JPH02273422A - Buffer type gas circuit breaker - Google Patents

Abstract

PURPOSE:To produce arc from a fixed electrode always between arc electrodes by making the tip of the fixed arc electrode in the shape having two curvatures of different electrode diameters, and thinning the diameter of the endmost portion of the electrode. CONSTITUTION:The tip of a fixed arc electrode 8 is constituted with a first curvature portion 8a having the curvature of the diameter of the electrode 8 and with a second curvature portion 8b having the curvature smaller than the diameter of the first curvature portion 8a. When the maximum electric field E1 of the first curvature portion of the fixed arc electrode is compared with the maximum electric field E2 of the second curvature portion in the process of electrode opening, the relationship E1<=E2/2 is always held during the electrode opening. As a result, discharge of reingniting arc and restarting arc during the electrode opening always occurs between the second curvature portion of the fixed arc electrode tip and a movable arc electrode. Because the electric field E1 of the first curvature portion is in the relationship of E1<=E2/2, no electron discharge due to electric field radiation from the first curvature portion occurs even immediately before discharge, and no charging along the surface of an insulation nozzle occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a puffer type gas circuit breaker, and particularly to the structural shape of an arc electrode.

(Prior Art) In recent years, the capacity of power plants has been increasing steadily as the demand for electricity increases. Moreover, due to the difficulty in constructing power plants in urban areas where large amounts of electricity are consumed, power transmission lines are becoming longer and there is a trend toward higher voltages to improve power transmission efficiency.

As power transmission systems become larger and higher in voltage, the breaking capacity required of circuit breakers used in substations and switchyards continues to increase, and currently in 550kV systems, devices with breaking currents of 63kA are in practical use. has been made into This 550kV
- A 63 kA class circuit breaker is constructed with four disconnect points, but in order to improve the reliability of the circuit breaker, it is important to reduce the number of disconnect points and the number of parts.

For this purpose, it is necessary to improve the breaking capacity per breaking point, for example, to cut 550 kV and 63 kA at two points or one point.

In order to achieve this improvement in breaking capacity, conventional 168
Puffer type gas circuit breakers have been used in transmission voltage systems of kV or higher. This is due to the simple structure of the circuit breaker and the excellent performance of the insulating gas such as SF gas used as the insulation and arc extinguishing gas. Also,
In a sealed gas insulated switchyard where the entire substation equipment is insulated with SF, gas, the same insulating gas is used for the circuit breaker and other equipment, so it is difficult to isolate the equipment from other equipment. It is particularly frequently used because it allows for coordination and is efficient in terms of the arrangement of one device.

A conventional puffer-type gas circuit breaker has an insulating gas sealed in a tank, and a cutoff section that includes a fixed electrode section, a movable electrode section facing the fixed electrode section, and a puffer section adjacent to the movable electrode section. It will be stored.

The movable parts of the movable electrode part and the puffer part of the cutoff part are connected to the drive mechanism part through an operating rod connected to the movable electrode rod. Further, at the time of interruption, the movable part is operated by the drive mechanism part, and the insulating gas compressed by the puffer part is sprayed to extinguish the arc generated between the fixed and movable electrode parts.

The shutoff part of such a conventional puffer type gas circuit breaker is the fourth
It is configured as shown in the figure. That is, the cutoff section 1 includes a fixed electrode section 2, a movable electrode section 3, and a puffer section 4. The fixed electrode section 2 includes a fixed arc electrode section 8 at the center, a cylindrical fixed current-carrying contact 9 and a fixed shield 18 provided on the outside thereof.

On the other hand, the movable electrode section 3 and the puffer section 4 are attached to the inside of a tank (not shown) via a supporting insulating tube (not shown). The puffer section 4 is composed of a puffer piston 11 fixed to the tank side, a puffer cylinder IZ that slides on the outside of the puffer piston 1 by being driven by a drive mechanism section, and a puffer chamber 5 formed by these two. ing. A movable electrode rod 13 connected to this puffer cylinder 12 is inserted into the inside of the puffer piston 11,
It is connected to the drive mechanism section via an operating rod. The movable electrode section 3 is provided with a movable arc electrode 14 made of, for example, an arc finger on the bottom 12a of the puffer cylinder 12, and an insulating nozzle 15 surrounding the movable arc electrode 14.

This insulating nozzle 15 is mounted so as to be held down by a movable energizing contact 19 which has the function of shielding 20 and energizing. Note that a gas flow path 15a is formed inside the insulating nozzle 15, and this gas flow path 5a is connected to the puffer chamber 5 and the communication hole 1. ], connected by b.

In the conventional puffer type gas circuit breaker configured as described above, when the movable electrode rod 13 moves reciprocally by the drive mechanism section, the movable electrode section 3 moves toward the fixed electrode section 2 facing the movable electrode rod 13.
Opening and closing operations are performed between the terminal and the terminal to interrupt the current.

When the interrupting section 1 is in the interrupting operation, an arc (not shown) is generated between the fixed arc electrode 8 and the movable arc electrode 14. However, when the puffer cylinder 12 moves to the right side in the figure due to the shutoff operation and the insulating gas is compressed in the puffer chamber 5, this insulating gas passes through the communication hole 11b and the gas flow path 1.5a and is blown onto an arc (not shown). The arc is extinguished.

(Problem to be solved by the invention) In such a high voltage puffer type gas circuit breaker,
If an attempt is made to reduce the number of breaking points of a circuit breaker, the transient recovery voltage after current interruption will become extremely high, such as early or delayed small current interruption, and the electric field strength generated between the poles of each circuit breaker will increase. .

Therefore, when re-ignition and re-ignition occur due to extremely high transient recovery voltages, the gas does not occur in the gas gap between the fixed and movable arc electrodes 8 and 14, but instead occurs from the fixed arc electrode 8 through the creeping surface of the insulated nozzle 15. This may occur at the movable arc electrode or the puffer cylinder 1z.

This is because, as shown in FIG. 5, the vector direction Ea of the maximum electric field of the fixed arc electrode 8 becomes approximately equal to the creeping direction of the insulating nozzle 15 during a certain stroke. In this way, the discharge at the time of re-ignition and re-ignition is caused by the insulating nozzle 15.
When passing through the creeping surface of the insulating nozzle 15, electrical charges are accumulated on the creeping surface of the insulating nozzle 15. For example, when positive charges are accumulated due to discharge, when a negative voltage is applied to the movable current-carrying contact 20 side, the electric field Em at the tip of the movable current-carrying contact 20 becomes several times higher than normal. Become. Therefore, the movable current-carrying contact 2
The probability that a discharge will occur from zero becomes high.

The present invention has been made in consideration of the above points, and its purpose is to
To provide a puffer type gas circuit breaker with high insulation performance in which the discharge from the insulating nozzle 15 does not pass through the creeping surface of the insulating nozzle 15 and the arc is always bridged between the arc electrodes.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the puffer type gas circuit breaker of the present invention has the tip of the fixed arc electrode formed into a shape having two curvatures with different electrode diameters. Reduce the diameter of the electrode with curvature.

(Function) By reducing the electrode diameter with curvature at the tip of the fixed arc electrode, the direction of the maximum electric field vector at the tip of the fixed arc electrode during opening always faces the movable arc electrode, which prevents restriking and The discharge during re-ignition always occurs between the arc electrodes. Therefore, a gas circuit breaker with high insulation reliability can be provided.

(Example) Hereinafter, one example of the puffer type gas circuit breaker of the present invention will be described as a first example.
-Explain with reference to figures. The same parts and parts having the same functions as those in FIG. 4 are given the same reference numerals.

The tip of the fixed arc electrode 8 is composed of a first curvature part 8a having a curvature at the diameter of the fixed arc electrode 8 and a second curvature part 8b having a curvature at a diameter smaller than the diameter of the first curvature part 8a. ing.

The operation of the present invention will be explained with reference to FIG. FIG. 5 shows the vector of the maximum electric field at the first and second curvature portions of the tip of the fixed arc electrode during opening. Here, the maximum electric field E in the first curvature part and the maximum electric field E in the second curvature part
2, it is possible to always maintain E1≦E2/2 during the opening. Therefore, re-ignition during opening and discharge during re-ignition always occur between the second curvature portion of the fixed arc electrode tip and the movable arc electrode. Since the electric field E1 at the first curvature section of the fixed arc electrode tip is E, ≦E2/2, even when the second curvature section is on the verge of discharge, electrons are emitted by field radiation from the first curvature section. There is no possibility of charging the creeping surface of the insulating nozzle.

18= FIG. 2 shows another embodiment in which the curvature surface of the first curvature portion 8a of the fixed arc electrode 8 is covered with a heat-resistant insulator 21.

Covering the first curvature with a heat-resistant insulator increases the effect. For these reasons, stable discharge occurs between the arc electrodes without accumulation of electrical charges along the surface of the insulating nozzle, resulting in high insulation reliability.

〔Effect of the invention〕

The present invention enables stable discharge between the arc electrodes and also prevents the accumulation of electrical charge along the insulated nozzle surface, completely preventing re-ignition or re-ignition occurring from the movable current-carrying contact. A puffer type gas circuit breaker with high insulation reliability can be provided.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the cut-off part of a puffer-type gas circuit breaker showing one embodiment of the present invention, and FIG. 2 is a cross-sectional view of the cut-off part of a puffer-type gas circuit breaker showing another embodiment of the present invention. Figure 3 is the first
The electric field vector diagram of the interrupting part shown in the figure, Figure 4 is a sectional view of the interrupting part of the conventional puffer type gas circuit breaker, and FIG. 5 is the electric field vector diagram of the interrupting part shown in FIG. 4. ]-... Interrupting part, 3... Movable electrode part, 5... Puffer chamber, 8a... First curvature part, 9 - Fixed energizing contact, 12... Puffer cylinder, 13... Movable electrode Rod, 15... Insulating nozzle, 18... Fixed shield, 20... Movable shield, 2... Fixed electrode part, 4... Puffer part, 8... Fixed arc electrode, 8b... Second Curvature portion, 11. Puffer screws 1 to 14, 14. Movable arc electrode, 15a. Gas flow path, 19. Fixed energizing contact, 21. Heat resistant insulator. Agent Patent Attorney Noriyuki Chika Yudo Ken Daishimaru

Claims (1)

[Claims] In a container filled with an insulating gas, a cutoff part having a fixed electrode part, a movable electrode part facing each other, and a puffer part adjacent to the movable electrode part is housed, and a fixed and movable current-carrying contactor is attached to the fixed and movable electrode parts. and a puffer-type gas provided with fixed and movable arc electrodes, an operating rod for moving the movable electrode part and the movable part of the puffer part in the axial direction of the circuit breaker, and a drive mechanism connected thereto. A puffer-type gas circuit breaker characterized in that a fixed arc electrode tip has two curved parts with different electrode diameters, and the curved part with a narrower diameter constitutes the leading edge.