RU217981U1 - Device for diagnosing the mechanical condition of power transformer windings - Google Patents

Abstract

The utility model relates to electrical engineering, in particular to devices for diagnosing the mechanical state of power transformer windings. The technical result is an increase in the dynamic range of voltage (amplitude component) of harmonic oscillations of the response of the transformer winding and a decrease in losses for matching wave impedances, which are the result of improved matching of measuring equipment and switching cables with the object under study in a wide frequency range. The specified technical result in the implementation of the utility model is achieved by the fact that the matching device is a broadband transformer (SHPT) with a known wave impedance, the primary bifilar windings of which are matched with the resistance of the measuring equipment (50 Ohm), and the secondary winding is matched with the resistance of the equipment under study (wave impedance power transformer windings). The SHPT is made on a ferrite toroidal core based on nickel-zinc ferrite with a permeability of at least 100 H/m, with overall dimensions of at least 32×20×9 mm, providing signal transmission with a level of at least +33 dBm (10 V at a resistance of 50 Ohm ) and frequency up to 30 MHz. The primary windings of the SHPT are a bifilar winding with paired turns in the amount of 40 turns of enameled copper or aluminum wire PETV-2 with a cross section of 0.5 mm. 2 w.p. f-s, 4 ill.

Description

The utility model relates to electrical engineering, in particular to devices for diagnosing the mechanical state of power transformer windings.

The closest device of the same purpose, to the claimed utility model in terms of a combination of features, is a device for diagnosing the mechanical state of the windings of power transformers, including the leads of the winding under study for connecting a measuring generator, an oscilloscope and an active additional resistance of 50 Ohm in accordance with the wave impedance of the measuring equipment (see Fig. 1.10, p. 29, table 3.1, p. 85 of the dissertation for the degree of Candidate of Technical Sciences Alexandrov N.M. Improving the method for diagnosing the mechanical state of power transformer windings: 09/05/01 / defended 12/15/2020, approved 07/15/2021 / Aleksandrov Nikolai Mikhailovich. - Samara, 2020. - 142 p.), taken as a prototype.

The reasons preventing the achievement of the technical result indicated below when using a known device adopted as a prototype include incomplete resistance matching in a wide frequency range from 20 Hz to 2 MHz, which leads to losses in the amplitude component of the transformer winding response fluctuations.

The technical result is an increase in the dynamic range of voltage (amplitude component) of harmonic oscillations of the response of the transformer winding and a decrease in losses for matching wave impedances, which are the result of improved matching of measuring equipment and switching cables with the object under study in a wide frequency range.

The specified technical result in the implementation of the utility model is achieved by the fact that in the device for diagnosing the mechanical state of the windings of power transformers containing the matching device, the peculiarity lies in the fact that the matching device is a broadband transformer with a wave resistance containing a ferrite toroidal core based on nickel-zinc ferrite with a permeability of at least 100 Gn / m, with overall dimensions of at least 32 × 20 × 9 mm, providing signal transmission with a level of at least +33 dBm and a frequency of up to 30 MHz, two primary bifilar windings with leads for connecting measuring equipment and a secondary winding, the primary bifilar windings of which are matched with the resistance of the measuring equipment 50 Ohm, and the secondary winding - with the resistance of the equipment under study.

Primary bifilar windings are winding with paired turns in the amount of 40 turns of enameled copper or aluminum wire PETV-2 with a cross section of 0.5 mm. The conclusions of the primary bifilar windings are made of copper or aluminum enameled wire with a cross section of at least 0.5 mm. The secondary winding is made of copper or aluminum and has a rectangular cross section.

In this case, measuring equipment is connected to the primary bifilar windings - an oscilloscope and a measuring generator, and the secondary winding is connected to the winding of the power transformer under study.

The matching device is a broadband transformer (SHPT) with a known wave impedance, the primary windings of which are matched with the resistance of the measuring equipment (50 Ohm), and the secondary winding is matched with the resistance of the equipment under study (the wave impedance of the power transformer winding). The SHPT is made on a ferrite toroidal core based on nickel-zinc ferrite with a permeability of at least 100 H/m, with overall dimensions of at least 32×20×9 mm, providing signal transmission with a level of at least +33 dBm (10 V at a resistance of 50 Ohm ) and frequency up to 30 MHz. The primary windings of the SHPT are a bifilar winding with paired turns in the amount of 40 turns of enameled copper or aluminum wire PETV-2 with a cross section of 0.5 mm.

In order for each line to be loaded with a matched resistance, the following conditions must be met:

R _in - input impedance, Ohm; Z _c - line impedance, Ohm;

R _n - wave impedance of the load, Ohm; N is the transformation ratio.

The drawings show:

figure 1 - diagram of the matching device, front view, where: 1 - ferrite toroidal core, 2 - outputs of the primary bifilar windings, 3 - secondary winding,

in fig. 2 - diagram of the matching device, side view, where: 1 - ferrite toroidal core, 3 - secondary winding;

in fig. 3 is a schematic diagram of a matching device, where 1 is a ferrite toroidal core, 3 is a secondary winding, 4 is the first primary bifilar winding, 5 is the second primary bifilar winding;

in fig. 4 - dependence of the amplitude of the response signal in the winding of a power transformer on time: a - matching with a matching device, b - matching with active resistance.

Fig. 4 illustrates the results of a study of the amplitude-time characteristics of the winding of the transformer under study with a classical matching circuit using active resistance and using a matching device.

The matching device contains a ferrite toroidal core 1 with a permeability of at least 100 H/m 1, the first primary bifilar winding 4 and the second primary bifilar winding 5, made of paired turns of enameled copper or aluminum wire, the outputs of the primary bifilar windings 2 for connecting measuring equipment - a generator and oscilloscope, wound with copper or aluminum enameled wire of the PETV-2 brand, secondary winding 3, represented by a copper or aluminum rectangular busbar for connecting the winding of the power transformer under study.

The conclusions of the primary bifilar windings 2 can be made of copper or aluminum enameled wire with a cross section of at least 0.5 mm.

The secondary winding 3, represented by a copper or aluminum bus, can be made of copper or aluminum and have a rectangular cross section.

Information confirming the possibility of achieving the above technical result.

In the proposed technical solution for diagnosing the mechanical state of the winding of a power transformer, a matching device is used that matches the resistance of the winding of the transformer under study with the resistance of the measuring equipment of 50 Ohms and contains a ferrite toroidal core based on nickel-zinc ferrite with a permeability of at least 100 Gn/m, with overall dimensions of at least 32×20×9 mm, providing signal transmission with a level of at least +33 dBm and a frequency of up to 30 MHz, two primary bifilar windings and a secondary winding.

To increase the dynamic voltage range (amplitude component) of the harmonic oscillations of the response of the transformer winding and reduce losses for matching wave impedances, the secondary winding 3 is connected to the investigated winding of the power transformer, represented by a copper or aluminum bus of rectangular cross section. The first primary bifilar winding 4 of the matching device is supplied with a measuring voltage pulse from the measuring generator (not shown in the figures), which leads to the appearance of a current pulse in the secondary winding 3 of the matching device due to magnetic coupling in the ferrite toroidal core 1. To remove the response signal of the winding under study an oscilloscope is connected to the second primary bifilar winding 5 of the matching device (not shown in the figures). By using a matching device with a wave impedance of the outputs of the primary bifilar windings 2 equal to 50 Ohm (resistance of the measuring equipment), a decrease in losses for matching wave impedances [2] and an increase in the amplitude component of the response signal of the winding of the transformer under study are achieved.

The results of the study of the dynamic voltage range of the harmonic oscillations of the response of the transformer winding, shown in Fig.4 show that the amplitude at the peaks of harmonic oscillations when using a matching device is 1.7 V greater than when using an active additional resistance. Thus, the increase in the dynamic range during measurements is 4.5%.

Bibliography

1. Alexandrov N. M. Improvement of the method for diagnosing the mechanical state of the windings of power transformers: dis. ... cand. those. Sciences: 05.09.01 / Alexandrov Nikolai Mikhailovich. - Samara, 2020. - 142 p.

2. Degtyar G.A. Transformers in matching circuits and power addition of radio frequency generators: a tutorial. - Novosibirsk: Publishing House of NGTU, 2003. - 504 p. - (Series "Textbooks of NSTU).

Claims (3)

1. A device for diagnosing the mechanical state of the windings of power transformers, containing a matching device, characterized in that the matching device is a broadband transformer with wave resistance, containing a ferrite toroidal core based on nickel-zinc ferrite with a permeability of at least 100 Gn/m, with overall with dimensions of at least 32×20×9 mm, providing transmission of signals with a level of at least +33 dBm and a frequency of up to 30 MHz, two primary bifilar windings with leads for connecting measuring equipment and a secondary winding, the primary bifilar windings of which are matched with the resistance of the measuring equipment 50 Ohm, and the secondary winding - with the resistance of the equipment under study. 2. The device according to claim 1, characterized in that the primary bifilar windings are winding with paired turns in the amount of 40 turns of enameled copper or aluminum wire PETV-2 with a cross section of 0.5 mm. 3. The device according to claim 1, characterized in that the secondary winding is made of copper or aluminum and has a rectangular cross section.

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