JP2006172847A - Vacuum switching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve insulating characteristics of a vacuum bulb to which a voltage sharing element is connected. <P>SOLUTION: The vacuum switching device comprises vacuum insulating containers 2a, 2b connected by an intermediate fitting 3, a fixed side sealing fitting 4 sealed at the opening part on one end of the vacuum insulating containers 2a, 2b, a movable side sealing fitting 5 sealed at the opening part at the other end, a pair of contacts 7, 9 capable of contacting and separating, an arc shield fixed to the intermediate fitting 3, voltage sharing elements 16a, 16b respectively connected between the fixed side sealing fitting 4 and the intermediate fitting 3, and between the intermediate fitting 3 and the movable side sealing fitting 5, and an operating mechanism 19. The voltage sharing elements 16a, 16b are arranged along the surface in axial direction of the vacuum insulating containers 2a, 2b so that the electric field strength between the voltage sharing elements 16a, 16b and the vacuum insulating containers 2a, 2b may be suppressed, and are separated from the vacuum insulating containers 2a, 2b with a prescribed insulating distance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vacuum switchgear that can improve the insulation characteristics of a vacuum valve having an intermediate potential arc shield connected to a voltage sharing element.

  In a vacuum valve having an arc shield provided so as to surround a pair of contactable and separable contacts, the arc shield has an intermediate potential between the main circuit (potential 100%) and the ground (potential 0%). Then, by fixing the intermediate potential to approximately 50% of the intermediate value, a vacuum valve having excellent insulating characteristics and blocking characteristics can be obtained.

  In a conventional vacuum valve, a capacitor (voltage sharing element) is connected between one main circuit outside the vacuum valve and the arc shield, and between the arc shield and the other main circuit, so that the potential of the arc shield is approximately 50%. What is fixed is known (for example, refer to Patent Document 1).

On the other hand, in a vacuum switchgear in which a plurality of vacuum valves are connected in series, a capacitor is connected between the main circuits of the respective vacuum valves to make the voltage sharing of each vacuum valve uniform (for example, (See Patent Document 2).
Japanese Patent Laid-Open No. 10-12459 (pages 4-5, FIG. 9) Japanese Patent Laid-Open No. 10-224923 (third page, FIG. 3)

  The above conventional vacuum switchgear has the following problems.

  If a capacitor is connected between the main circuit of the vacuum valve and the arc shield, the electric potential of the arc shield is fixed, but electric field concentration occurs in each part depending on the shape and arrangement of the capacitor. That is, when the capacitor protrudes longer than the vacuum valve, the electric field concentrates on the end of the capacitor. Conversely, if the capacitor is shorter than the vacuum valve, the electric field distribution of the vacuum valve will be disturbed.

  In particular, when the capacitor is shorter than the vacuum valve and the potential distribution of the vacuum valve is pulled to the capacitor side, the potential distribution is greatly disturbed compared to when there is no capacitor. This may cause electric field concentration at each part such as the end of the vacuum valve or a pair of contacts.

  For this reason, the vacuum valve must be sufficiently separated from the capacitor or the distance from the ground must be increased. This goes against the recent trend of shrinking.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a vacuum switchgear that can improve the insulation characteristics of a vacuum valve connected to a voltage sharing element that fixes the potential of an arc shield.

  In order to achieve the above object, a vacuum switchgear according to the present invention is sealed to a cylindrical vacuum insulating container having an intermediate portion hermetically connected in series with an intermediate fitting, and an opening at one end of the vacuum insulating container. A fixed-side sealing metal fitting, a movable-side sealing metal fitting sealed in the opening at the other end of the vacuum insulating container, a pair of contactable and separable contacts provided in the vacuum insulating container, and the pair And an arc shield at an intermediate potential fixed to the intermediate metal fitting, between the fixed-side sealing metal fitting and the intermediate metal fitting, and between the intermediate metal fitting and the movable-side sealing metal fitting. Each of the voltage sharing elements connected to each other and an operation mechanism that opens and closes the pair of contacts, and the voltage sharing elements are arranged so that the electric field strength between the voltage sharing elements and the vacuum insulating container is suppressed. Along the creeping surface of the insulating container in the axial direction With the location, characterized in that it is spaced apart keeping this vacuum insulating container with a predetermined insulation distance.

  According to the present invention, the voltage sharing element connected and fixed between the main circuit of the vacuum valve and the arc shield is configured such that the mutual electric field strength is suppressed by the interaction of the electric field distribution between the vacuum valve and the voltage sharing element. Therefore, the electric field strength of each part of a vacuum valve and a voltage sharing element is suppressed, and an insulation characteristic can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a vacuum switchgear according to Embodiment 1 of the present invention will be described with reference to FIG. 1 is a cross-sectional view illustrating a configuration of a vacuum switchgear according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the vacuum switching device includes a vacuum valve portion 1a having a pair of contactable contacts at the upper part of the figure and an operation mechanism part 1b for opening and closing the pair of contacts at the lower part of the figure.

  Cylindrical vacuum insulating containers 2a and 2b made of alumina porcelain are hermetically connected in series with the vacuum valve portion 1a by a cylindrical intermediate fitting 3. In addition, a fixed-side sealing metal fitting 4 and a movable-side sealing metal fitting 5 are sealed in the opening portions at both ends of the vacuum insulating containers 2a and 2b, respectively.

  A fixed-side energizing shaft 6 is hermetically penetrated and fixed to the fixed-side sealing metal fitting 4, and a fixed-side contact 7 is provided at the end of the fixed-side energizing shaft 6 in the vacuum insulating containers 2a and 2b. An upper conductor 8 of a fixing member serving as one electric circuit is connected to the outside of the vacuum insulating containers 2a and 2b of the fixed side energizing shaft 6.

A movable energizing shaft 10 provided with a movable contact 9 that can be moved toward and away from the fixed contact 7 is movably penetrated through the central opening of the movable seal 5. The free end of the telescopic bellows 11 is fixed in an airtight manner in the intermediate portion of the vacuum insulating container 2 a, 2 b of the movable side energizing shaft 10, and the fixed end is airtight in the central opening of the movable side sealing fitting 5. It is fixed to. Thereby, it is possible to move the movable-side energizing shaft 10 in the axial direction while maintaining a vacuum with an internal pressure of 10 ⁻² Pa or less.

  In addition, a cylindrical arc shield 12 provided so as to surround both the contacts 7 and 9 is fixed to the intermediate metal fitting 3. The arc shield 12 prevents the metal vapor generated when the currents of the contacts 7 and 9 are opened / closed from adhering to the inner surfaces of the vacuum insulating containers 2a and 2b, thereby reducing the creeping insulation resistance. As will be described later, the potential of the arc shield 12 is an intermediate potential between the potential of both the contacts 7 and 9 (potential 100%) and the ground potential (potential 0%).

  Moreover, the movable-side energizing shaft 10 outside the vacuum insulating containers 2a and 2b penetrates the outer conductor 14 having the contact 13 so as to be movable. A lower conductor 15 of a fixing member serving as the other electric circuit is fixed to the outer conductor 14.

  Further, between the upper conductor 8 and the intermediate metal fitting 3 and between the intermediate metal fitting 3 and the lower conductor 15, for example, cylindrical voltage sharing elements 16a and 16b such as ceramic capacitors are connected to the vacuum insulating containers 2a and 2b. The insulation distance G is maintained and the connection conductors 17a and 17b are connected and fixed. At both ends of the voltage sharing elements 16a and 16b, for example, electrodes 16a1, 16a2, 16b1, and 16b2 attached by metal spraying are provided.

  Here, the electrostatic capacitances of the voltage sharing elements 16a and 16b are set to the same electrostatic capacitance, respectively, and more than the floating capacitance of the vacuum valve portion 1a. As a result, the potential of the arc shield 12 can be made approximately 50% of the intermediate value between the main circuit potential (contacts 7, 9 and the like) and the ground potential.

  In general, the stray capacitance is hundreds of tens of pF, so that the capacitances of the voltage sharing elements 16a and 16b are more than that. However, if it is more than ten times or several thousand pF, the phase advance current increases, which is not preferable. These voltage sharing elements 16a and 16b may be formed singly or a plurality of capacitors may be connected in series and parallel. Further, the voltage sharing elements 16a and 16b may be ones in which a capacitor and a resistor are connected in series and parallel.

  An insulating operation rod 18 is coupled to the operation mechanism portion 1b in the axial direction of the movable energizing shaft 10. In addition, an operating mechanism 19 such as an electromagnetic actuator is connected to the insulating operating rod 18 so that both the contacts 7 and 9 are opened and closed.

  In the vacuum valve to which the voltage sharing elements 16a and 16b are connected, the arrangement and size of the voltage sharing elements 16a and 16b will be described.

  First, the insulation distance G between the vacuum insulation containers 2a and 2b and the voltage sharing elements 16a and 16b is set to be a few millimeters to the radial distance of the cylindrical vacuum insulation containers 2a and 2b.

  At the lower limit of the insulation distance G, a minute gap is formed when they come into contact with each other as G = 0 mm, so that the electric field strength greatly increases. Similarly, the electric field strength increases even at an insulation distance G where foreign matter is caught. For this reason, the insulation distance G is set to a separated distance where foreign matters in a general electric chamber are sandwiched and an electrical defect is not formed, for example, G = 5 mm or more in the air.

  The upper limit of the insulation distance G is the distance to the radius of the vacuum insulation containers 2a and 2b, and the mutual electric field distribution between the vacuum insulation containers 2a and 2b and the voltage sharing elements 16a and 16b is buffered to suppress the mutual electric field strength. To be. That is, the effect of suppressing the electric field strength due to the electric field interaction is produced. Note that if the insulation distance G is increased beyond the radius, the effect of suppressing the electric field strength decreases, and the electric field distribution when using each of them alone is approached.

  For example, when the diameter of the vacuum insulation containers 2a and 2b is 200 mm and the insulation distance G is obtained with a rated voltage of 60 kV or less, the electric field strength of each other is suppressed at G = 5 mm to 100 mm. And in the insulation distance G = 35 mm vicinity, the electric field strength of both a vacuum valve and voltage sharing element 16a, 16b is suppressed most.

  Next, let L1 be the length between the electrodes 16a1 and 16a2 of the voltage sharing elements 16a and 16b, that is, the axial direction, and L2 be the length of the cylinder of the vacuum insulating containers 2a and 2b, that is, the axial length. , L1 = (0.7 to 1.2) × L2.

  This is because when the axial length L1 of the voltage sharing elements 16a and 16b is less than L1 = 0.7 × L2, the axial length of the voltage sharing elements 16a and 16b is shorter than the vacuum insulating containers 2a and 2b. The potential distribution in the vicinity of the vacuum insulating containers 2a and 2b is pulled to the potential of the electrodes 16a1, 16a2, 16b1 and 16b2, and the electric field strength at the end (A portion in the figure) of the fixed-side sealing fitting 4 and the movable-side sealing fitting 5 is increased. It is to rise.

  If the axial length L1 of the voltage sharing elements 16a and 16b exceeds L1 = 1.2 × L2, the voltage sharing elements 16a and 16b protrude from the vacuum insulating containers 2a and 2b. This is because the electric field strength at the ends (B portion in the drawing) of the electrodes 16a1 and 16b2 on the side of the fitting 4 and the movable side fitting 5 is increased.

  The length L1 in the axial direction of the voltage sharing elements 16a and 16b and the length L2 in the axial direction of the vacuum insulating containers 2a and 2b are the same lengths (L1 = L2), respectively. When the voltage sharing elements 16a and 16b are arranged along the axial creepage, both ends of the fixed-side sealing fitting 4, the movable-side sealing fitting 5 and the electrodes 16a1, 16a2, 16b1, and 16b2 are arranged. The respective electric field strengths are most suppressed and preferable.

  According to the vacuum switching device of the first embodiment, the voltage sharing elements 16a and 16b having a predetermined axial length are connected and fixed to the outside of the vacuum valve while maintaining a predetermined insulation distance G. Since the electric field is suppressed by the action, it is possible to suppress the electric field strengths of the fixed-side sealing fitting 4 and the movable-side sealing fitting 5 constituting the vacuum valve and the voltage sharing elements 16a and 16b, Insulation characteristics can be improved.

  Next, a vacuum switchgear according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view illustrating a vacuum valve portion of a vacuum switchgear according to Embodiment 2 of the present invention. The second embodiment is different from the first embodiment in the shape of the voltage sharing element. In FIG. 2, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 2, the voltage sharing elements 21a and 21b are made of cylindrical ceramic capacitors, for example, spaced apart from the outer periphery of the vacuum insulation containers 2a and 2b with a predetermined insulation distance, and arranged in the coaxial direction. . Further, between the upper conductor 22 and the lower conductor 23, which are larger than the outer diameter of the voltage sharing elements 21a and 21b, electrodes 21a1, 21a2, 21b1, and 21b2 are connected and fixed by a plurality of connection conductors 17a provided in the circumferential direction. Yes. The voltage sharing elements 21a and 21b are connected to the intermediate fitting 3 by a connection conductor 17b.

  According to the vacuum switching device of the second embodiment, in addition to the effects of the first embodiment, the voltage sharing elements 21a and 21b are arranged in the coaxial direction of the vacuum valve. The electric field strength at the ends of the fitting 5 and the intermediate fitting 3 can be further suppressed.

  Next, a vacuum switchgear according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating a vacuum valve portion of a vacuum switchgear according to Embodiment 3 of the present invention. The third embodiment is different from the second embodiment in the capacitance distribution of the voltage sharing element. In FIG. 3, the same components as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 3, the voltage sharing elements 25a and 25b are each divided into three in a direction orthogonal to the axial direction. The upper stage in the figure is the first voltage sharing elements 25a1 and 25b1, the middle stage in the figure is the second voltage sharing elements 25a2 and 25b2, and the lower stage in the figure is the third voltage sharing elements 25a3 and 25b3. Further, electrodes 25a4, 25a5, 25b4, and 25b5 are provided at both ends of the voltage sharing elements 25a and 25b, respectively.

  Here, the relative permittivity of the first voltage sharing elements 25a1, 25b1 is ε1, the relative permittivity of the second voltage sharing elements 25a2, 25b2 is ε2, and the third voltage sharing element 25a3 on the intermediate metal fitting 3 side, When the relative dielectric constant of 25b3 is ε3, the relative dielectric constant ε2 <ε1, ε3. That is, the relative permittivity at both end portions is made larger than that at the intermediate portion so that the capacitance is increased.

  According to the vacuum switchgear of the third embodiment, in addition to the effects of the first embodiment, the electric field strength at the ends of the fixed-side sealing metal fitting 4, the movable-side sealing metal fitting 5 and the intermediate metal fitting 3 constituting the vacuum valve is increased. Further suppression can be achieved.

  In the third embodiment, the voltage sharing elements 25a and 25b have been described as being divided into three parts. However, the voltage sharing elements 25a and 25b can be divided into a plurality of parts, and the capacitances at both ends can be made larger than the intermediate part.

  Next, a vacuum switchgear according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view showing a vacuum valve portion of a vacuum switchgear according to Embodiment 4 of the present invention. The fourth embodiment is different from the first embodiment in the capacitance of the vacuum insulating container. In FIG. 4, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, the vacuum insulating containers 27a and 27b are made of, for example, a high dielectric ceramic. This can be obtained by mixing alumina ceramic with a high dielectric material such as titanium oxide powder. The capacitances formed between the fixed-side sealing metal fitting 4 and the intermediate metal fitting 3 and between the intermediate metal fitting 3 and the movable-side sealing metal fitting 5 are set to the same capacitance, and the floating of the vacuum valve portion 1a. More than capacity.

  In general, the relative dielectric constant of alumina porcelain is close to 8, but when titanium oxide powder is mixed, the relative dielectric constant of titanium oxide is more than ten times that of alumina porcelain. Can do.

  According to the vacuum switchgear of the fourth embodiment, in addition to the effects of the first embodiment, it is not necessary to connect the voltage sharing element used in the first embodiment, and the structure of the vacuum switchgear can be simplified.

  In addition, this invention is not limited to the said Example, In the range which does not deviate from the summary of invention, it can implement in various deformation | transformation. In the above embodiment, two vacuum insulation containers 2a and 2b are connected in series with the intermediate metal fitting 3, and one arc shield 12 is fixed to the intermediate metal fitting 3. However, two or more vacuum insulation containers are used. Thus, it can also be used in a vacuum valve for fixing a plurality of arc shields. The same applies to the case of using two or more high dielectric vacuum insulating containers.

  In the above embodiment, the voltage sharing element is used in the air. However, in order to reduce the overall shape, the vacuum valve and the voltage sharing element may be integrally molded with an insulating material such as an epoxy resin. Further, a grounding layer may be provided on the surface of the molded insulating layer so as not to be affected by contamination. In this case, the insulation distance between the vacuum insulation container and the voltage sharing element is also filled with an insulating material in the meantime, so that the dielectric strength is improved. The distance may be 1 mm, for example.

Sectional drawing which shows the structure of the vacuum switchgear which concerns on Example 1 of this invention. Sectional drawing which shows the vacuum valve part of the vacuum switchgear which concerns on Example 2 of this invention. Sectional drawing which shows the vacuum valve part of the vacuum switchgear which concerns on Example 3 of this invention. Sectional drawing which shows the vacuum valve part of the vacuum switchgear which concerns on Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Vacuum valve part 1b Operation mechanism part 2a, 2b, 27a, 27b Vacuum insulating container 3 Intermediate metal fitting 4 Fixed side sealing metal fitting 5 Movable side sealing metal fitting 6 Fixed side electricity supply shaft 7 Fixed side contact 8, 8 Upper conductor 9 Movable side Contact 10 Movable side energizing shaft 11 Bellows 12 Arc shield 13 Contact 14 External conductors 15, 23 Lower conductors 16a, 16b, 21a, 21b, 25a, 25b Voltage sharing elements 16a1, 16a2, 16b1, 16b2, 21a1, 21a2, 21b1, 21b2, 25a4, 25a5, 25b4, 25b5 Electrodes 17a, 17b Connecting conductor 18 Insulating operating rod 19 Operating mechanism 25a1, 25b1 First voltage sharing element 25a2, 25b2 Second voltage sharing element 25a3, 25b3 Third voltage sharing element

Claims (6)

A cylindrical vacuum insulating container whose middle part is air-tightly connected in series with an intermediate fitting;
A fixed-side sealing fitting sealed at the opening at one end of the vacuum insulating container;
A movable side sealing fitting sealed in the opening of the other end of the vacuum insulating container;
A pair of detachable contacts provided in the vacuum insulating container; and
An arc shield having an intermediate potential fixed to the intermediate fitting, and arranged to surround the pair of contacts;
Voltage sharing elements connected between the fixed-side sealing bracket and the intermediate bracket and between the intermediate bracket and the movable-side sealing bracket,
An operating mechanism that opens and closes the pair of contacts, and the voltage sharing element is arranged along a creeping surface in the axial direction of the vacuum insulating container so that an electric field strength between the voltage sharing element and the vacuum insulating container is suppressed. And a vacuum switchgear characterized in that the vacuum switchgear is spaced apart from the vacuum insulation container while maintaining a predetermined insulation distance. The axial length of the voltage sharing element is L1,
When the axial length of the vacuum insulating container is L2,
The vacuum switchgear according to claim 1, wherein L1 = (0.7 to 1.2) × L2.   2. The insulation distance between the vacuum insulation container and the voltage sharing element is from a spaced distance where no electrical defect is formed therebetween to a radius distance of the vacuum insulation container. The vacuum switchgear described.   The vacuum switchgear according to any one of claims 1 to 3, wherein the voltage sharing element is divided into a plurality of electrodes and has a relative dielectric constant at both end portions larger than that at the intermediate portion. A cylindrical vacuum insulating container whose middle part is air-tightly connected in series with an intermediate fitting;
A fixed-side sealing fitting sealed at the opening at one end of the vacuum insulating container;
A movable side sealing fitting sealed in the opening of the other end of the vacuum insulating container;
A pair of detachable contacts provided in the vacuum insulating container; and
An arc shield having an intermediate potential fixed to the intermediate fitting, and arranged to surround the pair of contacts;
An operation mechanism for opening and closing the pair of contacts, and a capacitance of each of the vacuum insulating containers formed between the fixed-side sealing metal fitting and the intermediate metal fitting and between the intermediate metal fitting and the movable-side sealing metal fitting. Is larger than the stray capacitance formed between the pair of contacts and the ground.   6. The vacuum switchgear according to claim 5, wherein the vacuum insulating container is made by mixing titanium oxide powder with alumina porcelain.

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