HIGH-VOLTAGE COLUMN CURRENT TRANSFORMER

Abstract

A high-voltage column current transformer comprising a column insulating body and a head arranged thereon is disclosed, whereby the head defines a volume and comprises arranged therein a primary winding conductor, a secondary winding core assembly having secondary winding leads and a conical insulator spacer tapered from a base to an apex with a lateral face therebetween, the conical insulator spacer is arranged with its base on a bottom of the head facing the column insulating body and its apex holds the secondary winding core assembly distant from a wall of the head, the conical insulator spacer comprises at least one ring-shaped electrode embedded in and surrounding the base and another flat, circular shaped electrode embedded in and surrounded by the apex, and the conical insulator spacer comprises at least one opening in the lateral face.

Claims

1. A high-voltage column current transformer comprising a column insulating body and a head arranged thereon, whereby the head defines a volume and comprises arranged therein a primary winding conductor, a secondary winding core assembly having secondary winding leads and a conical insulator spacer tapered from a base to an apex with a lateral face therebetween, the conical insulator spacer is arranged with its base on a bottom of the head facing the column insulating body and its apex holds the secondary winding core assembly distant from a wall of the head, the conical insulator spacer comprises at least one ring-shaped electrode embedded in and surrounding the base and another flat, circular shaped electrode embedded in and surrounded by the apex, and the conical insulator spacer comprises at least one opening in the lateral face.

2. The high-voltage column current transformer according to claim 1, whereby the electrodes are provided as molded metal flanges integrated into the conical insulator spacer.

3. The high-voltage column current transformer according to claim 1, whereby the conical insulator spacer comprises epoxy.

4. The high-voltage column current transformer according to claim 1, comprising an O-ring sealing provided between the base and the bottom of the head and/or the apex and the secondary winding core assembly.

5. The high-voltage column current transformer according to claim 1, comprising a bolting connection between the apex and the secondary winding core assembly.

6. The high-voltage column current transformer according to claim 1, whereby the conical insulator spacer comprises two, three or four openings in the lateral face.

7. The high-voltage column current transformer according to claim 6, whereby the openings are arranged in equal distances with regard to each other.

8. The high-voltage column current transformer according to claim 1, whereby the primary winding conductor is fitted through the secondary winding core assembly, and the secondary winding leads of the secondary winding core assembly are passed through the column insulating body.

9. A method for operating a high-voltage column current transformer, comprising a column insulating body and a head arranged thereon, whereby the head defines a volume and comprises arranged therein a primary winding conductor, a secondary winding core assembly having secondary winding leads and a conical insulator spacer tapered from a base to an apex with a lateral face therebetween, the conical insulator spacer is arranged with its base on a bottom of the head facing the column insulating body and its apex holds the secondary winding core assembly distant from a wall of the head, the conical insulator spacer comprises at least one ring-shaped electrode embedded in and surrounding the base and another flat, circular shaped electrode embedded in and surrounded by the apex, and the conical insulator spacer comprises at least one opening in the lateral face, and the method comprising the step of: operating the high-voltage column current transformer at DC voltages up to 535 kV.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] These and other aspects of the present disclosure will be apparent from and elucidated with reference to the implementations described hereinafter.

[0029] In the drawings:

[0030] FIG. 1 shows a sectional view of a high-voltage column current transformer according to an exemplary implementation; and

[0031] FIG. 2 shows a perspective view of a conical insulator spacer of the high-voltage column current transformer according to FIG. 1.

DETAILED DESCRIPTION

[0032] FIG. 1 shows a sectional view of a high-voltage column current transformer 1 according to an exemplary implementation. The high-voltage column current transformer 1 comprises a metallic head 2, also referred to as tank. The head 2 is supported by a column insulating body 3 of the transformer 1. The rounded head 2 comprises a height of 1535 mm and a diameter of 1205 mm.

[0033] The column 3 represents an elongated hollow core insulating tube posted on a ground or pedestal, not shown in the figure. Terminals for the secondary winding leads 4 run from at least one secondary winding core assembly 5 located inside a volume 6 of the head 2 of the transformer 1. Windings of the secondary winding core assembly 5 can be arranged, in a known manner, around annular iron cores, or can be made as a Rogowski coils, without a magnetic core. A primary winding, consisting of a primary winding conductor 7, only schematically shown as line, runs through head openings 8 in the form of a hollow cylinder extending through the head 2.

[0034] Further arranged within the head 2 is a conical insulator spacer 9 made of epoxy, which comprise a base 10 and opposite thereto an apex 11, interconnected by a lateral face 12 therebetween, as can be seen in more detail in FIG. 2. The base 10 of the conical insulator spacer 9 is arranged on a bottom of the head 2 facing the column insulating body 3, while the apex 11 holds the secondary winding core assembly 7 distant from the head 2 within the volume 6. The ring-shaped base 10 comprise a diameter of 1000 mm, while the apex 11 comprises a diameter of 365 mm. The apex 11 further comprises a width of 90 mm, while the base 10 comprises a width of 80 mm.

[0035] One end of the primary winding conductor 7 and the head 2 are electrically connected to make the primary winding have nearly the same high voltage DC potential as the head 2. The secondary winding core assembly 5 is at ground electrical potential and the conical insulator spacer 9 is provided as a main insulation system between the secondary winding core assembly 5 and the head 2. Though, in the example dielectric stresses caused by application of continuous DC high-voltages are mentioned, it is clarified that the conical insulator spacer is capable of use with AC high-voltages or AC-DC (hybrid) high-voltages applications.

[0036] By also referring in particular to FIG. 2, the conical, hat-like insulator spacer 9 comprises molded metal flanges as electrodes 13, which are embedded in the base 10 and in the apex 11. The metal flange of the base 10 is basically ring-shaped and extends away in a radial direction from a conical epoxy body 14 of the insulator spacer 9 thereby surrounding the conical epoxy body 14 in radial direction. The conical epoxy body 14 comprises three parts with are provided one piece, namely said radially extending bottom part surrounded by the metal flange of the base 10, the lateral face 12 and a radially extending top part which surrounds the electrode 13 of the apex 11.

[0037] At the base 10 the bottom part extends radially ring-shaped outwards away from the lateral face 12 and axially surrounds the metal flange of the base 10. That is, in sectional view, the bottom part at its radial outwards end comprises a rounded concave shape, which in axial direction is surrounded by the metal flange of the base 10, which therefore also comprises an exactly fitting rounded convex shape. Similar, at the apex 11 the top part extends radially ring-shaped inwards from the lateral face 12 and axially surrounds the metal flange of the apex 11. That is, in sectional view, the top part at its radial inwards end comprises a rounded concave shape, which in axial direction surrounds the metal flange of the apex 11, which therefore also comprises an exactly fitting rounded convex shape.

[0038] Such way, both electrodes 13 are axially encapsulated by the conical epoxy body 14. The conical epoxy body 14 insulates the electrodes 13 of the base 10 and the apex 11 from each other. Further, each an O-ring sealing 17 is provided between the base 10 and the bottom of the head 2 and the apex 11 and the secondary winding core assembly 5.

[0039] In the lateral face 12, the conical insulator spacer 9 comprises four openings 15, which are arranged distant from each other in regular equal distances. Further, a bolting connection 16 is provided between the apex 11 and the secondary winding core assembly 5 for respectively connection the apex 11 and the secondary winding core assembly 5.

[0040] The conical insulator spacer 9 having the said conical epoxy body 14 molded metal flanges as electrodes 13 allows withstanding dielectric stresses under continuous operating DC voltage. Within prior art high-voltage column current transformers 1 existing, a fiber plastic tube with adherent metal shield can be removed and the conical insulator spacer 9 can be simply installed at a bottom part of the head 2. Such way the high-voltage column current transformer 1 with the described conical insulator spacer 9 can be operated with primary winding conductors having a DC voltage up to 535 kV, without re-dimensioning prior art high-voltage column current transformers.

[0041] While the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the claims are not limited to the disclosed implementations including the disclosed high voltage ratings. Other variations to the disclosed implementations can be understood and effected by those skilled in the art in practicing the claims, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting scope.

REFERENCE SIGNS LIST

[0042] 1 high-voltage column current transformer [0043] 2 head [0044] 3 column insulating body [0045] 4 secondary winding leads [0046] 5 secondary winding core assembly [0047] 6 volume [0048] 7 primary winding conductor [0049] 8 head opening [0050] 9 conical insulator spacer [0051] 10 base [0052] 11 apex [0053] 12 lateral face [0054] 13 electrode [0055] 14 conical epoxy body [0056] 15 opening [0057] 16 bolting connection [0058] 17 O-ring sealing