High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Vacuum
Reexamination Certificate
2001-02-08
2002-11-05
Enad, Elvin (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Vacuum
C218S123000, C218S130000, C218S134000
Reexamination Certificate
active
06476338
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a vacuum switch.
DESCRIPTION OF RELATED ART
22/33 kV and 66/77 kV grade special high-voltage transformers of the prior art have involved the problems of construction costs caused by the high cost of the necessary land, of insulation and safety problems when the charging parts become soiled and with noise when the switch is operated. Accordingly there has been progress with the size reduction and sealing of the switches and air-insulated switches have been replaced by gas-insulation-type gas-insulated switchgeares and cubicle-type gas-insulated switchgeares.
In the former type of gas-insulated switchgear. the interrupters, disconnecting switches and conductors connected to these are contained in a sealed metal tubular container and this tubular container is filled at high pressure with sulfur hexafluoride (SF
6
) gas as an insulating gas to achieve size reduction and sealing.
By contrast, the latter type, the cubicle-type gas-insulated switchgear, has been developed to have higher reliability, safety and ease of maintenance and inspection than the former gas-insulated switchgear, together with reducing the space required for installation, shortening construction time and meeting the demand for harmony with the environment surrounding the site of installation.
Thus, in the cubicle-type gas-insulated switchgear, all the electrical devices described above and connections and conductors are contained within a case that is filled with insulating gas at slightly greater than atmospheric pressure, and the interior is divided into gas zones for each circuit, which facilitates maintenance after installation.
Cubicle-type gas-insulated switchgears, which in their external appearance are very similar to the atmosphere-insulated metal enclosure switchgear formerly installed, have come into use to meet contemporary requirements, as described above.
FIG. 1
shows a right-side view (without the right-side plate) of one example of a cubicle-type gas-insulated switchgear, in this case a load-receiving board.
In
FIG. 1
, front door
14
A is attached to the front surface of case
13
, the external periphery of which is encased so as to be air-tight by mild steel sheet.
Within case
13
, U-shaped partition
15
A is welded at its top edges to the ceiling of the case, vertical partition
15
B is attached in an air-tight manner somewhat forward of the center of partition
15
A and bus-bar partition
15
C, which is formed in an L shape, is attached in an air-tight manner to the back of vertical partition
15
B.
As a result of this, a U-shaped air insulation cubicle
13
a
is formed in front of, behind and below partition
15
A, interrupter cubicle
13
b
is formed in front of partition
15
B, an L-shaped load-receiver cubicle
13
c
is formed between the bottom of partition
15
B and partition
15
A and a small busbar cubicle
13
d
is formed above load-receiver cubicle
13
c.
Interrupter cubicle
13
b,
load-receiver cubicle
13
c
and bus-bar cubicle
13
d
are filled with SF
6
gas
25
, as described above.
A vacuum interrupter
16
, with a vacuum valve as the switch part, is housed in interrupter cubicle
13
b
and operating mechanism part
17
, which is fitted with a wheel and which operates the switch part of vacuum interrupter
16
, is housed at the bottom of this vacuum interrupter
16
so as to be capable of being extracted into air-insulated cubicle
13
a.
Disconnecting switch operating mechanism
22
is attached to the front surface of partition
15
A at the front of vacuum interrupter
16
and an operating rod (not shown), which projects to the rear from this disconnecting switch operating mechanism
22
, passes through partition
15
B, at the rear of interrupter cubicle
13
b,
so as to be air-tight.
Insulating spacers
19
A (upper) and
19
B (lower) are fitted through partition
15
B. The front end of the upper insulating spacer
19
A is connected by connecting conductor
18
A, covered by a shield tube, to the upper terminal of vacuum interrupter
16
and the front end of lower insulating spacer
19
B is connected by a short connecting conductor to the bottom terminal of vacuum interrupter
16
.
In bus-bar cubicle
13
d,
disconnecting switch
20
is fixed to the base board, the terminal of the fixed side of disconnecting switch
20
is connected to the back of the insulating spacer
19
A, in front of it, and the rear end of an operating rod (not shown), which projects rearward from disconnecting switch operating mechanism
22
, as described above, is linked to the top end of lever
20
a
which stands at the rear of the disconnecting switch
20
.
The movable side terminal shown at the front of the top end of lever
20
a
of disconnecting switch
20
is connected by a connecting conductor to the bottom end of insulating bushing
21
which passes vertically through a thick attachment sheet welded to the ceiling sheet of bus-bar cubicle
13
d.
The top end of voltage-detecting insulator
23
is fixed to the rear lower surface of the base sheet of bus-bar cubicle
13
d
and the rear end of connecting conductor
18
B, covered by a shield tube, is connected to the terminal at the lower end of voltage-detecting insulator
23
and the front end of connecting conductor
18
B is connected to the rear part terminal of lower insulating spacer
19
B, in front of it.
The front end of the short connecting conductor
18
C, covered with a shield tube, is connected to the rear of the terminal at the bottom end of the voltage-detecting insulator
23
and the rear end of connecting conductor
18
C is connected to the front end of cable head
26
which is fitted so as to pass through from the rear of the rear end of partition
15
A.
The front end of cable head
26
is again connected to the bottom terminal of arrester
24
which is fitted so as to pass through the ceiling sheet of load-receiving cubicle
13
c
from above.
The top end of high-pressure cross-linked polyethylene cable
27
brought up from a pit formed, as indicated by the broken line, in the floor fitted to the case
13
, is connected to the underneath of the cable head
26
and the high-pressure cross-linked polyethylene cable
27
passes through a current transformer
28
fixed to the case.
The connection part of the top of the insulation bushing
21
that is fitted through the ceiling plate of case
13
, is connected, via a high-pressure cross-linked polyethylene cable (not shown) to the connection part of the top of an insulation bushing fitted through the ceiling plate of the load-receiving board (not shown) of another system fitted next to box
13
.
In a load-receiving board configured in this way as a cubicle-type gas-insulated switchgear, the power fed to the load-receiving board from the exterior disconnecting switch (not shown) fitted in this transformer, via the high-pressure cross-linked polyethylene cable
27
in the pit, passes though vacuum interrupter
16
and disconnecting switch
20
and is fed from a high-pressure cross-linked polyethylene cable fitted at the top of the ceiling surface of the case
13
of the load-receiving board to the load side, via a load-dispatching board (not shown).
The SF
6
which fills interrupter cubicle
13
b,
load-receiving cubicle
13
c
and bus bar cubicle
13
d
has arc-extinguishing capability 100-fold and a insulating capability 3-fold that of air and it is this SF
6
gas that allows the case to be reduced in size.
Moreover, this is a colourless, odorless, tasteless gas with stable uninflammabity and it is also non-toxic. If, however, it is brought into contact with an arc, highly toxic degradation gases and degradation products such as SOF
2
, SO
2
, SO
2
F
2
, SOF
4,
HF and SiF
4
are generated and special treatment and management are required to recover these degradation products and degradation gases from SF
6
gas.
In
FIG. 1
, of the switches incorporated into the load-receiving board, the vacuum interrupter
16
extinguishes the arc inside the vacuum valve, and Bo no degradation gases of SF
6
gas are generated but when in di
Ohshima Iwao
Shioiri Tetsu
Yokokura Kunio
Enad Elvin
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Fishman Marina
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