{Title of the Invention) PUFFER TYPE GAS CIRCUIT BIIEAICEK
{Technical Field)
(0001 }
The prescnt invention relates to a puffer type gas circuit breaker particularly to a puffcr
type gas circuit breaker for protecting an electrical generator circuit to interrupt a large current
associated with an accident and zero-miss current (also referred to as zero-missing current) while
ensuring a longer interruptible time approxinlately four cycles.
{Background A1-t)
{0002}
A circuit breaker co~nmonlyu sed in an electric power transn~ission-transforlnatio~syl stem
has been understood having necessary and sufficient interruption perfornlance if the arcing time
is 1 to 1.5 cycles. On the other hand, in a high-speed automatic grounding device (hereinafter
referred to as HSGS) for a 1100 kV ultra high voltage (UHV) system, zero-miss current (or zeromissing
current), an alternating current wave form of which does not pass through the zero point,
appears due to superposition of a direct current component on the induced static current to be
interrupted if an accident occurs in the other line on opening of operation of the device (i.e., at
the time of interruption ofthe electrostatically induced current come from the transmission line).
The zero-missing current is a current in which the zero current point does not appear for a longer
time about four cycles; a commonly used circuit breaker therefore cannot interrupt such current.
(0003)
Patent Literature 1 has disclosed the configuration of an HSGS that allows to ensure a
long interruptible time equivalent to approximately four cycles. The configuration and
constituents therein are as follows: A first puffer chanlber is formed by a puffer cylinder having
flange portion of an approximate-cylindrical shape and a shaft portion, and a fixed piston; and
the fixed piston is formed into a cylindrical shape that is sealed against the outside space and is
arranged so that it will be provided in the flange portion of the puffer cylinder when the
interruption section comes to the circuit interrupted position; and the inside space thereof is
arranged so as to work as a second puffer chamber that comnlunicates with the first puffer
chamber. Thercby, the acconl~nodationp art of the flange portion of the puffer cylinder is made
to have the second puffer chamber, which makes it possible to continue blowing the gas
accumulated in the second puffer chamber between electrodes permitting lengthening thc
effective arcing time.
(0004)
Fig. 11 shows the characteristic diagram showing the puffer pressure changcs in the
HSGS according to the conventional art in Patent Literature 1. S in the figure represents the
displacelllent of the movable clcctrodc fro111 the circuit closed position "C" of thc interruption
section to the circuit interrupted position "O" of the same. The pressure increase 1' at that time is
indicated in wnvcforms with the dotted line for the case where the configuration includes the first
puffer chamber only, and with the solid lille for the case where the configuration includes the
second puffer chamber in addition to the first one. Thus, the expanding of the puffer chamber
capacity by providing a second puffer chamber newly on the part that was conventionally only
an accommodation part of the flange portion of the puffer cylinder enables interruption of the
zero-missing current within a size comparable to conventional circuit breakers and with less
increase in weight.
{OOOS)
Characteristics of the interruption perfor~llanceo ft his conventional art include, as shown
in Fig. 1 1 , a gradual decrease of the puffer pressure in a longer arcing time. This means that the
art will be applied without any problems to an 11SGS that does not intend a use for interruption
of a large current. I-Iowever, this art includes such a problem as is not suitable for a reliable
interruption of a large current that flows at the time of accident ensuring a longer interruptible
time of approximately four cycles as in a circuit breaker for protecting an electrical generator
circuit.
{Literatures of Conventional Art}
{Patent Literatures)
{0006}
{Patent Literature 1 ) Japanese Patent Application Laid-open No. Hei 6-3 10000
{Summary of Invention)
{Problem the Invention Intends to Solve)
(0007)
In view of problei~ls stated above, the present invention particularly intends to provide a
purer type gas circuit breaker for protecting an electrical generator circuit, wherein such circuit
breaker is intended to be capable of interrupting a zero-missing current, which is difficult to
interrupt with an ordinary circuit breaker, by ensuring a longer interruptible time of
approximately four cycles and also capable of interrupting a large current associated with an
accident.
{Means for Solving the Problem)
(000s)
A puffer type gas circuit breaker by the present invention has: a vessel that is to be filled
with insulating gas; a stationary-side nlaill contact and a movable-side main contact that arc
provided in the vessel and arranged on the same axis so that they position to face each other in
opposite directions; a stationary-side arcing contact and a movable-side arcing contact that are
concentrically provided inside the stationary-side main contact and the movable-side main
contact respectively; a puffer cylinder that has, on its top end, the movable-side arcing contact; a
puffer shaf having a puffer chambcr-sidc cxhaust hole and an ol?eration rod-sidc exhaust hole,
wherein the puffer shaft is concentrically provided inside the puffer cylinder; a closilig member
that closes the operation rod-side exhaust hole; a puffer piston that slides on the inner surface of
a space fortiled by the puffer cylinder and the puffcr shaft; a flow control section having an
opening part that is communicable with the puffer chamber-side exhaust hole, wherein the flow
control section is providcd on the puffer piston and arranged in a puffer chambcr formed by the
puffer cylinder and the puffer shaft and the puffer piston; and an insulating nozzle provided
concentrically with the movable-side arcing contact, wherein the insulating nozzle blows an
insulating gas compressed within the puffer chaniber to the arc produced between the stationaryside
arcing contact and the movable-side arcing contact; wherein, on completion of the
intcrruption operation (also referred to as the interruption movement), a space having a givcn
extent is formed in the puffer chamber, the puffer chamber-side exhaust hole and opening part
communicate, and the closing member closes the opcration rod-side exhaust hole.
{0009)
It is preferable that the closing member is a pressure-activated valve, the pressureactivated
valve opens the operation rod-side exhaust hole activated by pressure increase in an
arcing space when arc is produced, aid the pressure-activated valve keeps the operation rod-side
exhaust hole closed even when the pressure in the arcing space increases again after the
completion of the interruption movement. In the above description, the arcing space is a space
enclosed with a stationary-side arcing contact 4, a movable-side arcing contact 5, and an
insulating nozzle 12.
(00 10)
Further, it is preferable that the closing member is an exhaust closing cylinder inside
which the puffer shaft slides, wherein the exhaust closing cylinder closes the operation rod-side
exhaust hole at the place in the vicinity of the final end of the stroke of the interruption
movement.
(001 1)
Furtherniore, it is preferable that an evaporable member that evaporates by a hightemperature
gas is provided on the interrupting section-side of the inside of the puffer shaft.
{Advantageous Effect of the Invention}
(0012)
According to the present invention, in the interruption process of the zero-missing
current, an arc-extinguish gas can be blown continuously from the insulating nozzle for a longer
time even after conipletion of the interruption movement by maintaining the gas pressure inside
the puffer chamber using the residual arc in the interruption section. Thereby, it becomes
practicable to interrupt not only a large current associated with an accident but also a zeromissing
current, which is difficult to interrupt with an ordinary circuit breaker.
{Brief Description of Drawings)
(0013)
Fig. 1 is a sectional vicw that illustrates an ovcrall configuration oftbe puffer typc gas circuit
breaker according to the first embodiment cxample of the present invention.
Fig. 2 is a sectional view that illustrates the circuit closed state of the puffer type gas circuit
breaker according to the first embodiment example of the present invention.
Fig. 3 is a sectional view that illustrates the beginning state of the interruption movement (at
the time when arc is produced) of the puffer type gas circuit breaker according to the first
embodiment example of the present invention.
Fig. 4 is a sectional view that illustrates the state of completion of the interruption niovelnent
of the puffer type gas circuit breaker according to the first embodiment example of the
present invention.
Fig. 5 is a detailed view that illustrates the flow control section 11 of the puffer type gas
circuit breaker according to the present invention.
Fig. 6 is a characteristics coinparison diagram that compares the puffing pressure curvc 1'1 in
a conventional method and the puffing pressure curve P2 in the puffer type gas circuit
breaker according to the present invention.
Fig. 7 is a sectional view that illustrates the circuit closed state of the puffer type gas circuit
breaker according to the second embodinlent example of the present invention.
Fig. 8 is a sectional view that illustrates the beginning state of the interruption movement (at
the time when arc is produced) of the puffer type gas circuit breaker according to the
second embodiment example of the present invention.
Fig. 9 is a sectional view that illustrates the state of completion of the interruption inovenlent
of the puffer type gas circuit breaker according to the second embodiment example of the
present invention.
Fig. 10 is a sectional view that illustrates the interruption section of the puffer type gas circuit
breaker according to the third embodiment example of the present invention.
Fig. 11 is a characteristics diagram that shows the variation of puffing pressure in an example
of conventional HSGS.
{Description of Embodiments)
{Embodiment Example 1)
(0014)
The following explains, referring to drawings, a puffer type gas circuit breaker by the
present invention. Fig. 1 illustrates the circuit closed state of the interruption section of the puffer
type gas circuit breaker according to an embodinlent exaniple of the present invention.
(0015)
A stationary-side main contact 2 and a movable-side main contact 3, each of which is
shaped annularly, are provided in a vessel 1 filled with an insulating gas such as SF6 and are
arranged on the same axis in such a manner that they position to face cach other in opposite
directions. Inside the stationary-side main contact 2, a stationary-side arcing contact 4 is
concentrically provided. Inside the movable-side main contact 3, a movable-side arcing contact 5
is concentrically provided.
{00 16)
The stationary-side main contact 2 and the stationary-side arcing contact 4 are electrically
connected to a stationary-side conductor 13. The movable-side nlain contact 3 and the movableside
arcing contact 5 are electrically connected to a movable-side conductor 14 through a puffer
cylindcr 6.
(0017)
Thc movable-side arcing contact 5 is provided on the top end of the puffer cylindcr 6.
Inside the puffer cylinder 6, a puffer shaft 7 is concentrically provided and one end thcrcof is
secured 011 the puffer cylindcr 6. The other end of the puffer shaft 7 is connected to an insulative
operation rod 8, thereby a driving force from an actuator (not illustrated) is transnlittcd to the
movable side. The puffer shaft 7 is hollow; the hollow space has a role of working as an exhaust
path of the hot gas caused by the arc produced in the interruption section.
(0018)
The puffer shaft 7 has a puffer chamber-side exhaust hole 7a and an operation rod-side
exhaust hole 7b for exhausting the hot gas caused by the arcing. On the actuator-side end of the
hollow space of the puffer shaft 7, a pressure-activated valve 15, which is constituted with a
valve 15a of conical shape and a return spring 15b, is provided.
{0019)
The pressure-activated valve 15 is pushed by the insulating gas of high-pressure, which is
produced in the interruption section, to open the operation rod-side exhaust port 7b at the time of
arcing as illustrated in Fig. 3, but works as a closing member for closing the operation rod-side
exhaust hole 7b after completion of the interruption movement as illustrated in Fig. 4. It is a
particularly preferable configuration that the operation rod-side exhaust hole 7b is kept closed
after completion of the interruption movement even if the gas pressure is increased again by the
zero-missing current. This configuration permits keeping the pressure inside a puffer chamber 10
higher than the gas pressure at the interruption section even after the co~upletiono f the
interruption movement and consequently permits blowing insulating gas to the arc for a longer
time.
(0020)
In the state of con~pletiono f thc interruption movement as illustrated in Fig. 4, the
insulation gas of high-pressure, which is higher than that in a conventional art, caused by heat of
the residual arc existing between the stationary-side arcing contact 4 and the movable-side arcing
contact 5 flows into the puffer chamber I0 through the puffer shaft 7, the puffer chanlber-side
exhaust hole 7a comn~unicatingth erewith, and an opening part I la.
{002 1)
And then, the insulation gas is discharged from the puffer chamber 10 through an exhaust
hole 16. The discharged gas flows out along an insulating nozzle 12 to blow the residual arc.
This movement cycle continues while residual arc exists between the stationary-side main
contact 2 and the movable-side main contact 3. Consequently, the insulation gas of high-pressure
can blow for a longcr tiinc thc area between the stationary-side arcing contact 4 and the
movable-side arcing contact 5.
(0022)
A puffer piston 6 slides on the inner surface of the space for~nedb y the puffer shaft 7 and
the puffer cylinder 6. This space for~nedb y the puffer shaft 7, the puffer cylinder 6, and the
puffer piston 9 is referred to as the puffer chainber 10. On the top end of the puffer pistoil 9, a
flow control section 11 is provided. The capacity of the puffer chamber 10 at the tiine of
colnpletion of the interruption movcinent is suitably adjustcd according to the noininal
interruption current rating. The adjustinent will generally be within the range of 30 to 50 %
compared to the capacity of the puffer chamber 10 at the time of the circuit closing.
(0023)
Fig. 5 illustrates details of the construction of the flow control section 11. The ilow
control section 11 has the opening part 1 la and a flow guide 11 b. As Fig. 4 illustrates, the
opening part 1 la communicates with the puffer chamber-side exhaust hole 7a at the time of
completion of the interruption operation. The flow guide 11 b is preferred to have a curved shape.
Giving a curved shape to the flow guide 1 lb allows the insulation gas of high-temperature and
high-pressure flowed in the puffer chamber 10 to easily flow back to the interruption section
through the exhaust hole 16.
(0024)
The insulation nozzle 12 illustrated in Figs. 1 to 4 is provided between the movable-side
main contact 3 and the movable-side arcing contact 5 concentrically with them so that the
insulation gas compressed in the puffer chainber 10 can bc blown to the arc produced between
the stationary-side arcing contact 4 and the movable-side arcing contact 5.
(0025)
Next, the working of the puffer type circuit breaker by the present invention will be
explained referring to Figs. 2 to 4. Fig. 2 illustrates the state of circuit closed, that is, the
interruption section is carrying current. In this state, the current path is formed in the route
passing through, as Fig. 1 describes, the stationary-side conductor 13, the stationary-side main
contact 2, the movable-side main contact 3, the puffer cylinder 6, and then the movable-side
conductor 14.
(0026)
The movement of the insulative operation rod 8 toward the right side of the illustration
from the state illustrated in Fig. 2 causes the movable-side to move toward the right side of the
illustration and their state consequently changes into the arcing state that Fig. 3 illustrates. Under
this situation, arc is produced between the stationary-side arcing contact 4 and the movable-side
arcing contact 5, and the interruption section becomes high-temperature condition as a
consequence. Thereby the pressure-activated valve 15 is pushed toward the right side of the
illustration and the operation rod-side exhaust hole 7b opens to blow out the insulation gas of
high-pressure from the puffer shaft 7.
(0027)
, . 1 hcrcafter, the movable-sidc further nlovcs toward thc right side of the illustration and
thc positional relationship between the stationary-side arcing contact 4 and the movable-side
arcing contact 5 becomes a nearly inter~ncdiates tate between the states illustrated in Fig. 3 and
Fig. 4. At this time, the insulating gas of high-pressure is blown to the arc along the insulating
nozzle 12 via the puffer cl~ainber-sidee xhaust hole 7a, the puffer chamber 10, and the exhaust
hole 16. The above is nlechanism ofa large current intcrruption.
(0028)
In addition, the nlovable-side further moves toward the right side ofthe illustration, and
the state changes into the condition where the interruption operation has conlpleted that Fig. 4
illustrates. In this statc, the pressure-activated valve 15 returns to close the operation rod-side
exhaust hole 7b because the pressure at the interruption section lowers to a reduced level
compared to the arcing state that Fig.3 illustrates. In addition, the opening part1 la ofthe flow
control section 11 and the puffer chan1be1.-side exhaust hole 7a of the puffer shaft 7 conlnlunicate
each other.
(0029)
If residual arc exists in this state between the stationary-side arcing contact 4 and the
movable-side arcing contact 5, the insulation gas of high-pressure heated by that arc flows
through the puffer shaft 7 and goes into the puffer chamber 10 through the communicated puffer
chamber-side exhaust hole 7a and the opening part 1 la.
{0030)
And then, the insulation gas flow out fiom the puffer chamber 10 through the blowing
port 16. Then, the discharged gas flows out along the insulating nozzle 12 to blow the residual
arc. This gas flow cycle continues while a residual arc exists between the stationary-side arcing
contact 4 and the movable-side arcing contact 5. Consequently, the insulation gas of highpressure
can blow for a longer time the area between the stationary-side arcing contact 4 and the
movable-side arcing contact 5.
(003 1)
The following compares, referring to Fig. 6, the characteristics of the puffer pressure
curve PI in a conventional method and the puffer pressure curve Pz in the present embodiment
example. The curve X represents the stroke of the interruption movement of a circuit breaker.
The puffer pressure curve PI in the conventional method shows that the gas pressure gradually
decreases in the latter half of the interruption movement. In contrast to this, the gas pressure in
the present embodiment example increases again in the latter half of the interruption movement
as the puffer pressure curve P2 shows.
(0032)
The next will explain, referring to Fig. 6 and contrasting to a conventional art, the
nlechanisrn of the interrupting of thc zcro-missing current I,,,,, in the puffer type circuit breaker
by the present invention. In Fig. 6, the waveform after the occurrence of the zero-missing current
crosses the zero line at first at the point A. At that time, the puffer chamber in the conventional
method has a residual pressure at the level that the point PIA 011 the puffer pressure curve PI
indicates. In illis case, tl~ercis a risk that the current cannot bc intcmupted because thc pressure in
the puffer chamber 10 is not sufficient.
(0033)
On the other hand, when the puffer type circuit breaker having a puffer chamber by the
present invention is used, the puffer chamber pressure corresponding to the point of the zerocurrent
state is indicated with the point PzA. As can be known from Fig. 6, the pressure at the
point P2,t, is 111uch higher compared to the pressure at the point PIAC. onsequently, in the case
where the puffer type circuit breaker having a puffer chamber by the present invention is used, it
becomes possible to continue blowing insulating gas for a longer time at a pressure higher than
the puffer pressure in an example of conventional art. Thereby, this enables the circuit breaker to
interrupt not only a large current caused by an accident but also the zero-missing current of
which interruption is difficult for an ordinary circuit breaker. Further, it becomes practicable to
prevent reignition oE the arc.
{Embodiment Exainple 2)
{0034)
Figs. 7 to 9 illustrate the second embodiment example of the present invention. The same
constituents as those in the first eillbodin~enet xample are denoted by the same reference
numerals and detailed description thereof will be omitted. In the embodiment example 2, an
exhaust closing cylinder 18 is used in place ofthe pressure-activated valve 15 of the embodiment
example 1. The exhaust closing cylinder 18, which is an exhaust closing cylinder and a puffer
shaft 7 slides on the inner periphery thereof, closes an operation rod-side exhaust hole 7b at the
place in the vicinity of the final end of the stroke of the interruption movement.
(0035)
In the same manner as in the embodiment example 1, the exhaust closing cylinder 18 has
a role of working as a sealing member for closing the operation rod-side exhaust hole 7b after
completion of the interruption operation illustrated in Fig. 9. It is more preferable that the
operation rod-side exhaust hole 7b should be closed at the timing when the pressure of the
interruption section begins to again rise after completion of the interruption operation.
(0036)
By doing so, it becomes possible to maintain the pressure in a puffer chamber 10 higher
than the gas pressure at the interruption section after the conlpletion of the interruption
movement, enabling the blowing of the insulating gas to the residual arc in the interruption
section for a longer time. In addition to the effect shown in the embodiment example 1, the
construction of the present embodiment example is simple and consequently leads to increase in
reliability and reduction in manufacturing cost.
{Embodiment Example 3)
{0037)
Figure 10 illustrates a third embodiment example of the present invention. The same
constituents as those in the first and the second embodiment examples are denoted by the same
reference numerals and detailed description thereof will be omitted. In the embodiment example
3. an cval3orable illelllbcr 19 such as polytetrafluoroetl~ylcne( I'1'1:1:), which evaporates by a high
temperature gas, is arranged on the interruption section-side in a puffcr shaft 7.
{0038}
In the interruption ~~IOV~IIICIaI~ h, ot gas generated by the arc flows into the pufrer shaft 7
to raise the temperature of the evaporable menlber 19 causing generation of evaporation gas. By
feeding the evaporation gas to a puffer chamber 10 through a puffer chamber-side exhaust hole
7a and an opening parl 1 la, temperaturc of the gas inside the puffer chamber 10 can be further
raised to increase the gas pressure more. Thus, it beconles possible in addition to the effects
shown in the first and second embodiment examples to interrupt illore efficiently a large current
and the zero-missing current. Further, it becomes possible to prevent more reliably reignition of
the arc that may occur after interruption of a large current.
{Name of Document} Claims
{Clainl 1 }
A puffer type gas circuit breaker comprising:
a vessel bcing filled with insulating gas;
a stationary-sidc main contact and a movable-side main contact that being provided in the
vessel and on the same axis so that they position to face each other in opposite directions;
a stationary-sidc arcing contact and a movable-side arcing contact that being
concentrically provided inside the stationary-side main contact and the movable-side main
contact respectively;
a puffer cylinder, the movable-side arcing contact being provided on the top end ofthe
puffer cylinder;
a puffer shaft having a puffer chamber-side exhaust hole and an operation rod-side
exhaust hole, the puffer shafi being concentrically provided inside the puffer cylinder;
a closing member closing the operation rod-side exhaust hole;
a puffer piston sliding on the inner surface of a space formed by the puffer cylinder and
the puffer shaft;
a flow control section having an opening part, the opening part is com~nunicablew ith the
puffer chamber-side exhaust hole, the flow control section being provided on the puffer piston
and in a puffer chamber formed by the puffer cylinder and the puffer shaft and the puffer piston;
and
an insulating nozzle being provided concentrically with the movable-side arcing contact,
the insulating nozzlc blows an insulating gas compressed within the pufcer chamber to the arc
produced between the stationary-side arcing contact and the movable-side arcing contact;
wherein, when an interruption operation is completed,
a space having a given extent is formed in the puffer chamber; the puffer chamber-side
exhaust hole communicate with the opening part; and the closing member closes the operation
rod-side exhaust hole.
{Claim 2)
A puffer type gas circuit breaker according to claim 1, wherein the closing member is a
pressure-activated valve; the pressure-activated valve opens the operation rod-side exhaust hole
activated by pressure increase in an arcing space when arc is produced; and the pressureactivated
valve keeps the operation rod-side exhaust hole closed even when the pressure in the
arcing space increases again after the co~npletiono f the interruption movement.
{Claim 3)
A puffer type gas circuit breaker according to claim 1, wherein the closing member is an
exhaust closing cylinder inside which the puffer shaft slides; and the exhaust closing cylinder
closes the operation rod-sidc exhaust hole at the place in the vicinity of the final end of the stroke
of the interruption movement.
{Claim 4)
A puffer type gas circuit breaker according to any one of claim 1 to claim 3, wherein an
evaporable me~nberth at evaporates by a high-tc111peratur.eg as is provided on Lhe interrupting
seclion-side of the inside of the purfer shatt.