JPH035014B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a gas disconnector equipped with a resistor for suppressing abnormal voltage. A disconnect switch is usually installed in a substation in a position adjacent to a line breaker, and is used, for example, to open and close lines that have been disconnected by a line breaker. When switching a no-load line using such a so-called disconnector, the opening and closing speed of the disconnector is relatively slow compared to a straight disconnector. It is known that so-called disconnector surges occur. Conventionally, in systems up to 500kV, equipment
The LIWL (Lightning Impulse Insulation Level) was 4 to 6 times higher than the normal ground voltage peak value, and disconnector surges had little effect on the insulation design of equipment. However, from the viewpoint of equipment economy, etc., 500kV
Grid LIWL tends to be reduced to 1100kV
In so-called UHV systems such as
~3.0 times. In this way, in systems using reduced LIWL, the effects of disconnector surges on equipment and systems cannot be ignored. In order to deal with these problems, it is possible to improve the dielectric strength of the equipment itself and absorb surges by installing lightning arresters in each part of the substation, but these methods are not effective from an economic point of view. is not advantageous. On the other hand, it is well known that a resistor is temporarily inserted in series between the poles of a disconnector when it is opened or closed to suppress the generated surge itself, and it is also advantageous from an economic point of view, so it is currently not available. This method is commonly used to reduce surges. As shown in FIG. 1, the conventional type includes shield bodies 61 and 62 in which a resistor 8 is incorporated, and
A fixed contact 7 and an arc contact 10 are arranged within the shield bodies 61 and 62. The movable contact 13 passing through the opening 6a of the shield body 61 is configured to be able to approach and separate from the fixed contact 7 and the arc contact 10. Further, the movable contactor 13 is connected to a link mechanism 16 via an insulated operating rod 15. The above-mentioned parts are housed in a tank 1 filled with arc-extinguishing gas, and are connected to other equipment (not shown) via conductors 4 and 5. In the figure, link mechanism 1 is driven by a drive source (not shown).
6 to move the movable contact 13 to the right, the movable contact 13 is separated as shown in FIG. At this time, an arc 22 is generated between the movable contactor 13 and the shield body 61. the result,
Since the circuit is composed of conductor 5 - movable contact 13 - shield body 61 - resistor 8 - shield body 62 - conductor 4, a high degree of disconnection occurs in various parts of the substation due to restriking between poles. The resistor 8 can suppress the device surge. However, if such a structure is used, damage to the surface of the shield body is unavoidable due to multiple arc discharges occurring during one injection or interruption. Furthermore, in order to avoid this, it is necessary to construct part or all of the shield body from an arc-resistant conductive material, which is, of course, economically disadvantageous. Furthermore, if the movable contact and the arc contact are in a positional relationship within a certain distance, an arc during interpolar discharge may occur between the arc contact and the movable contact. In this case, since no resistor is inserted into the electric circuit bridged by the arc, the disconnector surge cannot be suppressed by the resistor. Furthermore, even if an arc occurs between the shield body and the movable contact as shown in Figure 2 during interelectrode discharge, the arc column may move due to its movement, and the potential between the disconnector electrodes The distribution is likely to be disturbed, which may lead to a ground fault to the tank. This invention was made in view of the above, and since the arc contact protrudes from the shield body when the movable contact is separated, the arc during interelectrode discharge is always between the movable contact and the arc contact. To provide a gas disconnector in which a current generated and as a result of discharge flows from a resistor disposed in the shield body to the shield body. The figures will be explained below. In FIGS. 3 and 4, 1 is a tank 2, 3 filled with an arc-extinguishing gas, an insulating spacer that seals the tank 1, 4, 5 is a conductor fixed to each insulating spacer 2, 3, A shield body 6 is fixed to the conductor 4 and has an opening 6a, and is made of a conductive material. A fixed contact 7 is fixed to the shield body 6 and is disposed in the shield body 6 so as to face the opening 6a, and is electrically connected to the shield body 6. A resistor 8 has one end fixed to the shield body 6, and is composed of an insulating rod 8a and a resistor element 8b. 9 is resistor 8
A spring case 10 is fixed to the other end, and 10 is an arc contact placed in the fixed contact 7, movably supported by the case 9, and having an arc-proof piece 10a fixed to its tip, whose tip protrudes from the shield body 6. It can be moved to any position. Note that the arc contactor 10 is connected to the other end of the resistor 8 via the case 9. 1
Reference numeral 1 denotes a spring that presses the arc contact 10 in the direction of protrusion from the shield body 6, and 12 a shield body fixed to the conductor 5 and having an opening 12a, which is made of a conductive material. Reference numeral 13 denotes a movable contact which is movably supported by the shield body 12 and has an arc-proof piece 13a fixed to its tip. When moving to the right from the state shown in FIG. 3, it comes into arc contact after separating from the fixed contact 7. Separate from child 10. Reference numeral 14 denotes a current-carrying contact that can slide on the movable contact 13 and is connected to the shield body 12 . 15 is an insulated operating rod connected to the movable contact 13; 16 is a link mechanism that transmits the driving force of a drive source (not shown) to the movable contact 13 via the insulated operating rod 15; and 17 is an arc. Next, the operation will be explained. In Figure 3,
When the insulated operating rod 15 is moved to the right, the movable contact 13 separates from the fixed contact 7. Then, the arc contactor 10 follows the movable contactor 13 by the action of the spring 11, and moves forward until the electric field strength at the tip of the arc-proof piece 10a becomes stronger than the electric field strength at each part of the shield body 6; That is, it stops at a position protruding to the outside of the shield body 6. Since the movable contactor 13 continues to open and open after this, an arc 17 is generated between both arc-proof pieces 10a and 13a, but the electric field strength at the tip of the arc-proof piece 10a is equal to the electric field at each part of the shield body 6. Since it is stopped at a position where the strength is stronger than that of the other arc-resistant pieces 10, any of the many arc discharges (re-ignitions) that occur during the opening/closing operation will
This occurs between a and 13a. the result,
It is possible to prevent damage to the shield body, which was a drawback of the conventional structure, and since the arc discharge itself is concentrated more in the center than in the conventional structure, there is less disturbance of the electric field between the electrodes due to the arc discharge. , the possibility of developing a ground fault to the tank is reduced. In addition, since arc discharge always occurs against the arc-proof piece provided at the tip of the arc contact, a resistor is always connected in series in the electrical circuit formed in the disconnector during the discharge between electrodes. As a result, the surge suppressing effect of the resistor can be obtained against disconnector surge caused by any discharge during opening/closing operations. At this time, the maximum value VRmax of the potential difference generated across the resistor inserted in the circuit is the potential difference between the poles at the time of discharge is V, the resistance value of the resistor to be inserted is R, and the no-load bus connected to the disconnector is Letting Z be the surge impedance of , it can be approximated by the following formula. VRmaxR/R+Z·V (1) As is clear from this equation, the potential difference generated across the resistor changes depending on the resistance value of the inserted resistor. Therefore, we assumed a model substation (6 lines, 4 banks, double bus system) for the UHV class, which is the most severe voltage condition.
The table shows some of the results of an analysis of transient phenomena during opening and closing of disconnectors using a digital computer. In this analysis, the maximum potential difference V between electrodes during discharge is assumed to be 2E.

[Formula] and the surge impedance Z of the no-load bus bar is 60
It was set to Ω. In addition, the analysis was performed using the resistance value to be inserted as a parameter.

[Table] As is clear from the analysis results shown in the table, a resistor value of several tens of Ω is sufficient to suppress surges. Also, as is clear from equation (1), the lower the resistance value inserted, the lower the voltage applied to both ends of the resistor.
It is about 100kV. This kind of voltage applied across a resistor
VRmax is also added to the voids such as P, Q, R, and S shown in Fig. 4, but in each of these parts, for example,
Because it is filled with insulating gas such as SF ₆ gas,
It is easy to obtain dimensions and shapes that can withstand such voltages. In addition, since this voltage value VRmax is approximately proportional to the potential difference V between electrodes during discharge, it is possible to achieve similar performance not only in the UHV class but also in gas disconnectors of other voltage classes by using a similar shape. It is easy to obtain. FIGS. 5 to 8 show main parts of other embodiments of the present invention. In FIG. 5, at least one insulating support 18 is provided at a position independent of the resistor 8, and the arc contact 10 and the case 9 are fixed to the shield body 6. If such a structure is used, the number of resistors 8 to be installed can be arbitrarily selected, which has the advantage that various resistance values can be realized only by combining resistors having the same resistance value. be. Figure 6 shows the arc contact 10 that occurs when opening and closing.
This is an example in which an insulating support body 19 is provided to stably hold mechanical vibrations caused by movement of the body. Such an insulating support 19 can also be used in the embodiments shown in FIGS. 4 to 8. FIG. 7 shows an embodiment in which a metal wire is used as the resistor. The total energy consumed by the resistor due to the multiple discharges that occur during one opening or closing operation of the disconnector is a relatively small value as shown in the table, so the heat capacity of the metal wire resistor etc. Even if a resistor material that is difficult to obtain in sufficient quantities is used, it is easy to obtain a resistor that meets the intended purpose. For example, a 10Ω resistor can be realized using a nichrome wire with a diameter of about 1.3 mm and a length of about 12 m. And the heat capacity of this resistor is
That's enough to absorb 9.3 kilojoules of energy in 10 milliseconds. Based on such analysis, insulating columns 18 and 20 are provided in the figure for the purpose of fixing the arc contactor 10 and the case 9 to the shield body 6. Then, the insulating column 20 is a metal wire resistor 2
It is convenient to use a structure as shown in FIG. 8 in order to make it easy to attach the windings 1 and to ensure mutual insulation between the windings. In addition, the reversal of the spiral groove is caused by the metal wire resistance 2
This is for making winding 1 non-inductive. In FIG. 8, a resistor 8 is fixed to the side opposite to the fixed contact 7 of the shield body 6, and a case 9 is attached to the fixed contact 7 side.
was supported. Such an arrangement is the fourth
The embodiments shown in FIGS. 7 to 7 can also be used.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a conventional gas disconnector in a closed state, FIG. 2 is a cross-sectional view of the main part showing a state in the middle of opening in FIG. 1, and FIG. 3 is a cross-sectional view of a gas disconnector according to the present invention. 4 is a cross-sectional view of the main part showing the state in the middle of opening of FIG. 3, and FIGS. 5 to 9 are main parts of other embodiments of the gas disconnector according to the present invention. FIG. In the figure, 1 is a tank, 6 is a shield, 7 is a fixed contact, 8 is a resistor, 10 is an arc contact, 13 is a movable contact, 18 is an insulating column, and 19 is an insulating support. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A tank filled with gas having arc-extinguishing properties, a shield body housed in the tank and having an opening,
a fixed contact disposed in the shield body facing the opening and electrically connected to the shield body; a fixed contact housed in the tank and capable of coming into contact with and separating from the fixed contact; When a movable contact having a predetermined distance from the shield body outside the shield body is disposed within the fixed contact at a predetermined distance from the fixed contact, and the two contacts are separated from each other. an arc contact that opens slowly and protrudes from the opening and faces the movable contact at a predetermined distance; an arc contact that is electrically connected between the arc contact and the shield body and disposed within the shield body; and a resistor that is fixed to the shield body and supports the arc contact, the resistor having a resistance value in the range of 10Ω to 60Ω. 2. The gas disconnector according to claim 1, wherein the resistor comprises an insulating rod and a hollow disc-shaped resistance element fitted into the insulating rod.