JP2875671B2 - Patch type gas circuit breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-type circuit breaker, and more particularly to a gas-type circuit breaker using an insulating nozzle having a plurality of throat portions.

[0002]

2. Description of the Related Art Generally, a buffer type gas circuit breaker includes a pair of contacts that can be relatively separated from each other, and a gas compression device that compresses an arc-extinguishing gas with the opening of the contacts. ,
An arc extinguishing gas compressed by a gas compression device is guided by an insulating nozzle to the arc generated by the separation between the contacts, thereby blowing the arc.

[0003] As a conventional type of gas circuit breaker of this type, one disclosed in Japanese Patent Application Laid-Open No. 1-243328 is known, and this is shown in FIG. FIG. 1 shows a cut-off portion formed in an atmosphere of an arc-extinguishing gas. Among the contacts forming a pair, a fixed contact 11 has a small-diameter portion 11a at its tip.
And a large diameter portion 11c on the base side, and a gradual diameter change portion 11b in the middle between them. The outer diameter of the small diameter portion 11a is D1, and the outer diameter of the large diameter portion 11c is D2.
It is. On the other hand, the movable contact 2 has the small diameter portion 11a in the closed state.
Attached to the buffer cylinder 1 so that
It is covered with an insulating cover 3 and further covered with an insulating nozzle 4 so as to form a flow path on its outer periphery. The insulating nozzle 4 has a first throat portion 4a on the upstream side of a blowing gas flow described later, and has a second throat portion 4b on the downstream side of the gas flow, and the throat portions 4a, 4b.
The inner surface between b is recessed to form a space S. The inside diameter of the first throat portion 4a is DA and the small-diameter portion 11a is inserted, and the inside diameter of the second throat portion 4b is DB and the large-diameter portion 11c is inserted. The gas compression device 8 is constituted by the piston 7 fitted in a slidable relationship with the buffer cylinder 1, and the shaft 6 of the buffer cylinder 1 is formed.
Is connected to an operating device (not shown).

In the inserted state shown in the drawing, the second throat portion 4b enters the large-diameter portion 11c of the fixed contact 11 by the fitting dimension X, and is substantially closed by the large-diameter portion 11c, while the first throat portion 4b is closed. A small-diameter portion 11a is inserted into the throat portion 4a, and a gas inflow portion G communicating between the gas compression device 8 and the space S is formed by the diameter difference (DA-D1).

When the shaft 6 is driven rightward by an operating device (not shown), the contacts 2 and 11 are separated while the arc-extinguishing gas is compressed by the gas compressing device 8. After that, the relative positional relationship between the fixed contact 11 and the movable contact 2 is in the state A shown by the dashed line in FIG. Since the first throat portion 4a moves along the small-diameter portion 11a from the start of the shut-off operation to this state, the first throat portion 4a moves through the gas inflow portion G formed between the first throat portion 4a and the gas thrust portion 4a. High-pressure gas is supplied as indicated by arrow 25. On the other hand, the second throat portion 4b is substantially closed by the large-diameter portion 11c. For this reason, in the space S, a pressure substantially equal to that of the facing portion between the contacts 2 and 11 is maintained. As described above, since the second throat portion 4b is substantially closed by the large-diameter portion 11c so that a substantial gas flow is not formed, the gas density at the distal end portion of the fixed contactor 11 is kept high. Therefore, the arc generated due to the separation between the contacts disappears and the contacts 2, 2
Even in the case of advanced small current interruption in which a high recovery voltage is applied during 11, good interruption performance can be obtained.

When the second throat portion 4b comes out of the large-diameter portion 11c as the interrupting operation further proceeds, a gas flow indicated by an arrow 25 is formed, and the gas density at the tip of the fixed contact 11 decreases. Since the separation distance between the contacts 2 and 11 is sufficiently large, the electric field strength is very small, and it is said that a high withstand voltage can be obtained.

Japanese Patent Application Laid-Open No. Sho 60-150521 discloses a similar type of gas-type circuit breaker.
In this case, the gas flow is changed downstream of the blowing gas flow from the throat portion to form a tapered portion that increases the gas pressure at the tip of the fixed contact.

[0008]

However, the relative position of the fixed contact 11 that can be cut off when a short-circuit current of several tens of thousands A is cut off is in the range of B to C shown in FIG. That is, when a large current is interrupted by a circuit breaker having a fast interrupting speed, the relative positional relationship shown in FIG. 5B is already reached at the time when the current zero point at which the alternating current of the commercial frequency can be interrupted is reached. Accordingly, the small-diameter portion 11a of the fixed contact 11 comes out from the tip of the insulating nozzle 4, and the high-pressure arc-extinguishing gas from the gas compressor 8 is not effectively blown to the fixed contact 11, so that the fixed contact 11 is not fixed. The gas density in the vicinity of the tip of the contact 11 decreases, and as a result, the dielectric strength between the opposing portions of the contacts 2 and 11 decreases, and the large current interrupting performance deteriorates.
FIG. 5C shows the relative position of the fixed contact 11 close to the full stroke, and the fixed contact 11 is the second throat portion 4b of the insulating nozzle 4 in the moving range from the position B to the position C. , And the gas pressure at the tip of the fixed contact 11 further decreases. The same applies to the buffer type gas circuit breaker disclosed in JP-A-60-150521.

It is an object of the present invention to provide a breaking performance in the case where the breaking is performed at a point where the separation length is relatively small as in the case of a small current advance, and a breaking performance in which the breaking length is relatively small as in the case of a large current break. It is an object of the present invention to provide a buffer-type gas circuit breaker which can improve both the breaking performance when breaking is performed at a large time.

[0010]

In order to achieve the above object, the present invention forms a second throat portion downstream of the first throat portion in the blowing gas flow, and forms a second throat portion in the second throat portion. The downstream side of the blast gas flow has at least one inflection point after enlargement at a divergent opening angle, and the inflection point is directed to the second throat portion downstream of the blast gas flow. While having an opening angle smaller than the opening angle and having an opening angle of 15 degrees or less with respect to the axis of the fixed contactor,
Downstream end of the blowing gas stream above Symbol insulating nozzle or
The length to the inflection point not less than 15mm from the lower
The inner diameter of the flow side end is set to be 1.2 times or less the inner diameter of the inflection point.

[0011]

Since the buffer type gas circuit breaker according to the present invention has the above-described configuration, even if the tip of the fixed contact comes off from the first throat portion, the second gas blower provided downstream of the blowing gas flow.
Unnecessary release of gas is suppressed by the throat section, so that the gas density at the tip section is increased to cut off when the cutoff is performed at a relatively small separation length, such as when cutting off a small current. And an inflection point is formed on the downstream side of the blowing gas flow from the second throat portion,
The inflection point, as well as smaller than the opening angle of the downstream side of the blowing gas stream of the second throat portion has a open angle below 15 degrees with respect to the axis of the fixed contact, insulation nozzle was or The length from the downstream end of the blowing gas flow to the inflection point is 15 mm or more, and the inner diameter of the downstream end is 1.2 times or less the inner diameter of the inflection point, so that when a large current is interrupted, Even under the most severe breaking conditions, the gas density at the tip of the fixed contact can be increased by the narrowed opening angle after the inflection point, and the breaking is performed at a relatively large separation length. The blocking performance can also be improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a buffer type gas circuit breaker according to one embodiment of the present invention, and the illustrated portion is configured in a container filled with an arc-extinguishing gas. The shaft 6 provided at the center of the buffer cylinder 1 is connected to an operating device (not shown), and the inner surface of the buffer cylinder 1 is connected to the shaft 6.
The fixed piston 7 is fitted in a slidable relationship between the outer surfaces of the fixed piston 7. The arc-extinguishing gas in the space called the buffer chamber formed by these components is compressed by driving the shaft 6 in the right-hand opening direction, and the gas compression device 8 is constituted by these components. . On the left end surface of the buffer cylinder 1, a movable contact 2 attached to a mount 12, an insulating cover 3 surrounding the movable contact 2, and an insulating cover 3 surrounding the insulating cover 3 so as to form a flow path. Nozzle 4
Are fixed by the holding metal 5. Insulation nozzle 4
A first throat portion 4a formed on the upstream side of the blowing gas flow close to the movable contact 2, a second throat portion 4b formed on the downstream side of the blowing gas flow, and further positioned downstream thereof. Each of the airflow guide portions 4c is formed. The opening angle θ ₁ on the downstream side of the blowing gas flow of the second throat portion 4b gradually increases the cross-sectional area of the hollow portion serving as the gas flow path so as to have a divergent shape. An inflection point L is provided in the vicinity of a position where the current can be interrupted at the time of the first interruption, and the opening angle θ of the airflow guide portion 4c located downstream from the inflection point L to the blowing gas flow.
₂ is summer smaller than the angle θ ₁ Open earlier. The insulating nozzle 4 has a recess between the throat portions 4a and 4b, and the recess S forms a space S. The fixed contact 11 has a small-diameter portion 11a at its tip, and the diameters D1 and DA of the respective portions are selected such that a gas inflow portion G is formed between the fixed contact 11 and the first throat portion 4a fitted with the small-diameter portion 11a. I have.
The base of the fixed contact 11 has a large-diameter portion 11c, and the diameter D of each portion is set so as to substantially close the gap with the second throat portion 4b.
2, DB is selected.

Next, the shut-off operation will be described. When the shaft 6 is driven rightward by an operating device (not shown) from the input state shown in FIG. 1, the arc-extinguishing gas is compressed by the gas compression device 8 and the fixed contact 11 is opened from the movable contact 2. Then, the state shown in FIG. 2 is obtained. When the current to be interrupted is a small current, the distal end of the small-diameter portion 11a of the fixed contact 11 relatively comes out of the first throat portion 4a, and the gas is compressed from the gas compression device 8 via the gas inflow portion G. As a result, the arc between the contacts 2 and 11 is extinguished by the blowing gas flow that reaches the space S, and a high recovery voltage is applied between the contacts 2 and 11 having a relatively small separation distance. However, since the blowing gas flow is restricted by the second throat portion 4b, the gas density at the distal end portion of the fixed contact 11 is increased, thereby exhibiting a high dielectric strength and enabling interruption. Becomes

However, when the current to be interrupted is a large current, the interrupting operation is not interrupted at this point and the interrupting operation further proceeds to reach the state shown in FIG. When the distal end of the fixed contact 11 reaches the relative position B indicated by the two-dot chain line, the distal end of the fixed contact 11 is located near the inflection point L and reaches the first breakable minimum opening position. The relative position C of the full stroke is reached. Here, the result of studying the gas density characteristics of the tip of the fixed contact 11 by analysis will be described with reference to FIG. In the case of the conventional shape (a) shown in FIG. 4, the gas density increases with the time after the arc extinguishing, temporarily decreases, and then increases again. The shape (b) is the opening angle θ _{2 of the} airflow guide 4c.
There shows the gas density of the same when the angle theta ₁ open second throat portion 4b, the ratio of the temporarily reduced gas density is less summer but occurred yet gas density reduction itself. However, open as shown in FIG. 1 an angle theta ₂ inflection point L
In the shape (c) having a smaller size thereafter, the gas density does not temporarily decrease, but has a characteristic of uniformly increasing with time. This characteristic is the same at the position C where the fixed contact 11 is close to the full stroke. Further, even if the downstream angle θ ₂ of the opening angle is zero degrees, that is, parallel to the axial direction of the fixed contact 11, the same effect as that of the shape (c) can be obtained. Therefore, FIG.
Even if a high recovery voltage is applied after cutting off a large current within the range of the relative positions B to C of the tip of the fixed contact 11 shown in FIG. Therefore, a high withstand voltage can be maintained.

[0015] Figure 11 is a longitudinal sectional view showing only the insulating nozzle 4, the length from the tip of the air flow guide portion 4c to the inflection point L l, the inner diameter at the inflection point L D3, the airflow guide portion 4c And the opening angle of the fixed contact with respect to the axis line on the downstream side of the blowing gas flow from the inflection point L is θ.
_Shown as ₂ . FIG. 12 shows the results of examining the breaking performance by changing the dimensions and angles of the above-described respective parts in FIG. 11, where D4 / D3 is plotted on the vertical axis and length 1 is plotted on the horizontal axis. The mark indicates a failure to shut off. As can be seen from FIG. 12, the angle θ ₂ is 15 degrees or less, and the length 1 is 15
Under the conditions of not less than mm and the inner diameter D4 being 1.2 times or less of the inner diameter D3, that is, about 1.4 times or less in area ratio, a remarkable effect on the improvement of the withstand voltage was recognized.

FIG. 7 is a partial sectional view showing an insulating nozzle 4 of a buffer type gas circuit breaker according to another embodiment of the present invention.
The insulating nozzle 4 will be described. Two protrusions are provided between a first throat 4a located on the right side of the movable contact (not shown) and a second throat 4b located downstream of the blowing gas. 4d and 4e are formed. Therefore, a plurality of surfaces are formed to prevent the gas flow discharged from the first throat portion 4a from going straight while spreading, and the gas flow colliding with this surface until the fixed contactor 11 reaches the relative position B is formed. The fixed contact 11 is deflected toward the center line in the axial direction, that is, toward the vicinity of the front end, so that the gas density at the front end of the fixed contact 11 can be prevented from lowering. The airflow guide 4c at the tip of the insulating nozzle 4 is the same as in the previous embodiment, and the withstand voltage at the time of interrupting a large current can be improved.

FIG. 8 is a partial sectional view showing an insulating nozzle 4 of a buffer type gas circuit breaker according to still another embodiment of the present invention. The insulating nozzle 4 is manufactured by dividing the insulating nozzle 4 into two parts in the axial direction, and the insulating nozzle 4A in the portion having the first throat portion 4a is improved in arc resistance, for example, a filler is filled in Teflon to improve the arc resistance. The second throat part 4
The part of the insulating nozzle 4B having b is inferior in arc resistance but excellent in insulation, for example, made of Teflon, and these two insulating nozzles 4A and 4B are mechanically connected.

FIG. 9 is a partial sectional view showing an insulating nozzle 4 of a buffer type gas circuit breaker according to still another embodiment of the present invention. The insulating nozzle 4 in this embodiment forms a plurality of inflection points L ₁ and L ₂ on the downstream side of the blowing gas flow from the second throat portion 4b, and sets the respective opening angles to θ ₁ and L ₂ .
When θ ₂ and θ ₃ are set, θ ₁ > θ ₂ > θ ₃ is set so that the opening angle becomes smaller as being located on the downstream side of the blowing gas flow. As described above, the insulating nozzle 4 may have a shape in which at least one inflection point is formed on the downstream side of the blowing gas flow from the second throat portion 4b.

FIG. 10 is a partial sectional view showing an insulating nozzle 4 of a buffer type gas circuit breaker according to still another embodiment of the present invention. The insulating nozzle 4 in this embodiment is the second nozzle.
Are formed at _two inflection points L ₁ and L ₂ on the downstream side of the blowing gas flow from the throat portion 4b of the throat portion 4b.
_When θ ₁ , θ ₂ , and θ ₃ , θ ₂ is zero.

In the above embodiment, the fixed contact 11
Has a small-diameter portion 11a at its distal end and a large-diameter portion 1 at the base side.
1c was formed. For example, ANSI (American)
National Standards Insti
In the case where the duty of the advanced small current interruption is not strict as in (Tute) (supply voltage is 1.2 times the phase voltage), the fixed contact 1
The diameter of the large-diameter portion 11c may be the same as the diameter of the small-diameter portion 11a, or the diameter DA of the first throat portion 4a and the diameter of the fixed contact 11 may be substantially equal. Further, the first throat portion 4a usually has a parallel portion to minimize the diameter enlargement due to wear at the time of current interruption.
Since the second throat 4b is cooled by the blowing gas and has a small diameter expansion, the second throat 4b may or may not have a parallel portion.

[0021]

As described above, according to the present invention, an inflection point is formed on the downstream side of the second throat portion of the insulating nozzle, and this inflection point is located downstream of the blowing gas flow of the second throat portion. while smaller than the opening angle to the side, an angle of opening of 15 degrees or less with respect to the axis of the fixed contact, the length from the downstream end of the or blowing gas stream insulation nozzle to the inflection point And the inner diameter of the downstream end is 1.2 times or less the inner diameter of the inflection point. Even when the interruption is performed at a relatively small point, a decrease in the withstand voltage due to a decrease in the gas density at the tip of the fixed contact is prevented, and a large current is generated by forming the inflection point of the specific configuration as described above. Interruption occurs when the separation length is relatively large, such as during interruption It is possible to prevent a decrease in withstand voltage due to gas density reduction of the distal end portion of the fixed contact in case.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a closed state of a buffer type gas circuit breaker according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of the buffer type gas circuit breaker shown in FIG. 1 in an initial cutoff state.

FIG. 3 is an enlarged sectional view of a main part of the buffer type gas circuit breaker shown in FIG.

FIG. 4 is a longitudinal sectional view showing a closed state of a conventional gas-type circuit breaker.

FIG. 5 is an enlarged sectional view of a main part of the buffer type gas circuit breaker shown in FIG. 4 during a shut-off operation.

FIG. 6 is a characteristic diagram showing a gas density change after arc extinction.

FIG. 7 is a longitudinal sectional view showing only a main part of a buffer type gas circuit breaker according to another embodiment of the present invention.

FIG. 8 is a longitudinal sectional view showing only a main part of a buffer type gas circuit breaker according to still another embodiment of the present invention.

FIG. 9 is a longitudinal sectional view showing only a main part of a buffer type gas circuit breaker according to still another embodiment of the present invention.

FIG. 10 is a longitudinal sectional view showing only a main part of a buffer type gas circuit breaker according to still another embodiment of the present invention.

11 is an enlarged sectional view of the insulating nozzle shown in FIG.

FIG. 12 is a cutoff characteristic diagram when each dimension and angle shown in FIG. 11 are changed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 buffer cylinder 2 movable contact 4 insulating nozzle 4 a first throat 4 b second throat 4 c airflow guide 8 gas compressor 11 fixed contact B first position where large current can be cut off L inflection point

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukio Kurosawa 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masatomo Ohno 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture (56) References JP-A-1-243328 (JP, A) JP-B-60-57169 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01H 33/70 H01H 33/91

Claims (2)

(57) [Claims] 1. A detachable fixed contact and a movable contact, a gas compressor for compressing an arc-extinguishing gas in connection with an opening operation between the contacts, and a high-pressure gas of the gas compressor. An insulating nozzle for controlling the spraying of the arc between the contacts, the insulating nozzle comprising a first throat portion, and a second throat portion provided downstream of the first throat portion in the blowing gas flow. The downstream side of the blown gas flow of the second throat section has at least one inflection point after being enlarged at a divergent opening angle in the buffer type gas circuit breaker having: Kyokuten is configured to be smaller than the opening angle of the downstream side of the blowing gas stream of the second throat portion, an angle of opening of 15 degrees or less with respect to the axis of the fixed contactor, or above SL Insulation nozzle A buffer type gas circuit breaker, wherein the length from the downstream end to the inflection point is 15 mm or more, and the inner diameter of the downstream end is 1.2 times or less the inner diameter of the inflection point. 2. An apparatus according to claim 1, wherein an opening angle of said blowing gas flow at said inflection point on a downstream side is set to zero degree which is substantially parallel to an axis of said fixed contact. Gas-type circuit breaker.