JPS60218722A - 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 gas circuit breaker, and more particularly to a nozzle with excellent advanced small current interrupting performance.

[Background of the invention]

With the miniaturization of gas circuit breakers, the voltage applied to one breaking section of the circuit breaker has become higher than the conventional voltage. In order to counter this, conventionally, as shown in FIG. 1, performance has been improved by changing the divergence angle of a nozzle having a divergent section A-D with a straight cross section and the opening speed of the circuit breaker.

In FIG. 1, the movable arc contactor 6 moves together with the buffer cylinder 4 and the nozzle 1, and the gas compressed in the cylinder is transferred to the movable mark contactor 6 by the nozzle 1.
and spray it onto the fixed arc contact 2. The compressed gas is accelerated at the throat of the nozzle and becomes subsonic or supersonic at the wide end. When gas flows at such high speed,
The gas pressure in the widening part depends on the cross-sectional area of the flow path,
Here, 1==1.2. At*As: Cross-sectional area at any two positions of the divergent part, Mt, Mt: Matsuno number at the position corresponding to A4 and A2, P, , P,: Gas pressure at the position corresponding to A, and A2 , Al less Al, then generally Pl>Pl. In the diverging portion A-D, the flow path cross-sectional area increases toward the downstream side, so the gas pressure continues to decrease. In a circuit breaker, a fixed arc contact is located at the wide end of the nozzle, but as opening progresses at the tip opposite to the movable arc contact, the cross-sectional area of the flow path increases, so the gas pressure in the palm of the hand decreases. ing. The solid line in FIG. 2 is a typical measured example. When the distance between poles d is dl, the tip of the fixed arc contact passes through the throat part T-B of the nozzle, and when the length between poles is d3, the tip of the fixed arc contact pulls out the throat and reaches a distance of 10 to 20 m. position has been reached. Gas pressure H at the tip of a fixed arc contact with a strong electric field
is temporarily cut off.

The energetic pressure of the vessel! As shown in FIG. 2, the dielectric strength between the fixed arc contact and the movable arc contact decreases significantly compared to the dielectric strength when the circuit breaker is stationary. This transient drop in gas pressure cannot be essentially avoided even by changing the inclination angle of the diverging portion or the moving speed of the rougher cylinder, and has become an essential drawback. In the figure, E is the interelectrode dielectric strength at rest, the lower part is the dielectric strength when the electrodes are opened, and G is the filling pressure.

Recently, as a solution to this drawback, a variable fluid having a reverse tapered part that acts to narrow the cross-sectional area of the flow path is installed in the diverging part of the nozzle, and by preventing the rapid expansion of p1 gas, the pressure of p1 gas can be reduced. Attempts are being made to prevent transient declines.

FIG. 3 is a schematic structural diagram thereof, and B-C-D is the noodle body 8.
, CD is the inverted taper part. Curve A-
Sudden gas expansion is almost avoided in the space surrounded by B-C and the fixed arc contact 2, and the pressure is almost the same as the filling pressure of the circuit breaker. It will be almost the same as the proof strength. However, even with this method, vortices are generated in the triangular region connected by B-C-D, resulting in a microscopic drop in gas pressure and preventing a significant increase in dielectric strength.

[Purpose of the invention]

An object of the invention is to provide a nozzle with a reverse tapered portion and a variable fluid having a shape of the reverse tapered portion that prevents the generation of vortices.

[Summary of the invention]

The inventors have made extensive analysis of the shape of a reverse theno (variable fluid with parts) and have clarified the following fact.

The presence or absence of vortices at the stator position t (near the distance between poles d2 in Fig. 2), where the transient pressure drop at the tip of the stator is large and the insulation is difficult to maintain, was determined by comparing the divergent part A-B and the reverse taper. Part B-C
We analyzed the angle θ1 (Figure 4) as a variable. As shown in Fig. 5, the vortex is connected to the main stream of gas indicated by the arrow A-B-
It occurs in the area surrounded by C, roughly the area of triangle ABC. The analysis was performed under the conditions of the cross-sectional area of the flow path where this vortex is generated ((cross-sectional area of the throat portion) (cross-section 1 surrounded by point C and the fixed arc contact 2)). As a result, as shown by the * mark in FIG. 6, it was found that when 01≦90°, a vortex was generated in the triangular region, and when θl≧100@, no vortex was generated. It can be easily inferred that the boundary lies at 95°.

Also, by using the angle θ between the divergent part A-B and the nozzle center axis as a parameter, the vortex flow between the interpolar lengths d1 to d in FIG. 2 can be determined.
When we analyzed the occurrence, as shown in Figure 7, 02≦
At 40°, no vortex is generated, but at θ≧50°, vortices are generated in the triangular region.

It can be easily inferred that the boundary is 45°.

Note 1. The relationship shown in FIG. 7 also holds true for a nozzle with a straight cross section as shown in FIG.

Therefore, if θ1≧95° and θ8≦45°, the generation of vortices can be prevented.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described using FIG. 8. The insulating gas compressed by the cylinder 4 and the piston 5 is guided by a nozzle l made of an insulating material, and is blown onto the arc generated between the fixed arc contact 2 and the movable arc contact 60, thereby suppressing the arc. blow out. The nozzle 1 is fixed to a cylinder 4 by a nozzle holder 3, and a movable arc contactor 6
is fixed to the cylinder. A large current is collected by the current collector 7, and when the current collector 7 is opened, the time when the current collector 7 and the nozzle holder 3 are separated is earlier than the time when the movable-fixed arc contactor 6.degree.2 is separated. A variable fluid 8 (B-C-D) is provided in the diverging portion of the nozzle 1 on the downstream side of the slow T-A to suppress rapid expansion of the insulating gas flow. The angle between straight line A-B and the nozzle center axis is 43°, and the angle between straight line A-B and straight line B-C is
The angle ABC formed by the two is selected to be 110°. In addition, the flow path cross-sectional area of the slow) T-A section and the variable fluid 8σ maximum restriction → section C
The cross-sectional area of the flow path surrounded by the fixed arc contact 2 is fli
t is equal. In this way, by forming the diverging part of the nozzle, p, j, the distance between the poles d in Figure 2 can be reduced.

Not only is the transient pressure drop significantly reduced to almost equal to the filling pressure of the circuit breaker, but also the generation of vortices as shown in FIG. 5 can be prevented. As a result, 01= in Figure 9
As shown by the curve 110, the dielectric strength of F increases significantly during the opening operation and becomes equal to that during the standstill state. Accordingly, the advanced small current interrupting performance is significantly improved.

The figure in the figure shows the case without variable fluid.

〔Effect of the invention〕

According to the present invention, it is possible to prevent the generation of vortices that locally reduce the gas pressure at the tip of the stator where the electric field is strong, so that the ultimate strength is significantly increased and the small current cutting performance is significantly improved.

[Brief explanation of drawings]

Fig. 1 is a schematic structural diagram of a conventional breaking section of a circuit breaker, Fig. 2 is an explanatory diagram of the transient gas pressure and decrease in dielectric strength of the conventional breaking section of a circuit breaker, and Fig. 3 is an improved breaking section. Figure 4 is a detailed explanatory diagram of the present invention, Figure 5 is a schematic diagram showing gas flow and vortex generation, and Figures 6 and 7 are critical conditions for vortex generation. FIG. 8 is a schematic diagram of an embodiment of the present invention, and FIG. 9 is a diagram showing dielectric strength actually measured in an embodiment of the present invention. l... Nozzle, 2... Fixed arc contact, 3... Tuzzle holder, 4... Cylinder, 5... Piston, 6...
- Movable arc contactor, 7... Current collector, 8... Variable fluid. Figure 1, figure 2 - 1 [notes, figure 4, figure 6, figure 1, figure 8, figure 9, length

Claims (1)

[Claims] 1. A fixed arc contact, a movable arc contact, and a nozzle for introducing compressed arc-extinguishing gas, and an arc generated between the fixed arc contact and the movable arc contact when the contacts are opened. In a gas circuit breaker that extinguishes an arc by spraying an arc-extinguishing gas onto the nozzle, a variable fluid having an inverted tapered part that reduces the cross-sectional area of the gas flow path is provided on the flow side of the throat part 87 of the nozzle, and the throat outlet and the inverted tapered part are connected to each other. A gas circuit breaker characterized in that the angle formed between the straight line connecting the bases of the parts and the inversely tapered part is 95 degrees or more. 2. In claim 1, the angle between the straight line connecting the outlet of the throat and the base of the reverse tapered portion and the central axis of the nozzle is 45 degrees or less! A gas circuit breaker featuring the following features: 2 & In claim 1, □ Angle # made by the straight line connecting the outlet of the throat and the reversed tee 75 portion and the reversed taper portion! A gas circuit breaker characterized in that the angle formed by the straight line connecting the throat outlet and the base of the inverted tapered part with the central axis of the nozzle is 95' or more and 45 or less.