JP5702022B2 - Lightning arrestor - Google Patents

Description

  The present invention relates to a lightning arrester according to the preamble portion of claim 1.

  A lightning arrester is, for example, a protection system for a switchgear, and when an overvoltage occurs due to a lightning strike or other part system malfunction, it leads the overvoltage to ground and thereby other parts of the switchgear Protect.

  Such a lightning arrester includes one or more cylindrical lightning protection elements, which have a single varistor stack composed of a plurality of separate, also cylindrical, varistor elements. The varistor element has a feature of voltage-dependent resistance. The varistor element functions as an insulator at low pressure. Varistors exhibit good electrical conductivity above a certain voltage threshold determined by the material. Varistor elements are often made from metal oxides such as zinc oxide. The lightning protection element is bounded at both ends by end attachment parts, and electrical connection to the switchgear and ground is made by these end attachment parts. The varistor stack must be held together under pressure to ensure good electrical contact even when mechanically loaded. This can be realized by applying a tensile force by sandwiching a plurality of tensile elements such as ropes or poles, preferably made of glass fiber reinforced resin, between the attachment portions at both ends. In this case, these tension elements surround the varistor stack and form a cage around the varistor stack.

  For use in gas insulated switchgear, the lightning arrester has a fluid tightly sealed housing that surrounds the lightning protection element. This housing is filled with a fluid to increase flashover strength, which is often sulfur hexafluoride. This housing is often made of metal and is electrically grounded. One mounting end of the lightning protection element stack is grounded through a single contact that is guided through the housing. The other attachment end is electrically connected to one contact on the outside of the housing via a bushing, and connection with the switchgear is performed by this contact. In particular, large lightning arresters often have one operating cover at the high voltage end, which is wrapped around the end of the lightning stack as a cylinder closed on one side. Each varistor element has a large capacitance with respect to the ground potential. However, when connected in series, the longitudinal capacitance becomes extremely small. As a result, when the constituent length of the varistor stack exceeds a certain length, a non-uniform voltage distribution occurs. Therefore, a higher voltage is applied to the plurality of varistor elements in the varistor stack portion far from the ground potential, and as a result, undesired heating occurs in combination with the resistance function of the elements. This is exactly what this operating cover helps to equalize the longitudinal voltage distribution of the varistor stack.

  When conducting an electrical test of the switchgear, a high voltage is applied and the lightning arrester must be disconnected from the switchgear. Otherwise, the lightning arrester will lead the voltage to ground and correct measurement results will not be obtained.

  Conventionally, a lightning arrester having a disconnection point for separating the lightning arrester from the switchgear is known. In order to manipulate this disconnect point, the housing must be opened, resulting in leakage of sulfur hexafluoride. Since sulfur hexafluoride is a harmful global warming gas, this is a problem that must be avoided.

  A lightning arrester of this type in which the lightning arrester stack is disconnected from the switchgear is known from US Pat. Here, the electrical connection is closed or opened by the cooperation of the mechanism composed of the lightning protection stack and the operation cover. In this case, a linear movement is performed through the housing wall in a gastight manner for operation.

Japanese Patent Laid-Open No. 10-322822

  An object of the present invention is to provide a lightning arrester of the kind described at the beginning, which can be closed or opened in an electrical connection in a structurally simpler manner.

  This problem is solved by a lightning arrester of this kind having the features described in the characterizing part of claim 1.

  The present invention includes one lightning protection element, one operation cover electrically connected to the lightning protection element, and one housing sealed fluid-tightly, and the lightning protection element and the operation cover are provided in the housing. And a housing in which the housing has two terminals that electrically connect the inside and the outside, respectively. Here, the lightning protection element and the operation cover are configured to be able to move relative to each other, and by their relative movement, electrical connection from one terminal to the other terminal via the lightning protection element is achieved. It can be closed or open. Due to this relative movement between the operating cover and the lightning protection element, the electrical connection to the switchgear can be closed or opened in a particularly simple manner. For example, the operating cover and the lightning protection element can cooperate to move, for example, in opposite directions. As an alternative, it is possible to move only the lightning protection element without moving the operation cover. In either case, the kinetic mass is smaller than in the case of the prior art, so that the mechanical elements necessary for the movement can be made simpler.

  In one advantageous form of the lightning arrester according to the invention, the lightning protection element is arranged along the longitudinal axis of the housing and the operating cover is arranged so that it can slide in the direction of the longitudinal axis. In this way, a particularly compact mechanism can be constructed. Since the operation cover is slidable along the longitudinal axis, it is possible to switch between the supply state and the stop state of the electrical connection to the switchgear while optimizing the space utilization and ensuring the necessary insulation distance. .

  In another advantageous form of the lightning arrester according to the invention, the operating cover can be slid by means of a sliding device which can be operated from outside the fluid-tightly sealed housing. The advantage is that this makes it possible to close or open the electrical connection to the switchgear of the lightning protection element in a sealed housing. In this way, it is possible to avoid the release of the housing and the loss of gas resulting therefrom.

  The lightning arrester according to the present invention is particularly advantageous when configured as follows. That is, the slide device has one shaft that can be operated by rotational motion, one slide rod connected to the operation cover, and one gear that converts the rotational motion of the shaft into the translational motion of the slide rod. Configure to be. Such a slide device can be particularly compact and can be operated easily. The rotational movement of the shaft guided inside the housing can be easily sealed by various appropriate measures.

  In another advantageous form of the lightning arrester according to the invention, the thrust bar is at least partly made of electrical insulation. This can be, for example, a glass fiber reinforced resin. Thereby, the flashover between the slide bar and the operation cover can be avoided, so that the insulation strength can be advantageously ensured.

  In another form of the lightning arrester according to the invention, the shaft is guided fluid-tightly from the inside to the outside of the housing. This advantageously prevents fluid leakage from the housing. In this way, harmful environmental pollution by this fluid can be prevented. Furthermore, since the withstand voltage strength is maintained in this way, the lightning arrester needs almost no maintenance.

  Furthermore, in an advantageous form of the invention, one end of the lightning protection element is electrically connected to one of the two terminals and the other end of the lightning protection element to the operation cover. The electrical connection with the other terminal can be closed or opened by sliding. In this way, only the operation cover needs to be moved in order to close or open the connection. The operation cover is lighter than the lightning protection element. Therefore, less mechanical force is required for moving the operation cover.

  According to another advantageous form of the lightning arrester according to the invention, when the electrical connection is closed, the mating coupling is such that both the operating cover and the other terminal are fixed in the radial direction of the longitudinal axis. So they mesh. Thus, the operation cover and the terminal are centered with respect to each other when the contact is closed, and are not inclined with respect to each other. By making the shape of the operation cover and the terminal exactly opposite each other, the largest possible contact area between the operation cover and the terminal can be generated. A more secure connection of the operating cover is guaranteed.

  Furthermore, it is advantageous if the operating cover is coupled to the lightning protection element via a plurality of sliding bearings in order to be able to slide in the longitudinal direction. These sliding bearings are advantageously provided on the lateral side of the end electrodes and guide and fix the operating cover in the radial direction of the longitudinal axis. When the electrical connection is closed, the operating cover is fixed radially by its terminals in addition thereto. Furthermore, when the ground side end of the lightning protection element is fixed in the radial direction with the lid of the housing, for example, by a fixed connection of the ground side electrode end, the lightning protection element and the operation cover are both connected to the housing. Because it is fixed, it is resistant to vibration during transportation and earthquakes, for example.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

Cross section of a lightning arrester with an open electrical connection Cross section of a lightning arrester with closed electrical connection 2 is a partial perspective view of the cross-sectional view of FIG. 2. In all the drawings, equivalent parts are denoted by the same reference numerals.

  1 and 2 show a lightning arrester 1 in a cross-sectional view. One lightning protection element 20 is arranged in the fluid-tightly sealed housing 2. The lightning protection element 20 includes one cylindrical varistor stack 25, one upper mounting portion 22, one lower mounting portion 21, and a plurality of tension elements 23. The varistor stack 25 is assembled from a plurality of separate, also cylindrical, varistor blocks. Attachment portions 21 and 22 are installed at both ends of the varistor stack 25. In FIG. 1 and FIG. 2, only the lower mounting part 21 can be seen. The attachment portions 21 and 22 are usually made of a conductive material. The plurality of tension elements 23 are sandwiched between the attachment portions 21 and 22 and applied with a tensile force, and thus hold the varistor stack 25 integrally. A plurality of holding discs 24 having a plurality of holes are inserted into the varistor stack 25, and a plurality of tension elements 23 are guided through these holes, whereby the lightning protection element 20 is additionally provided. To be stable. The housing 2 is substantially cylindrical. A longitudinal axis 50 extends along the cylindrical axis. The lightning protection elements 20 are arranged along the longitudinal axis 50. The housing 2 is fluid-tightly sealed on both lid surfaces.

  On the ground connection side of the lightning protection element 20, the cover surface of the housing 2 is sealed with a simple housing cover 4. The terminal 8 is electrically insulated, penetrates through the housing lid 4 and is guided from the inside to the outside of the housing 2 and serves as a ground terminal. Inside the housing 2, the terminal 8 is electrically connected to the lightning protection element 20 by, for example, a single cable 15. This connection is made here via a conductive terminal board 13. Between the terminal plate and the lower mounting portion 21, there is another insulating intermediate member 14. As an alternative, the cable 15 can be directly connected to the lower mounting portion 21. In this case, the insulating intermediate member 14 is not necessary. The lower mounting portion 21 of the lightning protection element 20 is fixed to the housing lid 4. The housing lid 4 is electrically insulated from the varistor stack 25. This insulation is here made by the intermediate member 14. As an alternative, one insulating layer can be inserted between the lower mounting portion 21 and the housing lid 4. The housing lid 4 generally has a connection not shown here through which a fluid, for example sulfur hexafluoride, can be filled or discharged into the housing 2.

  On the high voltage connection side of the lightning arrester 20, the cover surface of the housing 2 is provided with a high voltage bushing 5, so that there is no danger of flashover between the high voltage part and the grounded housing 2. The electric potential can be guided to the inside of the housing 2 from the outside. The bushing 5 includes one retaining ring 12, one insulator 6, and a terminal 7, which is used here as a contact plug. The lightning arrester 1 can be connected through this terminal 7 to a gas insulated switchgear not shown here. Inside the housing 2, the terminal 7 is provided with a conductive insert 9. The bushing includes a plurality of seal rings (10) on a contact surface between the housing 2 and the opening / closing device.

  An operation cover 40 having a substantially cylindrical shape and sealed at one end is provided on the high voltage side of the lightning protection element 20. The operation cover 20 is coupled to one slide device 30, which is fluid-tight through one slide bar, one gear that can be configured as, for example, a trapezoidal gear, and the housing lid 4. One shaft 31 to be guided and one operating element 34 coupled to the shaft 31 outside the housing 2 are provided. One indicator 35 can be added to the operating element 34, which indicates whether the electrical connection is closed or open.

  Here, the shaft 31 can be rotated by means of an operating element 34 shown as a hand crank. This rotational movement is converted into a linear movement of the slide bar 33 in the direction of the longitudinal axis 50 via the gear 32. The slide bar 33 transmits a linear motion to the operation cover 40. In order to better guide the slide bar 33, the slide bar is guided through a plurality of holes in a plurality of holding plates. Thus, the operating cover 40 can move in the direction of the longitudinal axis 50 towards the terminal 7 and away from it, whereby the electrical connection is closed or opened. In FIG. 1, the electrical connection is open.

  In FIG. 2, the operation cover 40 is moved toward the terminal 7 until the operation cover 40 and the terminal 7 come into contact with each other. The electrical connection is thus closed. From the outside of the high voltage side of the housing 2, the terminal 7, the operation cover 40, the lightning protection element 20 electrically connected to the operation cover 40, and finally the terminal 8 electrically connected to the lightning protection element 20. The electrical connection from the end to the end is established to the outside of the earth side.

  FIG. 3 is a partial cross-sectional view of the end portion on the high voltage side of the lightning arrester 1. Here, the electrical connection is closed. The operation cover 40 is in contact with the insert 9 of the terminal 7. The operation cover 40 and the insert 9 are formed in a shape such that the bulge of the insert 9 firmly captures the corresponding recess at the sealed end of the operation cover 40. In this way, the operation cover is fixed in the radial direction of the longitudinal axis 50.

  The upper mounting portion 22 includes a plurality of sliding bearings 41. These sliding bearings fix the operation cover 40 in the radial direction of the longitudinal axis 50, and guide the operating cover 40 in the direction of the longitudinal axis 50 when sliding. These sliding bearings 41 can be made conductive, and thereby the electrical connection between the operation cover 40 and the mounting portion 22 is performed at the same time. However, these plain bearings can be made of a non-conductive material such as resin. In that case, for example, the electrical connection between the attachment portion 22 and the operation cover 40 can be performed via a flexible conductive band.

DESCRIPTION OF SYMBOLS 1 Lightning arrester 2 Housing 4 Lid 5 Bushing 7, 8 Terminal 9 Insert 10 Seal ring 12 Holding ring 13 Terminal plate 14 Intermediate member 15 Cable 20 Lightning protection element 21 Lower attachment part 22 Upper attachment part 23 Tensile element 24 Holding disk 25 Varistor stack 30 Slide device 31 Shaft 32 Gear 33 Slide bar 34 Operation element 35 Display unit 40 Operation cover 41 Slide bearing 50 Long axis

Claims (9)

One lightning protection element (20), one operation cover (40) electrically connected to the lightning protection element (20), and one housing (2) hermetically sealed, the housing The lightning protection element (20) and the operation cover (40) are arranged in (2), and the housing (2) has two terminals (7, 8) for electrically connecting the inside and the outside, respectively. In a lightning arrester having
The lightning protection element (20) and the operation cover (40) are configured to move relative to each other, and the lightning protection element (20) from one terminal (7, 8) by this relative movement. A lightning arrester characterized in that the electrical connection to the other terminal (7, 8) can be closed or opened via the. The lightning arrester according to claim 1,
The lightning protection element (20) is disposed along the longitudinal axis (50) of the housing, and the operation cover (40) is slidably disposed in the direction of the longitudinal axis (50). And a lightning arrester. The lightning arrester according to claim 2,
The lightning arrester characterized in that the operation cover (40) is slidable by a slide device (30) operable from the outside of the fluid-tight housing (2). The lightning arrester according to claim 3,
The slide device (30) is capable of rotating a single shaft (31) that can be operated by a rotary motion, a single slide bar (33) coupled to the operation cover (40), and the rotary motion of the shaft (31). A lightning arrester having one gear (32) which converts into a translational movement of the slide rod (33). The lightning arrester according to claim 4,
A lightning arrester, characterized in that the slide bar (33) is at least partly made of an electrically insulating material. The lightning arrester according to claim 4 or 5,
The lightning arrester characterized in that the shaft (31) is guided fluid-tightly from the inside to the outside of the housing (2). The lightning arrester according to one of claims 2 to 6,
One end of the lightning protection element (20) is electrically connected to one of the terminals (7, 8), and the other end of the lightning protection element (20) is electrically connected to the operation cover (40). A lightning arrester characterized in that the electrical connection with the other of the terminals (7, 8) is closed or open by sliding the cover (40). The lightning arrester according to claim 7,
When the electrical connection is in a closed state, the operation cover (40) and the other terminal (7, 8) are engaged with each other by a fitting connection so that both are fixed in the radial direction of the longitudinal axis. Lightning arrestor. The lightning arrester according to claim 8,
The lightning arrester characterized in that the operation cover (40) is coupled to the lightning arrester element (20) via a plurality of slide bearings (41) so as to be slidable in the longitudinal axis direction.

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