JP2002352675A - Switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switch capable of avoiding generation of an arc at an unspecified position on the live part in a body case in an internal short- circuit accident. SOLUTION: Power-side arc electrodes 73 are respectively formed at an inside end part of an power-side bushing 21. The distances between the arc electrodes 73 and the body case 12 or various grounding members in the body case 12 are respectively structurally set at the minimum insulation distance from the ground. Thereby, when an internal short-circuit accident occurs due to a lighting stroke or the like and a lightning arrester 56 is broken, an arc is generated between the arc electrode 73 having the smallest insulation distance and an arc target 58. That is to say, the arc is generated at a specific position on the power live part in the body case 12. Accordingly, arc at an unspecified position on the power-side live part side in the body case 12 can be avoided, and damage to this switch 11 such as breake or the like of an insulator part of the bushing 21 due to the arc is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch provided with an arc fixing means for specifying a location of an arc generated inside a switch, for example, when an internal short circuit occurs.

[0002]

2. Description of the Prior Art Opposite load side and power supply side bushings for each phase are supported through both side walls of a main body case of a switch. A fixed electrode is provided at the inner end of the power supply side bushing. A movable electrode is provided at the inner end of the load-side bushing so as to be rotatable and to be able to contact and separate from the fixed electrode. The movable electrode is operatively connected to an opening / closing mechanism including a plurality of links, and the movable electrode comes into contact with and separates from the fixed electrode as the opening / closing mechanism is driven. Depending on the type of switch, a lightning arrester or the like may be installed inside the main body case. It is connected to the.

In the conventional switch, an internal short circuit may occur due to a lightning strike or the like. Then, the arc generated at the time of the internal short circuit is transferred to an unspecified portion of the main body case, and there is a possibility that the main body case may be damaged such as a hole. In order to avoid this, for example, it has been conventionally proposed to provide an arcing horn for fixing an arc in a main body case. Such arc fixing structures include a ground fault priority type and a different-phase short-circuit type. In the ground fault priority type, a ground electrode is provided in a grounded main body case, and an arc is generated between the load side charging section and the ground electrode in the event of an internal short circuit. In the different-phase short-circuit type, each load-side charged part conductor is provided with a short-circuit electrode whose tip is directed to an adjacent load-side charged part conductor, and in the event of an internal short circuit, an arc is generated between the short-circuit electrodes. (For example, Japanese Patent Application Laid-Open No. 9-147792).

[0004]

However, the conventional switch has the following problems. That is, in the ground-fault priority type switch, although an earth electrode for inducing an arc is provided in the main body case, an electromagnetic force due to an energizing current acts on the arc generated in the main body case. It was difficult to fix the arc on one side. Further, even if the arc could be fixed on the main body case side, the arc point on the charging section (fixed electrode or movable electrode) side could not be specified. For this reason, the load side bushing and the lightning arrester may be destroyed by the arc. On the other hand, in a switch of a different-phase short-circuit type, it is necessary to provide a certain or more insulation distance between the short-circuit electrodes of each phase in a normal state (ie, at the time of a non-internal short-circuit accident). For this reason, there is a limit in reducing the overall width of the switch.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to avoid occurrence of an arc at an unspecified portion on a charging portion side in a main body case in the event of an internal short circuit. To provide a switch that can be used.

[0006]

According to a first aspect of the present invention, there is provided a switch in which an open / close portion forming a pair of a fixed electrode and a movable electrode is accommodated for three phases in a grounded main body case. The gist of the invention is to provide an arc fixing means for generating an arc at a specific position on at least one of the phase fixed electrode and the movable electrode.

According to a second aspect of the present invention, in the first aspect, the arc fixing means is an arc electrode provided on at least one of the fixed electrode and the movable electrode of each phase. The gist is that there is.

According to a third aspect of the present invention, in the first or second aspect of the present invention, an electrical connection is provided near the arc fixing means inside the main body case facing the arc fixing means. The gist of the present invention is to provide an arc receiving portion in which a grounded state is maintained. (Operation) In the invention described in claim 1, for example, at the time of an internal short circuit accident, an arc is generated at a specific portion on at least one of the fixed electrode and the movable electrode of each phase. For this reason, generation of an arc at an unspecified location on the charging section side in the main body case is avoided.

According to the second aspect of the invention, in addition to the operation of the first aspect, an arc is generated at the arc electrode, for example, when an internal short circuit occurs. For this reason, the arc generating portion on the charging section side in the main body case is fixed.

According to the third aspect of the invention, in addition to the operation of the first or second aspect of the invention, when the arc is generated, direct contact of the arc with the main body case is avoided.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is embodied in a switch having an internal device such as an arrester is shown in FIGS.
It will be described according to.

(Overall) As shown in FIG. 1, the main body case 12 of the switch 11 includes a bottom case 12a having a bottomed box shape having an open upper portion, and an upper case 12b having a closed box shape having an open lower portion. The upper opening of the bottom case 12a is closed by the upper case 12b. That is, the plate-shaped fastening member 13 provided on the opening side edge of the upper case 12b.
Is tightened with bolts and nuts (not shown) to a plate-shaped connecting member 14 provided on the opening side edge of the bottom case 12a, so that the upper case 12b
a is detachably connected to a. Bottom case 12
A packing 15 is interposed between the upper case 12a and the upper case 12b, whereby the airtightness of the switch 11 is maintained.

A power supply-side bushing 21 and a load-side bushing 22 are supported through the opposite side walls of the bottom case 12a so as to face each other for each of the three phases (only one phase is shown in FIG. 1). ing. A fixed electrode 24 is fixed to the inner end of the power supply side bushing 21 via a power supply side conductive rod 23, and an arc extinguishing member 25 made of synthetic resin is provided so as to cover the fixed electrode 24. A support member 27 is fixed to the inner end of the load-side bushing 22 by a bolt via a load-side conductive bar 26, and a proximal end of a movable electrode 29 is connected to a distal end side of the support member 27 via a shaft 28. Are rotatably supported. The movable electrode 29 is composed of a single sickle-shaped contact blade,
And constitute the opening / closing part for one phase.

On the other hand, as shown in FIGS. 1 and 2, an upper portion of the main body case 12 near the load-side bushing 22 is provided with an opening / closing mechanism 31 composed of a plurality of links or the like to operate the outside of the main body case 12. A pivot shaft 33 operatively connected to the handle 32 is provided. The rotating shaft 33 is operatively connected to the movable electrode 29 via a lever 34, a drive link 35, and a connecting member 36. Accordingly, by operating the operation handle 32, the movable electrode 29 moves between a closing position indicated by a solid line and an open position indicated by a two-dot chain line in FIG.

(Insulation Barrier) As shown in FIGS. 1 and 2, both bushings 21,
An insulating barrier 41 is provided to cover the fixed electrode 24 and the movable electrode 29 from below. Insulation barrier 4
1 includes a bottom-to-ground insulation barrier 42, a pair of side-to-ground insulation barriers 43, and a pair of heterophase insulation barriers 44.

The bottom-to-ground insulating barrier 42 is a bottom case 1
It is formed along the inner bottom surface of 2a. As shown in FIG. 1, both side edges in the in-phase direction of the bottom-to-ground insulating barrier 42 are respectively connected to the bottom case 12a.
Are extended upward along the inner surfaces of both bushing fixing walls at the position, and are engaged with the lower surfaces of both bushings 21 and 22. As shown in FIG. 2, both side-to-ground insulation barriers 43, 43 are bottom-to-ground insulation barriers 42, respectively.
Are fixed to both side edges in the direction between different phases. The two different-phase insulating barriers 44 are disposed at predetermined intervals between the two side-to-ground insulating barriers 43 in the bottom-to-ground insulating barrier 42, respectively.

As shown in FIGS. 1 and 2, both side-to-ground insulating barriers 43, 43 and both out-of-phase insulating barriers 44, 44 are provided.
And between the two different-phase insulating barriers 44, 44, both bushings 21, 22 of each phase and both electrodes 2
An insulating barrier 41 is provided so that the positions 4 and 29 are located.

(Arrestor Mounting Member) As shown in FIGS. 1 and 2, an arrester mounting member 51 is disposed in the upper portion of the main body case 12 near the power supply side bushing 21. The arrester mounting member 51 is formed by bending a single plate. The arrester mounting member 51 is electrically grounded via the main body case 12.

As shown in FIG. 2, the arrester mounting member 51
The scattered object prevention member mounting portions 52, 52 extend obliquely downward at both sides in the interphase direction of the arrestor mounting member 51 at a predetermined angle with respect to the upper wall thereof. Have been. Further, arrestor attachment member fixing portions 53, 53 are respectively extended downward from the leading edges of the scattered object prevention member attachment portions 52, 52 along the inner surfaces of both bushing fixing walls of the bottom case 12a. .

The arrester mounting member fixing portions 53 and 53 are respectively bolted to the pair of fixing members 54 and 54 fixed to the inner surfaces of the pair of side walls facing each other in the different phase direction of the bottom case 12a. Thus, the arrester mounting member 51 is fixed in the main body case 12 (more precisely, in the upper case 12b).

An inclined surface 55 inclined downward by a predetermined angle is provided on the load-side bushing 22 side of the arrester mounting member 51.
Are formed. A base end of a lightning arrester (arrestor) 56 is fixed to the inner surface of the inclined surface 55 by a bolt for each phase. The lightning arrester 56 is configured such that the charged portion at the tip thereof is fixed electrode 24.
It is arranged to face the side. The leading end charging portion of each lightning arrester 56 is connected to the power supply side conductive rod 23 via a conductive member 57.
It is connected to the.

In the arrester mounting member 51, an arc target 58 as an arc receiving portion is formed on the power supply side bushing 21 side. Arc target 5
Reference numeral 8 denotes a first parallel to the inner top surface of the upper case 12b.
A target portion 58a and a second target portion 58b bent downward at a predetermined angle with respect to the first target portion 58a are provided.

(Spatter Prevention Member) As shown in FIGS. 1 and 2, the inner top surface of the upper case 12b and the arrester mounting member 5
A scattered object preventing member 61 is disposed between the scattered member 1 and the scattered object preventing member 61.
The flying object preventing member 61 is formed in a helmet shape (a closed box shape having an open lower portion) covering the entire inner surface of the upper case 12b.

The inner surface of the upper wall of the scattered object preventing member 61 can be brought into close contact with the outer surface of the upper wall of the arrester mounting member 51. In addition, inclined surfaces 62, 62 inclined at a predetermined angle with respect to the upper wall of the scattered object prevention member 61 are formed at both upper corners in the different phase direction of the scattered object prevention member 61. When the inner surface of the upper wall of the scattered object preventing member 61 and the outer surface of the upper wall of the arrester mounting member 51 are brought into close contact with each other, the inner surfaces of the two inclined surfaces 62
1 so as to be in close contact with the outer surfaces of the two scattered object preventing member mounting portions 52, 52.

The scattered object preventing member 61 is connected to the arrester mounting member 5.
1, the upper surface of the upper wall of the arrester mounting member 51 and the outer surfaces of both the scattered object preventing member mounting portions 52, 52, and the inner surface of the upper wall of the scattered object preventing member 61 and the two inclined surfaces 62,
62 are adhered to each other. Then, in this state, the scattered object preventing member 61 is fixed to the arrester mounting member 51 by tightening bolts from outside the both inclined surfaces 62, 62. That is, the flying object prevention member 61 is fixed to the main body case 12 via the arrester mounting member 51.

(Power-Side Arc Electrode) As shown in FIG.
The inner end of each power supply side bushing 21 has a section L
A letter-shaped support member 71 is fixed. This support member 7
1 is a fixed portion 71a inserted into the power supply side conductive rod 23,
And a supporting portion 71b that is substantially perpendicular to the fixing portion 71a. A female screw part 72 is formed at the center of the support part 71b. The support member 71 is fixed to the inner end of the power supply side bushing 21 by inserting the fixing portion 71 a into the power supply side conductive rod 23 and tightening a nut from the inner end side of the power supply side conductive rod 23. The support portion 71b is located above the power supply side conductive rod 23 and is parallel to a plane including the central axis of the power supply side conductive rod 23.

In the center of the upper surface of the support portion 71b, a power supply side arc electrode 73 is grounded from the power supply side charging portion side (the main body case 1).
2 (inner top surface) side. The power-supply-side arc electrode 73 is formed, for example, in a rod shape from a steel material, and has a male screw portion 74 protruding from the bottom center thereof. This male screw part 74 is connected to the female screw part 7 of the support part 71b.
2, the power supply side arc electrode 7
3 is fixed to the supporting portion 71b. The central axis of the power supply side arc electrode 73 is orthogonal to the upper surface of the support 71b.

The power supply-side arc electrode 73 has a sufficient volume so that even if a short-circuit current of a predetermined magnitude flows for a predetermined time, the arc electrode 73 is not melted by Joule heat.
When the arc of the power supply side arc electrode 73 is insufficient and the arc is generated between the power supply side arc electrode 73 and the arc target 58 due to an internal short circuit accident or the like, the power supply side arc electrode 73 is melted by Joule heat. May be lost. As a result, the arc length increases, and the arc voltage increases by the increase in the arc length. Then, the influence of an increase in the internal pressure due to the arc in the main body case 12 increases.

The support member 71 is provided with the power supply side arc electrode 7.
3 must be strong enough to support
It is necessary to secure a sufficient current carrying capacity for the lightning arrester 56.
For this reason, iron is selected as the material of the support member 71. If the fixing portion 71a is formed in an annular shape, an eddy current is generated in the fixing portion 71a which is inserted and fixed to the power-supply-side conductive bar 23 and is located on the periphery of the power-supply-side conductive bar 23, and generates Joule heat. I do. However, as shown in FIG. 4, in the present embodiment, since the fixing portion 71a is formed in a C-shape, generation of an eddy current is prevented.

(Insulation Distance) As shown in FIG. 3, the distance between the center of the tip of each power-supply-side arc electrode 73 and the arc target 58 is the minimum insulation distance to the ground. Arcs are most likely to occur. That is, as shown by a two-dot line in FIG. 3, the inner surface of the first target portion 58a, the second target portion 58b, and the flying object preventing member 61 on the power supply side bushing 21 side centering on the center of the front end portion of the power supply side arc electrode 73. When a sphere in contact with is drawn, the power-supply-side arc electrode 73 and the grounding members (the arc target 58 and the scattered object preventing member 61) are arranged such that the radius of the sphere becomes the minimum insulation distance between the ground and the ground.

The minimum insulation distance to the ground is determined based on the discharge characteristics of the lightning arrester 56. That is, the power supply-side arc electrode 73 is provided so that the dielectric strength (withstand voltage) between the center of the distal end portion of the power supply-side arc electrode 73 and the arc target 58 is higher than the discharge voltage of the lightning arrester 56. The center of the tip of the power supply side arc electrode 73 and the arc target 5
8 is lower than the discharge voltage of the lightning arrester 56, an arc is generated between the power source side arc electrode 73 and the arc target 58 before the lightning arrester 56 operates. For this reason, the better the performance of the lightning arrester 56, the shorter the insulation distance to the ground. Further, there is no splatterable member other than the lightning arrester 56 in each of the spherical spaces.

(Insulation Coordination) As shown in FIG. 2, the distance between the power supply side arc electrodes 73 adjacent to each other among the power supply side arc electrodes 73 is the minimum insulation distance between different phases. Further, as shown in FIG. 1, the distance between the distal end of each fixed electrode 24 and the distal end of each movable electrode 29 at the open position is a minimum in-phase minimum insulation distance. When the discharge voltage of the lightning arrester 56 is Va, the dielectric strength between the ground is Ve, the dielectric strength between the different phases is Vs, and the dielectric strength between the phases is Vf, the voltage between the ground and the ground is set so as to satisfy “Va <Ve <Vs <Vf”. An insulation distance, an insulation distance between different phases, and an insulation distance between the same phases are respectively set.

(Load-side arc electrode) As shown in FIG.
A load side arc electrode 81 is fixed to the upper part of the load side conductive rod 26 together with the support member 27 by bolts. The load-side arc electrode 81 is fixed to the load-side conductive bar 26 and is fixed to a distal end side of the fixed portion 81a extending in a direction along the central axis of the load-side conductive bar 26. Electrode portion 81b. The rotating shaft 33 is located above the load-side arc electrode 81, and also serves as an arc receiving portion on the load side. In FIG. 2, the position of the electrode portion 81b is indicated by hatching for only one phase (the rightmost phase in FIG. 2). As shown in FIG. 2, the shortest distance between the electrode portion 81b of the load-side arc electrode 81 and the rotating shaft 33 is the same as the distance between the center of the tip of the power-supply-side arc electrode 73 and the arc target 58. It is the minimum insulation distance between the ground.

The power supply side conductive rod 23 constitutes a power supply side charging section. The load-side conductive rod 26 constitutes a load-side charging unit. The rotating shaft 33, the arrester mounting member 51, and the flying object preventing member 61 constitute a grounding member grounded via the main body case 12. Each lightning arrester 56 is provided so as to correspond to at least the power supply side charging unit, and constitutes a plurality of internal devices connected to each charging unit. In addition, the lightning arrester 56 constitutes a splatterable member that may be scattered by the arc. Arc target 5
Reference numeral 8 denotes a protection member for preventing an arc generated at least on the power supply side charging section from coming into contact with the main body case 12 at the time of an internal short circuit accident. The power-supply-side arc electrode 73 and the load-side arc electrode 81 constitute arc fixing means for generating an arc at least at a specific location on the power-supply-side charging unit side in the event of an internal short circuit accident. The load-side arc electrode 81 constitutes load-side arc fixing means for generating an arc at a specific location on the load-side charging unit side in the event of an internal short circuit.

(Operation of the Embodiment) Next, the operation of the switch constructed as described above will be described. When an internal short circuit occurs in the main body case 12 due to a lightning strike or the like, an overvoltage is applied between both terminals of the lightning arrester 56 (between the charging unit side contact and the ground side contact). Then, the surge arrester 56 cannot withstand the overvoltage and cannot be interrupted by the downstream current to be destroyed, and a fault current as an arc flows between both terminals of the surge arrester 56.

At this time, the arc between both terminals of the lightning arrester 56 tends to shift to the load side charging section side. However, the power supply side arc electrode 73 is located near the power supply side charging section.
Is provided, the arc is transferred between the power supply side arc electrode 73 and the arc target 58 or the flying object prevention member 61 located closest to the power supply side arc electrode 73. The arc is concentrated on the power supply side arc electrode 73, thereby avoiding occurrence at an unspecified portion on the power supply side charging unit side. In addition, there is no scatterable object other than the lightning arrester 56 (one that may be broken and scattered by the arc) on the arc path. For this reason, the generation of flying objects from the switch 11 is suppressed. By the way, the lightning arrester 56 is not destroyed,
When the operation continues normally, the arc does not fly from the power supply side arc electrode 73.

On the other hand, on the side of the arc target 58 or the scattered object preventing member 61, the arc from the power source side arc electrode 73 is not completely fixed at one place. This is because the arc shakes in the interphase direction due to the effect of the electromagnetic force acting between the electrodes adjacent to each other in the interphase direction. For this reason, it is difficult to fix the arc point on the main body case 12 side. However, in the present embodiment, the arc target 58 is provided so as to cover a region where the arc is likely to fly inside the main body case 12. Therefore, the inner surface of the main body case 12 is not directly exposed to the arc. Therefore, breakage of the switch 11, such as a hole in the main body case 12 caused by the arc, is prevented.

Incidentally, in the switch 11, the arc flies most above the power supply side arc electrode 73 (ie, in the direction of the first target portion 58a), and then diagonally above and to the left in FIG. 1 (ie, the second target portion). It has been confirmed in advance by an experiment using an apparatus model that the airplane flies a lot toward the portion 58b). In the present embodiment, the arc target 58, that is, the first
A target portion 58a and a second target portion 58b are formed.

(Effects of Embodiment) Therefore, according to the present embodiment, the following effects can be obtained. (1) A plurality of power supply side arc electrodes 73 are provided at the inner end of the power supply side bushing 21 so as to correspond to the power supply side charging sections.
Was provided. Then, the distance between each power supply side arc electrode 73 and the main body case 12 or various grounding members in the main body case 12 is configured to be the minimum insulation distance between the ground. Therefore, when the lightning arrester 56 is destroyed due to an internal short circuit accident due to lightning strike or the like, an arc is generated between the power supply side arc electrode 73 and the arc target 58 having the shortest insulation distance. That is, the arc is generated at a specific location on the power supply side charging unit side in the main body case 12. Therefore, the occurrence of an arc at an unspecified portion on the power supply side charging portion side in the main body case 12 is avoided, and the breakage of the switch 11 such as the breakage of the insulator portion of the power supply side bushing 21 due to the arc is prevented. In addition, variations in the arc point on the power supply side including a large number of scattered elements such as the lightning arrester 56 are prevented, and generation of scattered objects is suppressed.

(2) The insulation distance between the power supply-side arc electrode 73 and the ground is set based on the discharge characteristics of the lightning arrester 56 so that the insulation strength Ve between the grounds is greater than the discharge voltage of the lightning arrester 56. That is, the insulation distance to the ground is set in accordance with the discharge voltage of the lightning arrester which differs between the manufacturers. Therefore, it is possible to use lightning arresters of different manufacturers with different discharge voltages. In addition, since the dielectric strength Ve between the ground and the discharge voltage of the lightning arrester 56 is higher than that of the lightning arrester 56, no arc is generated between the power supply side arc electrode 73 and the arc target 58 before the lightning arrester 56 operates in the event of an internal short circuit. .

(3) The power supply side arc electrode 73 is provided so as to be detachable from the support member 71 fixed to the inner end (power supply side charging section) of the power supply side bushing 21. That is, the power supply side arc electrode 73 was formed in a rod shape, and a male screw portion 74 was protruded from the bottom surface thereof. Then, the power supply side arc electrode 73 is fixed to the support member 71 by tightening the male screw portion 74 to the female screw portion 72 of the support portion 71b of the support member 71. Therefore, the arc can be fixed to the power supply side charging unit side without complicating the configuration. Further, the support member 71 of the power supply side arc electrode 73
Can be easily attached and detached.

(4) In each spherical space having a radius centered on the center of the tip end of the power-supply-side arc electrode 73 as the insulation distance to the ground, no splatterable members other than the lightning arresters 56 are allowed to exist. . For this reason, generation of flying objects can be suppressed.

(5) At the time of an internal short circuit accident, a scattered object preventing member 61 for preventing contact of at least an arc generated in the power supply side charging section with the main body case 12 is provided in the main body case 12. For this reason, even if the arc generated at the time of the internal short circuit accident goes around to the top of the main body case 12, the arc contacts the inner surface of the scattered object prevention member 61 and the main body case 12
(Accurately, it does not contact the inner top surface of the upper case 12b). Therefore, damage such as perforation of the main body case 12 due to the arc can be prevented.

(6) A plurality of load-side arc electrodes 81 are provided at the inner end of the load-side bushing 22 so as to correspond to the load-side charging units. And each load side arc electrode 8
The distance between the main body 1 and the main body case 12 or the various grounding members (rotating shafts 33) in the main body case 12 is configured to be the minimum insulation distance between the ground. Therefore, when an internal short circuit accident occurs due to a lightning strike or the like, an arc is generated between the load-side arc electrode 81 having the shortest insulation distance and the rotating shaft 33. That is, an arc is generated at a specific location on the load-side charging unit side in the main body case 12. Therefore, the main body case 1
The occurrence of an arc at an unspecified location on the load-side charging unit side in 2 is avoided, and breakage of the switch 11 such as breakage of the insulator portion of the load-side bushing 22 due to this arc is prevented.

(7) In the switch 11, the power supply-side arc electrode 7 extends from the inner end (power supply-side charging portion) of the power supply-side bushing 21 toward the ground (the inner top surface of the main body case 12).
3, and the scatterable member (in the present embodiment, the lightning arrester 56) is not provided on the arc path. Therefore, at the time of an internal short circuit accident, the arc does not fly toward the lightning arrester 56 which may be a flying object. Further, the power supply side arc electrode 73 can be provided toward an appropriate position (for example, a dead space) side with respect to the power supply side charging unit. For this reason, for example, unlike the case of a short circuit between different phases,
It is possible to avoid an increase in the size of the switch in the interphase direction due to the setting of the space gap distance in consideration of the projecting dimension of the arcing horn and the edge between the different phases in the normal state.

(8) When the discharge voltage of the lightning arrester 56 is Va, the dielectric strength between the ground and the ground is Ve, the dielectric strength between the different phases is Vs, and the dielectric strength between the phases is Vf, the relation of Va <Ve <Vs <Vf is satisfied. The insulation distance between the ground, the insulation distance between different phases and the insulation distance between the same phases were respectively set. Therefore, when the lightning arrester 56 is destroyed in the event of an internal short circuit, an arc is generated between the ground and the ground, and only a ground fault occurs.

(Alternative Example) The above embodiment may be modified as follows. In the present embodiment, the lightning arrester 56 is provided on the power supply side in the main body case 12, but the lightning arrester 56 may be omitted. Further, the lightning arrester 56 may be provided on the load side in the main body case 12.

In the present embodiment, the arc electrodes 73 and 81 are provided on the power supply side and the load side, respectively. However, the load side arc electrode 81 is omitted, and only the power supply side arc electrode 73 is provided on the power supply side.
May be provided.

In this embodiment, different arc electrodes 73 and 81 are provided on the power supply side and the load side, respectively.
A power supply side arc electrode 73 similar to the power supply side may be provided on the load side. At this time, the position of the rotation shaft 33 is changed so that a predetermined insulation distance is secured between the power supply side arc electrode 73 provided on the load side charging unit side and the rotation shaft 33. In the present embodiment, since the rotating shaft 33 is grounded near the load-side charging section, it is not possible to dispose the power-side arc electrode 73 having the same length in the load-side charging section.

The power supply side arc electrode 73 and the load side arc electrode 81 may be formed integrally with the support members 71 and 27, respectively. By doing so, the number of components can be reduced.

The installation direction of the switch 11, that is, the power supply side and the load side may be reversed. Since the arc electrode is provided in both the power supply side charging unit and the load side charging unit, there is no problem at all.

The arrester mounting member 51 and the scattered object preventing member 61 may be integrally formed. By doing so, the number of components can be reduced. In the present embodiment, the arc target 58 and the scattered object preventing member 61 are arranged in the main body case 12, respectively. That is, at least one of the arc target 58 and the scattered object preventing member 61 is omitted, and the inner surface of the main body case 12 and the power supply side arc electrode 73 are omitted.
The power supply side arc electrode 73 may be provided such that the distance between the power supply side and the ground becomes the minimum insulation distance between the power supply side and the ground. Even in this case, the arc can be fixed to the power supply side charging unit side.

On the main body case 12 side, for example, one or a plurality of ground electrodes may be provided at a portion closest to the tip of the power supply side arc electrode 73, and an arc may be blown between the ground electrode and the ground electrode. This makes it easier to fix the arc on the main body case 12 side than when no ground electrode is provided.

[0054]

According to the present invention, at the time of an internal short circuit accident, it is possible to avoid the occurrence of an arc at an unspecified location on the charging portion side in the main body case.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a switch according to an embodiment.

FIG. 2 is a side sectional view of the switch according to the embodiment.

FIG. 3 is a front sectional view of a main part of the switch according to the embodiment.

FIG. 4 is a perspective view showing the shape of a support member according to the embodiment.

[Explanation of symbols]

Reference numeral 11: switch, 12: main body case (earth), 23: power supply side conductive rod (power supply side charging unit), 26: load side conductive rod (load side charging unit), 33: rotating shaft constituting a grounding member ( Arc receiving part), 51: arrester mounting member constituting a grounding member, 58 ... arc target constituting a protection member, 58
a: first target portion, 58b: second target portion, 6
DESCRIPTION OF SYMBOLS 1 ... Scattering prevention member which comprises a grounding member, 56 ... Lightning arrestor which comprises an internal apparatus and a possibility of scattering, 73 ... Power supply side arc electrode which comprises an arc fixing means, 81 ... Arc fixing means and load side arc fixing means Constituting the load side arc electrode.

Claims (3)

[Claims] 1. A switch in which a pair of open / close sections formed by a fixed electrode and a movable electrode are housed in a grounded main body case for three phases, wherein at least one of the fixed electrode and the movable electrode of each phase is provided. A switch provided with an arc fixing means for generating an arc at a specific location on the electrode side. 2. The switch according to claim 1, wherein the arc fixing means is an arc electrode provided on at least one of the fixed electrode and the movable electrode of each phase. 3. The switch according to claim 1, wherein a grounded arc receiving portion is provided near the arc fixing means and inside the main body case facing the arc fixing means.