JPS60150521A - Gas breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a 5Fs (sulfur hexafluoride) gas circuit breaker. [Background of the Invention] The circuit breaker of an SF6 gas circuit breaker is generally shown in FIG. As shown, a fixed arc contact 1, a movable arc contact 2, a fixed main contact 3, a movable main contact 4. Buffer chamber 8 formed by insulating nozzle 5, buffer cylinder 6 and buffer piston 7
Consisting of When this SF6 gas circuit breaker is energized, the fixed arc contact 1 and the movable arc contact 2 and the fixed main contact 3 and the movable main contact are connected, respectively, as shown in the upper part of Fig. 1. . In addition, during 2-opening operation, as shown in the lower part of FIG. 1, the movable arc contact 2. The movable main contactor 4 and the insulating nozzle 5 move to the left in the illustrated example. In this process, the movable main contact 4 and the fixed main contact 3 are separated, and after this, the fixed arc contact 1 and the movable arc contact 2 are separated. Therefore, at the time of opening, an arc occurs between the fixed arc contact 1 and the movable arc contact 2, but no arc occurs between the fixed main contact 3 and the movable main contact 4. On the other hand, the buffer cylinder 6 is the first
In the example shown in the figure, the SF6 gas in the buffer chamber 8 formed by the buffer cylinder 6 and buffer piston 7 is compressed in order to move to the left, and when the fixed arc contact 1 passes through the throat part of the insulating nozzle 5, the SF6 gas is buffered. The SF6 gas compressed in the chamber 8 flows out of the nozzle through this space.

When a large current is interrupted, the current value is large, so even if fixed arc contact 1 and movable arc contact 2 are separated, arcing continues between the poles, and fixed arc contact 1 and movable arc contact 2 are connected to insulated nozzle 5. When the fixed arc contact 1 is completely removed from the throat of the insulating nozzle 5, gas compressed in the buffer chamber 8 is blown onto the arc and the arc is extinguished. Therefore, the gas flow after the fixed arc contact 1 is extracted from the throat portion of the insulating nozzle 5 is effective for interrupting large currents.

However, in the case of advance small current interruption, in order to ensure that the current to be interrupted is small, fixed arc contact 1 and movable arc contact 2 are
The current may be cut off at arc time 0 at the same time as the arc opens. In the case of this advance small current interruption, a high transient recovery voltage is immediately applied between the poles because the phase difference between the voltage and the current is 90 degrees in electrical angle. Fixed arc contact 1 and possible
Since such a high voltage is applied between the poles when the distance between the two contacts 2, that is, the length between the poles is small, it becomes extremely difficult to advance the circuit breaker and interrupt small currents as the voltage borne between the poles increases. Become. Generally, the rate at which dielectric strength increases due to contact opening is smaller than the rate of increase in transient recovery voltage, so discharge is most likely to occur at the position where the voltage between electrodes is maximum and 0.5 cycles after contact opening.

If the arc time is long, the distance between the electrodes will be large, so even if there is some pressure drop, no discharge will occur between the electrodes.

Figure 2 shows the pressure change at nine points at the end of the fixed arc contact 1 and the dielectric strength between the poles during the opening operation when using the insulated nozzle with the conventional structure shown in Figure 1. be. In the interpolar length dI trench, the pressure at point Q increases. This corresponds to the position where the fixed arc contact 1 begins to come out from the throat portion of the insulating nozzle 5. As the distance between the electrodes further increases, the pressure at point Q begins to drop suddenly and reaches its lowest point at the distance between the electrodes d2. When the distance between poles becomes even larger, the pressure at point Q gradually returns to the filling pressure. This sudden drop in pressure is caused by the fixed arc contact 1
passes through the throat and the gas flow near point Q suddenly becomes high-speed.The reason why the pressure gradually rises after that is because the gas flow path formed by the wide end of the nozzle and the fixed arc contact 1 becomes large and the gas This is due to a gradual decrease in flow velocity.

Also, as shown in the figure, the dielectric strength between electrodes is the distance between electrodes d! And V! However, there is a drawback that the pressure decreases to V2 at the distance d2 where the pressure is minimum. This is because the interelectrode dielectric strength during the contact opening operation depends on the pressure at point Q of the fixed arc contact 1.

Another known example is shown in FIG. Fixed arc contact 1.
Movable arc contact 2, fixed main contact 3゜movable main contact 4
．． The structure consisting of an insulating nozzle 5, a buffer cylinder 6, and a buffer piston 7 is the same as that shown in FIG. It's a shame. This was provided for the purpose of improving large current interrupting performance, and when the distance between poles becomes large enough to interrupt a large current, it disturbs a part of the gas flow blown out from the nozzle and causes an arc. 13 in an attempt to help extinguish the arc. Disturbing the gas flow by scattering protrusions like this creates a vortex in the gas flow inside the cutoff part, which creates a low pressure at the center of the vortex, which has the disadvantage of lowering the dielectric strength and reducing the distance between poles. 2. It is not preferable to provide this type of protrusion at a position where a high electric field occurs.

[Purpose of the invention]

An object of the present invention is to eliminate the pressure drop in the vicinity of a fixed arc contact when opening a gas circuit breaker, and to improve the small current breaking performance.

[Summary of the invention]

The present invention extends the insulating nozzle throat downstream of the gas circuit breaker.
The tapered-divergent structure prevents a drop in gas pressure at the end corner of the fixed arc contact during opening around 0.5 cycles after opening.

[Embodiments of the invention]

FIG. 4 shows the structure of the interrupting part of the gas circuit breaker according to the present invention.

The configuration of the fixed arc contact 1, movable arc contact 2, and insulating nozzle 5 is exactly the same as the conventional one. The feature of the present invention lies in the shape of the insulating nozzle 5. Conventionally, as shown in FIG. 1, the downstream side of the throat portion of an insulating nozzle has a diverging structure, or the diverging portion is dotted with protrusions as shown in FIG. 3. On the other hand, in the present invention, the tip A of the throat portion T of the insulating nozzle 5 is
On the downstream side, wide end part A-B, tapered part B-C, and wide end part C
-D structure. The purpose of this structure is to create a high electric field when the gas circuit breaker progresses and interrupts small currents, especially when interrupting small currents with a short arc time (0.5 mm after opening).
The objective is to prevent the gas pressure from decreasing at the nine corner points of the fixed arc contact during the cycle and to increase the dielectric strength between the electrodes.

The SF6 gas compressed in the buffer chamber at the time of opening passes through the arc extinguishing chamber 11 and flows from the insulating nozzle throat portion T through the space between the fixed arc contact 1 and the inner wall of the insulating nozzle 5 to the outside of the insulating nozzle. At this time, the gas flowing along the divergent part A-B immediately after the insulating nozzle throat collides with the wall of the tapered part B-C, and a part of the flow is diverted to the fixed arc contact side l. This redirected gas flow applies dynamic pressure to the surface of the fixed arc contact, increasing the gas pressure on the surface. As a result, the dielectric strength between the electrodes increases when the electrodes are opened. - The dielectric strength between the electrodes increases.

FIG. 5 shows the dielectric strength of a gas circuit breaker constructed using the insulated nozzle structure according to the present invention during an opening operation in comparison with that using a conventional insulated nozzle. It can be seen that according to the present invention, the interelectrode dielectric strength during contact opening is significantly increased.

As shown in Fig. 4, if the shape of the insulating nozzle 5 is simply taken from the throat part to a wide end A-B, a tapered B-C, and a wide end C-D, any shape and dimension will be shown in the fifth south. The characteristics are not improved as described above, and there are limits to this shape. According to the analysis results, in order to effectively increase the pressure at the nine tip corners of the fixed arc contact 1, the steps shown in Figs.
As shown in the figure, in the structure of wide end-taper-wide end,
The following conditions must be met.

(1) The tip C of the tapered part is placed before the Q point of the fixed arc contact 1 is 0.6 cycles after opening.

(2) The cross-sectional area of the gas flow path at the throat T section is SI, and the cross-sectional end of the gas flow path formed by the tip C of the tapered part of the first stage and the corner (point Q) of the end of the fixed arc contact 1 is 82 (3) The tip C of the tapered part of the first stage of the insulating nozzle 5 is on the inner (central axis) side of or on the line connecting the downstream end A of the throat and the inner tip of the insulating nozzle.

(4) When the lengths between the perpendicular lines drawn from the first-stage diverging part tip B of the insulating nozzle 50 and the first-stage tapered part tip C to the nozzle center axis are 41 and t2, points A and B are shown in the figure.
, C, D, and E are all angles that intersect in a straight line, but
A similar effect can be expected even if this surface is a smooth curved surface.

FIG. 8 shows another embodiment, and in this embodiment, the tapered-divergent part downstream of the first step wide-divergent part tip B is divided in the entire circumferential direction. In this case as well, part of the gas flow is diverted to the fixed L-shaped contact 1 (not shown) side, which has the effect of increasing the pressure. However, in this case, the effect is achieved only when the interval W between the protrusions 12 is small, and when the interval W becomes large, the gas flow velocity in this part increases and a vortex is generated downstream of the protrusions 12, so that there is no protrusion. The interelectrode dielectric strength when the electrodes are open is lower than when the electrodes are opened. According to the back side results, the allowable value of W is 3 or less, although it varies depending on the dimensions of the insulating nozzle 5.

〔Effect of the invention〕

According to the present invention, it is possible to prevent a drop in the gas pressure at the tip of the fixed arc contact during the opening operation of the cass breaker, thereby improving the inter-electrode dielectric strength during the opening operation, leading to advanced small current interruption. This has the effect of improving performance.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the tA structure of a conventional gas circuit breaker.
The figure is an explanatory diagram of the dielectric strength between poles and internal pressure characteristics during the opening operation of a conventional cass breaker, Figure 3 is a diagram of the breaking part of another conventional circuit breaker, and Figure 4 (a) is a diagram of the main circuit breaker. A cross-sectional view of the insulating nozzle of the embodiment of the cass breaker of the invention, (b) is a side view of (a), fifth
The figure is an explanatory diagram of the dielectric strength characteristics between the poles during the opening operation of the conventional circuit breaker and the circuit breaker of Figure 4, and Figures 6, 7, and 8 (a) are respectively of the gas circuit breaker of the present invention. A sectional view of another embodiment of the insulating nozzle, FIG. 8(B) is a side view of FIG. 8(A). 1... Fixed arc contactor, 2... Movable arc contactor. 3... Fixed main contact, 4... Movable arc contact, 5
- Insulating nozzle, 6... Buffer cylinder, 7... Buff multi-port 4-port') or I', i

Claims (1)

[Claims] 1. Fixed arc contact, movable arc contact, device for compressing arc-extinguishing gas, insulated nozzle metal bias to guide compressed arc-extinguishing gas, between fixed arc contact and movable arc contact when opening. A gas circuit breaker that extinguishes an arc by spraying an arc extinguishing gas onto the generated arc, is equipped with an insulating nozzle whose throat downstream is wide-to-taper-to-wide, and the tip of the tapered part is 0.6 mm after opening.
A gas circuit breaker with all the features of being before the cycle.