SU1357886A1 - Device for checking condition of power transformer insulation - Google Patents

Abstract

The invention relates to a control and measuring technique and serves to increase the reliability of control of a power transformer. The device contains parametric converters 1 and 2, voltage dividers 4 and 6, resonant amplifiers 5 and 7, differential amplifier unit 10, executive unit 13. Introduction of formers 8 and 14 pulses, rectifiers 9 and 15 with filter, key element 11, pulse formers 16 and 18 and the two-input element And 17 eliminates the false alarms that occur when high-frequency signals pass from the low voltage winding to the high voltage winding. 3 il. SS (L / „co 00 00 05

Description

The invention relates to a control and measuring technique and can be used in devices for monitoring the state of the insulation in power transformers without disconnecting it from the network.

The aim of the invention is to increase the reliability of control of a power transformer by eliminating the false alarms that occur when high-frequency signals pass from the low voltage winding to the high voltage winding.

FIG. 1 shows the scheme of the proposed device; - FIG. 2 and 3 - - time diagrams stress, ill. p.oziruyu- 1 CIE operation devices ;.

The device contains nerve 1 and second 2 parametric converters, the primary winding of each of which is connected to the corresponding current outputs of the control object 3 (power transformer), and the secondary winding of the first parametric converter 1 is connected to the input of the first resonant voltage through the first divider 4 amplifier 5. The secondary winding of the second pair.metric converter 2 through the second de. Voltage pgl 6 is connected to the input of the second resonant amplifier 7. The output of the first1H resonant amplifier 5 is connected to the input of the first shaper 8 pulses and through the first inverter 9 with a filter to the first input of the differential amplifier 10, which through the key element 11 is connected to the input of power amplifier 12. The output of the power amplifier 12 is connected to the input of the preemptive block 13. The output of the second resonant amplifier 7 is connected to the input of the second driver 14 imiuls and through the second converter 15 with a filter to the second input of the differential. PzNo-amplifying block 10. The output of the nerve-forming device 8 pulses through the first form-building; 1 16 times the number of pulses connected to the first input of the two-input element And 17, the output of which is connected to the control input of the key element I. The output of the second form .ch 14 pmnu / .sow through the second shaper 18 of the pulse duration is connected to the second input of the two-input element I 17. In addition, the device contains a high-frequency source generator (not shown) connected to the electrical network in which the object is connected) .: 1, most measure to the high voltage winding of the power transformer. Taki. sources of high-frequency signals could be inverters, electric arc switches, etc.

FIG. 1-3, the following signals are marked: U, U-2 - signals, respectively, from the outputs of the first 1 and second 2 and parametric transducers; L l {fi,),) - signals, respectively, from the outputs of the nerve1C) o and the second 7 resonant amplitudes; U. U - signals respectively from the outputs

the first 9 and the second 15 c) Shch ture; AL U {- Uy - signal from the output of the differential amplifier unit 10; U l. iy - signals, respectively, from in;; 3 of the first 8 and second 14 pulse formers; t, - is the delay time of the high-frequency | -o signal, 1a as it passes through the windings of the transformer,

Uetroyetvo works as follows.

In the electrical network where the controlled transformer is connected, high-frequency signals are generated with the help of other radio sources. Such sources of high-frequency signals can be inverters, electric arc furnaces and so on.

; 1 more, and are permanently included in the network. Finally, out-of-network signals can be detected in the network due to its nonlinearity and asymmetry.

High-frequency signals from each of the windings of the monitored transformer 3, respectively, through the corresponding parametric converters 1 and 2 are supplied via high-frequency cables to, respectively, 1 and 4 and 6, and their outputs are respectively connected to the inputs of the corresponding resonant amplifiers 5 and 7, where they are amplified , and then the images are fi lt. respectively, with signals 9 and 15, the remote signals with each, 010 of the rectifying signals: 1 9 and 15, and the corresponding inputs of the differential amplifier unit 10, Result s eignal connected through iosle- sequence key element 11 and ueilitel ioetupaet 12 in the execution unit 13, for example made in the form of voltage relays and latching the delayed r-2 activation and signaling the state of the insulation.

In the normal state of isolation of the monitored transsormator 3, the voltage, nostating, to the input of the executive unit 13, is zero. In the case of the isolation of a pip of a co-controlled transformer,

corresponding to the emergency stage, the first is their reduction, due to changes,: the values of the capacitance and active conductivities of the replacement circuit 1, coitromatorized transformer 3, With this, I have measured and eaten with the level of 1 through the transformer 3 signals of the corresponding frequency. The executive unit 13 at the same time triggers issues a sigpal about reducing nzo; 1 c; c1 ciicpx of the set of the total porma.

In this key element 11 otkrygg,

EU, 1I in the test area, the high-frequency signal is not false, t, e, passes from the winding to 1p into the winding of a low voltage and the output device will display information about the insulation of the test object. In this case, 1yats

to the inputs of the element I 1 and do not arrive simultaneously, but with an interval of delay time t .. In this case, the input from the inputs of the element P 17 comes from a pulse of duration L iiTi) (FIG. 2), but through the delay time r

a pulse of greater duration arrives at the other input of the element 17 (U2 (t2), as a result of which the signal at the output of the element 17 does not exist, key element 11 is opened and the execution unit gives information about the state of the insulation of the object.

If there is a spurious high-frequency signal in the electrical network (the passage of this signal in the opposite direction — from the low voltage winding to the high voltage winding), the signal is blocked to the executive unit and, accordingly, the false information about the object state is blocked. . In this case, after the appearance of the And 17 pulses U 2 {r 2) on one of the inputs from the pulse width generator 16 connected from the low voltage winding side of the transformer 3, the pulse U (where T :) of shorter duration (Fig. 3), which is delayed compared with the first pulse by the time t / determined by the capacitive isolation parameters of the power transformer 3. As a result, two pulses appear on both inputs of the And 17 element and, accordingly, a control pulse key ale input coagulant last 11 closes and locks the operation execution unit 13 and the issuance of the false signal at the output device.

The invention makes it possible to eliminate the false triggering of the device, as a result of which the reliability of information on the state of the insulation of the object is increased.

Claims (1)

Invention Formula A device for monitoring the isolation state of power transformers containing a source of high frequency signals, uLjJf with connected to the corresponding terminals of the control object, the first and second para-, metric converters, the primary winding of each of which is connected to corresponding current outputs of the control object, and the secondary winding of the first parametric converter is connected to the input of the first resonant amplifier through the first voltage divider, The secondary winding of the second parametric converter is connected via a second voltage divider to the input of a second resonant amplifier, a differential-amplifier unit and serially connected power amplifiers and an executive unit, characterized in that, in order to increase the control reliability, the first and second rectifiers with filters, the first and second pulse formers, the first and second pulse formers for impu, 1сso, the key element, the amplifier, the two-input element And, and you od the first resonance amplifier is connected to the input of the first pulse shaper and through a first rectifier-filter - the first vhodo.m the differential amplifier unit, the output of which is connected to the input of the power amplifier through the key element, the output of the second resonant amplifier is connected to the INPUT of the second pulse generator and through the second rectifier with a filter - with (the second input of the differential amplifying unit, the output of the first pulse generator through the first pulse shaper is connected to the first input of the two-input element I, the output of which is connected to the control input the key element, the output of the second pulse shaper through the second shaper of the impu duration, is connected to the second pulse of the two-input element I. g (M  / L, rt vIT 17 VJ uEjjy vy 42 (i Vr r r  v: / Fig2 vniipi Order 550546 Production and printing company, Uzhgorod, st. Design. four Fbr Uidil CL LT TJ i. ffi. m m or Figz Circulation 730 Subscription