CN101702368A - High voltage dry-type current transformer and ground protection method thereof - Google Patents
High voltage dry-type current transformer and ground protection method thereof Download PDFInfo
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- CN101702368A CN101702368A CN200910172739A CN200910172739A CN101702368A CN 101702368 A CN101702368 A CN 101702368A CN 200910172739 A CN200910172739 A CN 200910172739A CN 200910172739 A CN200910172739 A CN 200910172739A CN 101702368 A CN101702368 A CN 101702368A
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- high voltage
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- current transformer
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- 238000000034 method Methods 0.000 title claims abstract description 9
- 238000004804 winding Methods 0.000 claims abstract description 45
- 239000003990 capacitor Substances 0.000 claims abstract description 29
- 230000001012 protector Effects 0.000 claims abstract description 29
- 238000003825 pressing Methods 0.000 claims description 15
- 230000001681 protective effect Effects 0.000 claims description 10
- 239000000725 suspension Substances 0.000 claims description 6
- 239000004593 Epoxy Substances 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 238000009413 insulation Methods 0.000 abstract description 6
- 230000015556 catabolic process Effects 0.000 abstract description 3
- 230000004888 barrier function Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000005266 casting Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 230000005283 ground state Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
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Abstract
The invention discloses a high voltage dry-type current transformer and a ground protection method thereof, a ground wire is arranged on an end screen of a primary winding of the high voltage dry-type current transformer, a ground protection branch is further parallel-connected on the end screen of the primary winding of the high voltage dry-type current transformer, the ground protection branch is provided with a ground protector which mainly consists of a capacitor, one end of the ground protector is connected with the end screen of the primary winding, and the other end is grounded for increasing the equivalent capacitance value of the end screen of the primary winding to the ground. The capacitor type ground protector is parallel-connected between the end screen of the primary winding and a housing in the technical scheme of the invention, thereby increasing the equivalent capacitance value of the end screen to the ground, clamping the loaded floating voltage on the end screen to a smaller value which is much lower than the tolerant voltage of the end screen, further avoiding the accidents of insulation breakdown of the primary winding and greatly increasing the reliability of the user of the high voltage dry-type current transformer.
Description
Technical field
The invention belongs to the high voltage power distribution technical field, definite saying so relates to a kind of high voltage dry-type current transformer and supporting earth leakage protector thereof.
Background technology
The ground protection structure of existing high voltage dry-type current transformer is on the ground lead 2 direct access shells of the end of a winding 1 of high voltage dry-type current transformer screen on the ground wire terminal 3 on earthy terminal block 4 as shown in Figure 1.At present, the main insulation of a winding of high voltage dry-type current transformer adopts the capacitor type structure of being connected around the multilayer that forms by insulating barrier and metal forming alternating packets substantially, and the voltage to earth of its winding is evenly distributed between each layer.In equipment operation, screen necessary reliable ground in the end of current transformer makes it be in earth potential.As shown in Figure 2, among the figure, A is the high-pressure side of instrument transformer, and B is an end screen lead end, and C is the earth potential end, and U is added in the phase voltage of a winding high-pressure side, C when being normal the operation
1Be the equivalent capacity of a winding, C
0For the end screen is missed time Mo screen equivalent capacity over the ground.Because the main insulation of a winding of high voltage dry-type current transformer is formed by the multi-layer capacity serial connection, and end screen to be electric capacity with outermost one deck connect, if during the screen reliable ground of end, it is in earth potential, if screen earth connection in end is missed or during loose contact, make the end screen become insulation over the ground, the end screen becomes equivalence capacitor C 0 over the ground, the appearance value of this capacitor C O is very little, be far smaller than the capacitor C 1 of a winding,, be carried in the high voltage U on the winding and will go here and there and shield to the end according to the capacitance partial pressure principle, form the suspension voltage that voltage is very high, under the long duration of action of suspension voltage, will discharge to make between each layer capacitance and the dielectric forms current path, adds that the arc potential of generating comes and go, thereby cause the capacitor field intensity distortion of each layer, the partial discharge of product inside increases, and final forming device built-in electrical insulation punctures, and causes interruption of services such as line tripping, when serious, even the serious accident of equipment explosion can take place.But need in routine duties often high voltage dry-type current transformer to be overhauled and safeguard; need therebetween end screen dielectric loss is measured; during measurement; end screen lead-in wire must be separated with ground wire terminal; after measurement finishes; through regular meeting survey crew takes place and forget end screen lead-in wire is returned to the ground state operation of just casting net, thereby this earthing mode exists major safety risks.
Summary of the invention
Miss high voltage dry-type current transformer and the earthing protecting method thereof that ground or loose contact also can not cause insulation breakdown, line tripping even the purpose of this invention is to provide a kind of winding end screen.
Technical scheme of the present invention is: a kind of earthing protecting method of high voltage dry-type current transformer; on a winding end screen of this high voltage dry-type current transformer, be provided with an earth connection; on a winding end screen of this high voltage dry-type current transformer, be connected with a ground protection spur track; be serially connected with an earth leakage protector that constitutes by Da Rong value capacitor in this ground protection spur track; one end of this earth leakage protector connects winding end screen one time; other end ground connection makes the suspension voltage of the equivalent capacitance value over the ground of a winding end screen greater than the end screen to strengthen winding end screen equivalent capacitance value over the ground.
Also be covered with protective casing in described capacitor outside, this protective casing comprises outer tube, the two ends of outer tube are arranged with end cap respectively, be equipped with connection bolt on the end cap at two ends respectively, two lead-in wires of described capacitor are connected on the connection bolt of two end caps, also are cast with blending epoxy between capacitor and housing.
A described winding is fixed in the transformer casing by pressing plate; this transformer casing is in earth potential; pressing plate is provided with the set bolt that connects transformer casing; the connection bolt of one end of described earth leakage protector is connected electrically on the screen of end by lead, and its other end is connected electrically on the set bolt of pressing plate by brace.
A kind of high voltage dry-type current transformer; comprise shell; be fixed with winding in the shell one time; be connected with an earth connection between the end screen of this winding and the shell; between the end of described winding screen and shell, also be arranged in parallel an earth leakage protector; this earth leakage protector mainly is made of Da Rong value capacitor, and two lead-in wires of this capacitor are electrically connected with winding end screen and transformer casing respectively.
Also be covered with protective casing in described capacitor outside, this protective casing comprises outer tube, the two ends of outer tube are arranged with end cap respectively, be equipped with connection bolt on the end cap at two ends respectively, two lead-in wires of described capacitor are connected on the connection bolt of two end caps, also are cast with blending epoxy between capacitor and housing.
A described winding is fixed in the transformer casing by pressing plate; this pressing plate is provided with set bolt; the connection bolt of one end of described earth leakage protector is connected electrically on the screen of end by lead, and its other end is connected electrically on the set bolt of pressing plate by brace.
The present invention is by adopting technique scheme; it is between winding end screen and housing behind the capacitive based earth leakage protector in parallel; the end screen becomes equivalence the earth leakage protector equivalent capacitance to shield the combination in parallel of flying capacitor over the ground with the end over the ground; according to electric capacity increase-volume principle in parallel; its existing relatively situation has strengthened last screen capacitance over the ground; earth connection is missed or the situation of loose contact even occur at work; because end screen direct-to-ground capacitance value strengthens; according to the series circuit voltage divider principle; the suspension voltage that is loaded on the screen of end can be clamped at a less value; the voltage that this value can tolerate far below the end screen; thereby avoided the breakdown accident of winding insulation to take place, increased the dependability of high voltage dry-type current transformer greatly.
Description of drawings
Fig. 1 is the structural representation of existing earth protective device;
Fig. 2 misses for end screen or a winding of voltage transformer equivalent circuit diagram over the ground during loose contact;
Fig. 3 is the structural representation of voltage transformer among the present invention;
Fig. 4 is winding equivalent circuit diagram over the ground among the present invention;
Fig. 5 is the structural representation of earth leakage protector among the present invention.
Embodiment
As Fig. 3, shown in Figure 5, high voltage dry-type current transformer comprises shell 12, is fixed with winding 11 one time by pressing plate 17 in the shell 12, and pressing plate 17 is fastened on the shell 12 by set bolt.Also be provided with ground plate 16 on the shell 12, ground plate 16 is provided with earth terminal 14.On a winding 11, the condenser type insulating barrier is installed; the end screen of this condenser type insulating barrier is provided with end screen ground lead 13; be parallel with two ground connection branch roads between this end screen ground lead 13 and the shell 12; wherein branch road directly is connected on the earth terminal 14 on the shell 12 by the ground protection line; be serially connected with an earth leakage protector 15 in another branch road; this earth leakage protector 15 comprises an outer tube 102; the two ends of outer tube 102 fixed cover respectively are provided with end cap 101; be equipped with connection bolt 105 respectively on two end caps 101; in outer tube 102, be provided with a capacitor 104, be cast with composite epoxy resin in the space 103 between this capacitor 104 and the outer tube 102.The lead-in wire at capacitor 104 two ends is welded on respectively on the connection bolt 105 on the outer tube 102 two ends end caps 101.One end of this earth leakage protector 15 ties by link and is connected on the end screen lead-in wire 13, and its other end is connected on the set bolt of pressing plate 17 by brace.
After high-tension current inductor of the present invention adopted said structure, as shown in Figure 4, among the figure, A was the high-pressure side of instrument transformer, and B is an end screen lead end, and C is the earth potential end, and U is added in the phase voltage of a winding high-pressure side, C when being normally operation
1Be the equivalent capacitance amount of a winding, C
0Miss time Mo screen equivalent electric capacity over the ground for the end screen, D is an earth leakage protector, C
2Equivalent capacitance amount for earth leakage protector.Because earth leakage protector D in parallel between end screen lead end B and earth potential end C, it is equivalent to last the screen and over the ground equivalence is become earth leakage protector equivalent capacitance C
2Shield equivalent capacity C over the ground with the end
0Parallel connection combination, it has been equivalent to strengthen last screen capacitance over the ground, because the capacitance C of earth leakage protector
2Equivalent capacity C is over the ground shielded at the end relatively
0Big a lot, so shunt capacitance is approximately equal to the equivalent capacitance value C of earth leakage protector
2According to the series circuit voltage divider principle, because end screen direct-to-ground capacitance value strengthens, and makes the suspension voltage of end screen be clamped at a less value, this value is lower than the voltage that last screen can tolerate, thereby has avoided the generation of accident.In the practical application, need use the capacitance partial pressure principle, select the capacitance parameter of suitable earth leakage protector according to the concrete condition of high voltage dry-type current transformer.
Claims (6)
1. the earthing protecting method of a high voltage dry-type current transformer; on a winding end screen of this high voltage dry-type current transformer, be provided with an earth connection; it is characterized in that; on a winding end screen of this high voltage dry-type current transformer, be connected with a ground protection spur track; be serially connected with an earth leakage protector that constitutes by Da Rong value capacitor in this ground protection spur track; one end of this earth leakage protector connects winding end screen one time; other end ground connection makes the suspension voltage of the equivalent capacitance value over the ground of a winding end screen greater than the end screen to strengthen winding end screen equivalent capacitance value over the ground.
2. the earthing protecting method of high voltage dry-type current transformer according to claim 1; it is characterized in that; also be covered with protective casing in described capacitor outside; this protective casing comprises outer tube; the two ends of outer tube are arranged with end cap respectively; be equipped with connection bolt on the end cap at two ends respectively, two lead-in wires of described capacitor are connected on the connection bolt of two end caps, also are cast with blending epoxy between capacitor and protective casing.
3. the earthing protecting method of high voltage dry-type current transformer according to claim 2; it is characterized in that; a described winding is fixed in the transformer casing by pressing plate; this transformer casing is in earth potential; pressing plate is provided with the set bolt that connects transformer casing; the connection bolt of one end of described earth leakage protector is connected electrically on the screen of end by lead, and its other end is connected electrically on the set bolt of pressing plate by brace.
4. high voltage dry-type current transformer; comprise shell; be fixed with winding in the shell one time; be connected with an earth connection between the end screen of this winding and the shell; it is characterized in that; also be arranged in parallel an earth leakage protector between the end of described winding screen and shell, this earth leakage protector mainly is made of Da Rong value capacitor, and two lead-in wires of this capacitor shield with winding end respectively and transformer casing is electrically connected.
5. high voltage dry-type current transformer according to claim 4, it is characterized in that, also be covered with protective casing in described capacitor outside, this protective casing comprises outer tube, the two ends of outer tube are arranged with end cap respectively, be equipped with connection bolt on the end cap at two ends respectively, two lead-in wires of described capacitor are connected on the connection bolt of two end caps, also are cast with blending epoxy between capacitor and housing.
6. high voltage dry-type current transformer according to claim 5; it is characterized in that; a described winding is fixed in the transformer casing by pressing plate; this pressing plate is provided with set bolt; the connection bolt of one end of described earth leakage protector is connected electrically on the screen of end by lead, and its other end is connected electrically on the set bolt of pressing plate by brace.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910172739XA CN101702368B (en) | 2009-11-26 | 2009-11-26 | High voltage dry-type current transformer and ground protection method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200910172739XA CN101702368B (en) | 2009-11-26 | 2009-11-26 | High voltage dry-type current transformer and ground protection method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101702368A true CN101702368A (en) | 2010-05-05 |
| CN101702368B CN101702368B (en) | 2011-11-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200910172739XA Active CN101702368B (en) | 2009-11-26 | 2009-11-26 | High voltage dry-type current transformer and ground protection method thereof |
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| Country | Link |
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| CN (1) | CN101702368B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102455401A (en) * | 2010-10-20 | 2012-05-16 | 鹤岗电业局 | Device for improving test efficiency of capacitive current transformer |
| CN106483349A (en) * | 2016-11-23 | 2017-03-08 | 国网重庆市电力公司江津供电分公司 | A kind of transformer secondary side earthing detection protection system |
-
2009
- 2009-11-26 CN CN200910172739XA patent/CN101702368B/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102455401A (en) * | 2010-10-20 | 2012-05-16 | 鹤岗电业局 | Device for improving test efficiency of capacitive current transformer |
| CN106483349A (en) * | 2016-11-23 | 2017-03-08 | 国网重庆市电力公司江津供电分公司 | A kind of transformer secondary side earthing detection protection system |
| CN106483349B (en) * | 2016-11-23 | 2019-01-22 | 国网重庆市电力公司江津供电分公司 | A kind of mutual inductor secondary side earthing detection protection system |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101702368B (en) | 2011-11-16 |
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Inventor after: Wang Hongqing Inventor after: Ping Haitao Inventor after: Dong Sensen Inventor after: Yuan Duanlei Inventor after: Han Guohui Inventor after: Luo Ganping Inventor after: Tian Gangling Inventor before: Wang Hongqing Inventor before: Ping Haitao Inventor before: Dong Sensen |
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Free format text: CORRECT: INVENTOR; FROM: WANG HONGQING PING HAITAO DONG SENSEN TO: WANG HONGQING PING HAITAO DONG SENSEN YUAN DUANLEI HAN GUOHUI LUO GANPING TIAN GANGLING |
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Owner name: STATE ELECTRIC NET CROP. Effective date: 20130125 |
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Effective date of registration: 20130125 Address after: South East of Pingdingshan city in Henan province 467001 No. 22 Patentee after: Pinggao Group Co., Ltd. Patentee after: State Grid Corporation of China Address before: South East of Pingdingshan city in Henan province 467001 No. 22 Patentee before: Pinggao Group Co., Ltd. |
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Effective date of registration: 20151225 Address after: South East of Pingdingshan city in Henan province 467001 No. 22 Patentee after: Pinggao Group Co., Ltd. Patentee after: State Grid Corporation of China Patentee after: Henan high General Electric Co., Ltd. Address before: South East of Pingdingshan city in Henan province 467001 No. 22 Patentee before: Pinggao Group Co., Ltd. Patentee before: State Grid Corporation of China |