METHOD FOR DETERMINING ASYMMETRIC VIBRATIONS IN AN ELECTRIC DEVICE

Abstract

A method for determining a direct current component in an electric device that is connected to a high-voltage supply network. The method includes the following steps: acquiring operating noises of the electric device with the aid of acoustic sensors that are part of a portable unit and that provide acoustic signals at the output; breaking the acoustic signals down into their frequency components by a Fourier transformation, yielding a frequency spectrum; determining odd and even frequency components of the frequency spectrum in dependence upon a basic frequency of the high-voltage supply network and setting them in a ratio to one another; concluding that a direct current component is present if the ratio exceeds a predefined threshold value.

Claims

1-7. (canceled)

8. A method for identifying a DC current component in an electrical device that is connected to a high-voltage supply grid, the method comprising: providing a portable unit with acoustic sensors; acquiring operating noise of the electrical device with the acoustic sensors and forming corresponding acoustic signals; breaking down the acoustic signals into frequency components by way of a Fourier transformation to obtain a frequency spectrum; ascertaining even and odd frequency components of the frequency spectrum based on a fundamental frequency of the high-voltage supply grid and determining a ratio R between the odd and even frequency components; and when the ratio R exceeds a predetermined threshold value, concluding that a DC current component is present in the electrical device.

9. The method according to claim 8, wherein the portable unit is a mobile telephone.

10. The method according to claim 9, wherein the mobile telephone has a storage unit, and the method further comprises storing the acoustic signals or the frequency spectrum in the storage unit.

11. The method according to claim 8, which comprises performing the entire method on a mobile telephone.

12. The method according to claim 8, which comprises acquiring the acoustic signals at different locations in a vicinity to the electrical device.

13. The method according to claim 8, which comprises acquiring the acoustic signals over a predefined duration.

14. The method according to claim 8, wherein the mobile device is configured for connection to a cloud via a long-range communication connection.

Description

[0022] Further expedient embodiments and advantages of the invention are the subject matter of the following description of exemplary embodiments of the invention with reference to the FIGURE of the drawing, with the same reference signs referring to functionally identical components, and wherein the

[0023] FIGURE schematically illustrates one exemplary embodiment of the method according to the invention.

[0024] The FIGURE shows one exemplary embodiment of the method according to the invention, in which a transformer 1 is schematically illustrated as electrical device. The transformer 1 has a tank 2 that is filled with an insulating fluid. A magnetizable core 3 is arranged in the tank and forms a closed magnetic circuit. The limbs of the core 3 are each enclosed by two windings arranged concentrically to one another, only the outer high-voltage winding 4 of which is able to be seen. The windings are connected to the phases of a high-voltage grid carrying an AC voltage via bushings 5.

[0025] An expansion vessel 6 is used to compensate for temperature-induced volume fluctuations of the insulating fluid in the tank 2 of the transformer 1. A Buchholz relay 7 is able to be seen in the connecting line between the tank 2 and expansion vessel 6.

[0026] The FIGURE furthermore shows a mobile telephone 8, likewise illustrated only schematically, by way of which the operating noise of the transformer 1 is acquired at four different locations A, B, C and D. To this end, the mobile telephone 8 contains software or an “app” that asks the person applying the method to perform the noise measurement over a predefined duration and then to change location in order to perform the measurement again there.

[0027] A microphone, not illustrated in the FIGURE and already installed in the mobile telephone, is used for the noise measurement. The mobile telephone 8 stores the time-resolved acoustic signals generated by its microphone based on the measurement, after they have been digitized, in its storage unit, likewise not shown. The software then performs a Fourier transformation. This is followed by the formation of the ratio R, as already described above.

[0028] From the size of R, the method according to the invention derives whether and possibly to what order of magnitude the transformer is impacted by a DC current component. The user, by virtue of the result of the method, gains knowledge thereof and is then able to initiate appropriate countermeasures in order to suppress the possibly identified DC current component.

[0029] The sensors A and B are for example buried in the ground, and the measurements at the positions C and D take place in the high-voltage range. The measurements take place here for example roughly halfway up the tank (the windings).