JPH05135668A - Puffer type gas circuit breaker - Google Patents

Abstract

PURPOSE:To enhance both the leading small current limiting performance and the large current limiting performance of a buffer type gas circuit breaker. CONSTITUTION:A first throat portion 4a and a second throat portion 4b are formed in the respective portions of an insulating nozzle 4 and an inflection point L is provided at which the aperture angle gets smaller toward the downstream of puffing gas flow than at the second throat portion 4b. The inflection point L is formed near a position at which large current can be first limited at the end portion of a fixed contact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buffer type gas circuit breaker, and more particularly to a buffer type gas 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 is provided with a pair of contacts that can be relatively separated and a gas compression device that compresses an arc-extinguishing gas as the contacts are separated. ,
The arc extinguishing gas compressed by the gas compressing device is guided by the insulating nozzle to the arc generated by the separation of the contacts to blow off the arc.

As a conventional type of gas circuit breaker of this type, there is known one disclosed in Japanese Patent Application Laid-Open No. 1-243328, which is shown in FIG. This figure shows a breaker constructed in an arc-extinguishing gas atmosphere. Of the pair of contacts, the fixed contact 11 has a small diameter portion 11a at its tip.
And a large-diameter portion 11c on the base side, and a gentle diameter-changing portion 11b in between. The outer diameter of the small-diameter portion 11a is D1, and the outer diameter of the large-diameter portion 11c is D2.
Is. On the other hand, the movable contactor 2 has the small diameter portion 11a in the closed state.
Attached to the buffer cylinder 1 so as to come into contact with
It is covered with an insulating cover 3, and further covered with an insulating nozzle 4 so as to form a flow path on the outer periphery thereof. The insulating nozzle 4 has a first throat portion 4a on the upstream side of a blowing gas flow, which will be described later, and a second throat portion 4b on the downstream side of the same gas flow.
The inner surface between b is recessed to form a space S. The inner diameter of the first throat portion 4a is DA and the small diameter portion 11a is inserted, and the inner diameter of the second throat portion 4b is DB and the large diameter portion 11c is inserted. The buffer cylinder 1 constitutes a gas compression device 8 with a piston 7 fitted in a slidable relationship, and a shaft 6 of the buffer cylinder 1 is formed.
Is connected to an operating device (not shown).

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

Now, when the shaft 6 is driven to the right by an operating device (not shown), the arc extinguishing gas is compressed by the gas compression device 8 and the contacts 2 and 11 are separated. Then, the relative positional relationship between the fixed contactor 11 and the movable contactor 2 is in the state of A shown by the alternate long and short dash line in FIG. Since the first throat portion 4a moves in the small-diameter portion 11a from the start of the shut-off operation to this state, the first throat portion 4a passes through the gas inflow portion G formed between the first throat portion 4a and the first throat portion 4a. High-pressure gas is supplied as shown by arrow 25. On the other hand, the second throat portion 4b is almost closed by the large diameter portion 11c. Therefore, in the space S, a pressure substantially equal to that of the facing portion between the contacts 2 and 11 is maintained. In this way, the second throat portion 4b is substantially closed by the large-diameter portion 11c so as not to form a substantial gas flow. Therefore, the gas density at the tip portion of the fixed contactor 11 should be kept high. Therefore, the arc generated by the separation between the contacts is extinguished and the contacts 2,
Even in the case of advanced small current interruption in which a high recovery voltage is applied between 11, good interruption performance can be obtained.

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

As a similar buffer type gas circuit breaker, Japanese Patent Laid-Open No. 60-150521 discloses a first insulating nozzle.
Of FIG. 2 is formed by changing the gas flow downstream of the blowing gas flow with respect to the throat part to form a tapered portion for increasing the gas pressure at the tip of the fixed contact.

[0008]

However, the relative positions of the fixed contacts 11 that can be interrupted when the short-circuit current of which the current is tens of thousands A are interrupted are in the range B to C shown in FIG. That is, when a large current is cut off by a circuit breaker with a fast breaking speed, the relative positional relationship shown in B of FIG. Therefore, the small-diameter portion 11a of the fixed contactor 11 comes out from the tip of the insulating nozzle 4, and the high-pressure arc-extinguishing gas from the gas compression device 8 cannot be effectively blown to the fixed contactor 11. The gas density in the vicinity of the tips of the contacts 11 decreases, and eventually the dielectric strength between the facing parts of the contacts 2 and 11 decreases, resulting in poor high-current interruption performance.
Note that C in FIG. 5 shows the relative position of the fixed contactor 11 close to the full stroke, and in the moving range from the position B to the position C, the fixed contactor 11 has the second throat portion 4 b of the insulating nozzle 4. However, 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.

The object of the present invention is to provide a breaking performance in the case where the breaking is performed at a time point when the opening length is comparatively small, such as the advance small current breaking, and a comparatively long breaking length such as the large current breaking. (EN) Provided is a buffer type gas circuit breaker capable of improving both the breaking performance when the breaking is performed at a large time.

[0010]

In order to achieve the above-mentioned object, the present invention forms a second throat portion on the downstream side of the blowing gas flow with respect to the first throat portion, and in this second throat portion. The downstream side of the blowing gas flow has at least one inflection point after being expanded by a divergent opening angle, and the inflection point is the downstream opening of the blowing gas flow of the second throat portion. The opening is smaller than the angle, and the tip of the fixed contact is formed so as to be located near the position where the large current can be interrupted first.

[0011]

Since the buffer type gas circuit breaker according to the present invention has the above-mentioned structure, even if the tip of the fixed contact is removed from the first throat, the second gas breaker is provided downstream of the blowing gas flow.
The unnecessary throat of the gas suppresses the unnecessary discharge of gas, so the breaking performance is achieved when the breaking is performed at a point when the opening length is relatively small, such as a small current break, which is advanced by increasing the gas density at the tip. In addition, since the inflection point is formed on the downstream side of the blowing gas flow with respect to the second throat and in the vicinity of the first interruptable position at the time of breaking the large current, the most inflection point at the time of breaking the large current is achieved. Even under 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 breaking occurs when the breaking length is relatively large. Performance can also be improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing a buffer type gas circuit breaker according to an embodiment of the present invention, and the illustrated portion is constructed in a container filled with arc extinguishing gas. The shaft 6 provided in the center of the buffer cylinder 1 is connected to an operating device (not shown), and the inner surface of the buffer cylinder 1 and the shaft 6 are connected.
A fixed piston 7 is fitted in a slidable relationship between the outer surfaces of the. The arc-extinguishing gas in the space formed by these, which is called a buffer chamber, is compressed by driving the shaft 6 in the right-side open circuit direction, and the gas compression device 8 is constituted by these. .. On the left end surface of the buffer cylinder 1, the movable contactor 2 mounted on the mounting base 12, the insulating cover 3 surrounding the movable contactor 2, and the insulating cover 3 surrounding the insulating cover 3 so as to further form a flow path. Nozzle 4
And are fixed by means of a retainer fitting 5. Insulation nozzle 4
The first throat portion 4a formed on the upstream side of the blowing gas flow close to the movable contact 2, the second throat portion 4b formed on the downstream side of the blowing gas flow, and further located downstream thereof. Airflow guide portions 4c are formed respectively. 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 that serves as the gas flow passage so as to have a divergent shape, but details will be described later. An inflection point L is provided in the vicinity of the first interruptable position when the current is interrupted, and the opening angle θ of the airflow guide portion 4c located on the downstream side of the blowing gas flow from the inflection point L.
₂ is smaller than the opening angle θ _{1 described} above. Further, the insulating nozzle 4 has a recessed portion between the throat portions 4a and 4b, and the space S is formed by the recessed portion. The fixed contactor 11 has a small diameter portion 11a at its tip, and the diameters D1 and DA of the respective portions are selected so that the gas inflow portion G is formed between the fixed contactor 11 and the first throat portion 4a fitted to this. There is.
Further, there is a large-diameter portion 11c at the base of the fixed contactor 11, 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 breaking operation will be described. When the shaft 6 is driven to the right from the input state shown in FIG. 1 by an operating device (not shown), the arc extinguishing gas is compressed by the gas compression device 8 and the fixed contact 11 is opened from the movable contact 2. The state becomes as shown in FIG. When the current to be interrupted advances and is a small current, the tip of the small-diameter portion 11a of the fixed contactor 11 relatively comes out from the first throat portion 4a, and the gas compression device 8 passes through the gas inflow portion G via the gas inflow portion G. The arc between the contacts 2 and 11 is extinguished by the blowing gas flow reaching the space S, and a high recovery voltage is applied between the contacts 2 and 11 having a relatively small opening distance. However, since the blowing gas flow is restricted by the second throat portion 4b, the gas density at the tip portion of the fixed contact 11 is increased, and as a result, high dielectric strength is exhibited and interruption is possible. Becomes

However, when the current to be interrupted is a large current, the current is not interrupted at this point and the interrupting operation further proceeds to the state shown in FIG. When the tip of the fixed contact 11 reaches the relative position B indicated by the chain double-dashed line, the tip of the fixed contact 11 is located near the inflection point L and reaches the first minimum openable position where interruption is possible. The relative position C of almost full stroke is reached. Here, the result of studying the gas density characteristics of the tip of the fixed contactor 11 by analysis will be described with reference to FIG. The gas density in the case of the conventional shape (a) shown in FIG. 4 has a characteristic that it increases with time after extinguishing the arc, then temporarily decreases, and then increases again. Further, the shape (b) is the opening angle θ _{2 of the} airflow guide 4c.
Indicates the gas density when the opening angle θ _{1 of} the second throat portion 4b is the same, and the rate of temporary decrease in the gas density is decreasing, but the decrease in gas density itself still occurs. However, as shown in FIG. 1, the opening angle θ ₂ is equal to the inflection point L.
In the shape (C) that is made smaller thereafter, the gas density does not temporarily decrease and has a characteristic that it uniformly increases 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 side angle θ ₂ of the opening angle is zero degree, that is, parallel to the axial direction of the fixed contactor 11, the same effect as the shape (C) can be obtained. Therefore, FIG.
Even if a high recovery voltage is applied after shutting off a large current within the range of relative positions B to C of the tip of the fixed contact 11 shown in FIG. 6, there is no decrease in gas density at the tip of the fixed contact 11. Therefore, high withstand voltage can be maintained.

FIG. 11 is a longitudinal sectional view showing only the insulating nozzle 4, in which the length from the inflection point L to the tip of the air flow guide portion 4c is 1, the inner diameter at the inflection point L is D3, and the air flow guide portion 4c. The inner diameter at the tip is D4, the inflection point L is good, and the opening angle to the axis of the fixed contact is θ on the downstream side of the blowing gas flow.
_Shown as ₂ . FIG. 12 shows the results of examining the breaking performance by changing the size and angle of each part of FIG. 11 described above, where D4 / D3 is taken on the vertical axis and length 1 is taken on the horizontal axis. The mark indicates failure in shutoff. As can be seen from FIG. 12, the angle θ ₂ is 15 degrees or less and the length l is 15 degrees.
Under the condition that the inner diameter D4 is 1.2 mm or less and the inner diameter D4 is 1.2 times or less that of the inner diameter D3, that is, about 1.4 times or less in area ratio, a remarkable effect of improving 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 the first throat portion 4a located on the movable contact side (not shown) on the right side and the second throat portion 4b located on the downstream side of the blowing gas. 4d and 4e are formed. Therefore, until the fixed contact 11 reaches the relative position B, the gas flow that collides against this surface is formed until the fixed contact 11 reaches the relative position B. The fixed contactor 11 is deflected toward the axial centerline, that is, toward the vicinity of the tip thereof, so that the gas density at the tip of the fixed contactor 11 can be prevented from lowering. Further, the airflow guide 4c at the tip of the insulating nozzle 4 is the same as that of the previous embodiment, and the withstand voltage when a large current is interrupted 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. This insulating nozzle 4 is manufactured by dividing the insulating nozzle 4 into two parts in the axial direction, and the insulating nozzle 4A having the first throat portion 4a has excellent arc resistance, for example, Teflon is filled with a filler to improve the arc resistance. And the second throat section 4
The insulating nozzle 4B in the portion having b is assumed to have a low arc resistance but an excellent insulating property, for example, one made of Teflon, and these insulating nozzles 4A and 4B are mechanically coupled.

FIG. 9 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 in this embodiment forms a plurality of inflection points L ₁ and L ₂ on the downstream side of the blowing gas flow with respect to the second throat portion 4b, and the respective opening angles are θ ₁ and
When θ ₂ and θ ₃ are set, θ ₁ > θ ₂ > θ ₃ is set, and the opening angle is made smaller as the position is 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 with respect to the second throat portion 4b.

FIG. 10 is a partial cross-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 in this embodiment is the second
2 inflection points L ₁ and L ₂ are formed on the downstream side of the blowing gas flow with respect to the throat portion 4 b, and the opening angle of each of them is θ.
_{When 1} , θ ₂ and θ ₃ are set, θ _{2 is set} to zero degree.

Incidentally, in the above-mentioned embodiment, the fixed contact 11
Has a small diameter portion 11a at its tip and a large diameter portion 1a at the base side.
1c is formed, for example, ANSI (American)
National Standards Insti
fixed contactor 1 when the advance small current interruption duty is not strict (the supply voltage is 1.2 times the phase voltage), such as
The diameter of the first 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 in order to minimize the diameter expansion due to consumption when the current is cut off.
Since the second throat portion 4b is cooled by the blowing gas and the diameter expansion is small, the parallel portion of the second throat portion 4b may or may not be provided.

[0021]

As described above, according to the present invention, the insulating nozzle is located on the downstream side of the second throat portion, and the tip of the fixed contact is the first position where the large current can be cut off. Since there is an inflection point in the vicinity and the opening angle is made smaller at this inflection point, the gas density decreases at the tip of the fixed contact even when a small current is cut off due to the formation of the second throat. It is possible to prevent the withstand voltage from being lowered by the inflection point, and the inflection point can prevent the withstand voltage from being lowered due to the gas density drop at the tip portion of the fixed contactor when a large current is interrupted.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view of essential parts showing an initial disconnection state of the buffer type gas circuit breaker shown in FIG.

FIG. 3 is an enlarged cross-sectional view of essential parts showing a final shutoff state of the buffer type gas circuit breaker shown in FIG. 1.

FIG. 4 is a vertical cross-sectional view showing a closed state of a conventional buffer gas circuit breaker.

5 is an enlarged cross-sectional view of an essential part showing the interruption operation of the buffer gas circuit breaker shown in FIG.

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

FIG. 7 is a vertical 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 vertical cross-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 vertical 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 cross-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]

 1 Puffer Cylinder 2 Movable Contact 4 Insulation Nozzle 4a First Throat 4b Second Throat 4c Air Flow Guide 8 Gas Compressor 11 Fixed Contact B First Breakable Position for Large Current Break L Inflection point

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Kurosawa 4026 Kuji-cho, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Masatomo Ono 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture Kokubun Plant of Hitachi, Ltd.

Claims (3)

[Claims] 1. A separable fixed contact and a movable contact, a gas compression device for compressing an arc-extinguishing gas in association with a separation operation between the contacts, and a high pressure gas of the gas compression device. An insulating nozzle for controlling to spray the arc between the contacts is provided, and the insulating nozzle includes a first throat part and a second throat part provided downstream of the first throat part in the blowing gas flow. And a downstream side of the blown gas flow of the second throat section, which has at least one inflection point after expansion with a divergent opening angle. The bending point has an opening angle smaller than the opening angle of the second throat portion toward the downstream side of the blown gas flow, and the opposite end of the fixed contact can be interrupted for the first time when a large current is interrupted. Formed near the position A backup type gas circuit breaker. 2. A separable fixed contact and a movable contact, a gas compression device for compressing an arc-extinguishing gas in association with a separation operation between the contacts, and a high pressure gas of the gas compression device. An insulating nozzle for controlling to spray the arc between the contacts is provided, and the insulating nozzle includes a first throat part and a second throat part provided downstream of the first throat part in the blowing gas flow. And a downstream side of the blown gas flow of the second throat section, which has at least one inflection point after expansion with a divergent opening angle. The bending point is smaller than the opening angle of the second throat portion toward the downstream side of the blowing gas flow, has an opening angle of 15 degrees or less with respect to the axis of the fixed contact, and has the inflection point. From the point of the insulation nozzle A buffer type gas circuit breaker characterized in that a length of the gas flow to the downstream end is set to 15 mm or more, and an inner diameter of this end is set to 1.2 times or less of an inner diameter of the inflection point. 3. The method according to claim 1 or 2,
A puffer-type gas circuit breaker, wherein an opening angle of the blowing gas flow toward the downstream side at the inflection point is set to zero degree substantially parallel to the axis of the fixed contact.