JPH0435857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of an insulating nozzle for a gas circuit breaker, particularly a puffer type gas circuit breaker.

[Conventional technology]

As the voltage of power systems becomes higher, the voltage applied to gas circuit breakers is on the rise. Increasing the voltage of gas circuit breakers has been dealt with by increasing the voltage per interrupting unit, but in this case, the duty of interrupting small progressive currents with extremely high voltage applied over a short opening distance becomes extremely severe. It is desired to improve its performance.

As a conventional example of this type of gas circuit breaker,
A nozzle with pleats disclosed in Publication No. 12491,
Examples include a nozzle having a vertical groove as disclosed in Japanese Unexamined Patent Publication No. 56-93230, and a nozzle having an island-like protrusion as disclosed in Japanese Utility Model Application No. 54-42979.

[Problem to be solved by the invention]

In conventional nozzles with pleats or vertical grooves, the grooves are formed perpendicular to the central axis of the nozzle or at a greater angle, which causes the arc-extinguishing gas to expand discontinuously in that area. As a result, a vortex is generated in that area. The pressure at the center of this vortex is extremely low compared to the surrounding pressure. Therefore, if this vortex grows and reaches the fixed arc contact, there is a risk that the inter-electrode dielectric strength will drop significantly. In addition, in the case of a nozzle with island-like protrusions, since they only protrude at intervals in the circumferential direction, arc-extinguishing gas leaks from between each protrusion, resulting in gas that is not blown to the fixed arc contact side. As a result, there was still a problem that the interelectrode dielectric strength decreased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a gas circuit breaker with less risk of deterioration in interelectrode dielectric strength.

[Means to solve the problem]

In order to achieve the above object, the gas circuit breaker according to the present invention extinguishes the arc generated between the fixed contact and the movable contact in the arc extinguishing chamber through an insulating nozzle with an arc extinguishing gas. In the arcing gas circuit breaker, the insulating nozzle is formed such that its base end is attached to the movable contact side and moves relative to the fixed contact, and the insulating nozzle has a diverging portion downstream of the throat portion of the insulating nozzle. A forward tapered portion is provided continuously in the circumferential direction, and a reverse tapered portion is provided continuously in the circumferential direction in connection with this forward tapered portion, and the direction in which the arc-extinguishing gas is blown is movable within the insulating nozzle. It is formed from the contact side to the fixed contact side. Furthermore, in the oblique gas circuit breaker, the minimum cross-sectional area of the space surrounded by the axially protruding part formed by the reverse tapered part and the fixed contact is equal to the cross-sectional area of the space of the throat part. It is preferable that the size be smaller than 1.5 times.

[Effect]

During the breaking operation, the movable contact moves away from the fixed contact, and arc-extinguishing gas is blown onto the arc generated between both contacts, but the insulating nozzle moves together with the movable contact. The arc-extinguishing gas is blown in a flow from the movable contact side to the fixed contact side, and by forming the inner surface of the insulating nozzle into a predetermined shape described later, the pressure can be reduced. It becomes possible to spray gas onto a relatively moving fixed contact, that is, an arc, without deterioration, thereby making it possible to maintain a high interelectrode dielectric strength. In the present invention, the predetermined shape of the inner surface of the insulating nozzle means that a forward tapered part is provided continuously in the circumferential direction in the diverging part on the downstream side of the throat part of the insulating nozzle, and a reverse tapered part is continuous with this forward tapered part. It has a shape that is continuous in the circumferential direction.
Because of this shape, when compressed arc-extinguishing gas flows into the fixed arc contact side through the throat of the nozzle during the cut-off operation, the gas is guided by the forward taper and does not generate a vortex. It collides with the reverse taper, where it is reflected and blown toward the axis of the nozzle. Therefore, the amount of gas blown increases, that is, there is no pressure drop and the interelectrode dielectric strength does not decrease.

〔Example〕

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, in which compressed gas generated by the puffer cylinder 4 and the fixed piston 5 is generated between the movable arc contact 6 and the fixed arc contact 2 during the breaking operation. This is a movable insulated nozzle that also serves as a guide for spraying onto the arc. 3 is a movable current collector, and 7 is a fixed current collector.
The insulating nozzle 1 is provided with a forward tapered portion BC and a reverse tapered portion CD continuous in the circumferential direction at a diverging portion BE on the downstream side of the throat portion A-B. A protruding portion 8 formed by this reverse tapered portion CD is formed continuously in the circumferential direction. Unlike short-circuit current interruption, in advance small current interruption, the interruption current is small, so there is almost no ionization of the gas, and performance is influenced by dielectric strength in a cold gas state. Since the dielectric strength of gas depends on gas pressure, advanced small current interrupting performance is closely related to gas pressure. The above-mentioned protrusion 8 is formed for the purpose of preventing pressure drop within the insulating nozzle.

Next, the operation of the above embodiment will be explained. The arc-extinguishing gas that has passed through the throat section A-B of the nozzle 1 during the shutoff operation is smoothly and continuously guided to the forward tapered section B-C, led to the reverse tapered section CD, and collides there. . Here, the forward taper section BC prevents the generation of vortices, and all the gas collides with the reverse taper section CD. The gas is reflected by the collision and is blown in the axial direction of the nozzle 1. As a result, there is no pressure drop near the tip of the fixed arc contact, and a decrease in interpolar dielectric strength is also prevented.

Further, through research carried out by the applicant, it has been found that there is a special relationship with the cross-sectional area of the gas flow path in order to effectively exhibit the effect of the protrusion. Figure 2 shows this situation.

The shaded width is the pressure variation. S ₀
is the cross-sectional area of the gas flow path of the throat portion A-B, _S1 is the cross-sectional area of the gas flow path surrounded by the tip D of the protrusion 8 and the stator 2, and the horizontal axis is indicated by _S1 / _S0 . . The vertical axis represents the gas pressure P at the tip of the stator 2 and the charging pressure of the gas circuit breaker when the tip of the stator 2 is in the region B-C-D between the nozzle throat outlet and the tip D of the protrusion.
It is expressed as a ratio of P _L. Stator 2 is nozzle 1
Since the dielectric strength tends to decrease near where the stator exits the throat, the gas pressure P at the tip of the stator is compared as the value at that position. S ₁ /S ₀ ≧1.5
When P/P _L <1, the gas pressure P is lower than the charging pressure P _L . As S ₁ /S ₀ decreases from 3 to 1.5, P/P _L gradually decreases, and S ₁ /S ₀ =
At 1.5, P/P _L becomes minimum. Furthermore, as S ₁ /S ₀ becomes smaller, P/P _L increases rapidly, and S ₁ /S ₀ ≦1
Then, P/P _L ≧1, and the gas pressure P does not decrease. Therefore, if a protrusion having a reverse taper is provided so that S ₁ /S ₀ ≦1.5, gas compression by the reverse taper will be effectively performed and a drop in pressure at the tip of the stator will be effectively prevented. . Figure 3 shows S ₁ /S ₀ = 1
An example formed in this example is shown below. The cross-sectional area of the flow path surrounded by the narrowest gap D of the protrusion 8 and the stator 2 is equal to the cross-sectional area of the flow path along the throat A-B of the nozzle 1. Naturally, the protrusion 8 is an annular continuous body that is continuous in the circumferential direction. According to this embodiment, the following effects are achieved.

(1) Since the gas pressure at the tip of the stator, where the electric field is strong, does not decrease, the dielectric strength is high during opening operation, and the performance of small currents is improved.

(2) Since the flow passage cross-sectional area of the throat part and the flow passage cross-sectional area of the protrusion are equal (when the stator is located upstream of the narrowest part of the protrusion), the gas flow rate is the same as when there is no protrusion. It is equivalent and does not affect the opening speed and time of the circuit breaker.

(3) For the same reason as (2) above, the amount of gas sprayed does not adversely affect the large current interrupting characteristics, which is an important point.

〔Effect of the invention〕

As explained above, according to the present invention, the insulating nozzle moves together with the movable contact, and the arc-extinguishing gas flows from the movable contact side toward the fixed contact side, and the arc-extinguishing gas flows inside the insulating nozzle. It is possible to obtain an insulated nozzle with a small drop in gas pressure because the gas is blown onto the arc and the forward and reverse tapered parts on the inner surface of the insulated nozzle effectively exert the gas compression action without generating a vortex. A significant improvement in the performance of circuit breakers can be achieved.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a gas circuit breaker showing one embodiment of the present invention, Fig. 2 is a characteristic diagram that is the basis of the invention, and Fig. 3 is a sectional view of a gas circuit breaker according to another embodiment of the invention. be. 1... Insulated nozzle, 2... Fixed arc contact, 3...
Movable current collector, 4...Puff cylinder, 5...Fixed piston, 6...Movable arc contactor, 7...Fixed current collector, 8...Protrusion part, A-B...Throat part, B-C...
Forward taper section, C-D...reverse taper section.

Claims (1)

[Claims] 1. A gas circuit breaker that extinguishes an arc generated between a fixed contact and a movable contact in an arc extinguishing chamber by blowing an arc extinguishing gas through an insulating nozzle when the arc is interrupted,
The insulating nozzle has a proximal end attached to the movable contact and is formed to move relative to the fixed contact, and a forward tapered part is formed in the diverging part downstream of the throat part of the insulating nozzle in the circumferential direction. A reverse tapered portion is provided continuously in the circumferential direction in series with the forward tapered portion, and the arc-extinguishing gas is blown in the insulating nozzle from the movable contact side to the fixed contact side. A gas circuit breaker characterized by being formed so as to face. 2. In claim 1, the minimum cross-sectional area of the space surrounded by the axially protruding part formed by the inverse tapered part and the fixed contact is the cross-sectional area of the space of the throat part. A gas circuit breaker that is smaller than 1.5 times.