JP2011040302A - Grounding switching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grounding switching device having the responsibility of short-circuit input, while suppressing potential sharing between vacuum contacts. <P>SOLUTION: The grounding switching device includes a fixed side vacuum contact 2; a movable side vacuum contact 3 freely engaging therewith; a movable connection movable shaft 10 connected to the movable-side vacuum contact 3; an opening spring 15 provided on the outer periphery of the connection movable shaft 10 and energized, to open a circuit between the fixed side vacuum contact and the movable side vacuum contact; a fist air circuit 11 fixed to the end of the connection movable shaft 10; a second air contact 12 freely engaging with the first air contact 11; an operation shaft 13 connected to the second air contact 12 and movable with grounding potential; a vacuum-side insulating layer 8a, provided around the fixed side vacuum contact 2 and the movable side vacuum contact 3; and an air-side insulating layer 8b, provided around the opening spring 15 and the first and second air contacts 11, 12. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a grounding switchgear that can form a ground-to-ground insulation between a contact in vacuum and a contact in air, and can reliably open and ground an electric circuit.

  2. Description of the Related Art Conventionally, a switch has been downsized by utilizing an excellent dielectric strength and breaking performance in a vacuum. Examples of the switch include a circuit breaker, a disconnect switch, and a ground switch (for example, see Patent Document 1).

  However, the variation in discharge in vacuum is 10 to 13% in standard deviation, which is larger than that in air or gas. Furthermore, the breakdown voltage is lowered and the variation is further increased simply by opening and closing the contacts. For this reason, in order to make it a low destruction probability, the insulation distance between contacts had to be enlarged (for example, refer patent document 2).

JP 2007-305524 A (Page 4, FIG. 1) Japanese Patent Laid-Open No. 2003-92051 (pages 3 to 4, FIG. 1)

  In a switch using a vacuum as an insulating medium, there is a problem that the variation in discharge is large and the insulation distance between the contacts must be increased. On the other hand, when air is used as the insulating medium, the variation in discharge is reduced, but the dielectric strength is small, and as a result, the insulation distance between the contacts must be increased. Moreover, it is not preferable from an environmental viewpoint to use an insulating gas such as SF6 gas for the insulating medium.

  For this reason, there has been a demand for a switch that can be reduced in size by forming a switch with an insulating medium having excellent dielectric strength, such as a vacuum, as in the air, and having a small variation in discharge. Here, as the switch, a ground switch having a duty of short-circuiting is targeted. In general, a circuit breaker mainly requires a breaking characteristic that opens and closes a large current, and a circuit breaker mainly requires a dielectric strength to open and close an electric circuit, which is different from the responsibility of a grounding switch.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a grounding switchgear having a duty of short-circuiting using an insulating medium having a small discharge variation and excellent dielectric strength.

  In order to achieve the above object, a ground switchgear according to the present invention includes a fixed-side vacuum contact connected to a main circuit, a movable-side vacuum contact that can be freely connected to and separated from the fixed-side vacuum contact, and the movable-side vacuum contact. A connected movable movable shaft connected, an open spring biased to open the fixed-side vacuum contact and the movable-side vacuum contact provided on an outer periphery of the connected movable shaft, and the connected movable shaft 1st air contact fixed to the end, 2nd air contact which can be contacted and separated from the 1st air contact, and ground potential connected to the 2nd air contact An operating shaft, a vacuum-side insulating layer provided around the fixed-side vacuum contact and the movable-side vacuum contact, and an open spring and the first air contact that are connected to the vacuum-side insulating layer An air-side insulating layer provided around the second air contact. It is characterized in.

  According to the present invention, the contacts in the vacuum and the contacts in the air are connected in series, the potential is shared between the two contacts when the circuit is opened, and the final circuit is closed at the contacts in the vacuum when the circuit is turned on. Therefore, the variation in discharge between the contacts on the vacuum side can be reduced, and the responsibility for short-circuiting can be provided.

Sectional drawing which shows the structure of the earthing | grounding switchgear which concerns on Example 1 of this invention. The figure explaining operation | movement of the earthing | grounding switchgear which concerns on Example 1 of this invention. Sectional drawing which shows the structure of the earthing | grounding switchgear which concerns on Example 2 of this invention. Sectional drawing which shows the structure of the earthing | grounding switchgear which concerns on Example 3 of this invention.

  A pair of contactable and separable contacts with the insulating medium in a vacuum is provided on the main circuit side, and a pair of contactable and separable contacts with the insulating medium in the air are provided on the ground side. These are connected in series. In this circuit, the main circuit potential is shared, and when the circuit is closed, the air contact is first closed, and then the vacuum contact is closed. Embodiments of the present invention will be described below with reference to the drawings.

  First, a ground switchgear according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view illustrating the configuration of a ground switchgear according to Embodiment 1 of the present invention, and FIG. 2 is a diagram illustrating the operation of the ground switchgear according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the grounding switchgear is composed of an upper vacuum part 1a and a lower air part 1b with a middle part in the vertical direction in the figure as a boundary.

  The vacuum part 1a is provided with a vacuum valve 4 having a pair of fixed-side and movable-side vacuum contacts 2 and 3 that contact and separate in vacuum. A fixed-side energizing shaft 5 is fixed to the fixed-side vacuum contact 2 and is connected to a fixed-side main circuit conductor 5 outside the vacuum valve 4. The stationary main circuit conductor 5 is connected to a main circuit of a switch gear (not shown).

  A movable energizing shaft 7 is fixed to the movable vacuum contact 3. Around the vacuum valve 4, a vacuum side insulating layer 8a formed of an insulating material such as an epoxy resin is provided. On the outer periphery of the vacuum side insulating layer 8a, for example, a vacuum side ground layer 9a formed by applying a conductive paint is provided.

  A connecting movable shaft 10 that is movable in the axial direction and connected to the movable energizing shaft 7 is provided in the aerial part 1b. A first air contact 11 is fixed to the end of the connecting movable shaft 10. A second air contact 12 facing and separating from the first air contact 11 in the air is fixed to the end of the operation shaft 13 connected to the ground electrode and movable in the axial direction. A spring receiving plate 14 is fixed to the intermediate portion of the connecting movable shaft 10. On the outer periphery of the connecting movable shaft 10 between the spring receiving plate 14 and the vacuum valve 4, an open circuit spring 15 that is urged to open the vacuum contacts 2 and 3 is provided.

  Around the first and second air contact points 11 and 12 and the open spring 15, an air insulating layer 8 b having a hollow portion 16 at the axial center connected to the vacuum insulating layer 8 a is provided. ing. An air-side ground layer 9b connected to the vacuum-side ground layer 9a is provided on the outer periphery of the air-side insulating layer 8b.

  Note that an annular guide plate 17 fixed to the inner surface of the intermediate portion of the cavity 16 is provided at the intermediate portion of the coupled movable shaft 10 so that the coupled movable shaft 10 can move in parallel with the axial direction. . The hollow portion 16 has a size such that the open spring 15 can freely expand and contract on the open spring 15 side. On the air contact points 11 and 12 side, the air contact points 11 and 12 and between the air contact points 11 and 12 and the air-side grounding layer 9b are sized to maintain a predetermined dielectric strength.

  A cylindrical first electric field relaxation shield 18 having the same potential as that of the connecting movable shaft 10 is embedded in the air-side insulating layer 8 b so as to surround the first air contact 11. In addition, a cylindrical second electric field relaxation shield 19 having a ground potential is embedded so as to surround the second air contact 12. The end of the air-side insulating layer 8 b is fixed to the fixed mount 20.

  Thereby, at the time of circuit opening, the main circuit voltage is shared by the vacuum contacts 2 and 3 and the air contacts 11 and 12, and insulation between the ground is maintained. The vacuum contacts 2 and 3 have a larger potential sharing than the air contacts 11 and 13 and the gap length is narrow, but good insulation is maintained by the excellent dielectric strength of the vacuum. This is because the main circuit voltage is shared between the vacuum contacts 2 and 3 and the air contacts 11 and 12, but the voltage applied between the vacuum contacts 2 and 3 is reduced, so that variation in discharge can be reduced, and irregular discharge. This is because it is suppressed. That is, since the electric field stress between the vacuum contacts 2 and 3 is reduced, the insulation distance between the vacuum contacts 2 and 3 can be shortened as compared with the case where the vacuum valve 4 is used alone for a ground switch.

  In addition, the first electric field relaxation shield 18 and the second electric field relaxation shield 19 can reduce the electric field in the cavity 16 and improve the dielectric strength between the air contacts 11 and 12. The variation in the air discharge is as small as 2-3%. In terms of operating force, if the movable energizing shaft 7, the connecting movable shaft 10, and the operating shaft 13 are arranged linearly in the axial direction, transmission loss can be suppressed.

  Next, the operation will be described with reference to FIG.

  As shown in FIG. 2A, an operating mechanism (not shown) such as an electromagnetic actuator is operated to move the operating shaft 13 upward in the drawing, and the air contacts 11 and 12 are closed. The first aerial contact 11 is provided with a recess, and the second aerial contact 12 is fitted therein, so that the first air contact 11 can be closed reliably. Further, when the operating shaft 13 is moved, as shown in FIG. 2B, the connecting movable shaft 10 is moved upward in the drawing, the open spring 15 is compressed, and the vacuum contacts 2 and 3 are closed.

  Between the vacuum contacts 2 and 3, the pre-arc just before closing is small due to excellent dielectric strength and breaking performance, and a large current such as a short-circuit current can be reliably supplied. That is, the vacuum contacts 2 and 3 can be responsible for short-circuiting. When the operation shaft 13 is moved downward in the figure when the circuit is opened, the vacuum contacts 2 and 3 are first opened, and then the air contacts 11 and 12 are opened by the releasing force of the circuit spring 15.

  According to the ground switching device of the first embodiment, the vacuum contacts 2 and 3 and the air contacts 11 and 12 are connected in series, and the main circuit is connected between the vacuum contacts 2 and 3 and between the air contacts 11 and 12 when the circuit is opened. Since the voltage is shared, the shared voltage between the vacuum contacts 2 and 3 can be reduced, the discharge variation can be reduced, and the overall shape, particularly the vacuum bulb 4 can be reduced in size. Moreover, since the final closing is performed by the vacuum contacts 2 and 3 when the circuit is closed, the duty of short-circuiting can be given.

  Next, a ground switchgear according to Embodiment 2 of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating a configuration of a ground switchgear according to a second embodiment of the present invention. The second embodiment is different from the first embodiment in that the potential sharing between the vacuum contacts is improved. In FIG. 3, 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. 3, a cylindrical fixed-side potential sharing shield 21 having the same potential as that of the fixed-side vacuum contact 2 is embedded in the vacuum-side insulating layer 8 a so as to surround the vacuum valve 4. The end of the fixed-side potential sharing shield 21 extends to an intermediate portion in the axial direction of the vacuum valve 4. In addition, a cylindrical movable-side potential sharing shield 22 having the same potential as the coupled movable shaft 10 is embedded so as to surround the vacuum valve 4 while maintaining a predetermined insulation distance from the fixed-side potential sharing shield 21. The movable side potential sharing shield 22 also extends to an intermediate portion in the axial direction of the vacuum valve 4.

  Here, as shown in FIG. 3, if the outer diameter of the fixed-side potential sharing shield 21 is made larger than the movable-side potential sharing shield 22, the capacitance between the vacuum contacts 2 and 3 can be increased, and the sharing voltage can be increased. Can be greatly reduced. Further, if the fixed potential sharing shield 21 end and the movable potential sharing shield 22 end are coaxially wrapped, the capacitance can be further increased. In contrast to the above, even if the outer diameter of the fixed-side potential sharing shield 21 is made smaller than the movable-side potential sharing shield 22, the sharing voltage between the vacuum contacts 2 and 3 can be reduced.

  According to the grounding switching device of the second embodiment, in addition to the effects of the first embodiment, the potential sharing between the vacuum contacts 2 and 3 can be improved, and the overall shape can be further downsized.

  Next, a ground switch according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view showing a configuration of a ground switchgear according to Embodiment 3 of the present invention. The third embodiment is different from the second embodiment in that the potential sharing between the vacuum contacts is improved. In FIG. 4, 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. 4, a potential improving insulating layer 23 for improving the potential is provided between the fixed side potential sharing shield 21 and the movable side potential sharing shield 22. The relative permittivity of the potential improving insulating layer 23 is larger than that of the inner and outer vacuum side insulating layers 8a. For example, if barium oxide is mixed with epoxy resin, the relative dielectric constant can be increased, and the potential improving insulating layer 23 is formed in advance and molded integrally with the vacuum valve 4 so that the inside of the vacuum side insulating layer 8a can be obtained. A potential improving insulating layer 23 can be provided.

  According to the grounding switching device of the third embodiment, the potential sharing between the vacuum contacts 2 and 3 can be further improved, and the overall shape can be reduced in size.

DESCRIPTION OF SYMBOLS 1a Vacuum part 1b Air part 2 Fixed side vacuum contact 3 Movable side vacuum contact 4 Vacuum valve 5 Fixed side energizing shaft 6 Fixed side main circuit conductor 7 Movable side energizing shaft 8a Vacuum side insulating layer 8b Air side insulating layers 9a, 9b Contact The stratum 10 The connecting movable shaft 11 The first air contact 12 The second air contact 13 The operation shaft 14 The spring receiving plate 15 The open spring 16 The hollow portion 17 The guide plate 18 The first electric field relaxation shield 19 The second electric field relaxation shield 20 Fixed stand 21 Fixed-side potential sharing shield 22 Movable-side potential sharing shield 23 Potential improvement insulating layer

Claims (5)

A fixed-side vacuum contact connected to the main circuit;
A movable-side vacuum contact that is freely movable toward and away from the fixed-side vacuum contact;
A movable connecting movable shaft connected to the movable-side vacuum contact;
An open-circuit spring biased to open the fixed-side vacuum contact and the movable-side vacuum contact provided on the outer periphery of the connecting movable shaft;
A first air contact fixed to the end of the connecting movable shaft;
A second air contact that is freely contactable and disengageable from the first air contact;
An operation shaft movable at a ground potential connected to the second air contact;
A vacuum-side insulating layer provided around the fixed-side vacuum contact and the movable-side vacuum contact;
An air-side insulating layer connected to the vacuum-side insulating layer and provided around the open spring, the first air contact, and the second air contact;
A grounding switchgear characterized by comprising: A first electric field relaxation shield having the same potential as the connecting movable shaft is embedded in the air-side insulating layer so as to surround the first air-contact,
The ground switch according to claim 1, wherein a second electric field relaxation shield having a ground potential is embedded in the air-side insulating layer so as to surround the second air contact. A fixed-side potential sharing shield having the same potential as the fixed-side vacuum contact is embedded in the vacuum-side insulating layer, and
The grounding switchgear according to claim 1 or 2, wherein a movable-side potential sharing shield having the same potential as the connected movable shaft is embedded in the vacuum-side insulating layer.   The ground switchgear according to claim 3, wherein the fixed potential sharing shield end and the movable potential sharing shield end are wrapped in the vacuum insulating layer.   5. The ground opening / closing according to claim 3, wherein the dielectric constant of the potential improving insulating layer between the fixed-side potential sharing shield and the movable-side potential sharing shield is larger than that of the vacuum-side insulating layer. apparatus.

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