CURRENT CONVERTER

Abstract

A current converter contains a primary conductor, a housing through which the primary conductor is led, an inductive alternating-current sensor which has at least one secondary coil arranged in the housing, and a compensation current sensor having a compensation coil arranged in the housing for producing a compensation magnetic field, which compensates a primary magnetic field produced by the primary conductor. A magnetometer is further provided for detecting a sum of the primary magnetic field and the compensation magnetic field.

Claims

1-15. (canceled)

16. A current converter, comprising: a primary conductor; a housing and through said housing said primary conductor is led; an inductive alternating current sensor having at least one secondary coil which is disposed in said housing; and a compensation current sensor having a compensation coil which is disposed in said housing for producing a compensation magnetic field, the compensation magnetic field compensating a primary magnetic field produced by said primary conductor, said compensation current sensor further having a magnetometer for detecting a sum of the primary magnetic field and the compensation magnetic field.

17. The current converter according to claim 16, wherein said inductive alternating current sensor has at least one measuring core and/or at least one protective core.

18. The current converter according to claim 16, wherein said magnetometer is a fluxgate magnetometer.

19. The current converter according to claim 18, wherein said fluxgate magnetometer has two compensation cores configured in an annular configuration about the primary conductor within said housing, and an excitation winding wound in an inverse direction about said two compensation cores.

20. The current converter according to claim 18, wherein said fluxgate magnetometer has an additional core and an additional secondary winding, which are configured in an annular configuration about said primary conductor within said housing, said additional secondary winding and said compensation coil are wound about said additional core.

21. The current converter according to claim 16, wherein said magnetometer contains a Hall effect sensor.

22. The current converter according to claim 21, wherein said compensation current sensor has a magnet core which is configured in an annular configuration about said primary conductor, within said housing, and about said magnet core said compensation coil is wound, and said magnet core has an air gap formed therein and in said air gap said Hall effect sensor is disposed.

23. The current converter according to claim 16, further comprising a winding housing disposed in said housing, and within said winding housing said at least one secondary coil and said compensation coil are disposed.

24. The current converter according to claim 23, wherein said winding housing is electrically insulated vis--vis said housing.

25. The current converter according to claim 16, wherein said housing is filled with an insulating gas or an insulating fluid, or with an insulating compound.

26. The current converter according to claim 16, wherein said inductive alternating current sensor contains a first measuring circuit, which is disposed outside said housing and is electrically connected to each said secondary coil.

27. The current converter according to claim 16, wherein said compensation current sensor has a second measuring circuit, which is disposed outside said housing and is electrically connected to said compensation coil and said magnetometer.

28. The current converter according to claim 16, wherein said compensation current sensor is deactivable.

29. The current converter according to claim 16, further comprising a post insulator, and upon said post insulator said housing is disposed.

30. A method for measuring currents by means of a current converter, the current converter containing a primary conductor, a housing and through the housing the primary conductor is led, an inductive alternating current sensor having at least one secondary coil which is disposed in the housing, and a compensation current sensor having a compensation coil which is disposed in said housing for producing a compensation magnetic field, the compensation magnetic field compensating a primary magnetic field produced by the primary conductor, the compensation current sensor further having a magnetometer for detecting a sum of the primary magnetic field and the compensation magnetic field, which comprises the steps of: detecting an alternating current flowing in the primary conductor or an alternating current component of a current flowing in the primary conductor by means of the inductive alternating current sensor; and detecting, by means of the compensation current sensor, a direct current flowing in the primary conductor or a direct current component of a current flowing in the primary conductor.

Description

[0021] The above-mentioned properties, characteristics and advantages of the present invention, and the manner in which these are achieved, are elucidated and clarified by reference to the following description of the exemplary embodiments, which are described in greater detail with reference to the drawings. In the drawings:

[0022] FIG. 1 shows a schematic representation of an exemplary embodiment of a current converter,

[0023] FIG. 2 shows a schematic sectional representation of a current converter head of the current converter represented in FIG. 1,

[0024] FIG. 3 shows a schematic representation of the current converter represented in FIG. 1, with the compensation current sensor deactivated,

[0025] FIG. 4 shows a schematic representation of an exemplary embodiment of a compensation current sensor, having a Hall effect sensor.

[0026] Mutually corresponding components are identified in the figures by the same reference numbers.

[0027] FIG. 1 shows a schematic representation of an exemplary embodiment of a current converter 1. The current converter 1 comprises a current converter head 3, a post insulator 5, upon which the current converter head 3 is arranged, and a pedestal 7, upon which the post insulator 5 is arranged and on which a terminal box 8 is arranged.

[0028] FIG. 2 shows a schematic sectional representation of the current converter head 3. The current converter head 3 comprises a housing 9, through which a primary conductor 11 is led. In the housing 9, a torus-shaped winding housing 10 is configured, which is arranged around the primary conductor 11.

[0029] The current converter 1 comprises an inductive alternating current sensor 13 and a compensation current sensor 15.

[0030] The inductive alternating current sensor 13 of the present exemplary embodiment comprises two annular protective cores 17 and two annular measuring cores 19, upon each of which a secondary coil 21 is wound and each of which is arranged about the primary conductor 11 within the winding housing 10.

[0031] The compensation current sensor 15 comprises a compensation coil 23 and a magnetometer 25. In the present exemplary embodiment, the magnetometer 25 is configured as a fluxgate magnetometer, and comprises two soft magnetic compensation cores 27, an optional soft magnetic additional core 29, an excitation winding 31 and an optional additional secondary winding 33. The compensation cores 27 and the additional core 29 respectively assume an annular configuration, and are arranged about the primary conductor 11 within the winding housing 10. The excitation winding 31 is wound in the inverse direction about the two compensation cores 27. The additional secondary winding 33 is wound about the additional core 29. The compensation coil 23 is wound about the two compensation cores 27 and the additional core 29.

[0032] In the operation of the compensation current sensor 15, an alternating excitation current is generated in the excitation winding 31, which periodically drives the compensation cores 27 to a state of magnetic saturation. As the excitation winding 31 is wound in the inverse direction about the two compensation cores 27, the magnetic fields of the compensation cores 27 thus generated are in mutual opposition. The compensation cores 27, and the turns of the excitation winding 31 arranged about the latter, are identical, including with respect to the winding directions thereof, such that the magnetic fields of the compensation cores 27 are of equal magnitude, where no external magnetic field is acting upon said compensation cores 27. However, if an external magnetic field is acting on the compensation cores 27, this results in mutually differing magnitudes of the magnetic fields of said compensation cores 27, the difference in which constitutes a measure of the magnetic field strength of the external magnetic field. The external magnetic field acting on the compensation cores 27 is the sum of a primary magnetic field generated by a primary current in the primary conductor 11, and of a compensation magnetic field generated by a compensation current in the compensation coil 23. The setting of the compensation current in the compensation coil 23 is adjusted such that the compensation magnetic field compensates the primary magnetic field in the compensation cores 27, or the magnetic fields of the compensation cores 27 are of equal magnitude. The current strength of the compensation current thus constitutes a measure of the current strength of the primary current, and permits the measurement thereof. The function of the compensation cores 27 is the measurement of direct currents or direct current components flowing in the primary conductor 11.

[0033] The optional additional core 29 is employed for the additional measurement of alternating currents or alternating current components flowing in the primary conductor 11, for example for the measurement of alternating currents or alternating current components, for the measurement of which the measuring cores 19 of the inductive alternating current sensor 13 are not designed. Thus, by means of the compensation current in the compensation coil 23, primary magnetic fields are also compensated which are generated in the additional core 29 by alternating currents or alternating current components flowing in the primary conductor 11. Alternating current components of the primary current and the compensation current generate changes in a magnetic field in the additional core 29, which induces a secondary current in the additional secondary winding 33. The setting of the alternating current component of the compensation current is therefore adjusted such that no secondary current is induced in the additional secondary winding 33.

[0034] For the detection of secondary currents flowing in the secondary coils 21, which are induced by an alternating current or an alternating current component flowing in the primary conductor 11, the inductive alternating current sensor 13 comprises a first measuring circuit 35. For the generation of the excitation current flowing in the excitation winding 31, the generation and adjustment of the compensation current flowing in the compensation coil 23 and, optionally, for the detection of the secondary current flowing in the additional secondary winding 33, the compensation current sensor 15 comprises a second measuring circuit 37. The first measuring circuit 35 is connected by means of first connecting lines 39 to the secondary coils 21. The second measuring circuit 37 is connected by means of second connecting lines 41 to the excitation winding 31 and the compensation coil 23 and, optionally, to the additional secondary winding 33. The connecting lines 39, 41 are brought out of the winding housing 10 and the housing 9, and are led through the post insulator 5 to the terminal box 8, and from thence to the measuring circuits 35, 37.

[0035] The compensation current sensor 15 is deactivable. To this end, components of the second connecting lines 41 which connect the terminal box 8 to the second measuring circuit 37 are detachably connected to said terminal box 8, for example by means of a plug-in connection. Further to the release of these components of the second connecting lines 41 from the terminal box 8, the excitation winding 31, the optional additional secondary winding 33 and the compensation coil 23 are respectively short-circuitable, for example by means of a short-circuit plug connector 43, which is connectable to the terminal box 8 in place of said components of the second connecting lines 41.

[0036] FIG. 3 shows the current converter 1 with a short-circuit plug connector 43, which respectively short-circuits the excitation winding 31, the optional additional secondary winding 33 and the compensation coil 23.

[0037] The post insulator 5 is configured as a hollow insulator, and comprises a plurality of insulating shields 6, which are respectively arranged in an annular manner about a longitudinal axis of the post insulator 5. The post insulator 5 is formed, for example, from a ceramic material, or is configured as a tube of a glass fiber-reinforced plastic, on which silicone insulating shields 6 are arranged.

[0038] The winding housing 10 is electrically insulated vis--vis the housing 9. For example, the housing 9, to this end, is filled with an insulating gas, for example with sulfur hexafluoride or nitrogen, or with an insulating fluid, for example with an insulating oil, or with an insulating compound, for example with a silicone insulating compound.

[0039] The exemplary embodiment represented in the figures can be modified in a variety of ways. For example, the inductive alternating current sensor 13 can comprise a number of protective cores 17 and/or measuring cores 19 other than two. In particular, it can comprise no protective core 17 or no measuring core 19 whatsoever. The compensation current sensor 15 can further comprise a magnetometer 25 other than a fluxgate magnetometer, for example a magnetometer 25 with a Hall effect sensor 49 (see FIG. 4).

[0040] FIG. 4 shows a schematic representation of an exemplary embodiment of a compensation current sensor 15, which comprises a magnet core 45 configured in an annular arrangement about the primary conductor 11 within the winding housing 10, about which the compensation coil 23 is wound, and which incorporates an air gap 47, in which a Hall effect sensor 49 is arranged. By means of the Hall effect sensor 49, the sum of the primary magnetic field which is generated by the primary conductor 11 and of the compensation magnetic field which is generated by the compensation coil 23 is detected at the location of the Hall effect sensor 49, and the setting of the compensation current flowing in the compensation coil 23 is adjusted such that said sum is cancelled out.

[0041] Although the invention has been described and illustrated in greater detail with reference to preferred exemplary embodiments, the invention is not limited by the examples disclosed, and further variations can be inferred herefrom by a person skilled in the art, without departing from the protective scope of the invention.