CA2143657C - A current transformer - Google Patents
A current transformerInfo
- Publication number
- CA2143657C CA2143657C CA002143657A CA2143657A CA2143657C CA 2143657 C CA2143657 C CA 2143657C CA 002143657 A CA002143657 A CA 002143657A CA 2143657 A CA2143657 A CA 2143657A CA 2143657 C CA2143657 C CA 2143657C
- Authority
- CA
- Canada
- Prior art keywords
- current transformer
- shielding body
- annular core
- ground
- capsule
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/22—Instruments transformers for single phase ac
- H01F38/28—Current transformers
- H01F38/30—Constructions
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F38/20—Instruments transformers
- H01F38/22—Instruments transformers for single phase ac
- H01F38/28—Current transformers
- H01F38/30—Constructions
- H01F2038/305—Constructions with toroidal magnetic core
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B13/00—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle
- H02B13/02—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle with metal casing
- H02B13/035—Gas-insulated switchgear
- H02B13/0356—Mounting of monitoring devices, e.g. current transformers
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transformers For Measuring Instruments (AREA)
Abstract
In a current transformer for incorporating in a metal capsule (1) that is at ground potential and surrounds a high-voltage line (2) there is at least one annular core (5), a secondary winding that is wound onto this, and at least one grounded protective winding (6). In order to provide protection against over-voltages, the annular core (5) is coaxially surrounded on its outer side by a hollow cylindrical electrically conductive shielding body (8) that forms a reference ground for the ground connection (7) of the protective winding (6) that extends essentially radially.
Description
CA 021436~7 1998-08-31 A CURRENT TRANSFORMER
The present invention relates to a current transformer that is to be incorporated into a metal capsule that is at ground potential and surrounds a high-voltage line, this having at least one annular core, a secondary winding that is wound onto the annular core, and at least one grounded protective winding.
A current transformer of this kind is known from DE-41 06 034Al. The current transformer described therein comprises an inner tube that combines a plurality of annular cores and passes through the annular cores, this tube being of electrically conductive material and connected at one face end of the cylinder with the grounded capsule. In this known current transformer, in order to protect the current transformer from over-voltages in the secondary winding that are caused by switching processes, there is a protective winding that is installed on the annular core in addition to the secondary winding and one end of this is connected to ground so as to be electrically conductive; this can consist of a wire, a strip, or a foil.
It is the task of the present invention to describe a current transformer of the type described in the introduction hereto, in which over-voltages caused by switch-on and switch-off procedures of the most rapid current and voltage variations are kept small.
According to the present invention, this task has been solved in that the annular core is surrounded coaxially on the outer side of the ring by a hollow cylindrical electrically conductive shielding body that is arranged within the metal capsule; this forms a reference ground for the ground connection of a protective winding that extends essentially radially.
The present invention relates to a current transformer that is to be incorporated into a metal capsule that is at ground potential and surrounds a high-voltage line, this having at least one annular core, a secondary winding that is wound onto the annular core, and at least one grounded protective winding.
A current transformer of this kind is known from DE-41 06 034Al. The current transformer described therein comprises an inner tube that combines a plurality of annular cores and passes through the annular cores, this tube being of electrically conductive material and connected at one face end of the cylinder with the grounded capsule. In this known current transformer, in order to protect the current transformer from over-voltages in the secondary winding that are caused by switching processes, there is a protective winding that is installed on the annular core in addition to the secondary winding and one end of this is connected to ground so as to be electrically conductive; this can consist of a wire, a strip, or a foil.
It is the task of the present invention to describe a current transformer of the type described in the introduction hereto, in which over-voltages caused by switch-on and switch-off procedures of the most rapid current and voltage variations are kept small.
According to the present invention, this task has been solved in that the annular core is surrounded coaxially on the outer side of the ring by a hollow cylindrical electrically conductive shielding body that is arranged within the metal capsule; this forms a reference ground for the ground connection of a protective winding that extends essentially radially.
2 1 4 ~
By application of the concept of the present invention it is possible to keep the ground connection short so that the inductivity of the ground connection can be disregarded. The electrically conductive shielding body, which forms the reference ground, constitutes a bus bar for high frequency currents which is intended to make contact with a plurality of ground connections of a number of annular cores. Accordingly, the protective winding can have a plurality of ground connections that are distributed evenly around the outer periphery of the annular core and extend essentially radially, each of which makes individual contact with the shielding body.
In a first embodiment, the shielding body is formed by a cylindrically shaped sheet metal or foil body. The cylindrical casing that is formed in this manner can incorporate passage openings for the ground connections that are electrically connected to the outer side of the shielding body. The shielding body can also be formed by a cage with rods that are parallel to the line of the casing and which are connected to each other so as to be electrically conductive.
In another embodiment of the present invention, the shielding body can be formed by cylindrical segments that are arranged evenly around the periphery with intervening spaces that are parallel to the line of the casing.
In another example of a current transformer according to the present invention, it is preferred that the cylindrical body is electrically connected at the face end of the cylinder at both sides with the capsule.
Embodiments of the present invention will be described in greater detail below on the basis of the drawings appended hereto and the operation of these will also be explained. These drawings show the following:
. . . .
2 1 ~ 7 ~igure 1: a metal capsule with a current transformer and a high-voltage line shown diagrammatically in longitudinal section;
Figure 2: a cross-section through the metal capsule as in figure 1, showing two different details from figure 1, each of which is in half section;
Figure 3: a further cross-section through the metal capsule as in figure l;
Figure 4: a second embodiment of a current transformer in a cross-section corresponding to figure 3;
Figure 5: a third embodiment of the current transformer according to the present invention in a cross-section corresponding to figure 3.
Figure 1 shows a current transformer for a high-voltage switching system that is insulated by high-pressure gas; this is filled, for example, with SF6; this high-voltage switching system incorporates an electrically grounded capsule 1. The capsule 1 is in the form of a tube and supports a high-voltage line 2 through supporting insulators (not shown in greater detail herein). Within the space 3 between the capsule 1 and the high-voltage line 2, there is SF6 at a pressure of 5 bar, for example.
A current transformer is built into the capsule 1 and this incorporates an essentially tubular supporting body 4. In the embodiment that is shown, the supporting body comprises four annular cores that are kept spaced apart by means of a filler compound and cemented to the supporting body. In addition to its secondary winding, each annular core 5 is provided with a grounded protective winding 6 that can consist of a wire or a strip. The protective winding 6 has ground connections 7 that are distributed evenly about its periphery and extend essentially radially and these are led by the shortest path to a shielding body 8 to form a contact there. The shielding body 8 surrounds the annular core 5 coaxially on the outer side 5a of the ring and is made from electrically conductive material. It can be seen ~1~3~7 that the hollow body 8 is a hollow cylinder that is formed, for example, from sheet metal or a foil.
In the embodiment that is shown above the dashed centre line 11, the shielding body 8 is fixed in its position in the area of the face side by screws 9. The unattached face end areas 10 are slotted and pressed outwards against the capsule l. In order to ensure electrical contact between the shielding body 8 and the capsule 1, the slotted end area 10 is acted upon by a spring ring 12 and pressed outwards.
In the embodiment that is shown beneath the mid-line 11 in figure 1, contact between the slotted edge area 10 is made by way of screws 13 that are adjustably arranged in the annular part 4a of the tubular supporting body 4. It can be seen that the parts 4, 4a are electrically separated by a gap 4b, optionally with an interposed part of insulating material, although they are electrically connected through the shielding body 8. The screws 13 also serve to position the current transformer that is connected rigidly to the capsule 1 on a stop tab or flange 14 that projects radially inward.
In figure 2, in the upper part of the cross-section, the edge area 10 is provided with slots 15 and is acted upon by a cylindrical helical spring 16 as a pressure element 12. The lower part of the cross-section shows the version in which the screws 13 make the contact between the slotted edge area 10 of the shielding body 8 and the capsule 1.
Figure 3 is a diagrammatic drawing showing a shielding body 8 that is produced from a foil or sheet metal with passage openings 8a for the ground connections 7 that extend essentially radially, and a number of these emerge radially from the protective winding of an annular core 5. The ground connections 7 make contact with the outside 8b of the shielding body.
21~3~i7 In the embodiment that is shown in figure 4, the shielding body 8 is formed from four hollow cylindrical segments 17 and each two ground connections 7 contact an annular core 5.
Figure 5 shows an embodiment of a current transformer in which the shielding body 8 is formed by a cage 18a with rods 18 that extend parallel to the outline of the casing and each ground connector 7 connects an annular core 5 and are electrically connected to each other by means of a strip 19 or the like. For the remainder, in all of the figures, identical parts bear the same reference numbers.
By application of the concept of the present invention it is possible to keep the ground connection short so that the inductivity of the ground connection can be disregarded. The electrically conductive shielding body, which forms the reference ground, constitutes a bus bar for high frequency currents which is intended to make contact with a plurality of ground connections of a number of annular cores. Accordingly, the protective winding can have a plurality of ground connections that are distributed evenly around the outer periphery of the annular core and extend essentially radially, each of which makes individual contact with the shielding body.
In a first embodiment, the shielding body is formed by a cylindrically shaped sheet metal or foil body. The cylindrical casing that is formed in this manner can incorporate passage openings for the ground connections that are electrically connected to the outer side of the shielding body. The shielding body can also be formed by a cage with rods that are parallel to the line of the casing and which are connected to each other so as to be electrically conductive.
In another embodiment of the present invention, the shielding body can be formed by cylindrical segments that are arranged evenly around the periphery with intervening spaces that are parallel to the line of the casing.
In another example of a current transformer according to the present invention, it is preferred that the cylindrical body is electrically connected at the face end of the cylinder at both sides with the capsule.
Embodiments of the present invention will be described in greater detail below on the basis of the drawings appended hereto and the operation of these will also be explained. These drawings show the following:
. . . .
2 1 ~ 7 ~igure 1: a metal capsule with a current transformer and a high-voltage line shown diagrammatically in longitudinal section;
Figure 2: a cross-section through the metal capsule as in figure 1, showing two different details from figure 1, each of which is in half section;
Figure 3: a further cross-section through the metal capsule as in figure l;
Figure 4: a second embodiment of a current transformer in a cross-section corresponding to figure 3;
Figure 5: a third embodiment of the current transformer according to the present invention in a cross-section corresponding to figure 3.
Figure 1 shows a current transformer for a high-voltage switching system that is insulated by high-pressure gas; this is filled, for example, with SF6; this high-voltage switching system incorporates an electrically grounded capsule 1. The capsule 1 is in the form of a tube and supports a high-voltage line 2 through supporting insulators (not shown in greater detail herein). Within the space 3 between the capsule 1 and the high-voltage line 2, there is SF6 at a pressure of 5 bar, for example.
A current transformer is built into the capsule 1 and this incorporates an essentially tubular supporting body 4. In the embodiment that is shown, the supporting body comprises four annular cores that are kept spaced apart by means of a filler compound and cemented to the supporting body. In addition to its secondary winding, each annular core 5 is provided with a grounded protective winding 6 that can consist of a wire or a strip. The protective winding 6 has ground connections 7 that are distributed evenly about its periphery and extend essentially radially and these are led by the shortest path to a shielding body 8 to form a contact there. The shielding body 8 surrounds the annular core 5 coaxially on the outer side 5a of the ring and is made from electrically conductive material. It can be seen ~1~3~7 that the hollow body 8 is a hollow cylinder that is formed, for example, from sheet metal or a foil.
In the embodiment that is shown above the dashed centre line 11, the shielding body 8 is fixed in its position in the area of the face side by screws 9. The unattached face end areas 10 are slotted and pressed outwards against the capsule l. In order to ensure electrical contact between the shielding body 8 and the capsule 1, the slotted end area 10 is acted upon by a spring ring 12 and pressed outwards.
In the embodiment that is shown beneath the mid-line 11 in figure 1, contact between the slotted edge area 10 is made by way of screws 13 that are adjustably arranged in the annular part 4a of the tubular supporting body 4. It can be seen that the parts 4, 4a are electrically separated by a gap 4b, optionally with an interposed part of insulating material, although they are electrically connected through the shielding body 8. The screws 13 also serve to position the current transformer that is connected rigidly to the capsule 1 on a stop tab or flange 14 that projects radially inward.
In figure 2, in the upper part of the cross-section, the edge area 10 is provided with slots 15 and is acted upon by a cylindrical helical spring 16 as a pressure element 12. The lower part of the cross-section shows the version in which the screws 13 make the contact between the slotted edge area 10 of the shielding body 8 and the capsule 1.
Figure 3 is a diagrammatic drawing showing a shielding body 8 that is produced from a foil or sheet metal with passage openings 8a for the ground connections 7 that extend essentially radially, and a number of these emerge radially from the protective winding of an annular core 5. The ground connections 7 make contact with the outside 8b of the shielding body.
21~3~i7 In the embodiment that is shown in figure 4, the shielding body 8 is formed from four hollow cylindrical segments 17 and each two ground connections 7 contact an annular core 5.
Figure 5 shows an embodiment of a current transformer in which the shielding body 8 is formed by a cage 18a with rods 18 that extend parallel to the outline of the casing and each ground connector 7 connects an annular core 5 and are electrically connected to each other by means of a strip 19 or the like. For the remainder, in all of the figures, identical parts bear the same reference numbers.
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. A current transformer for incorporation in a metal capsule that is at ground potential and surrounds a high voltage line, this having at least one annular core, a secondary winding that is wound onto the annular core, and at least grounded protective winding, characterized in that the annular core is on its outer side surrounded coaxially by a hollow cylindrical electrically conductive shielding body that is arranged within the metal capsule coaxially that forms a reference ground for a ground connection of the protective winding that extends essentially radially.
2. A current transformer as defined in claim 1, characterized in that the protective winding incorporates a plurality of ground connections that are distributed evenly around the outer periphery of the annular core and extend radially, each of which makes contact with the shielding body.
3. A current transformer as defined in claim 1 or claim 2, characterized in that the shielding body is formed from a cylindrically-shaped sheet metal or foil body.
4. A current transformer as defined in claim 1 or 2, characterized in that the shielding body is formed by a cage with rods that extend parallel to a line of the casing.
5. A current transformer as defined in claim 1 or claim 2, characterized in that the shielding body is formed from cylindrical segments that are arranged so as to be equally spaced about the periphery and with intervening spaces that are parallel to the line of the casing.
6. A current transformer as defined in claim 1 or claim 2, characterized in that the shielding body is electrically connected at the face ends of the cylinder on both sides with the capsule.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4229680.3 | 1992-09-02 | ||
| DE4229680A DE4229680A1 (en) | 1992-09-02 | 1992-09-02 | Power converter |
| PCT/DE1993/000543 WO1994006135A1 (en) | 1992-09-02 | 1993-06-18 | Current transformer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2143657A1 CA2143657A1 (en) | 1994-03-17 |
| CA2143657C true CA2143657C (en) | 1999-01-26 |
Family
ID=6467302
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002143657A Expired - Fee Related CA2143657C (en) | 1992-09-02 | 1993-06-18 | A current transformer |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0658271B1 (en) |
| CA (1) | CA2143657C (en) |
| DE (2) | DE4229680A1 (en) |
| WO (1) | WO1994006135A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2118038B1 (en) * | 1996-06-13 | 1999-04-16 | Abb Subestaciones S A | INTENSITY TRANSFORMER ISOLATED IN SULFUR HEXAPHLORIDE, INTEGRATED IN A HIGH VOLTAGE SWITCH. |
| FR2828003B1 (en) | 2001-07-25 | 2003-09-12 | Alstom | HIGH THERMAL STABILITY CAPACITOR FOR SHIELDED TYPE POWER LINES |
| CN102496446B (en) * | 2011-11-29 | 2014-04-16 | 中国西电电气股份有限公司 | Zero magnetic flux direct-current current transformer |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3223890A (en) * | 1963-09-30 | 1965-12-14 | Gen Electric | Electric protective equipment |
| DE1807996B2 (en) * | 1968-11-07 | 1972-03-30 | Siemens AG, 1000 Berlin u. 8000 München | SINGLE CONVERTER |
| DE3166324D1 (en) * | 1981-04-28 | 1984-10-31 | Sprecher & Schuh Ag | Current transformer with annular case to be built in a metal cast high-tension switchgear installation |
| DE4106034A1 (en) * | 1991-02-22 | 1992-08-27 | Siemens Ag | POWER CONVERTER |
-
1992
- 1992-09-02 DE DE4229680A patent/DE4229680A1/en not_active Withdrawn
-
1993
- 1993-06-18 DE DE59302389T patent/DE59302389D1/en not_active Expired - Fee Related
- 1993-06-18 CA CA002143657A patent/CA2143657C/en not_active Expired - Fee Related
- 1993-06-18 WO PCT/DE1993/000543 patent/WO1994006135A1/en active IP Right Grant
- 1993-06-18 EP EP93912610A patent/EP0658271B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0658271A1 (en) | 1995-06-21 |
| EP0658271B1 (en) | 1996-04-24 |
| DE59302389D1 (en) | 1996-05-30 |
| CA2143657A1 (en) | 1994-03-17 |
| DE4229680A1 (en) | 1994-03-03 |
| WO1994006135A1 (en) | 1994-03-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |