Gas insulated switching apparatus

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention is related to gas insulated switching apparatus, and especially, it concerns gas insulated switching apparatus which compacted line side unit.

2. Description of Related Art

Gas insulated switching apparatus are configured such that electric conductors for electrically connecting circuit-breakers, disconnectors, earth switches, and transformers for instruments to each other are housed in enclosed vessels filled with insulating gas. These gas insulated switching apparatuses advantageous in terms of miniaturization, insulating performance, and safety have been extensively installed at electric stations such as transforming stations.

In a prior art gas insulated switching apparatus disclosed in Japanese Patent Laid-open No. Hei 4-109808, a disconnector unit is provided between a lightning arrestor element unit and a high voltage conductor unit in such a manner that the lightning arrestor element unit is movable to open/close the disconnector, and an operating unit is disposed outside a vessel of the lightening arrestor element unit for opening/closing the disconnector by driving the lightening arrestor element unit using the external operating unit, thereby allowing the lightning arrestor element unit to be contacted with or separated from the high voltage conductor unit.

In a prior art gas insulated switching apparatus disclosed in Japanese Patent Laid-open No. Hei 8-265925 and Japanese Utility Model No. Sho 60-117610, a movable contact is provided on a lightening arrestor main body on the power supply side, and a straightforward sliding shaft is provided on the lightning arrestor on the earth side in such a manner as to air-tightly pass through the bottom plate of a tank, wherein the lightning arrestor main body is vertically moved to be turned on/on.

However, the concrete means for compacting the container that lightning arrester was put was not considered in conventional gas insulated switching apparatus.

SUMMARY OF THE INVENTION

A first object of the present invention is to provide a gas insulated switching apparatus which compacted the container that lightning arrester was put.

To achieve the above object, according to the present invention. there is provided a gas insulated switching apparatus including a line side unit has a electric power line, which comprising, a lightning arrester is established in the line side unit, which relatively moves for the container of the line side unit, and connected on/off the electric power line. and a cover which supports said lightning arrester is in the position which is lower than the basal plane of the line side unit

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a vertical sectional view of a gas insulated switching apparatus according to one embodiment of the present invention.

FIG. 2

is a transverse sectional view of the gas insulated switching apparatus in the embodiment.

FIG. 3

is a vertical sectional view showing a separator for separating a lightning arrestor in this embodiment.

FIG. 4

is a vertical sectional view showing a sealing terminal of a lightning arrestor in another embodiment of the present invention.

FIG. 5

is a vertical sectional view showing a sealing terminal of a lightning arrestor in a further embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

One embodiment of the present invention will be described with reference to

FIGS. 1

to

3

. As shown in

FIGS. 1 and 2

, a gas insulated switching apparatus in this embodiment includes bus line units

1

, a circuit-breaker unit

2

, and a line side unit

3

. Two pieces of the bus line units

1

are provided in the vertical direction on one side of the circuit-breaker unit

2

, and the line side unit

3

is connected to the other side of the circuit-breaker unit

2

. An operating device

4

is disposed under the circuit-breaker unit

2

and a control box

5

is disposed on one side of the operating device

4

.

The configuration of the bus line unit

1

will be described below. In a bus line vessel

7

, three-phase bus line conductors

6

a

,

6

b

and

6

c

are disposed at respective vertexes of an isosceles triangle. The bus line vessel

7

is formed by a combination of a cylindrical vessel portion

7

a

extending in the axial direction of the bus line conductor

6

and a cylindrical vessel portion

7

b

extending in the direction perpendicular to the cylindrical vessel portion

7

a

. The upper and lower bus line conductors

6

a

and

6

b

are arranged in the vertical direction on the center line of the cylindrical vessel portion

7

a

, and the bus line conductor

6

c

is arranged on the circuit-breaker unit

2

side. Flanges are provided at both ends of the cylindrical vessel portion

7

a

of the bus line vessel

7

, and an expansion joint

15

configured as a bellows is connected to one of the ends of the cylindrical vessel portion

7

a.

Branch conductors

8

a

,

8

b

and

8

c

of the bus line conductors

6

a

,

6

b

and

6

c

are arranged in a row in the vertical direction at the center line portion of the cylindrical vessel portion

7

b

. A movable electrode

13

is provided at the center portion of each of the branch conductors

8

a

,

8

b

and

8

c

. The movable electrode

13

is driven to be reciprocated in each of the branch conductors

8

a

,

8

b

and

8

c

by an operating device

9

disposed between the two bus line vessels

7

. Fixed electrodes

12

are fixed, via conductors

11

, to an insulating spacer

10

provided between the bus line unit

1

and the circuit-breaker unit

2

. The movable electrode

13

and the fixed electrode

12

constitute a disconnector. The insulating spacer

10

is provided between each of the upper and lower bus line units

1

and the circuit-breaker unit

2

for keeping air-tightness, and conductor connecting portions

14

are arranged in a row in the horizontal direction at the center line portion of the insulating spacer

10

The conductor connecting portions

14

are connected to conductors

11

in the circuit-breaker unit

2

The configuration of the circuit-breaker unit

2

will be described below. The vessel of the circuit-breaker unit

2

is composed of a cylindrical vessel portion

16

a

having an axial line in the vertical direction, and cylindrical vessel portions

16

b

formed on both sides in the horizontal direction on the upper side of the cylindrical vessel portion

16

a

and a cylindrical vessel portion

16

b

formed on the bus line unit side in the horizontal direction on the lower side of the cylindrical vessel portion

16

a

. Threephase circuit-breakers

17

are arranged in the same direction as the axial direction of the bus line conductor

6

at the center line portion of the cylindrical vessel portion

16

a.

The conductor connecting portions

14

provided on the upper insulating spacer

10

are connected to the conductor connecting portions

14

provided on the lower insulating spacer

10

via reciprocating conductors

18

, and the lower sides of the reciprocating conductors

18

are connected to the lower sides of the breaking portions of the circuit-breakers

17

via conductors

24

.

Fixed electrodes

19

of earth devices, which are provided on the lower portions of the reciprocating conductors

18

, are allowed to be contacted with or separated from movable electrodes driven by an operating device (not shown) provided outside the vessel of the circuit-breaker unit

2

.

Connecting conductors

20

are provided on the upper portions of the circuit-breakers

17

. The connecting conductors

20

are connected to conductor connecting portions

22

arranged in a row in the transverse direction on an insulating spacer

21

provided between the circuit-breaker unit

2

and the line side unit

3

. Branch portions are provided on the connecting conductors

20

on the circuit-breaker portion side, and fixed electrodes

23

of earth devices are provided on end portions of the branch portions. Movable electrodes reciprocated by an operating device (not shown) provided outside the vessel of the circuit-breaker unit

2

are allowed to be contacted with or separated from the fixed electrodes

23

.

Of three-phase of the circuit-breakers

17

, the center circuit-breaker

17

is arranged on the straight line connecting the center conductor connecting portion

14

provided on the insulating spacer

10

to the center conductor connecting portion

22

provided on the insulating spacer

21

; and the side circuit-breakers

17

located on both the sides of the center circuit-breaker

17

are each offset outwardly from the straight line connecting the associated conductor connecting portions

14

and

22

to each other for ensuring the insulating distance. Accordingly, at each of the side circuit-breakers

17

, the connecting direction of the conductor

24

is inclined outwardly. The circuit-breaker

17

is formed into a cylindrical shape; however, the planes of the circuit-breaker

17

in the arrangement direction are flattened, to reduce the width of the circuit-breaker

17

in the arrangement direction. The upper portions of the circuit-breakers

17

are connected to the conductor connecting portions

22

arranged in a row in the horizontal direction on the insulating spacer

21

provided between the circuit-breaker unit

2

and the line side unit

3

.

The configuration of the line side unit

3

will be described below. The vessel of the line side unit

3

is composed of a cylindrical vessel portion

25

a

extending in the vertical direction and a cylindrical vessel portion

25

b

formed in the horizontal direction on the upper portion of the cylindrical portion

25

a

. Conductors

26

are connected to the conductor connecting portions

22

provided on the insulating space

21

, and movable electrodes

28

reciprocated in the vertical direction by an operating device

27

provided outside the vessel of the line side unit

3

are provided at central portions of the conductors

26

. The movable electrode

28

is allowed to be contacted with or separated from a fixed electrode

29

. These movable electrode

28

and fixed electrode

29

constitute a disconnector. The fixed electrodes

29

are fixed on conductors

31

directly fixed on cable heads

30

. The cable heads

30

are disposed in the lower portion of the cylindrical vessel portion

25

a

on the side opposed to the circuit-breaker unit

2

. Lightning arresters

32

are disposed beside the cable heads

30

on the circuit-breaker unit

2

side, and transformers

33

for instruments are disposed over the cable heads

30

. The cable heads

30

and the lightning arresters

32

are connected to common conductors

31

. Fixed electrodes

34

of earth devices are provided on the conductors

31

, and movable electrodes driven by an operating device

35

provided outside the vessel of the line side unit

3

are allowed to be contacted with or separated from the fixed electrodes

34

. The transformers

33

for instruments are allowed to be contacted with or separated from the conductors

31

via separators

36

.

A frame

37

on which the line side unit

3

is mounted is disposed under the line side unit

3

. A bottom plate

38

is provided on the lower portion of the vessel of the line side unit

3

, and connecting portions

39

, to be connected to cables

40

, of the cable heads

30

are extracted from the bottom plate

38

via a sealing portion, and current transformers

41

are mounted to the cables

40

.

FIG. 2

is a top view of the gas insulated switching apparatus of this invention. As shown in

FIG. 2

, the three-phase lightning arresters

32

and the three-phase cable heads

30

in the line side unit

3

are arranged substantially along a concentric circle of the cylindrical vessel portion

25

a

, wherein the three-phase cable heads

30

are positioned opposite to the circuit-breaker unit

2

and the three-phase lightning arresters

32

are positioned on the circuit-breaker unit

2

side. With this arrangement, the workability in mounting of the current transformers

41

upon the field installation of the apparatus is improved. The disconnectors are arranged in a row, and are located at positions which are substantially the same as those of the two-phase lightning arresters

32

, apart from the circuit-breaker unit

2

, of the three-phase lightening arresters

32

arranged at vertexes of an isosceles triangle. In this way, the three-phase cable heads

30

and the three-phase lightning arresters

32

are arranged in the concentric circle, so that it is possible to make small the outside diameter of the cylindrical vessel portion

25

a

of the line side unit

3

. Further, since the cable heads

30

and the lightning arresters

32

are arranged by the lower side of the cylindrical vessel portion

25

a

and at least the two-phase cable heads

30

are disposed close to the associated two-phase lightening arresters

32

, it is possible to reduce the applied voltage ratio of the lightning arresters

32

and hence to prolong the service life of the lightning arresters

32

.

The more detailed composition of lightning arrester in

FIG. 3

is shown.

A monitor

42

is mounted on a side surface of a box for housing the operating device

4

for circuit-breakers under the line side unit

3

. Earth lines

43

extracted from the lower portions of the lightning arresters

32

are connected to the monitor

42

. Since the earth lines

43

are extracted from the lower portions of the lightning arresters

32

, it is possible to shorten the length of each earth line

43

and hence to make small a potential superimposed on the operational potential of the lightning arrester

32

. As a result, it is possible to accurately operate the lightening arresters

32

at the operational potentials.

The structure for supporting each of the lightning arrestors

32

by the bottom plate

38

is shown in

FIG. 3. A

flange portion of a cover

52

is bolted to the bottom plate

38

via a sealing material with an insulating plate

51

put therebetween. By this structure, cover

52

and bottom plates

38

would have electrically been insulated. A cylindrical sealing terminal

53

is connected to the lower portion of the lightning arrestor

32

, and the earth line

43

is mounted to the lower end of the sealing terminal

53

. An O-ring

54

is provided around the inner surface portion, in which the sealing terminal

53

is to be fitted, of the cover

52

for sealing the sealing terminal

53

from the exterior. A flange is provided at the lower end of the cover

52

, and is bolted on a flange portion provided on the lower end side of the sealing terminal

53

. Then, cover

52

becomes a cylindrical geometry so that the lightning arresters

32

may can move for top and bottom. Therefore, it is constituted in order to be the position of bottom plates

38

located higher than bottom plate of the cover

52

. By this structure, the space of line side unit

3

narrows, and the quantity of insulation gas which line side unit

3

uses is decreased. And when the condition that lightning arrester

32

is connected with conductors

31

, it is constituted that the position of the height of the bottom plates

38

is located in the near place of the most grounding side of lightning arresters

32

. So the electrical insulation between lightning arrester

32

and bottom plate

38

in the condition that lightning arrester

32

are connected with conductor

31

is ensured. And then, the capacity of line side unit

3

is decreased, and the quantity of insulation gas which line side unit

3

is decreased.

A connection portion between the lightning arrestor

32

and the conductor

31

has a slidable structure composed of a male portion provided on the lightning arrestor

32

side and a female portion provided on the conductor

31

side. A shield

59

is mounted on the lightning arrestor

32

side in such a manner as to cover the male portion, to relieve the electric field even if the lightning arrestor

32

is separated from the conductor

31

.

The lightning arrestor

32

is separated from the conductor

31

as follows: Namely, as shown in

FIGS. 4 and 5

, a fixed plate

56

having a threaded hole is mounted to the cover

52

via stud bolts

55

, and a spindle

57

is pressed to the sealing terminal. In such a state, the bolts fastened in the flange formed on the lower end side of the sealing terminal

53

are removed. At this time, the lightning arrestor

32

is moved downwardly to the bottom of the cover

52

by the gas pressure in the vessel of the line side unit

3

and the dead weight of the lightning arrestor

32

, so that the lightning arrestor

32

can be separated from the conductor

31

by turning the spindle

57

. On the other hand, the lightning arrestor

32

is connected to the conductor

31

by turning the spindle

57

to lift the lightning arrestor

32

. In addition, if it is difficult to move downwardly the lightning arrestor

32

for the reasons that the weight of the lightning arrestor

32

is light or the sealing pressure of the O-ring

54

is strong, it may be desirable to adopt a method of forming one or several grooves

58

in either or both of the cover

52

and sealing terminal

53

in the circumferential direction as shown in FIG.

4

and moving downwardly the lightning arrestor

32

by applying a force to the grooves

58

. Alternatively, as shown in

FIG. 5

, the outside diameter of the flange of the sealing terminal

53

may be larger than the outside diameter of the flange of the cover

52

. With this configuration, the lightning arrestor

32

can be moved downwardly by applying a force to the flange of the sealing terminal

53

mounted to the lightning arrestor

32

.

The monitor

42

is mounted on the frame

37

, and the earth line

43

extracted from the lower portion of the lightning arrestor

32

is connected to the monitor

42

. Since the earth line

43

is extracted from the lower portion of the lightning arrestor

32

, it is possible to eliminate the necessity of provision of a separator in the line side unit

3

and to separate the lightning arrestor by moving the lightning arrestor

32

to the underside of the bottom plate

38

.

Since the lightning arrestor

32

is disposed near the ground, the length of the earth line

43

can be shortened, so that a potential superimposed to an operational potential of the lightning arrestor

32

can be reduced. As a result, the lightning arrestor

32

can be accurately operated at the operational potential.

As described above, according to the present invention, since a separator for separating a lightning arrestor serves as a sealing terminal, the number of parts can be reduced and also the separation of the lightning arrestor can be simply performed. Also, since the lightning arrestor is disposed near the ground, the length of the earth line can be shortened and thereby a potential superimposed on an operational potential of the lightning arrestor can be made small. As a result, the lightning arrestor can be accurately operated at the operational potential. Further, since the shield is mounted on the lightning arrestor side in such a manner as to cover the male portion, the electric field can be relieved even in the state in which the lightning arrestor is separated from the conductor.