JPS6155834A - Sf6 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 an 8F6 gas circuit breaker, and more particularly to an SF gas circuit breaker having a parallel capacitor.

[Background of the invention]

The positional relationship between the interrupting part of the conventional SF6 gas circuit breaker and the large current interrupting component was determined. Therefore, no consideration has been given to the potential distribution between the electrodes during the opening operation, depending on the arrangement of the interrupting part and surrounding components. In particular, when a high voltage is applied between the electrodes before the open strain distance between the electrodes becomes sufficiently large, as in the case of advance/J1 current interruption, the dielectric strength between the electrodes is insufficient with the component arrangement described above. However, it had the disadvantage of being inferior in flow rate cutting performance at small advances.

During the advanced small current interruption test, a high voltage of about 60 to 70% of the lightning impulse withstand voltage value is applied between the electrodes at a relatively small separation distance between the electrodes of 30 to 40% of the open state.

For this reason, in a circuit breaker with a small number of breaking points and a high rated voltage, it becomes more difficult to interrupt a small advance current.

Furthermore, the transient recovery 'cL pressure rise rate when the thick IW flow is interrupted also increases, and in order to suppress this, a method is used in which a parallel capacitor 1 is connected between the poles. However, the conventional S i,
The T6 gas circuit breaker was designed to withstand the lightning impulse withstand voltage trial sales in the open state, and did not pay much attention to the dielectric strength between the poles during the open operation, so it was designed to withstand the lightning impulse withstand voltage trial sales in the open state. The electric field is higher on the movable contact side than on the fixed contact side. Therefore, the center position between the poles in the open state and the center potential position of the parallel capacitor are almost the same, or the potential difference between the parallel capacitor and the contact is almost the same on the fixed contact side and the movable contact side. In the conventional 8F6 gas circuit breaker, in which the interrupting part and the parallel capacitor are arranged, when a high voltage is applied between the poles while the separation distance between the poles is small, such as when interrupting a small advanced current, the parallel This has the disadvantage that the electric field strength on the movable contact side increases due to the influence of the potential distribution of the capacitor.

[Purpose of the invention]

An object of the present invention is to provide an 8F gas circuit breaker with excellent advance small current interrupting performance.

[Summary of the invention]

In order to improve the electric field distribution at the separation distance between poles, which causes a high electric field when cutting off a small advancing current, the center potential position of the parallel capacitor is moved closer to the fixed contact side than before, and the center potential position is moved closer to the movable contact side. It is characterized by a relaxed electric field.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows a buffer type circuit breaker. The left half shows the state where the circuit breaker is in the process of opening and is at the distance between the poles where a large voltage is applied after the small current is cut off, and the right half shows the state where the circuit breaker is not opening. It shows the finished state.

A pair of arc contacts consists of a fixed arc contact 1 and a movable arc contact 3, and a pair of main contacts consists of a fixed main contact 2 and a movable main contact 4. A movable main contact 4 is constructed on the outside of an insulating nozzle 5 surrounding the movable arc contact 3, and these are attached to a buffer cylinder 6. The buffer cylinder 6 is connected to an operating device (not shown) and compresses the SF and gas between it and the piston 7 by being driven upward. The explanation was a bit confusing, but the illustrated part is science fiction.

It is constructed in a sealed container filled with gas. The gas compressed as described above is guided by the insulating nozzle 5 and used for arc extinguishing. Forming parallel conde positions. The fixed main contact 2 is provided surrounding the fixed arc contact 1, and a parallel capacitor support fitting 9a is provided on the outer periphery of the fixed main contact 2, and these fixed side members are electrically connected and are the same. It forms a potential section.

A parallel capacitor 8 is configured between the support fittings 9a and 9b. This parallel capacitor 8 is provided for the purpose of equalizing the shared voltages and suppressing the rate of increase in the re-electromotive voltage. It is used for both purposes. The configuration of the parallel capacitor 8 is, for example, a combination of rod-shaped capacitors, as is known for use in 8F gas circuit breakers, and three or more rod-shaped capacitors are arranged at approximately equal intervals around the outer periphery of the solid contact or insulating nozzle 5. There is. Arranging the rod-shaped capacitors at approximately equal intervals in this manner is effective in this embodiment. Each rod-shaped capacitor is formed by stacking a plurality of capacitor elements in an insulating cylinder.

In the visiting operation of the interrupting section having such a configuration, the movable side of the interrupting section is driven upward by an operating device (not shown), and first, the movable main contactor 4 is connected from the fixed main contact 2 constituting the main current path r. Release. Next, the movable arc pendulum 3 is separated from the fixed arc contact 1, and an arc is generated between both the arc contacts 1 and 3 along with this separation operation. This arc compresses the guide SF and gas formed by the buffer cylinder 6 and the piston 7 along with the opening operation, and the compressed gas is guided by the insulating nozzle 5 and acts to extinguish the arc.

Next, a description will be given of the time when a small current is interrupted.

In this case, since the breaking current is small, if the fixed main contact 2 and the movable main contact 4 are opened and then the fixed arc contact 1 and the movable arc contact 3 are opened, an arc occurs at the same time as this opening. Current interruption may occur at time zero. In addition, in the case of advanced small current interruption, the phase difference between current and voltage is approximately 90 degrees in electrical angle, so when current interruption occurs, the load side of the circuit breaker is charged with the peak value of the voltage to ground. Become. On the other hand, since a voltage to ground with a frequency of 300 nm is applied to the power supply side of the circuit breaker, for example, in the case of 3-phase AC, the following (
1) A potential difference V given by the formula is generated.

However, vp: power supply voltage (line voltage, effective value), ω=2
πf, f: power supply frequency, t: time (seconds).

In order to verify the advance small current breaking performance, the circuit breaker is
JS current test is required. The test voltage at this time varies depending on the applicable standard, the rated voltage of the circuit breaker, and the test method, but it is 1.1 to 1.3 times the voltage shown by equation (1), and there is a movement to further increase it. be. The voltage expressed by equation (1) reaches its maximum 0.5 cycles after the electrodes are opened, and this rate of increase is greater than the rate of increase in the distance between the electrodes when the electrodes are opened, so the electric field strength between the electrodes is 0 after the electrodes are opened. It reaches its maximum at a time earlier than .5 cycles.

On the other hand, when we examine the relationship between the maximum electric field strength on the fixed contact side and the movable contact side and the distance between poles, assuming that the potential difference between the poles of the circuit breaker is constant, we find that when the distance between poles is small, the electric field strength on the fixed contact side This relationship tends to reverse as the distance between the poles increases and the distance between the poles increases. This is due to the problem of the shape of the circuit breaker, which is restricted from the functional point of view. This is due to the fact that the curvature of the contact portion cannot be increased in order to increase the length.

The potential distribution of the parallel capacitor 8 shown in FIG. 1 is generally not influenced much by surrounding components and is almost constant regardless of the distance between poles. Therefore, the electric field of the movable contact can be alleviated by appropriately selecting the position of the movable contact that matches the potential distribution of the parallel capacitor 8 and has the maximum electric field strength when a small current is interrupted.

This will be explained with reference to FIG. This figure shows the relationship between the maximum electric field strength and the distance between poles on the movable contact side and the fixed contact side. Support metal fitting 9a of parallel capacitor 8 in open state
, 9b, the maximum electric field on the fixed contact side is curve A when 1tP, which is half the potential between the fixed contact and the movable contact, is approximately the center position Q of the fixed contact and the movable contact. The maximum electric field on the side is curve B. On the other hand, when the 1/2 potential position P between the support fittings 9a and 9b of the parallel capacitor 8 is opened, the maximum electric field on the fixed contact side is curve C, and the maximum electric field on the movable contact side is The electric field is curved.

The reason why the maximum electric field strength on the movable contact side can be reduced in this way is as follows.

(1) In a region where the distance between poles is small, the maximum electric field portion on the movable contact side is in the movable arc contact 3, and in a region where the distance between poles is large, the maximum electric field portion changes to the movable main contact 4.

(2) The movable main contactor 4 is located close to the parallel capacitor 8, and the electric field is relaxed by the potential distribution of the parallel capacitor 8.

(3) On the other hand, in the fixed contact IKl+, the maximum electric field portion is at the tip of the fixed arc contact 1 and is not affected by the potential distribution of the parallel capacitor 8 due to the shielding effect of the fixed main contact 2.

(4) The electric field strength of the fixed main contact 2 is affected by the potential distribution of the parallel capacitor 8, but since the curvature of the shield (curvature on the outside of the fixed main contact 2) can be increased in this area, the electric field strength does not become high. .

In the example shown in FIG. 2, the distance between the poles that gives the maximum electric field strength in the advanced small current interruption test is 0.3 to 0.4, and the distance between the poles is 0.3 to 0.4. /2'a
By locating the position of the fixed contact and the movable contact in the open state, that is, the fixed arc contact 1 and the movable arc contact 3, closer to the fixed arc contact 1 than the approximate center of the open state, the advanced small current interrupting performance is improved. It can be improved by 11-15%. How far the intermediate potential position of the parallel capacitor 8 should be moved toward the fixed contact is determined by comprehensively considering the lightning impulse withstand voltage test value, the supply voltage for the advanced small current interruption test, the opening speed, the opening length, etc. is good. Further, the intermediate potential position of the parallel capacitor 8 may be determined by changing the position of the entire parallel capacitor or by changing the capacitance of each capacitor element.

FIG. 3 is a sectional view of a blocking section according to another embodiment of the present invention, showing the left half after opening.

In this example, a plurality of fixed contacts 10-1 to 10-n are electrically connected to several capacitor elements on the movable contact side of the parallel capacitor 8.

Sliding contact 1 paired with these fixed contacts 10-1 to 10-n
1 is electrically and mechanically connected to the movable contact, and in the closed state, several capacitor elements are short-circuited, and in the open state, the number of parallel capacitors 8 connected in series increases as the distance between poles increases. increase.

According to this configuration, the intermediate potential portion P having a potential of 1/2 between the supporting metal fittings 9a and 9b of the parallel capacitor 8 after opening is the same as that between the fixed arc contact 1 and the movable arc contact 3 in the same state. The center position! Fixed arc contactor 1i141 than Q
1, but not as high as the example in FIG. but,
At the time of interruption of the advanced small flow, the sliding contact 11 is in contact with the fixed contact and short-circuits several capacitor elements, so the above-mentioned intermediate potential part P of the parallel capacitor 8 is It can be the same as the example. In other words, by improving the advanced small current interrupting performance, the relationship between each part in the open state will change from the relationship based on the conventional design method, but in the example shown in Figure 3, the advanced small current interrupting performance is improved. By improving the structure, it is possible to obtain a cutoff section that does not significantly change the relationship between the various parts in the open state, and therefore does not reduce the lightning impulse withstand voltage performance.

The movable contact explained in the above embodiment is the movable arc contact 3.
Although the fixed contact is made up of the fixed arc contact 1 and the fixed main contact 2, various known structures can be adopted for this glazed circuit breaker.

〔Effect of the invention〕

As explained above, in the present invention, the intermediate potential portion, which is approximately 1/2 the potential between the supporting metal fittings of the parallel capacitor, is located closer to the fixed liquid j stator than the approximately central position between both contacts after opening. Therefore, it is possible to reduce the maximum electric field strength of the interrupting part during the opening operation and improve the small current interrupting performance.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of an 8J4''6 gas circuit breaker according to an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the relationship between pole length and maximum electric field strength, and Fig. 3 is another embodiment of the present invention. It is a vertical cross-sectional view of an SF6 gas circuit breaker according to an example. 1... Fixed arc contact, 2... Fixed main contact, 3... Movable arc contact, 4 ...
...Movable main contact, 5...ABfi nozzle,
8...Parallel capacitor, 9a. 9b... Support metal fittings. Figure 1 Figure 2 Leap length (a month) No.

Claims (1)

[Claims] 1. A pair of separable movable contacts and fixed contacts;
SF_6 is applied to the arc generated by the opening of both contacts above.
an insulated nozzle for guiding the gas to be blown; and 1 electrically connected to the movable contact and the fixed contact, respectively.
In the SF_6 gas circuit breaker having a parallel capacitor configured between a pair of support fittings, the parallel capacitor is
Three or more rod-shaped capacitors are arranged at approximately equal intervals around the outer periphery of both of the contacts and the insulating nozzle, and are used to improve the potential distribution between the poles, thereby alleviating the maximum electric field during opening operation when cutting off a small advance current. so that the intermediate potential portion of the parallel capacitor, which has approximately 1/2 the potential between the supporting metal fittings, is located closer to the fixed contact than the center position of the opposing portion between the two contacts in an open state. SF_6, which is characterized by
Gas circuit breaker. 2. In the device described in claim 1 above, each rod-shaped capacitor includes a plurality of laminated capacitor elements, and a plurality of capacitor elements provided in a predetermined number of capacitor elements from the movable contact side of the capacitor elements. It has a fixed contact and a sliding contact that is linked to the movable contact so as to sequentially connect and separate from the fixed contact, and when the movable contact opens, the intermediate potential portion of the parallel capacitor is moved toward the center position. An SF_6 gas circuit breaker characterized by being configured to move.