JPH0119299Y2 - - Google Patents

Description

[Detailed description of the invention] This invention improves the dielectric strength between the electrodes by reducing the local concentration of the electric field that occurs between the electrodes when the electrodes are opened, in switching devices such as power circuit breakers and disconnectors. The present invention relates to the structure of such a switchgear.

Conventional impedance is to connect an impedance element in parallel between the open poles to suppress the re-electromotive voltage when the power grid is disconnected, or to divide the voltage at each point in the case of multi-point disconnection or disconnection. They were provided to equalize the electric field, and no consideration was given to alleviating the local concentration of electric field that occurs between the electrodes.

In recent years, with the increase in the amount of power transmitted by power switchgears, there has been an increasing demand for reductions in the number of power switchgears, and it has become necessary to reduce the number of conventional disconnections and disconnections by reducing the number of disconnections. The only solutions to this problem have been to increase the opening distance of the switchgear or to increase the size of the entire device so that the electric field can be relaxed by using other shield rings.

Figure 1 shows a cross-sectional view of a conventional puffer-type SF ₆ gas shield disconnector for power use.

In the figure, 1 is a fixed arc contact, 2 is a movable arc contact, and an arc is generated between the two contacts 1 and 2 when the arc breaks. In addition, when the movable contact 2 is disconnected, the movable contact 2 moves to the right in the figure, and the SF ₆ is compressed.
Extinguish the arc by blowing gas onto it.

Reference numeral 9 denotes a fixed main contact, which separates from the movable main contact 10 a little earlier than the arc contacts 1 and 2 separate, and conducts current when the contact is closed. In addition, the shields 3 and 4 are connected to the contacts 1, 9, 2, 1
This is an electric field relaxation electrode arranged to relieve the electric field concentrated at zero. 5 is an impedance element (usually connected to a resistor or capacitor) connected in parallel for the purpose of suppressing re-electromotive voltage or for evenly distributing voltage in the case of series duplication or discontinuity; is connected to the fixed contact 1 via a conductive member 7, and the other end is connected to the movable contact 2 via a conductive member 8. In addition, multiple impedance elements 5 of a predetermined capacity are internally connected in series and parallel, but the number of impedance elements 5 in series must be large enough to withstand the voltage applied between the poles, and the length Lb is the capacitance of the element. It's decided by then. When the voltage per line break point is low as in the conventional case, for the distance La between the end face of the fixed arc contact 1 and the connecting end face of the movable arc contact 2, that is, the conductive members 7 and 8,
Since the length Lb of the impedance element is sufficiently short,
The spacer 6 allows easy placement between the poles.

Reference numeral 11 indicates an equipotential line that appears when the equipotential surface that appears between the poles in the open state is cut by a plane that includes the center lines of the contacts 1 and 2.

Generally, the electric field is generated at the tip of the shield 3 in order to forcibly distribute the potential by the impedance element 5.
The electric field is extremely concentrated at _E1 and the tip _E2 of the shield 4.

For this reason, the arrangement of the impedance element 5 in the axial direction is important, but in order to increase the voltage per line and break and reduce the number of lines and breaks in the switchgear, it is important to The length Lb, which is determined based on the withstand voltage of the impedance element described above, may be larger than the distance La between the supporting parts. Therefore, it is necessary to increase the distance between the poles in accordance with the length Lb of the impedance element 5. Therefore, the contact member becomes unnecessarily large. Also, for the dimension La
Even if Lb does not increase, if the longitudinal arrangement of the impedance elements is not appropriate, the electric field concentration at the E ₁ or E ₂ points mentioned above will increase, and the shape of the shields 3 and 4 should be enlarged or the radial direction of the outer impedance elements should be increased. It was necessary to increase the size of the arrangement to alleviate the electric field. For this reason, there was a drawback that the entire arc extinguishing chamber became large. The present invention was developed to eliminate the above-mentioned drawbacks, and by appropriately arranging impedance elements connected in parallel between the poles, it is possible to alleviate the electric field concentration between the poles, and also reduce the opening distance and radial dimension. The object of the present invention is to obtain a switchgear having high voltage resistance without increasing the voltage.

An embodiment of the present invention will be described below with reference to the drawings. The present invention aims to eliminate local concentration of the electric field and improve voltage resistance by arranging the impedance elements 5 under specific conditions.

FIG. 2 is a cross-sectional view of a buffer-type gas shield and disconnector showing an embodiment of the present invention, and since the reference numerals in the figure are the same as those of the conventional device, only the essential parts will be explained.

In the figure, the length dimension Lb of the impedance element 5 is larger than the distance dimension La from the viewpoint of withstand voltage. Without changing the dimensions of this La, the impedance element 5 is
Therefore, it is necessary to place them appropriately. Outer diameter D ₁ of shield 3 determined by the outer diameter of contacts 9 and 10
is smaller than the outer diameter D ₂ of the shield 4.
For this reason, the distances to impedance element 5 l ₁ , l ₂
The relationship is l ₁ > l ₂ .

The length of the fixed side impedance 5 is L ₁ with respect to the center 0 line of the shields 3 and 4, and the length of the movable side is L ₂ , so that the impedance center is shifted from the 0 line. That is, the arrangement is such that L ₁ >L ₂ . Here, shields 3 and 4 for the above l ₁ , l ₂ L ₁ and L ₂ shown in FIG.
This will be explained using a curve diagram showing the electric fields E ₁ and E ₂ calculated by electric field.

In the figure, L ₂ and L ₁ are determined for l _{1 and} l ₂ in order to make the electric fields of E 1 and E ₂ match the permissible electric field and have the optimum dimensions. This results in the relationships l ₁ > l ₂ and L ₁ > L ₂ , and the minimum optimal size is determined. Also, since L ₁ is larger than L ₂ , the center of the impedance element 5 is placed to the left of the center 0 line of the shields 3 and 4, so the electric fields E ₁ and E ₂ are adjusted appropriately as shown in Figure 3. Can be set to value. For this reason, the conductive member 71 that electrically and structurally connects the fixed mounting surface B of the fixed arc contactor 1, fixed main contactor 9, and shield 3 and the mounting surface A of the impedance element 5 is made into a convex shape as shown in the figure. It is adapted. Compared to the case where both the mounting surfaces A and B are made the same surface (lower the B surface to the A surface), the fixed contactor and the shield 1, 3,
The entire device can be made compact and inexpensive without making the member 9 unnecessarily long.

In the above embodiment, the conductive member 71 is an integral member that serves both the electrical connection and the attachment, but it may be formed as a separate component. Further, in the embodiment, the conductive member is attached to the fixed side, but the same effect can be achieved by attaching it to the movable side, or it may be attached to both sides.

Furthermore, although the case where the present invention is applied to a power buffer-type SF ₆ gas shield and disconnector is shown, it goes without saying that it can also be applied to other types of switchgear such as shields and disconnectors.

As described above, according to the present invention, it is possible to prevent concentration of the electric field between the open poles of the contacts of the switchgear, thereby improving the voltage resistance, and at the same time making the switchgear smaller.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the open state of a conventional buffer-type gas shield and disconnector, and FIG. 2 is a cross-sectional view showing the open state of a buffer-type gas shield and disconnector, which is an embodiment of the present invention. FIG. 3 is a curve diagram showing the calculation results of electric field strength, which is the main part of the present invention. Note that the same reference numerals in the figures indicate the same or corresponding parts. In the figure, 1 is a fixed arc contact, 2 is a movable arc contact, 3 and 4 are shields, 5 is an impedance element, 7, 71, and 8 are conductive members, 9 is a fixed main contact, and 10 is a movable main contact It is.

Claims (1)

[Scope of utility model registration request] a shield arranged substantially parallel to the axial direction of at least one pair of relatively movable contacts, having an impedance connected in parallel between both the contacts, and arranged outside the contacts for electric field mitigation; Let the distance between the above impedance and the above impedance be l ₁ and l ₂ respectively, and the length of the impedance on the shield side that is a distance l ₁ from the center between both shields is L ₁ and the length of the impedance on the shield side that is a distance l ₂ from the center of both shields. A power switchgear _configured to have a relationship of _{L 1} >L ₂ when L ₂ .