JPH0569250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit breaker, and more specifically to a puffer-type gas circuit breaker, particularly a circuit breaker rated for high current interrupting.

[Conventional technology] In recent years, the rated breaking current of circuit breakers has increased as the capacity of single generators has increased, or as grids have become higher in voltage and capacity. It is expected that up to 250kA will be required. Usually, in the rated duty of a circuit breaker, the rated breaking current (effective value) is the rated closing current.
The ability to inject an asymmetrical current with a peak value of 2.5 times is required. For example, rated breaking current 250kA
In this case, it is necessary to input a current of 250 x 2.5 = 625kA peak without any problem. At the moment when such a large current is applied, the contact pressure of the contact part increases due to the electromagnetic pressure of the contact part, which is called a so-called pinch effect, and as a result, a reaction force is generated due to an increase in frictional force against the operation in the application direction. In addition, the current flow path of the puffer-type arc extinguishing chamber generates a large electromagnetic repulsive force acting on the moving parts of the arc extinguishing chamber, and as the input current increases, it is also necessary to increase the input force of the operating mechanism. This will lead to an increase in costs.
The second method to reduce such electromagnetic repulsion is
What is shown in the figure is shown in Japanese Unexamined Patent Publication No. 163323/1983.

That is, in FIG. 2, the first flange 1
A fixed main contact 3 is fixed to a fixed arc contact support 2 and a plurality of finger contacts arranged in an annular manner at the end thereof, and which slides into or out of contact with the puffer cylinder 4. The puffer cylinder 4 also serves as a movable main contact for energizing, and is driven by the operating rod 8. The second flange 5 has
A plurality of finger contacts are arranged in an annular manner at the end, and an energizing finger contact 6 which is in sliding contact with the puffer cylinder 4 and a piston 7 into which the puffer cylinder 4 is slidably fitted are fixed. The operating rod 8 has a communication hole 8a and is driven in the axial direction by a drive mechanism (not shown) via an insulating rod (not shown).
It is slidably supported by a piston 7. The operating rod 8 connects the puffer cylinder 4 and the insulation tube 14.
The puffer cylinder 4, insulating tube 14, and operating rod 8 are fixed together by a combination of screw connection and adhesive. 15 is a current collector pressed by a ring spring 16. The puffer cylinder 4, the piston 7, and the operating rod 8 form a puffer chamber 10, and when the puffer cylinder 4 moves to the right in the figure, the gas fluid in the puffer chamber 10 is compressed. Movable arc contact 1 fixed to operating rod 8
A fixed arc contact 12 that can be moved into and out of contact with the fixed arc contact 1 is fixed to a fixed arc contact support 2. The flow guide 13 is made of an insulating material such as Teflon,
It is arranged coaxially with the fixed arc contact 12 and is fixed to the operating rod 8 with a flow guide holder 9.

With the above configuration, in the fully closed position shown in the upper half of Figure 2, flange 1 → fixed main contact 3
→ Patshua cylinder 4 → Finger contact 6
→Electricity is applied through flange 5. When the current is cut off, the operating rod 8 is driven to the right by an operating mechanism (not shown). During the interruption, first the fixed main contact 3 and the puffer cylinder 4
is released. Puff cylinder 4 and operating rod 8
are electrically insulated by the insulating tube 14, so the current flows through the flange 1→fixed arc contact support 2→fixed arc contact 12→movable arc contact 11→operating rod 8→collector 1
5→piston 7→flange 5. Thereafter, the fixed arc contact 12 and the movable arc contact 11 are separated, and the generated arc is extinguished by the flow of compressed gas within the puffer chamber 10.

At the time of closing, the operation is opposite to that at the time of disconnection, and first, the fixed arc contact 12 and the movable arc contact 1 are connected.
1 makes contact (the state shown in the lower half of Figure 2), the current path at this time is as shown by the arrow in the lower half of Figure 2, and the current path of the movable part of the arc extinguishing chamber has a component in the radial direction. It has the advantage that the electromagnetic repulsion force upon injection is extremely small because there is almost no resistance.

[Problems to be Solved by the Invention] In the conventional circuit breaker as described above, since the insulating tube 14 is interposed between the puffer cylinder 4 and the operating rod 8, the weight of the movable part increases.
The mechanical coupling force between the puffer cylinder 4, the operating rod 8, and the insulating tube 14 is low, which requires an increase in operating force, and the reliability is poor.Difficulties occur due to the difference in thermal expansion due to heat generated by energization. There were some problems, such as how easy it was to use.

This invention was made to solve the above-mentioned problems, and is a simple, low-cost, and reliable method for insulating the radial current-carrying path to minimize the radial current-carrying path at the initial stage of power-on. The purpose is to obtain a circuit breaker with high performance.

[Means for Solving the Problems] In the circuit breaker according to the present invention, the puffer cylinder and the operating rod are made of aluminum or an aluminum alloy, and a film of aluminum oxide is formed on the connection portion between them.

[Function] In this invention, by utilizing the electrical insulating properties of aluminum oxide, the radial conduction path in the initial stage of charging the arc extinguishing chamber is insulated without using a special insulating tube.

[Embodiment] FIG. 1 shows an embodiment of the present invention. In the figure, the basic configuration of the puffer type arc extinguishing chamber is almost the same as that in FIG. 2, but the puffer cylinder 4 shown in FIG. The inner insulating tube 14 is removed, a protrusion 4a is provided inside the end of the puffer cylinder 4, and the protrusion 4a is sandwiched between the operating rod 8 and the holding plate 17 and fixed with bolts 18. Furthermore, the puffer cylinder 4 and the operating rod 8
The holding plate 17 is made of aluminum or an aluminum alloy, and a film of aluminum oxide is formed on the part (A part) where these parts come into contact with each other. With the above structure, an aluminum oxide (Al ₂ O ₂ ) film can be easily obtained through a surface treatment commonly called alumite treatment, and its insulation performance is 1000 V at a film thickness of 30 microns.
It has a withstand voltage of about 100 mL, and is suitable for practical use in insulating parts such as those mentioned above. In addition, the aluminum oxide film has extremely high hardness, so there is no risk of dielectric breakdown due to scratches during assembly, and a highly reliable insulation means can be obtained.

Note that the opening/closing operation of the circuit breaker is exactly the same as that described in the conventional example, so the explanation will be omitted.

[Effects of the Invention] As described above, according to the present invention, aluminum or an aluminum alloy is used for the puffer cylinder, the operating rod, and the holding plate, and a film of aluminum oxide is formed on the parts where these parts come into contact with each other. Since the current path with the operating rod is insulated, it is simple, inexpensive, and highly reliable.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, in which the upper half shows the state when the injection is completed and the lower half shows the state at the instant of injection. FIG. 2 is a longitudinal cross-sectional view of a conventional circuit breaker, with the upper half showing the state when the circuit breaker has been closed, and the lower half showing the state at the moment of closing. 3... Fixed main contact, 4... Puff cylinder, 7... Piston, 8... Operation rod, 11
. . . Movable arc contact, 12 . . . Fixed arc contact, 17 . In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A puffer cylinder that has the functions of a fixed main contact and a movable main contact that are energized during normal operation, a movable arc contact that is integrated with the puffer cylinder inside the puffer cylinder and is operated by an operating rod, and the movable arc A fixed arc contact is arranged opposite to the contact, and insulating fluid compressed by the puffer cylinder and a piston supporting the operating rod is sprayed when the two arc contacts are opened, and the fixed arc contact is arranged opposite to the fixed arc contact. After the main contact and the puffer cylinder are separated, while both the arc contacts are in contact, the arm contacts,
In a circuit breaker in which a current flows through the operating rod and the piston over time, the puffer cylinder and the operating rod are made of either aluminum or an aluminum alloy, and the connecting portion between the puffer cylinder and the operating rod is oxidized. A circuit breaker characterized by forming an aluminum film. 2. The circuit breaker according to claim 1, wherein a protrusion formed on the inside of the end of the puffer cylinder is sandwiched between an operating rod and a holding plate and tightened with a bolt.