The present application claims priority from Japanese Patent Application JP 2019-167169 filed on Sep. 13, 2019, the content of which is hereby incorporated by reference into this application.
The present invention relates to gas circuit breakers, and in particular relates to gas circuit breakers that blow an insulating gas onto an arc generated between contacts at the time of current interruption, and thereby extinguish the arc.
In recent years, voltages and currents that electrical power systems are required to support are increasing, and the capacities of gas circuit breakers are increasing in order to attain required interruption performance. In addition, for cost reduction, sizes of gas circuit breakers have also been reduced by optimization of structures such as interrupting sections, evacuating sections or shields. However, in terms of size-reduction of apparatuses, there is a limitation for puffer-type gas circuit breakers that use only mechanical compression to attain the pressure of a gas to be blown at the time of arc extinction. Along with the increase in operation energy of operation devices, thermal-puffer-type gas circuit breakers that expand a gas by using arc heat generated at the time of current interruption, and extinguish an arc by blowing the gas by using the pressure resulting from the expansion are under development.
Thermal-puffer-type gas circuit breakers extinguish an arc generated between a fixed arc contact and a movable arc contact by blowing a high-pressure insulating gas compressed in a mechanical puffer chamber and a thermal puffer chamber onto the arc. Since the gas pressure is formed by using arc heat in the thermal puffer chamber in thermal-puffer-type gas circuit breakers, the operation force required for an operation device can be reduced, and the size-reduction of the operation device is possible.
An example of conventional thermal-puffer-type gas circuit breakers is described in JP-2012-079601-A. In the gas circuit breaker described in JP-2012-079601-A, a thermal puffer chamber is provided in series to a mechanical puffer chamber, a partitioning member that divides the inner space of the thermal puffer chamber in the radial direction is provided in the thermal puffer chamber, a switch valve is provided as gas flow control means between an arc space and the thermal puffer chamber, and a movable valve is provided between the thermal puffer chamber and the mechanical puffer chamber. At the time of interruption of a large current, the switch valve causes a high-temperature, high-pressure arc-extinguishing gas from the arc space to pass through the space on the outer circumference side of the partitioning member and then through the space on the inner circumference side of the partitioning member, and to be blown onto an arc. At the time of interruption of an intermediate to small current, an arc-extinguishing gas from the mechanical puffer chamber is guided only to the space on the inner circumference side of the partitioning member and blown onto an arc.
Since a gas pressure is formed by using arc heat in a thermal puffer chamber in a thermal-puffer-type gas circuit breaker, a gas to be blown onto an arc generated at the time of current interruption becomes a hot gas at a high temperature, and there is a fear that the insulating performance of the gas deteriorates, and the interruption performance deteriorates. In particular, if a current to be interrupted is large, the arc heat increases. Accordingly, the gas temperature becomes higher, and sufficient interruption performance might not be attained.
The gas circuit breaker described in JP-2012-079601-A has improved arc extinction performance at the time of interruption of large currents and at the time of interruption of intermediate to small currents by including the partitioning member that divides the inner space of the thermal puffer chamber in the radial direction, the switch valve and the movable valve. However, since the partitioning member is provided in the thermal puffer chamber in the gas circuit breaker described in JP-2012-079601-A, the volume of the thermal puffer chamber, that is, the volume of the gas used for arc extinction, decreases, and there is a fear that the interruption performance deteriorates. In particular, since the gas is blown onto an arc only from the space on the inner circumference side of the partitioning member at the time of interruption of an intermediate to small current, the volume of the gas used for arc extinction might be halved. In addition, since the gas circuit breaker described in JP-2012-079601-A includes the partitioning member, the switch valve and the movable valve, there is a fear that the number of parts increases, and the cost increases.
In this manner, conventional gas circuit breakers have a problem that if a gas pressure is formed by using arc heat in a thermal puffer chamber, the temperature of a gas to be blown onto an arc rises to cause deterioration of the insulating performance of the gas or cause reduction of the gas volume, and there is a fear that the interruption performance deteriorates. In addition, they have a problem that there is a fear that if additional operation parts such as a switch valve or a movable valve are provided, the cost increases.
An object of the present invention is to provide a gas circuit breaker in which a high-temperature gas having flowed into a thermal puffer chamber is cooled, and blown onto an arc, thereby preventing deterioration of the insulating performance of the gas, and improving the interruption performance of the gas circuit breaker.
A gas circuit breaker of the present invention includes; a cylindrical gas tank that is filled with an insulating; a movable main contact that moves in an axial direction to separate from a fixed main contact and interrupt a current; a movable arc contact that generates an arc between the movable arc contact and a fixed arc contact at a time of the interruption of the current; a puffer cylinder having one end portion at which the movable main contact is provided; a hollow rod that is arranged inside the puffer cylinder, has one end portion at which the movable arc contact is provided, and has an inner space through which the insulating gas flows; a thermal puffer chamber that is formed by being surrounded by the puffer cylinder and the hollow rod; an insulating cover that is provided at one end portion of the hollow rod, and covers the movable arc contact; an insulating nozzle provided at one end portion of the puffer cylinder; and a flow guide that is a cylindrical member extending in the axial direction, the movable main contact, the movable arc contact, the puffer cylinder, the hollow rod, the thermal puffer chamber, the insulating cover, the insulating nozzle, and the flow guide being included in the cylindrical gas tank. The flow guide is installed in the thermal puffer chamber, is positioned on the outer circumference side of the hollow rod, and has one end portion connected to the insulating nozzle. The space between the flow guide and the hollow rod is connected to the space between the insulating nozzle and the insulating cover, and serves as a flow path of the insulating gas.
According to the present invention, in a gas circuit breaker that can be provided, a high-temperature gas having flowed into a thermal puffer chamber is cooled, and blown onto an arc. Thereby, deterioration of the insulating performance of the gas is prevented, and the interruption performance of the gas circuit breaker is improved.
In the following, gas circuit breakers according to embodiments of the present invention are explained by using the drawings. In the drawings used in the present specification, identical or corresponding constituent elements are given identical signs, and repetitive explanations about these constituent elements are omitted in some cases. Note that the embodiments illustrated below are merely examples of embodiments of the present invention, and the content of the present invention is not limited to the following aspects.
First, a conventional thermal-puffer-type gas circuit breaker is explained.
The gas circuit breaker includes the cylindrical gas tank 1 filled with an insulating gas, a movable arc contact 2, a fixed arc contact 3, a movable main contact 5 and a fixed main contact 4. The movable arc contact 2, the fixed arc contact 3, the movable main contact 5 and the fixed main contact 4 are housed inside the gas tank 1. SF6 can be used as an insulating gas, for example. Note that insulating gases that can be used are not limited to SF6, but other insulating gases such as dry air or a nitrogen gas may be used.
In the following, the direction of the axis of the gas tank (the horizontal direction in
The movable arc contact 2 faces the fixed arc contact 3 in the axial direction, can move in the axial direction, and generates an arc between the movable arc contact 2 and the fixed arc contact 3 at the time of interruption of current. The movable arc contact 2 is positioned in the interrupting direction relative to the fixed arc contact 3 (the right side of
The movable main contact 5 faces the fixed main contact 4 in the axial direction, can move in the axial direction, and performs opening operation of interrupting current and closing operation of not interrupting current. The movable main contact 5 is positioned in the interrupting direction relative to the fixed main contact 4 (the right side of
The gas circuit breaker further includes a puffer cylinder 8, a hollow rod 6, a puffer piston 7, a mechanical puffer chamber 9, the thermal puffer chamber 10, an insulating cover 13, an insulating nozzle 11, a shield 12 and an operation device 19.
The puffer cylinder 8 is positioned on the outer circumference side (radially outer side) of the movable arc contact 2, and is arranged so as to share a common central axis with the movable arc contact 2. The puffer cylinder 8 has one end portion in the non-interrupting direction at which the movable main contact 5 is provided, and the puffer cylinder 8 houses the hollow rod 6. Note that the inner circumferential surface of the puffer cylinder 8 is parallel with the axial direction.
The hollow rod 6 is arranged inside the puffer cylinder 8 so as to share a common central axis with the puffer cylinder 8. The hollow rod 6 has one end portion in the non-interrupting direction at which the movable arc contact 2 is provided. The hollow rod 6 has a hollow inner space through which the insulating gas flows. Note that the outer circumferential surface of the hollow rod 6 is parallel with the axial direction.
The puffer piston 7 is supported by a mounting eye provided on the inner circumferential surface of the gas tank 1, positioned inside the puffer cylinder 8, and moves in a space formed between the puffer cylinder 8 and the hollow rod 6.
The mechanical puffer chamber 9 is formed by being surrounded by the puffer cylinder 8, the hollow rod 6 and the puffer piston 7.
The thermal puffer chamber 10 is formed by being surrounded by the puffer cylinder 8 and the hollow rod 6, the insulating gas flows into or flows out of the thermal puffer chamber 10, and the thermal puffer chamber 10 has a constant volume. The thermal puffer chamber 10 includes a check valve 14, is adjacent to the mechanical puffer chamber 9 in the axial direction, and is connected to the mechanical puffer chamber 9 by a communicating hole 15. The communicating hole 15 is provided through a partition wall between the thermal puffer chamber 10 and the mechanical puffer chamber 9, and is opened and closed by the check valve 14. That is, communication between the thermal puffer chamber 10 and the mechanical puffer chamber 9 is controlled by the check valve 14.
Inside the thermal puffer chamber 10, the check valve 14 is provided on the outer circumferential surface of the hollow rod 6, and is moved in the axial direction by a pressure difference between the thermal puffer chamber 10 and the mechanical puffer chamber 9. When the pressure inside the thermal puffer chamber 10 is lower than the pressure inside the mechanical puffer chamber 9, the check valve 14 moves in the non-interrupting direction, and opens the communicating hole 15 to establish communication between the thermal puffer chamber 10 and the mechanical puffer chamber 9. When the pressure inside the thermal puffer chamber 10 is higher than the pressure inside the mechanical puffer chamber 9, the check valve 14 moves in the interrupting direction, and closes the communicating hole 15 to interrupt communication between the thermal puffer chamber 10 and the mechanical puffer chamber 9.
The insulating cover 13 is provided at one end portion of the hollow rod 6 in the non-interrupting direction, and covers the movable arc contact 2.
The insulating nozzle 11 is positioned on the outer circumference side of the insulating cover 13, and provided at one end portion of the puffer cylinder 8 in the non-interrupting direction. The space between the insulating nozzle 11 and the insulating cover 13 communicates with the thermal puffer chamber 10, and serves as a gas flow path.
The shield 12 covers the fixed arc contact 3 and the fixed main contact 4.
The operation device 19 can move the insulating nozzle 11, the puffer cylinder 8, the hollow rod 6, the movable arc contact 2, the movable main contact 5 and the like in the interrupting direction.
In the closing state of the gas circuit breaker (
At the time of a short-circuit failure or the like of an electrical power system, the gas circuit breaker receives an instruction for opening, and performs interrupting operation. The operation device 19 moves the hollow rod 6 and the puffer cylinder 8 in the interrupting direction, and moves the movable arc contact 2 and the movable main contact 5 in the interrupting direction to thereby perform the interrupting operation. The movable arc contact 2 is physically opened by being separated from the fixed arc contact 3, and the movable main contact 5 is physically opened by being separated from the fixed main contact 4 (
When the movable arc contact 2 and the movable main contact 5 move at the time of interruption, the puffer cylinder 8 moves relative to the puffer piston 7. Thereby, the puffer piston 7 compresses the insulating gas inside the mechanical puffer chamber 9. More specifically, a driving force of the operation device 19 is transmitted to the puffer cylinder 8 via an insulating rod (not illustrated) connected to the operation device, and the hollow rod 6, and the puffer cylinder 8 moves. Thereby, the insulating gas inside the mechanical puffer chamber 9 is compressed by the puffer piston 7. If the check valve 14 is opening the communicating hole 15, the compressed insulating gas passes through the communicating hole 15 to flow from the mechanical puffer chamber 9 into the thermal puffer chamber 10, flows through the space between the insulating nozzle 11 and the insulating cover 13 to be blown onto the arc 30, and extinguishes the arc 30 (the figure on the lower half of
In the thermal-puffer-type gas circuit breaker, a hot gas 31 which is a gas at a temperature raised by arc heat is taken into the thermal puffer chamber 10 to thereby form a pressure. Because of this, the thermal-puffer-type gas circuit breaker operates according to different principles of interruption depending on the magnitudes of current to be interrupted.
At the time of interruption of a large current when a current to be interrupted is relatively large (e.g. a current at the time near a peak), the energy of the arc 30 is high, the gas pressure in the arc space 34 (the space where the arc 30 is generated) is higher than the gas pressure in the thermal puffer chamber 10, and the hot gas 31 passes through the space between the insulating nozzle 11 and the insulating cover 13 to flow into the thermal puffer chamber 10 (the figure on the upper half of
At the time of interruption of an intermediate to small current when a current to be interrupted is relatively small, the pressure inside the thermal puffer chamber 10 is lower than the pressure inside the mechanical puffer chamber 9 even if the pressure inside the thermal puffer chamber 10 rises due to the arc heat. Because of this, the check valve 14 opens the communicating hole 15 to establish communication between the thermal puffer chamber 10 and the mechanical puffer chamber 9. The insulating gas compressed by the mechanical puffer chamber 9 passes through the communicating hole 15 from the mechanical puffer chamber 9 to flow into the thermal puffer chamber 10, and is blown onto the arc 30 from the thermal puffer chamber 10, and the arc 30 is extinguished.
When the gas flows into the thermal puffer chamber 10 (the figure on the upper half of
In particular, at the time of interruption of an intermediate to small current when a current to be interrupted is relatively small, the energy of the arc 30 is low. Accordingly, the gas flow rate is not high, and the hot gas 31 does not reach deep (the right side of
When the energy of the arc 30 becomes low, the pressure in the arc space 34 lowers, and the pressure in the thermal puffer chamber 10 becomes higher than the pressure in the arc space 34, the insulating gas starts being blown onto the arc 30 from the thermal puffer chamber 10. When the insulating gas is blown onto the arc 30 (the figure on the lower half of
A gas circuit breaker according to a first embodiment of the present invention is explained. In the following, explanations of configurations of the gas circuit breaker according to the present embodiment that are common to the conventional gas circuit breaker illustrated in
The gas circuit breaker according to the present embodiment includes a flow guide 16, which is a cylindrical member extending in the axial direction. The flow guide 16 is installed in the thermal puffer chamber 10, positioned on the outer circumference side (radially outer side) of the hollow rod 6, and has one end portion connected to the insulating nozzle 11. The flow guide 16 is a member provided in the thermal puffer chamber 10 such that the insulating nozzle 11 extends in the axial direction. The space between the flow guide 16 and the hollow rod 6 is connected to the space between the insulating nozzle 11 and the insulating cover 13, and serves as a gas flow path that establishes communication between the thermal puffer chamber 10 and the arc space 34.
The flow guide 16 forms, with the hollow rod 6, a flow path that guides the hot gas 31 deep (the right side of
The flow guide 16 can be formed with a material which is the same as the material of the insulating nozzle 11. The insulating nozzle 11 can be formed with a composite material containing a resin which is less heat-resistant than fluororesin, and an inorganic filler added to the resin. For example, the insulating nozzle 11 can be formed with a fluororesin mixed with boron-nitride (BN) powders or the like. The flow guide 16 may be fabricated integrally with the insulating nozzle 11 or maybe fabricated separately from the insulating nozzle 11, and installed onto the insulating nozzle 11.
Since the gas circuit breaker according to the present embodiment includes the flow guide 16, the hot gas 31 can be guided deep (the right side of
Preferably, the other end portion of the flow guide 16 (the end portion opposite, in the axial direction, to the end portion at which the flow guide 16 is connected to the insulating nozzle 11) is positioned farther from the insulating nozzle 11 in the axial direction than the center of the thermal puffer chamber 10 in the axial direction is. That is, preferably, the other end portion of the flow guide 16 is deeper in the thermal puffer chamber 10 in the interrupting direction (the right side of
Since at the time of interruption of an intermediate to small current, the pressure inside the thermal puffer chamber 10 is lower than the pressure inside the mechanical puffer chamber 9, the check valve 14 opens the communicating hole 15 to establish communication between the thermal puffer chamber 10 and the mechanical puffer chamber 9. The insulating gas compressed in the mechanical puffer chamber 9 passes through the communicating hole 15, flows from the mechanical puffer chamber 9 into the thermal puffer chamber 10, and, inside the thermal puffer chamber 10, forms the gas flow 32 in the space between the flow guide 16 and the puffer cylinder 8. Due to this gas flow 32, the hot gas 31 having flowed along the flow path between the flow guide 16 and the hollow rod 6 can be cooled over the entire internal space of the thermal puffer chamber 10.
Since the gas circuit breaker according to the present embodiment includes the flow guide 16, the hot gas 31 having flowed into the thermal puffer chamber 10 can be sufficiently mixed and cooled with the cool gas 33 inside the thermal puffer chamber 10, and the cooled gas can be blown onto the arc 30. Accordingly, deterioration of the insulating performance of the gas can be prevented, and the interruption performance can be improved.
In addition, preferably, the area of the gas flow path from the thermal puffer chamber 10 into the arc space 34 (the cross-sectional area of the flow path perpendicular to the direction of the gas flow) decreases from the upstream side to the downstream side in the direction of the flow of the gas from the thermal puffer chamber 10 to the arc space 34 (the direction of the gas flow formed when the gas is blown onto the arc 30).
As illustrated in
If the flow path area S3 is larger than the flow path area S2, and the flow path area S2 is larger than the flow path area S1, the flow path area decreases gradually as the gas flows when the gas is blown onto the arc 30. Accordingly, lowering of the gas flow rate due to expansion of the gas does not occur. Because of this, it is possible to prevent the gas flow from becoming still, and blow the gas onto the arc 30 from the thermal puffer chamber 10, to thereby improve the interruption performance of the gas circuit breaker.
A gas circuit breaker according to a second embodiment of the present invention is explained. In the following, configurations of the gas circuit breaker according to the present embodiment that are different from the gas circuit breaker according to the first embodiment are explained mainly.
In the gas circuit breaker according to the present embodiment, the flow guide 16 includes holes 17 penetrating therethrough in the radial direction. The holes 17 are provided through the side surface of the flow guide 16, and establish communication between the space inside the flow guide 16 and the space outside the flow guide 16. The flow guide 16 may include a single hole 17 in the circumferential direction, but preferably includes a plurality of holes 17 in the circumferential direction. In addition, the flow guide 16 may include a plurality of holes 17 in the axial direction. The number of the holes 17 may be optional.
As illustrated in the figure on the upper half of
The gas flow 32 at the time when the gas is blown onto the arc 30 from the thermal puffer chamber 10, that is, at the time of interruption, is explained by using the figure on the lower half of
At the time of interruption of an intermediate to small current, the gas having flowed from the mechanical puffer chamber 9 into the thermal puffer chamber 10 passes through the holes 17, flows along the flow path between the flow guide 16 and the hollow rod 6, and the flow path between the insulating nozzle 11 and the insulating cover 13, and is blown onto the arc 30. The hot gas 31 having reached the thermal puffer chamber 10 passes through the holes 17 and circulates through the inner space of the thermal puffer chamber 10 due to the gas flow from the mechanical puffer chamber 9, and is cooled more effectively.
At the time of interruption of a large current, the check valve 14 is closed, and there are no gas flows from the mechanical puffer chamber 9 into the thermal puffer chamber 10, but the cool gas 33 inside the thermal puffer chamber 10 is guided to the space between the flow guide 16 and the puffer cylinder 8, passes through the holes 17, and is blown onto the arc 30.
In the manner mentioned above, the gas circuit breaker according to the present embodiment can prevent deterioration of the insulating performance of the gas, and can improve the interruption performance.
As illustrated in the figure on the lower half of
Preferably, the holes 17 of the flow guide 16 have shapes with the flow path area S4 that decreases from the radially outer side toward the radially inner side.
A gas circuit breaker according to a third embodiment of the present invention is explained. In the following, configurations of the gas circuit breaker according to the present embodiment that are different from the gas circuit breaker according to the first embodiment are explained mainly.
In the first and second embodiments, the flow guide 16 extends in parallel with the axial direction (i.e. in parallel with the inner circumferential surface of the puffer cylinder 8), and causes the hot gas 31 to flow in parallel with the axial direction, and guides the hot gas 31 deep (the right sides of
In the present embodiment, the flow guide 16 extends in the axial direction obliquely toward the radially outer side, and when the hot gas 31 flows into the thermal puffer chamber 10 (the figure on the upper half of
A stopper 35 is installed on the outer circumferential surface of the hollow rod 6. The stopper 35 is a member that stops the motion of the check valve 14 when the check valve 14 moves in the non-interrupting direction to open the communicating hole 15. Since the flow guide 16 extends toward the radially outer side obliquely to the axial direction, the hot gas 31 flowing into the thermal puffer chamber 10 flows toward the check valve 14 without being inhibited by the stopper 35.
In the gas circuit breaker illustrated in
At the time of interruption of a large current when a current to be interrupted is relatively large, the pressure inside the thermal puffer chamber 10 is higher than the pressure inside the mechanical puffer chamber 9. Accordingly, the check valve 14 moves in the interrupting direction to close the communicating hole 15, and interrupts communication between the thermal puffer chamber 10 and the mechanical puffer chamber 9. There is a fear that if this operation of the check valve 14 is late, the pressure in the thermal puffer chamber 10 is transferred to the mechanical puffer chamber 9, the puffer reaction force increases due to a pressure drop of the thermal puffer chamber 10 or a pressure increase of the mechanical puffer chamber 9, and the speed of the interrupting operation lowers.
Since the gas flow path formed with flow guide 16 and the hollow rod 6 in the gas circuit breaker according to the present embodiment is formed such that the hot gas 31 flowing into the thermal puffer chamber 10 flows toward the check valve 14, the check valve 14 can move in the interrupting direction faster to close the communicating hole 15 upon receiving the dynamic pressure of the flow of the hot gas 31. In the gas circuit breaker according to the present embodiment, the check valve 14 can be moved faster in the interrupting direction when the hot gas 31 flows into the thermal puffer chamber 10, and a pressure drop of the thermal puffer chamber 10, a pressure increase of the mechanical puffer chamber 9, and lowering of the interruption speed can be prevented.
A gas circuit breaker according to a fourth embodiment of the present invention is explained. In the following, configurations of the gas circuit breaker according to the present embodiment that are different from the gas circuit breaker according to the third embodiment are explained mainly.
Note that in the gas circuit breaker according to the present embodiment, the outer circumferential surface of the hollow rod 6 may be parallel with the axial direction like the gas circuit breaker illustrated in
According to the present embodiment, in the gas circuit breaker according to the third embodiment, the flow guide 16 includes holes 17 penetrating therethrough in the radial direction, similar to the gas circuit breaker according to the second embodiment. Since the flow guide 16 include the holes 17, the gas flow similar to the gas flow explained in the second embodiment can be formed at the time of interruption. Accordingly, the gas circuit breaker according to the present embodiment can prevent deterioration of the insulating performance of the gas, and can improve the interruption performance at the time of interruption of an intermediate to small current and at the time of interruption of a large current.
Note that the present invention is not limited to the embodiments described above, but can be modified in various manners. For example, the embodiment described above are explained in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to aspects including all the configurations explained. In addition, some of the configurations of an embodiment can be replaced with configurations of other embodiments. In addition, configurations of an embodiment can be added to the configurations of another embodiment. In addition, some of the configurations of each embodiment can be deleted or subjected to addition/replacement of other configurations.
Number | Date | Country | Kind |
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2019-167169 | Sep 2019 | JP | national |