JP2016115596A - Electric field relaxing device of vacuum interrupter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which, when a ground layer is present around a VI having an intermediate shield, the voltage sharing of the potential of the intermediate shield joined to an insulating material of the VI is biased to the ground side by being affected by the ground capacitance, so, the electric field on the power-source side of the VI becomes high.SOLUTION: A second intermediate shield is provided between a power-source side energization part inside a VI and an intermediate shield joined to a ground side energization part and an insulating material. By interposing an intermediate insulating material between the second intermediate shield and the intermediate shield joined to the insulating material to form a portion of generating a ground voltage, a potential difference between the power-source side energization part and the second intermediate shield is made to be relatively small.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electric field relaxation device for a vacuum interrupter, and more particularly to an electric field relaxation device that reduces a potential difference between a power supply side energization section and an intermediate shield.

  Vacuum circuit breakers (hereinafter referred to as VCB) using a vacuum interrupter (hereinafter referred to as VI) in the circuit breaker have been widely adopted for circuit breakers due to their small size, high performance, and ease of maintenance and inspection. Higher voltage and larger capacity VCBs are demanded. For example, there is a tank type VCB in which the periphery of VI is surrounded by a ground metal as one corresponding to high voltage and large capacity.

  FIG. 5 shows a partial view of a VI used in the tank type VCB. 1 is a power supply side energization unit, 2 is a grounding side energization unit, and the grounding side energization unit 2 is connected via an operation mechanism not shown. The power supply side energization unit 1 is operated to be controlled to contact or open. Reference numerals 3 and 4 denote insulators which are joined by brazing or the like with an intermediate shield 5 interposed between both insulators while maintaining a predetermined degree of vacuum. Reference numeral 10 denotes a metal tank filled with an insulating gas.

  FIG. 6 shows a distribution state of capacitance and ground voltage of VI having the structure of FIG. Here, C0 is an electrostatic capacity between the power supply side energization part 1 and the grounding side energization part 2, C1 is an electrostatic capacity between the power supply side energization part 1 and the intermediate shield 5, C2 is an electrostatic capacity of the insulator 3, and C3. Is the capacitance between the power supply side current-carrying part 1 and the intermediate shield 5, C4 is the capacitance of the insulator 4, C5 is the ground capacitance due to the surrounding ground layer (tank), U0 is the power supply voltage, U1 is the intermediate shield 5 to ground voltage.

The potential difference between the power supply side energization section 1 and the intermediate shield 5 of VI shown in FIG.
U0-U1 [%]
The value depends on the magnitude of the ground capacitance C5 due to the ground layer (such as the tank 10) around the VI. In general, when the ground capacitance C5 increases, U0-U1 [%] increases, and the stress E1 in the power supply side energizing section 1 and the intermediate shield 5 is:
E1 = (U0−U1) / d1 [% / mm]
(However, d1 is the distance between the intermediate shield and the current-carrying part on the power supply side and ground side)
Increases, and the breakdown probability at the rising point increases. In order to solve this phenomenon, the ground voltage U1 of the intermediate shield 5 is increased by arranging a voltage sharing capacitor, or the ceramic and the shield are multi-staged, and the potential difference U0-U1 is decreased to reduce the dielectric breakdown probability. I am trying.

  Note that Patent Document 1 is known to provide a plurality of intermediate shields inside a VI. In this patent document 1, a direct flashover to the intermediate potential shield is prevented by attaching a shield between the contact and the intermediate potential shield.

Patent No. 5095614 JP-A-10-224923

  When there is a ground layer around the VI as in the VCB described above, the potential of the intermediate shield 5 is influenced by the ground capacitance, so that the voltage sharing is biased to the ground side, and the power supply side electric field of the VI increases. In order to solve this problem, as shown in Patent Document 2, a voltage sharing capacitor is provided in parallel with VI, and a ceramic and a shield are multistaged to equalize the potential. However, when a voltage sharing capacitor is provided, the purpose is to alleviate the electric field on the power supply side of the VI. Therefore, since the arrangement is connected in parallel with the VI, the tank diameter of the VCB increases, and in particular, the high voltage -There is a problem that the installation area of a large-capacity VCB increases.

  Further, in the VI having a multistage structure of ceramics and shields, a structure in which a plurality of ceramic cylinders are connected is provided, and a high voltage and large capacity one has a multistage structure including, for example, four ceramic cylinders. For this reason, there is a risk that the center axis between the ceramic cylinders is shifted during VI manufacturing. In addition, in the case of a multistage structure, adjacent ceramic cylinders are joined by a shield made of metal, so if the number of junctions between the ceramic and the shield increases, external flashing tends to occur and the length of VI also becomes longer. Have.

  An object of the present invention is to provide an electric field relaxation device in which a potential difference between a power supply side energization section and an intermediate shield is reduced.

The present invention is a vacuum interrupter configured by surrounding a power supply side energization part and a ground side energization part with an insulator having an intermediate shield interposed therebetween, and the vacuum interrupter surrounded by a ground layer.
A portion where a ground voltage is generated by disposing a second intermediate shield between the power supply side energization unit and the ground side energization unit and the intermediate shield, and interposing an intermediate insulator between the second intermediate shield and the intermediate shield. It is characterized by forming.

  The first intermediate shield of the present invention is characterized in that an intermediate insulator is fixed through a support, and the intermediate insulator is configured by fixing a second intermediate shield through the support. is there.

  In the present invention, the ground layer surrounding the vacuum interrupter is either a vacuum circuit breaker that houses the vacuum interrupter in a metal tank filled with an insulating gas, or a gas insulated switchgear. Is.

  As described above, according to the present invention, the potential difference between the power supply side current-carrying portion and the intermediate shield is reduced by providing the generating member of U2 that is the second ground voltage in the VI surrounded by the ground layer. Thus, the electric field can be relaxed and the VCB can be downsized.

The block diagram of VI which shows embodiment of this invention. The distribution figure of the electrostatic capacity and ground voltage in VI of the present invention. VCB tank diameter vs. tank ground potential characteristics. The relative dielectric constant of the intermediate insulator versus the second intermediate shield characteristic diagram. The block diagram of conventional VI. Distribution diagram of capacitance and ground voltage in conventional VI.

FIG. 1 is a partial block diagram of a VI according to the present invention. The same or corresponding parts as those of the conventional VI shown in FIG. In the present invention, a second intermediate shield 6 is provided opposite to the intermediate shield (first intermediate shield) 5, and the first intermediate shield 5 and the second intermediate shield 6 are made of ceramic or the like. A ring-shaped intermediate insulator 7 is provided. The second intermediate shield 6 faces the power supply side energization unit 1 and the ground side energization unit 2 and is disposed with a distance d2. Further, the intermediate insulator 7 is disposed at a position facing the vicinity of the contact position between the power supply side energization unit 1 and the ground side energization unit 2.
That is, in the VI of the present invention, the intermediate insulator 7 is fixed to the inner peripheral side of the first intermediate shield 5 that is the outer surface of the VI via the support, and further supported on the inner peripheral side of the intermediate insulator 7. The second intermediate shield 6 is fixedly arranged through the body.

FIG. 2 shows a distribution state diagram of the capacitance and ground voltage of VI shown in FIG. 1, where C6 is the capacitance of the intermediate insulator 7, and U2 is the ground voltage of the second intermediate shield 6. .
The potential difference (U2−U1) is generated by interposing the intermediate insulator 7 between the first and second intermediate shields 5 and 6, and the potential difference between the power supply side energization section 1 and the second intermediate shield 6 is U0− (U2−U1) [%], and the potential difference between the power supply side energization unit 1 and the second intermediate shield 6 is relatively small. At this time, if the distance d2 between the power supply side energization section 1 and the second intermediate shield 6 is d2 = d1, the electric field E2 between them is E2 = U0− (U2−U1) / d2 [% / mm] < E1 [%]
(However, E1 is the electric field in the conventional power supply side energizing section 1 and intermediate shield 5)
Thus, the electric field in the power supply side energizing section 1 and the second intermediate shield 6 is lowered, and the dielectric breakdown probability is also lowered. Therefore, in the same VCB, it is possible to reduce the dielectric breakdown probability of VI without using a voltage sharing capacitor as in the prior art or using a multi-stage configuration of ceramic and shield. As a result, the VCB can be miniaturized.

  FIG. 3 shows the test results of the relationship between the tank diameter of the VCB and the intermediate shield ground voltage (U1). In the conventional VI, since the electric field of E1 in the power supply side energization section 1 and the intermediate shield 5 is determined by U1 and d1, the diameter of the VCB tank 10 is changed from Φ500 to Φ650 in order to reduce the ground voltage U1 from 25% to 29%. And must be enlarged by about 150 mm.

  FIG. 4 shows the test result of the relative dielectric constant of the intermediate insulator 7 to the ground voltage (U2) relationship of the second intermediate shield 6 in the present invention. In the present invention, the ground voltage U2 is improved from 25 to 29% and the electric field E2 becomes lower than E1 by disposing the intermediate insulator 7 having a dielectric constant of 10 without changing the outer shape of the tank 10 having Φ500.

As described above, according to the present invention, by providing a member for generating U2 which is the second ground voltage in the VI surrounded by the ground layer, the potential difference between the power supply side energization part and the intermediate shield can be reduced. The relaxation can be achieved and the VCB can be downsized.
In addition, although VCB was demonstrated above, it has the same effect also about the gas insulated switchgear GIS in which VI is used.

DESCRIPTION OF SYMBOLS 1 ... Power supply side energization part 2 ... Ground side energization part 3, 4 ... Insulator 5 ... Intermediate shield (1st intermediate shield)
6 ... Second intermediate shield 7 ... Intermediate insulator 10 ... Tank

Claims (3)

In a vacuum interrupter in which a power supply side energization unit and a ground side energization unit are surrounded by an insulator having an intermediate shield (first intermediate shield) interposed therebetween, the periphery being surrounded by a ground layer,
A second intermediate shield is disposed between the power supply side energization section and the ground side energization section and the first intermediate shield, and an intermediate insulator is interposed between the second intermediate shield and the first intermediate shield. An electric field relaxation device for a vacuum interrupter, characterized in that it constitutes a part for generating ground voltage. 2. The vacuum according to claim 1, wherein the first intermediate shield has an intermediate insulator fixed through a support, and the intermediate insulator has a second intermediate shield fixed through the support. Electric field relaxation device for interrupters. 3. The grounding layer surrounding the vacuum interrupter is either a vacuum circuit breaker that houses the vacuum interrupter in a metal tank filled with an insulating gas, or a gas insulated switchgear. Vacuum interrupter electric field relaxation device.

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