invention relates to instrumentation engineering and can be used in devices for monitoring the state of the insulation in power transformers without disconnecting them from the network.

The purpose of the invention is to increase the reliability of monitoring the isolation of a power transformer without disconnecting from the network by fixing partial discharges occurring in the obt., Control object, and eliminating false alarms from sources of high-frequency pulses outside the controlled object.

Figure 1 presents the scheme of the device; in fig. 2 and 3 are timing diagrams illustrating the operation of the device.

The device contains the first 1 and second 2 parametric converters, the primary winding of each of which is connected to the corresponding control current outputs (power transformer) 3, and the secondary winding of the first parametric converter 1 through the first voltage divider 4 is connected to the input of the first resonant amplifier 5. Secondary winding the second parametric Converter 2 through the second voltage divider 6 is connected to the input of the second resonant amplifier 7, the output of the first resonant amplifier 5 st en with the input of the first driver 8 pulses and through the first exporter 9 with a filter with the first input of the differential amplifier unit 10, the output of which through key element I1 is connected to the input of the power amplifier 12, the output connected to the input of the executive unit 13. The output of the second resonant amplitude 7 connected to the input of the second pulse shaper 14 and through the second driver 15 with a J filter with the second input of the differential amplifier unit 10, the output of the first driver shaper 8 pulses through the first driver 16. the pulse duration is connected to 0 by the first input of the two-input element AND 17, the output of which is connected to the control input of the key element 11. The output of the second generator 14 of pulses through the second generator 18 of the pulse duration is connected to the second input of the two-input element And 17. The input of the third generator 19 the pulse duration is connected to the output of the first pulse generator 8 pulses, and at the output - to the first input of the second two-input element I 20, to the output of which a pulse counter 21 is connected. The input of the fourth shaper 22 pulse duration is connected to the output of the second shaper 14 pulses, and the output to the second input of the second two-input element And 20,

Partial discharges occur when the insulation condition deteriorates in the power transformer 3, which is under operating voltage. The intensity of the partial discharges increases with progressive deterioration of the insulation characteristics, for example, during wetting or aging.

FIG. 1-3 -. The following notation is used: U ,, U - impulses from the outputs of the first 1 and second 2-parameter converters;

and,, U-. - impulses from the outputs of the first 5 and second 7 resonant accelerators; and,, 1 - w puls from the outputs of the first 8 and second 14 form 1D6583

lei pulses; U {, - pulses from the outputs of the third 19 and fourth 22 formers of the pulse duration; G, 2. the time of support for the occurrence of pulses U and 11 at the inputs of the first 1 and second 2 parametric converters, when the source of the high-frequency pulse element AND 20 signal arrives at the pulse counter 21. According to the intensity of the readings of the counter 21, the intensity of the number of partial discharges is counted, which is how the insulation state of the monitored power transformer is evaluated. ,

In the presence of a source out of contact

high-frequency pulses arrive at the inputs of the drivers 8 and 14 pulses with delay intervals t j, which is determined by the resistance and capacitance of the winding of the power transformer. The pulse durations and, and Uj are chosen to be shorter than the delay times t. In this case (Fig. 3) at one input, the two leading edge of the pulse U,, the cut time from the second input of the element AND 20, appears

what of it

front of pulse I2 25 value

Owls are located in a controlled, objectified power transformer and outside it.

The device works as follows.

In a controlled power transformer, which is under operating voltage 15, with deterioration of its isolation, so-called partial discharges or creeping discharges arise in it, which are sources of high-frequency pulses in the control - 20 of the input element AND 20 appear the object . The intensity of these bits (pulses) is functionally dependent on the degree of deterioration of the insulation state.

Outside the controlled object, in the electrical network in which the monitored power transformer is included, third-party sources of high-frequency pulses also appear: microdischarges, corons, electric arc furnaces, inverters, switching equipment arc, etc. These high-frequency impulses from third-party sources for the device are interference. High-frequency pulses and, and Uj ,, arising in the insulation of the monitored power transformer 3, through parametric converters 1 and 2 are supplied via high-frequency cables to voltage dividers 4 and 6, and from their outputs to the inputs of resonant amplifiers 5 and 7, where amplified with significant amplitude30

Claims (1)

, since the pulse length and, (and) are shorter than the delay time t. the simultaneous presence of at least part of the pulses and, and at both inputs of the two-input element And 20 is excluded. As a result, there is no output signal on the course of this element and the pulse counter 21 does not work, i.e. It does not give false information on the state of the insulation of the object 35, which increases the reliability of the information on the state of the isolation of the power transformer. Invention Formula 40 worlds 19 and pulses and., and dah limited. Then the pulses U | and Ujj with an interval, postdata to the inputs, respectively, of the formers 8 and 14 pulses, through the duration of 22 times, the inputs of the second two-input element AND 20 are available at the corresponding inputs of the two-input element And 20 in a certain duration, two signals simultaneously from and u, respectively  2 at least for a time less (and to as a result 2 of this ). Moreover, and from the output of a two-input device for monitoring the state of isolation of power transformers by the auth.St. P 1357886, characterized in that, in order to increase the reliability of monitoring 45 the isolation of a power transformer, the third and fourth pulse duration drivers, the second And element and the pulse counter are entered into the device, with the inputs of the third and 50 fourth pulse formers duration connected to the outputs of the first and the second pulse formers, and the outputs of the third and fourth drivers for the extreme 55 pulse duration are connected to the inputs of the second element And, the output of which is connected to the input of the counter pulses. the high-frequency pulses are fed to the inputs of the driver formers 8 and 14 of the pulses with delay intervals tj, which is determined by the magnitude of the resistance and the winding capacity of the power transformer. The pulse durations and, and Uj are chosen to be shorter than the delay times t. In this case (FIG. 3) at one input of a two-controlled power transformer input element AND 20 appears the leading edge of the pulse U,, the cut-off time at the second input of the element And 20 appears the leading what of it input element AND 20 appears I2 pulse front input element AND 20 appears , since the pulse length and, (and) are shorter than the delay time t. the simultaneous presence of at least part of the pulses and, and at both inputs of the two-input element And 20 is excluded. As a result, there is no output signal at the output of this element and the pulse counter 21 does not work, i.e. It does not give false information on the state of the insulation of the object, which increases the reliability of the information on the state of the insulation of the power transformer. Invention Formula 40 45 50 55