Tank-type Gas-filled Circuit Breaker With Impulsive Seal Breaking Means For Initiating Piston Operation

Abstract

A tank type gas-filled circuit breaker has interrupting contacts contained in a pressurized insulating gas filled chamber provided within a tank which in itself forms a low-pressure gas chamber the circuit breaker includes, an operating rod of insulating material penetrating through the tank wall and the high pressure chamber and coupled to the interrupting contacts, a driving means for the operating rod including a piston operating in a cylinder disposed outside of the tank valve, means for sealing high-pressure gas, e.g., air, in a chamber formed at one side of the piston in the cylinder and means for creating an impulsive driving force for operating the valve means, whereby when the impulsive force acts to release the sealing of the valve means, the high-pressure gas is instantaneously introduced into the chamber at one side of the piston, and the insulating rod is operated by the piston to separate the contacts of the circuit breaker. The valve means per se may be operated by means using electromagnetic attractive or repulsion forces, or alternatively by an impulse caused by igniting an explosive agent.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to tank-type, high-voltage, gas-filled circuit breakers, more particularly of the type wherein the interrupting contacts are contained in a gas-filled chamber are operated through an insulating rod by impulsively operable members.

There is a general tendency in the design of recent electric power circuit breakers toward a shortening of the interrupting time of the circuit breakers and the use of SF.sub.6 gas as an arc extinguishing and insulating medium. The reason for this is that the circuit breakers employing SF.sub.6 gas as an arc extinguishing and insulating medium have characteristic features such as a great increase in the interrupting capacity due to its high capability in extinguishing arcs and the possibility of miniaturization of the circuit breaker due to the high dielectric strength of the gas.

The miniaturization of the circuit breaker is particularly realized in the distance between the main interrupting contacts when these contacts are opened, and in the insulation distances between high voltage members in the circuit breaker and the ground.

Furthermore, there has been proposed an electromagnetic repulsion type circuit breaker wherein an electromagnetic repulsion force produced between a driving coil and a short-circuited secondary ring in opposed relation thereto when an electric charge stored in a capacitor is discharged through the driving coil is employed as the driving force.

In a circuit breaker as described above, power interruption in a short time interval corresponding to one cycle which is nearly a technical limit in the art can be achieved by operating the circuit breaker in synchronism with the occurence of a specific phase position in the current passing through the circuit breaker.

However, the circuit breakers heretofore proposed and having the above described construction have had following drawbacks although having the advantageous feature of an extremely short interruption time.

1. Because the interrupting members of the circuit breaker are in a high potential region thereof insulated from the ground by porcelain insulators, equipment of a relatively high price is required for insulating the live parts and above mentioned capacitor from the ground.

2. A transmitting device which transmits a command for tripping the circuit breaker from the ground side to the high voltage portion of the circuit breaker is required.

3. Since the transmitting device is of a comparatively complicated construction, and requires a large number of parts, it the inclusion of such a transmitting device is disadvantageous in the maintenance the reliability of the circuit breaker.

The above described drawbacks of the electromagnetic repulsion type operating mechanism of the circuit breaker have been caused in the past by the direct operation of the interrupting members, included in the high tension portion of the circuit breaker, from the ground through the use of a straight insulated rod which requires an excessively long surface insulation or creepage distance along the insulated rod. Of course, the required surface insulating distance can be obtained by by employing a longer insulated rod. However, in such a case, the propagation speed of the operational force through the insulating rod becomes too low, and many disadvantages such as transmission delay accompanying an elongation of the insulated rod, difficulty in compensation for any thermal deformation of the insulating material, and difficulty in acquiring a material which withstands the high operational force required for the elongated insulated rod, all render the circuit breaker having an elongated insulated rod totally impracticable.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a high-speed, tank-type, gas-filled circuit breaker which can be produced economically.

Another object of the present invention is to provide a highspeed, tank-type gas-filled circuit breaker wherein the movable contact at a high potential can be driven at a high speed from the ground side employing an insulating operating rod.

Still another object of the invention is to provide a novel type high-speed circuit breaker wherein a valve seal for a compressed gas which is to operate a piston coupled to the operating rod is made releasable at a high speed at the required time of the interruption of the circuit breaker.

A further object of the invention is to provide a novel type high-speed circuit breaker which is simple in construction and economical in production.

An additional object of the invention is to provide a novel type high-speed circuit breaker which is reliable in operation and small in size.

The above and other objects of the present invention are achieved by a novel type of high-speed circuit breaker which comprises interrupting contacts included in a high-pressure gas-filled chamber provided within a tank which is, in itself a low-pressure gas-filled chamber; the circuit breaker uses an insulating operational rod penetrating through the tank wall to be coupled with the interrupting contacts for the operation thereof, a driving means including a piston disposed outside of the tank for driving the operational rod valve, means for sealing a chamber formed at one side of the piston from a compressed gas, and means for creating an impulsive driving force for releasing the valve means, whereby when the impulsive force releases the valve means, the compressed gas is instantaneously introduced into the chamber at one side of the piston, and the insulating rod is operated by the piston to separate the contacts of the circuit breaker.

The nature, principle, and the utility of the present invention will be more clearly understood from the following detailed description of the invention, with respect to preferred embodiments thereof, when read in conjunction with the accompanied drawings, wherein like parts are designated by like reference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a longitudinal sectional view, in diagrammatic form, showing the general arrangement of a circuit breaker according to the present invention;

FIGS. 2 and 3 are longitudinal sectional views, in more detail, of different examples of the driving means employed in the circuit breaker, wherein electromagnetic repulsive forces are utilized;

FIG. 4 is a longitudinal sectional view of another example of the driving means wherein an electromagnetic attractive force is utilized; and

FIG. 5 is a longitudinal sectional view of still another example of the driving means wherein an impulsive pressure caused by the explosion of an explosive is utilized.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1 showing the general arrangement of a circuit breaker according to the present invention, it is clearly seen that the circuit breaker is constructed symmetrically around a central axis thereof, and that the high voltage lines are introduced into the circuit breaker, for instance, through cable heads 1, 1, and placed in chambers filled with a high-pressure insulating gas. An interrupting contact arrangement of the circuit breaker is included in a high-pressure chamber 2 filled with SF.sub.6 gas, and in the example shown in FIG. 1, two such chambers are included in a low-pressure chamber 3 formed, for instance, by a steel tank 4. The tank 4 is placed at ground potential. Each of the interrupting contacts placed in the high-pressure chambers 2, 2, is operated through an insulated rod by means of a driving means 5 disposed outside of the tank 4 which is mounted on a base pedestal 7.

When the circuit breaker is to be thrown into the closed state, the contacts may be operated from outside as is done in the case of a circuit interruption, or if there is provided a separate auxiliary interrupting means (not shown), the closing operation may be achieved by separate interrupting contacts with the main interrupting contacts being closed automatically after they have once been opened.

Referring to FIG. 2, there is shown in detail an example of the driving means 5 shown in FIG. 1. The device 5 comprises a casing 10 forming therein a high-pressure chamber 11. Within the high-pressure chamber 11, there is fixed a guiding cylinder 12 for guiding moving members hereinafter described. At the centrally located end of the guiding cylinder 12, an inwardly projecting flange portion 12a is formed, and a ring-shaped driving coil 13 is disposed on the flange portion 12a. In opposed relation to the driving coil 13, another flange portion 14a acting as a short-circuited secondary ring is formed on a valve body 14 which is inserted in the guiding cylinder 12.

Rearwardly from the flange portion 14a of the valve body 14, a chamber 15 defined by a cylindrical portion 14b of the valve body and the guiding cylinder 12 is formed and communicates through a three-way valve (not shown) with either the atmosphere or a compressed air source. Sealing members 16, 17, and 18 are provided between the guiding cylinder 12 and the flange portion 14a and cylinder portion 14b of the valve body 14, respectively.

At the forward end of the flange portion 12a, the guiding cylinder 12 is further provided with a reduced diameter portion 12b having an inverted C-shaped cross section, whereby an exhausting chamber 19 ordinarily communicating with the outside atmosphere is thereby formed. Within the reduced diameter portion 12b, a pressure-receiving portion 21a of an operational rod 21 is inserted, and a seal 20 is provided between the inner surface of the reduced diameter portion 12b and the pressure-receiving portion 21a of the operating rod 21. The operating rod 21 penetrates through the casing 10 at a position where another sealing member 22 is provided for high-pressure within the casing 10. A retracting spring 23 is accommodated in a space between the reduced diameter portion 12b and the operating rod 21.

Through the guiding cylinder 12, a through hole 12C is provided so that a space formed between the rear surface of the flange portion 12a, on which the driving coil 13 is mounted, and the forward surface of the flange portion 14a is communicated with the high-pressure within the casing 10.

On the other hand, a sealing gasket 24 is provided on the flange portion 12a at a circumference outside of the driving coil 13, whereby the space formed between two flange portions 14a and 12a is sealed from the high-pressure air contained in the casing 10 when the flange portion 14a is moved to a position nearest to the driving coil 13. Likewise, another sealing gasket 26 is disposed on the valve body 14 at a position confronting the rearward end of the reduced-diameter portion 12b of the guiding cylinder 12, whereby a space 25 formed between the forward end of the valve body 14 and the rearward end of the operational rod 21 is brought into an air-tight condition when the rearward end of the reduced-diameter portion 12b abuts the sealing gasket 26 on the valve body 14.

The driving device as shown in FIG. 2 operates as follows. When a trip signal is received at the circuit breaker, an electric charge stored in a separate power source capacitor (not shown) is discharged through the driving coil 13. In this case, the flange portion 14a acts as a short-circuited secondary ring under the close influence of the driving coil 13, and an electromagnetic repulsive force is created between these two members.

Since the chamber 15 at the rear side of the flange portion 14a is ordinarily communicative with the atmospheric pressure through a three way valve (not shown), the valve body 14 subjected to the repulsive force from the driving coil 13 is quickly moved in a retracting direction from the driving coil 13, whereby the sealing effects of the sealing gaskets 24 and 26 are lost. As a result, the high pressure air in the casing 10 is introduced into the space between the flange 14a and the flange 12a via the through hole 12c, and the flange portion 14a is further retracted from the driving coil 13.

On the other hand, the operating rod 21 and the valve body 14, which have been maintained in a balanced state under substantially equal and opposite pressures acting on these two members, are now out of the balanced state because of the retraction of the valve body 14 causing the sealing of the sealing gasket 26 to break and allowing the space 25 to communicate with the exhausting chamber 19 maintained at atmospheric pressure.

As a result, the operating rod 21 is retracted into the guiding cylinder 12, and the interrupting contacts can be operated through an insulating rod 6 coupled directly to the operating rod 21.

By the above described arrangement of the driving device, no impulsive electromagnetic repulsion force is applied to the insulating rod 6, and the requirement for high-speed interruption of the circuit breaker can be fulfilled because of the rapid movement of the valve body caused by an electromagnetic repulsive force.

The driving means shown in FIG. 2 can be brought back to the indicated state as follows.

Compressed air is introduced into the chamber 15 through the three-way valve (not shown), and the valve body 14, is shifted forwardly due to the pressure applied to the flange portion 14a. Upon the assumption of the indicated state, the chamber 15 is connected with the atmospheric pressure through the three-way valve. The operating rod 21 is also restored to its original position by the retracting spring 23, and the interrupting contacts of the circuit breaker are closed through the insulated rod 6 (see FIG. 1).

Otherwise, the driving device as shown in FIG. 2 may be used only for the interruption of the main interrupting contacts, and the closure of the high-tension circuit may preferably be carried out by employing auxiliary contacts of a conventional type provided separately from the main interrupting contacts and connected in series with the main interrupting contacts.

For the hereinbefore described reason, it is preferable that the length of the insulating rod 6 be selected as short as possible, and because of the fact that the tank 4 is at the low potential side, no substantial length of the insulation distance is required between the tank 4 and the driving device 5. The length of the insulating rod 6 may be further shortened because a gas of a high dielectric strength is contained in the related part of the tank 4. Furthermore, with the above described organization of the driving device, a high-speed interruption of the interrupting contacts can be obtained without applying an excessive magnitude of impulsive force to the insulating rod 6.

While the driving device shown in FIG. 2 is of an exhaust-driving type wherein the chambers 15 and 19 are exhausted, or any other spaces are exhausted indirectly through these chambers 15 and 19, a high-pressure during type device may also be employed for a high-tension circuit breaker of this invention. Such an example is indicated in FIG. 3, wherein like parts are indicated by like reference numerals.

In FIG. 3, there is provided a casing 100 from which a flange portion 100a to which is attached driving coil 13 is internally projejected. Opposing the driving coil 13, another flange portion 140a of a valve body 140, which acts as a short-circuited secondary ring, is provided. A rod portion 140b of the valve body 140 is passed through the casing 100 in an air-tight manner through a sealing ring 30, and an operating rod 210 is passed through the valve body 140 in an air-tight manner through the use of sealing rings 31 and 32.

Within a chamber 33 in the casing 100, at one side of the inwardly projecting flange 100a thereof, there is provided a damping material 34 for abutting a flange portion 140a of the valve body 140 when the flange portion 140a is repelled by the driving coil 13, and also a return spring 29. Another chamber 35 in the casing 100, at the other side of the inwardly projecting flange 100 a thereof, is connected through a three-way valve 36 to either an intake pipe 37 or an exhausting pipe 38. The intake pipe 37 is further connected with a compressed air source (not shown), and the exhausting pipe 38 is open to the atmosphere.

Inside of the chamber 35, a guide portion 100b of the casing 100 is provided for guiding a pressure receiving portion 210a of the operating rod 210 in the axial direction of the latter. Inside of a chamber 39 formed between the pressure receiving portion 210a of the operating rod 210 and the rear wall 100c of the casing 100, there is provided a return spring 23 which urges the pressure receiving portion 210a rightwardly so that the interrupting contacts are thereby closed.

Also in the chamber 35, there is provided damping material 40 which abuts the pressure receiving portion 210a of the operational rod 210 when the latter moves leftwardly for opening the interrupting contacts of the circuit breaker. Through the rear wall 100c of the casing 100, small holes 41 are bored for providing an air damper constituted of the chamber 39. The chamber 33 communicates with the chamber 35 through a passage 42.

The pressure receiving portion 210a of the operating rod 210 is brought into contact with the inner surface of the guide portion 100b of the casing 100 in an air-tight manner through the use of a sealing ring 43 provided on the outer periphery of the pressure-receiving portion 210a, and the flange portion 140 a of the valve body 140 is brought into contact with pressure-receiving portion 210a of the operating rod 210 by means of a sealing gasket 44 attached to the rear surface of the flange portion 140a.

When the sealing gasket 44 operates effictively, the pressure-receiving surface area of the flange portion 140a on the side of the return spring 29 is greater than the surface area of the opposite-side surface of the flange portion 140a. When the seal of the sealing gasket 44 is broken, the above mentioned relation for the surface areas is just reversed.

The positions of moving members shown in FIG. 3 correspond to those for the thrown-in state i.e., of the conducting state of the circuit breaker. When the driving device is in a condition corresponding to the thrown in state of the circuit breaker, the three-way valve 36 is operated so that the chamber 35 communicates with the inlet pipe 37.

Upon reception of an interrupting command signal, the power source capacitor immediately discharges through the driving coil 13, and the flange portion 140a of the valve body 140 is quickly moved to the right-hand side, as viewed in FIG. 3, under the electromagnetic repulsive force caused by the energization of the driving coil 13. The movement of the flange portion 140a breaks the sealing of the sealing gasket 44, and the right-hand side of the pressure-receiving portion 210a of the operating rod 210 is subjected to a high pressure of compressed air from the chamber 35.

As a result, the operating rod 210 is driven to the left-hand side against the resilience of the return spring 23, and the interrupting contacts of the circuit breaker are abruptly disengaged. During the rightward movement of the flange portion 140a, the through passage 42 and the damper 34 absorb the impulsive force against the corresponding end wall of the casing 100. Likewise, the through holes 41 and the damper 40 dampen the impulsive force applied to the left end wall 100c.

When the driving means once operated as described above is to be brought back to the condition as shown in FIG. 3, the chamber 35 is connected to the atmosphere by operating the three-way valve 36 to the position of the exhaust pipe 38. In this manner, pressures in the chamber 35 and also in the chamber 33 communicated therewith are gradually lowered, and when the pressures become lower than predetermined values, the valve body 140 is driven back to its initial position under the action of the return spring 29, and the operating rod 210 is sent back to its initial position under the action of the return spring 23.

When the state shown in FIG. 3 is attained, the flange portion 140a is additionally urged to the right-side surface of the pressure-receiving portion 210a of the operating rod 210 under a pressure difference caused by the different pressure-receiving areas of the flange portion 140a, and the air-tight contacting state of the two portions is thereby strengthened. It should be noted that the high-pressure driving type device as shown in FIG. 3 is more profitable than the exhaust driving type device shown in FIG. 2 when the device is to be operated at a high speed.

Although in FIGS. 2 and 3, driving devices utilizing an electromagnetic repulsive force have been illustrated, it will be apparent that an electromagnetic attractive force may also utilized in the driving device, and such an example is indicated in FIG. 4.

As shown in the drawing, an operating rod 21 passes through a supporting structure 55, which may be any one of suitable stationary members in the circuit breaker. One end of the operating rod 21 is connected to an insulating rod 6 (see FIG. 1), while the othe end of the operating rod 21 is formed into a piston 210a. The piston 210a is driven leftward as seen in the drawing when compressed air delivered from a chamber 35 is applied to the rear surface of the piston 210a. The chamber 35 may be connected to a compressed air source or to the outside atmosphere through a three-way valve which can be transferred between an inlet pipe 37 and an exhaust pipe 38.

Ordinarily, the pressure chamber 35 is connected to the inlet pipe 37 so that the chamber 35 is maintained at a high pressure. The operating rod 21 passes through the inner bore of a movable magnetic core 50 in an air-tight manner with sealing rings 31 and 32 provided therebetween. The movable magnetic core 50 is driven toward the right as viewed in the drawing, when an electromagnetic coil 130 is energized as described before, through an attracting force acting between a stationary magnetic core 51 and the movable magnetic core 50, both constituting a magnetic path.

When the electromagnetic coil 130 is not excited, the movable core 50 is pushed back leftward by a return spring 29 inserted between the movable core 50 and the stationary structural member 55, whereby a sealing gasket 44, arranged at a portion confronting to the outer periphery of the piston 210a of the movable magnetic core 50, abuts the peripheral portion of the piston in an air-tight manner, and the pressure in the chamber 35 is prevented from arriving at the pressure receiving surface P of the piston 210a. The pressure in the chamber 35 is also prevented from leaking out between the two magnetic cores by means of sealing rings 52 and 53 disposed at the engaging portions of the stationary magnetic core 51 and the movable magnetic core 50.

In the above described driving device, wherein an electromagnetic driving force is utilized, it is a principal object of the invention to attain the speediest possible interruption of the contacts within a limited condition. In the conventional electromagnetic driving devices which are excited by a low voltage of the order of 100V, the operating speeds of the moving parts have been too slow, whereby the above described object of could not be achieved.

To eliminate the above described drawback of the conventional devices, a power source capacitor is charged beforehand to a substantially high voltage, say, several thousands of volts, and the electromagnetic coil 130 is excited by discharging the capacitor through the coil 130. For accelerating the build-up of the magnetic fluxes in the magnetic cores, the magnetic cores may be made of silicon steel plates.

In the driving device shown in FIG. 4, when a discharge current of the power source capacitor (not shown) flows through the electromagnetic coil 130 in response to a trip signal, the movable magnetic core 50 is attracted quickly to the right, whereby the sealing of the sealing gasket 40 is broken, and the high pressure air in the chamber 55 acts upon the pressure receiving surface P, whereby the piston 210 is driven to the left. As a result, the moving contact of the interrupting portion is opened through the operating rod 21 and the insulating rod 6 in combination. Under the damping action of the damping material 40 and holes 41, the piston 210a abuts the bottom wall of the chamber 39 towards the end of the stroke relatively slowly.

When a command signal for throwing the circuit breaker into a closed state is received, the three-way valve 36 is actuated into a position wherein the compressed air hitherto acting on the pressure-receiving surface P is exhausted into the outside atmosphere through the exhaust pipe 38, and the piston 210a is pushed back to its initial position by the return spring 23. At the same time, the moving core 50 is also pushed back by the spring 29, and the moving core 50 and the piston 210a are brought into contact with each other with the sealing gasket 44 sealing the space therebetween. The three-way valve 36 is then actuated to a position whereby the chamber 35 is connected to the outside atmosphere through the exhaust pipe 37, and the driving means is prepared for a subsequent interruption of the circuit breaker.

Referring to FIG. 5, there is indicated still another example of the driving device wherein the explosion of an explosive agent is utilized for the initiation of the operation of the operating rod.

In this example, a high pressure caused by the explosion of of an explosive agent in response to the trip command of the circuit breaker is guided into a chamber 61 through a guide hole 60. As a result, a piston 62 is quickly moved rightward through a small distance, and a gasket attached portion 63 of the piston 62 is also moved rightward to break the seal of a space formed between the left side surface of the piston 62 and the right side surface of another piston 210a.

The breaking of the seal causes a high pressure in a chamber 35 to be applied onto the pressure-receiving surface P of the piston 210a, and the driving device is operated in the same manner as described hereinbefore with respect to the examples shown in FIGS. 2 through 4. When the piston 210a is brought to its initial position, the chamber 35 is exhausted through the action of the three-way valve 36, and the piston 210a is retracted under the action of the return spring 23. Likewise, the piston 62 is brought back to its original position by the return spring 29 when the pressure in the chamber 61 is lowered.

In the above described device, the members driven by the exlosion energy are only the piston 62 with its sealing gaskets and the portion 63 integral therewith, and the realization of the highspeed driving of the device and the design of the explosion devices related thereto are thereby much facilitated. Furthermore, since the inflamable substance such as an explosive and the high-pressure air are separated with respect to their positions in the device, safety in the design of the driving device can be easily attained.

Since the explosion of an explosive agent can be initiated ordinarily by a small electrical energy, a suitable electrical ignition device for this purpose can be easily provided. Moreover, the explosive always has a great amount of energy stored internally therein, and this feature is advantageous in the design of a circuit breaker of a reclosing type.

Claims

I claim:

1. In a tank-type gas-filled circuit breaker having interrupting contacts disposed in a contact-chamber and an insulating operating rod which is directly connected to open the interrupting contacts by a pulling force on the operating rod, an operating mechanism comprising: a high pressure gas chamber disposed separate from and outside of said contact chamber; a cylinder arranged within said high-pressure gas chamber; a piston disposed to opeate witnin said cylinder and forming therein a first cylinder region in which one side of the piston is constantly exposed to be acted upon by high pressure gas contained in said high pressure gas chamber; a second cylinder region formed on the other side of the piston; a low pressure exhausting chamber disposed within said high pressure gas chamber so as to be capable of being connected with said second cylinder region; sealing means separating said low pressure exhausting chamber and said second cylinder region so as to prevent low pressure from being communicated to said second cylinder region when the sealing means is closed, said piston being directly connected to said insulating operating rod and being acted upon by a resilient biasing means for pushing the operating rod to hold the interrupting contacts in closed position; and means for impulsively breaking said seal and establishing instantaneous communication between said second cylinder region and the low pressure exhausting chamber, whereby the high pressure gas acting on said one side of the piston creates an impulsive pressure differential on the piston so as to pull the rod against said biasing means and operate the interrupting contacts when the means for impulsively breaking the seal opens the seal.

2. A circuit breaker as claimed in claim 1, wherein said means for impulsively breaking said seal comprises an electromagnetic driving means.

3. A circuit breaker as claimed in claim 2 where the electromagnetic driving means includes an electromagnetic coil and a soft-iron member disposed to be attracted thereby.

4. A circuit breaker as claimed in claim 2 where the electromagnetic driving means includes an electromagnetic ciil and a soft-iron member disposed to be repulsed thereby.

5. A circuit breaker as claimed in claim 1, wheein said means for impulsively breaking said seal comprises means utilizing explosive force from an ignited explosive agent.