JPS60150522A - 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 sulfur hexafluoride (SFsl gas circuit breaker). As shown, a buffer chamber 8 is formed by a fixed arc contact 1, a movable arc contact 2, a fixed main contact 3, a movable main contact 4, an insulating nozzle 5, a buffer cylinder 6, and a buffer piston 7.
It is formed from.

When the 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 4 are electrically connected, respectively, as shown in the upper part of FIG. During the opening operation, as shown in the lower part of FIG. 1, the movable arc contact 2. which is fixed to the buffer cylinder. The movable main contactor 4 and the insulating nozzle 5 move to the left in the illustrated example. In this process, the fixed main contact 3 and the movable main contact 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. On the other hand, the buffer piston 7 is fixed, and the buffer cylinder 6 moves to the left in FIG. Toko SFa
Gas flows out of the insulating nozzle 5 through the space between the fixed arc contact 1 and the diverging part of the insulating nozzle 5.

When a large current is interrupted, the current value is large, so even if the fixed arc contact 1 and the movable arc contact are separated, the arc continues between the poles, and when the fixed arc contact 1 is inside the insulating nozzle 5, The current cannot be interrupted, and after the fixed arc contact 1 escapes into the throat part kM of the insulating nozzle 5, SF6 scum compressed in the buffer chamber 8 is blown onto the arc and extinguished. Therefore, in order to interrupt large currents, it is effective to control the gas flow after the fixed arc contact 1 exits the throat part of the insulated nozzle 5, and the fixed arc contact 1 pulls out the throat part of the insulating nozzle 5, and the structure is such that the entire gas is blown onto the arc.

However, in the case of advanced small current interruption, since the interruption current is small, the current may be interrupted at the same time as the fixed arc contactor 1 and the movable arc contactor 2 are separated and the arc time is 0. In the case of a small lead current, the phase difference between voltage and current is 90 degrees in electrical angle, so when the arc is extinguished, the load side of the circuit breaker is charged with the peak value of the ground voltage at this time. To measure the power supply of a circuit breaker, the ground voltage at the power frequency is applied. As a result, for example, in the case of three phases, a phase difference ``'' shown by the following equation occurs between the poles.

However, VP: power supply voltage (effective value of phase voltage) ω: angular velocity of power supply frequency t: time This value reaches its maximum after 0.5 cycles of the power supply frequency.

In practical circuit breakers, the rate of voltage increase in equation (1) is larger than the rate of increase in the length between poles when the circuit is opened, so the electric field strength between the poles is at its highest after 0.5 cycle of opening. get high,
In particular, it is greatest when the arc time is 0. Therefore, as the burden voltage between the poles decreases, the progressive small current breaking duty has become one of the major issues that must be solved in the development of circuit breakers.

Figure 2 shows the pressure changes at the nine tip corners of the fixed arc contact 1 during the opening operation when the insulated nozzle with the conventional structure shown in Figure 1 is used, and the gap between the poles during the opening operation. Dielectric strength and opening operation? This shows the dielectric strength between electrodes at rest. During the electrode opening operation, the pressure at point Q rises higher than the filling pressure until the distance between poles d1 is reached, and thereafter, the pressure at point Q rapidly decreases until the distance between poles reaches d2. When examined in relation to the stroke characteristics of the circuit breaker, the distance between poles d1 corresponds to the position where the end Q of the fixed arc contact 1 begins to pass through the throat of the insulating nozzle 5, and d2
corresponds to a position where the cross-sectional area of the gas flow path between the divergent part of the insulating nozzle 5 and the fixed arc contact is slightly larger than the cross-sectional area of the throat part of the insulating nozzle 5. That is, d2 is the position where the gas flow velocity near the 9 points of the tip corner of the fixed arc contact 1 is maximum, and is the position where the static pressure on the surface of the fixed arc contact 1 suddenly decreases due to the increased gas flow velocity. I can say that.

On the other hand, in Fig. 2, when looking at the dielectric strength during electrode opening operation, it increases until the electrode gap length d, as in the case of stationary gas, and increases to the electrode gap length d1.
It shows the same tendency as the pressure change, in which it suddenly decreases when the contact distance exceeds d2, reaches a minimum value at the contact distance d2, and then rises again. It can be seen that it depends on As mentioned above, in order to improve the interrupting performance of large currents, if you try to forcefully apply gas to the arc from about 0.5 cycles after contact opening, the gap between the electrodes where the voltage between the electrodes is the highest when interrupting a small current advances. If the length is too long, the scum pressure at the tip of the fixed arc contact decreases, resulting in a decrease in inter-electrode dielectric strength.

Another known example is shown in FIG. fixed arc contact 1,
Movable arc contact 2, fixed main contact 3゜movable main contact 4
．． The insulating nozzle 5, bumper cylinder 6, and buffer piston 7 are the same as the example shown in FIG. That's amazing. This occurs immediately before the interruption of a large current, that is, when the distance between poles becomes sufficiently large and the current to be interrupted becomes small, part of the gas flow in the wide end of the insulating nozzle 5 and the insulating nozzle The direction toward the center of 5 is intended to fully promote arc extinction. Therefore, there is no effect on the advanced small current interrupting performance at a point in time when the distance between poles is short. If all the protrusions are scattered like this, a vortex will be generated in the gas flow, and the gas pressure at the center of the vortex will decrease, resulting in a decrease in dielectric strength. Therefore, it is not preferable to provide this kind of protrusion at a position where the distance between the poles is short and the electric field strength between the poles is high, which affects the interruption of small currents.

[Purpose of the invention]

An object of the present invention is to completely prevent pressure drop in the vicinity of a fixed arc contact during the opening operation of a gas circuit breaker, and to improve small current connection performance.

[Summary of the Invention] The present invention C. A variable fluid is provided on the downstream side of the insulating nozzle throat of the cass circuit breaker, and dynamic pressure due to the gas flow is applied to the surface of the fixed arc contact near 0.5 cycles after opening during the opening operation. This is to prevent a drop in gas pressure near the fixed arc contact.

[Embodiments of the invention]

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

The structure is exactly the same as the conventional one in that it is composed of a fixed arc contact 1, a movable arc contact 2 fixed to a buffer cylinder (not shown), an insulating nozzle 5, and the like. A feature of the present invention is that a variable fluid 13 is provided on the downstream side of the throat of the insulating nozzle 5, and the present invention can significantly improve the small current interrupting performance. This will be explained in detail with reference to FIG. 4 below. SF6 gas compressed in a puffer chamber (not shown) when the electrode is opened passes through the arc extinguishing chamber 11, passes through the throat of the insulating nozzle 5, and flows from around the fixed arc contact 1 to the outside (to the right side) of the insulating nozzle 5.

In this process, the SF6 scum hits the zero surface forming the tapered part of the variable fluid 13 attached to the widening part A-D of the insulating nozzle 5, and a part of the gas flow is directed toward the fixed arc contact 1 side in all directions. Apparently, this gas flow applies dynamic pressure to the surface of the fixed arc contact.

As a result, the gas pressure on the surface of the fixed arc contact 1 increases, increasing the total dielectric strength between the electrodes. The tip C of the variable fluid is provided at a position where the nine tip corners of the fixed arc contactor 1 pass after 0.5 cycles of polar opening. Therefore, the fixed arc contact l at the point where the electric field is highest in advanced small current interruption
The pressure at the end increases and progresses, improving small current interrupting performance. Even if this variable fluid 13 is annular and continuous, it is not easy.

As shown in FIG. 4, the grooves 140 may be discontinuous, but if they are discontinuous, the characteristics will vary depending on the dimensions of the grooves 140 formed between the variable fluids 13. FIG. 5 shows the value of the interelectrode dielectric strength when the electrodes are opened by changing the gas flow path area between the variable fluids 13 at a position 0.5 cycle after the electrodes are opened. The cross-sectional area of the gas flow between the tip C of the variable fluid 13 and the fixed arc contact 1 esl - The cross-sectional area of the gas flow between the variable fluid 13, that is, the fourth
The width W of the groove 14 and the height h of the variable fluid shown in the figure k S 2
If the horizontal axis is (82/S 1) 2 and the vertical axis is dielectric strength, it can be seen that when the value of (S2/S1)Σ becomes larger than 0.1, the dielectric strength decreases rapidly. The dielectric strength (relative value) in the case of fc using the conventional insulated nozzle shown in Fig. 1 is 0.7, and in order to achieve the same advanced small current interrupting performance, (S 2 / S +) T must be less than or equal to that of civil. I know it has to be. This is because when the cross-sectional area of the gas flow path between the variable fluids 13 increases, not only does the increase in gas pressure on the surface of the fixed arc contact 1 facing between the variable fluids 13 become smaller, but also the vortices of the gas flow around the variable fluids 13. This is because the pressure at the center of the vortex decreases and the absolute stiffness decreases. According to the theory of fluid dynamics, the pressure in the vortex is expressed by equation (2).

Here Po: Pressure at the center of the vortex■). :Pressure of vessel wall C:Sonic speed T:Gas feed temperature 1:Gas constant SFa For gas, C=134.9 (m/s)
.

R = 56.9 (l112152K) and T = 28
If it is 8 (0K), Po/Pooki will be 1/3.

Therefore, in the worst case, the pressure at the center of the vortex in the SFs gas decreases by 1/3 t of one ambient pressure, and the dielectric strength also decreases in proportion to this. As mentioned above, the variable fluid 13 is such that the gas flow path becomes the smallest near the position where the nine end points of the fixed arc contactor 1 pass 0.5 cycles after opening on the downstream side of the throat of the edge nozzle 5. 'fr: Provided (S 2
/S+)'≦1.5, the advanced small current interrupting performance can be greatly improved.

〔Effect of the invention〕

According to the present invention, it is possible to prevent a drop in gas pressure near the fixed arc contact during opening of a gas circuit breaker, which improves the dielectric strength between electrodes during opening operation, and is effective in improving the advanced small current breaking performance. It is.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the structure of a conventional gas circuit breaker, and Figure 2 is a diagram showing the structure of a conventional gas circuit breaker.
Figure 3 is an explanatory diagram of the inter-electrode dielectric strength and gas pressure change at the fixed arc contact end during opening operation of the gas circuit breaker. Figure 3 is an explanatory diagram of the structure of the breaking part of another conventional gas circuit breaker. A) is a sectional view of the insulating nozzle of the embodiment of the gas circuit breaker of the present invention, and (B) is (
The side view of a), FIG. 5, is a comparative explanatory diagram of the dielectric strength when the dimensions of the insulating nozzle shown in FIG. 4 are changed. 1... Fixed arc contact, 2... Movable arc contact, 3... Fixed main contact, 4... Movable main contact, 5.
...Insulating nozzle, 6...Buffer cylinder, 7...
Buffer piston, 8... Buffer chamber, 9... Protrusion, 11... Arc extinguishing chamber, 13... Variable fluid, 14... Groove.

Claims (1)

[Claims] 1.Equipped with a fixed arc contact, a movable arc contact, a device for compressing arc-extinguishing gas, and an insulated nozzle that guides the compressed arc-extinguishing gas, so that the arc-extinguishing gas generated between the fixed arc contact and the movable arc contact when the contact is opened is In a gas circuit breaker that extinguishes an arc by spraying an arc-extinguishing gas onto the arc, the gas flow path is located downstream of the throat of the insulating nozzle, near the position where the tip corner of the fixed arc contact passes after 0.5 cycles of opening. A gas hemorrhoid cutter characterized by having a variable fluid having a minimum cross-sectional area.